Annual Report For the Period of

July 1st, 2011 – June 30th, 2012

Multiphase Reaction Engineering At the

Chemical Reaction Engineering Laboratory

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OBJECTIVES

Education and training of students in fundamentals of reaction engineering

Advancement of multiphase reaction engineering knowledge base, methodology and tools

Transfer of state-of-the-art reaction engineering to industrial practice

Dr. M.P. Dudukovic Director 314-935-6021 (phone) dudu@wustl.edu

Multiphase Reaction Engineering (MRE) Chemical Reaction Engineering Laboratory (CREL)

Energy, Environmental and Chemical Engineering Department (EECE) http://crelonweb.eec.wustl.edu

ANNUAL REPORT July 1st, 2011-June 30th, 2012

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Preface: A Word to Our Industrial Colleagues and Partners

Our Chemical Reaction Engineering Laboratory (CREL) continues its long tradition (since 1974) in bridging the gap between academic research and industrial practice of reaction engineering. We provide the state of the art multiphase reaction engineering education to new generation of students, advance the multi-scale reaction engineering methodology and tools via research, and assist the transfer of academic research and tools to industrial practice. We have been internationally recognized for the breadth and depth of our graduates, for our research contributions, and for our excellent rapport with industry, involving strong interaction with numerous global companies. Science based multi-scale reaction engineering continues to be the key to successful transfer of bench scale discoveries into ‘green’ energy efficient technologies with low environmental impact. Risk reduction of commercializing these new technologies can only be achieved by increasing the level of science in each step of the multi-scale process engineering methodology. We at CREL are poised to lead these efforts. In this report we reiterate the vision and mission of CREL, highlight the active projects, and outline our plans for the future which involve expanding our efforts via our EECE department based broad effort on multi-scale process engineering for energy and environment (MPE3). We need the input and support of our industrial colleagues and friends in order to convert our plans to reality. We also hope to launch three initiatives for federal funding that involve interactions with industry. One is the development of a unique experimental facility for obtaining data on real catalysts, the other is the development of multiphase flow visualization and quantification laboratory for validation of multiphase fluid dynamic codes, and a third is a Center for multi-scale process engineering for energy and the environment (MPE3) that will contain the above two laboratories. Your involvement will greatly enhance your process engineering capabilities while efficiently leveraging resources as outlined in this report. M.P. Dudukovic Director, CREL

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Table of Contents Preface: A Word to Our Industrial Colleagues and Partners ......................................... 3

CREL Organization, Research and Programs ................................................................. 6

Brief History and Current Status ................................................................................. 6

CREL Vision .................................................................................................................. 6

CREL Mission ............................................................................................................... 7

CREL Research and Relationship to Global Trends: Past and Future ............................. 8

Project Summary: Multiscale Process Engineering for Energy and Environment (MPE3) ....................................................................................................................... 10

Project Summary: Development of the TAP-SPAN Instrument for Cyclical Surface Metals Modification of Real Catalysts and Intrinsic Kinetic Characterization .......... 12

Current Staff – 2011-2012 ......................................................................................... 15

Summary of CREL Current Activities .......................................................................... 17

CREL Achievements ................................................................................................... 18

Recent Ph.D Graduates ............................................................................................. 18

Recognition ............................................................................................................... 19

Proposed CREL Future Research ................................................................................ 20

Expansion of Faculty Expertise ............................................................................... 20

CREL – Industry Interactions .................................................................................. 21

Novel Energy Technology.......................................................................................... 21

Center for Multiphase Flows .................................................................................... 22

Experimental Facility ............................................................................................. 22

List of Active Projects ................................................................................................ 23

CREL Individual Reports ............................................................................................ 25

CREL Projects Funded By Industry .......................................................................... 25

MRE Funded Projects ................................................................................................ 25

Introduction to MRE ................................................................................................. 25

Micro-Scale CFD Modeling of Trickle-Bed Reactors ................................................. 26

Transient Kinetic Characterization of Multicomponent Catalysts with Thin Zone TAP experiments: the Y-Procedure Methodology ........................................................... 32

Goals for MRE Projects in 2011/2012 ....................................................................... 36

PROPOSAL FOR MRE PROJECT IN CATALYSIS to be initiated in 2012/2013: ............ 37

CAE-SBCR Funded Projects ....................................................................................... 40

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Introduction to CAE-SBCR ......................................................................................... 40

Mechanism of Gas Phase Mixing in Bubble Columns ............................................... 41

Mass Transfer in Bubble Column with Internals ....................................................... 46

General Reaction Engineering Research Funded by Non-Industrial Sources ............ 50

Introduction to General Research ............................................................................ 50

Catalytic Conversion of Methane and Carbon Dioxide to Higher Value Products ... 51

Advancing Optical Probe Measurement Techniques for Multi-Phase Reactors ...... 58

Bubble Induced Liquid Flow Field in Narrow Channels with Gas Evolution at Electrodes ................................................................................................................. 61

Optical Fiber Reflectance Probe for Detection of Supercritical Transition .............. 66

Projects by Visiting Researchers ............................................................................... 71

Supported Ionic Liquid Phase Catalysis (SILPC) ........................................................ 72

Engineering Analysis of Polycrystalline Silicon Deposition from SiHCl3 ................... 77

Process Intensification: Reactive Distillation in a Rotating Packed Bed ................... 81

Appendix A: .............................................................................................................. 85

Multiphase Reaction Engineering (MRE) Project: CREL Industrial Participation Plan ... 85

Appendix B: CREL List of Publications (2005-2012) .................................................... 90

Appendix C: Doctoral and Masters Degrees Granted (1995 - present) ....................... 98

Appendix D: Experimental Facilities ........................................................................ 100

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CREL Organization, Research and Programs

Brief History and Current Status The Chemical Reaction Engineering Laboratory (CREL –

http://crelonweb.eec.wustl.edu) is a research unit within the Department of Energy, Environmental and Chemical Engineering (EECE) at Washington University in St. Louis (WUStL). From its inception CREL focused on providing fundamental approaches to the solution of numerous industrial multi-phase reaction engineering challenges. Strong ties with industry from diverse technology sectors have been established and CREL graduates (over 80) have been sought for their unique skills in combining experimental and modeling work. CREL became known worldwide for its contributions in applying fundamentals to generate improved practical tools for the fuels and petroleum technologies, semiconductor silicon production, manufacture of composites, synthesis of chemicals and environmental remediation. CREL created much improved, fundamentally based models for various reactor types and provided needed validation of flow patterns and mixing in various opaque multi-phase systems. This work continues to the present day. Our EECE (www.eec.seas.wustl.edu) department created a critical mass of faculty and students in our Cluster for Multi-scale Processing where CREL maintains the focus on reaction engineering. The domain of the department has been expanded to include energy and environmental engineering, for which chemical engineering provides the needed strong intellectual basis. The time involved to hire new faculty and develop common research themes with them is a challenge we continue to deal with. We believe that our proposed MPE3 Program will provide an excellent opportunity for interdisciplinary interactions among faculty and with industry from various sectors.

CREL Vision We want to remain a leading, world-wide recognized research laboratory for

education of students in multi-scale approach to selection, design and scale up of multiphase reactors that lead to superior technologies with minimal environmental impact. We envision having a global impact via dissemination of our tools and interactions with industry. This is accomplished by several means. Our graduates grow to leading technical positions in industry and become professors at universities. Our industrial participation program via MRE (multiphase reaction engineering project) and SBCR (slurry bubble column reactor) consortium testify to the value of our methodology and developed tools. The WUSTL MAGEEP program with leading academic institutions in the world allows more rapid spreading of our reaction engineering methodology.

We envision that our industrial partnership program will grow and allow speedier transition of our methodology and tools to a variety of process industries resulting in improving their efficiency and reducing their environmental footprint. Having curtailed their in –house R&D programs in engineering, industrial companies need interactions with an organization like CREL and MPE3 now more than ever.

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CREL Mission Our mission is unchanged. We are committed to: 1) Do fundamental systematic integrated research on multi-scale aspects of

reaction engineering; 2) Educate students in scientifically based multi-scale approach to multi-phase

reaction engineering and develop novel tools for use in practice; and 3) Assist our industrial partners in employing our methodology and tools to

transfer more rapidly bench scale discoveries to commercialization via cleaner, more efficient processes. It is particularly important that with the help of our industrial partners involved in the production of fuels, chemicals, and materials, we reach the engineering contracting firms. All of them need much more science in their design calculations and would benefit greatly to exposure to MPE3. We also have to reach out to small companies that need help in basic their reaction engineering decisions on sound principles.

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CREL Research and Relationship to Global Trends: Past and Future

CREL research remains focused on using fundamentals in generating a firm

physical basis for a number of multi-phase reactor models. We made significant contributions to improved understanding of a many reactor types used across various industrial sectors and technologies. This includes stirred tanks, trickle bed reactors, ebullated beds, bubble columns and slurry bubble columns, risers, fluidized beds, electrolyzers and micro-reactors. We also used fundamentals to improve the selection, design and operation of reactors or other devices for specific technologies. Some examples are: fluidized bed for silane pyrolysis in production of silicon, autoclave process for manufacture of long carbon fiber reinforced composites, trickle bed for production of specialty chemicals, etc. In this research we relied on the expertise of our core faculty in modeling, numerical methods and experimental techniques. Our efforts provided a significant benefit to those industrial companies that supported our activities and used some of our techniques, approaches, models and tools for their own in-house problems. Our contributions to the state of the art in reaction engineering were published in top notch journals and presented at many conferences. With the opening of global markets, the increased amounts of capital needed to introduce new technology and build new plants almost guaranteed to those who were entrenched in the business increased profitability at low risk with old technology. Hence, licensing of spruced up ‘world war II’ technology spread. As a result the in-house R&D effort in reaction engineering in process technology oriented companies has been decreasing steadily. The scientific understanding of the phenomena that govern the performance of the reactors used in these technologies is still primitive, but the heuristics developed over decades provided some comfort that repeating the old designs for similar conditions will be successful and will not involve much risk. CREL work, by providing a scientific basis for some of the heuristics used, was valued by companies as a low cost alternative to an in-house R&D effort which was perceived not to be profitable. Hence, the memberships of companies from various industrial sectors in CREL soared. The last few decades have also brought us a tidal wave of investment of public and private money into ‘molecular sciences’, mainly, but not exclusively, biological. The notion that the new discoveries at the molecular level are the key to bringing us much improved cures for diseases and better health and leading us to environmentally friendly non-polluting technologies has been fueled by the global press. The reality is that, as important as improved molecular level understanding is, the barriers to transferring any new understanding at the molecular level and bench scale observations to non-polluting technologies lie most often in our incomplete understanding of transport-kinetic interactions which does not allow a rational approach to reactor selection, design and operation. It is well known that, for example, in organic synthesis over 90% of the new chemistries fail because the volumetric productivity and selectivity

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observed on the bench scale cannot be reproduced on a larger scale. Only advances in the science of the multi-scale approach to reaction engineering can overcome these difficulties. Instead of using their engineering talents to pursue these worthy, long-term goals, the companies involved in process technology cut their R&D efforts by focusing on short-term profits. They assumed that the old reactor types that they are familiar with will do the job and abandoned the research in reaction engineering. This led to the reduced activities in academia in this field also, as the field became known as ‘mature’. The truth is that the reactors currently in operation are still not understood in terms of the quantitative description of the phenomena that govern their performance. Thus, they are ill-suited to deal with systems that are offering higher volumetric productivity and selectivity, which are the two key performance indices vital for proper implementation of green chemistry to environmentally friendly technologies. Research on improved quantification of transport –kinetic interactions is needed more than ever. We at CREL have a tradition of providing fundamental understanding to traditional reactor types as well as tailoring novel reactors for specific applications. We look forward to continue to lead in this area of research and provide for our industrial partners leveraging of resources in this important activity.

The next five years will be critical in strengthening CREL. We plan to embrace more faculty and find gradual replacement for current faculty and build even stronger bridges with industry and government research laboratories.

Our whole EECE department has embraced the new initiative by which we will strive to develop a Scientific Center for Multi-scale Process Engineering for Energy and the Environment (MPE3). The summary of this project which upon endorsement by industry will be proposed to the National Science Foundation is enclosed below. We invite your participation in this important endeavor. As part of such a program we must with you help revitalize many of our unique experimental facilities. One such project will focus on establishing a unique catalysis research capability based on improved Temporal Analysis of Products Technology (TAP) technology, the other on modernizing our unique laboratory for multiphase flow visualization (CARPT-CT).

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Project Summary: Multiscale Process Engineering for Energy and Environment (MPE3) Process engineering is involved in conversion of raw materials to myriad of products, including fuels, and is essential to improving the living standards around the world. The atomic, mass and energy efficiency of the commercially used processes impact the environment and energy usage and determine the sustainability of the enterprise. Due to globalization, current business climate favors licensing of old ‘best available technologies’ which often have a large environmental footprint and are wasteful of energy. In other words, profitability trumps other considerations. Thus, the opportunity to introduce novel processes of higher efficiency in order to meet the exploding growth in process technology in developing countries is largely missed. The risk of introducing novel process technology is deemed too high due to lack of adequate scientific basis in design of process units and very high costs of large scale pilot plants deemed necessary to demonstrate new technology. It was recognized some time ago that the multi-scale approach, which allows for systematic improvement in the scientific basis of scale-up, is what is needed but this was abandoned as too complex and too costly for a single profit oriented organization to pursue as lrge profits could be realized by employing old technologies. Developing a new paradigm for process engineering is a natural task for a NSF Science and Technology Center, and this is proposed here. The proposed Multi-Scale Process Engineering (MPE3) Center for Energy and Environment, with headquarters at Washington University in St. Louis (WUStL), has the following multiple but related objectives: organize and grow the scientific basis for design and scale up of process units into new tools to be used over many industrial sectors; develop the experimental facilities needed for validation of scale-up concepts,;provide the science based efficiency measures for evaluation and ranking of potential new process schemes and technologies, and consider societal impact; educate new generation of process engineers in this modern approach and on the new tools and illustrate it via selected case studies of high impact; disseminate the information broadly and rapidly to industry and the public.

WUStL established the Energy, Environmental and Chemical Engineering Department which moved to the new 70M$ Brauer Hall in 2010 ((http://www.eece.wustl.edu/brauer). The faculty background is interdisciplinary and all are well connected to other universities in the US and abroad. WUStL invested much in promoting international collaborative efforts in the area of energy and the environment with 27 leading universities (http://www.mageep.wustl.edu). It is the intent of the proposed Center to focus and grow this interaction in the area of innovative process technology and the environment while capitalizing on the existing infrastructure for dissemination of the results. Examples of envisioned partnerships will be described in this preliminary proposal while detailed planning with goal of maximizing synergy will be done for the full proposal. The expected outcome of the Center is that it will provide a new science based metric for process selection, based on process efficiencies, and the theoretical basis, with experimental facilities, for scale-up. Since the new methodology will be applicable

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to a variety of technologies such as biofuels, chemical looping, solar energy utilization, catalyst synthesis, production of chemicals to name a few, it has the potential of transforming process engineering education and practice. To ensure rapid transition of these ideas to practice we will capitalize on our long term relations with Industry of our Chemical Reaction Engineering Laboratory (CREL) (crelonweb.eec.wustl.edu) providing the incentive via improved science for implementation of greener processes, as envisioned, which would benefit society globally.

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Project Summary: Development of the TAP-SPAN Instrument for Cyclical Surface Metals Modification of Real Catalysts and Intrinsic Kinetic Characterization Project PI: John Gleaves, Washington University Co PIs: Mike Dudukovic, Washington University Rebecca Fushimi, The Langmuir Research Institute Gregory Yablonsky, Saint Louis University Catalytic surfaces composed of mixed metal oxides and supported metals are general formed kinetically under nonsteady-state conditions. The most active/selective surface structure may exist in a metastable form and generally depends on many factors including reaction conditions, history, composition, etc. The long-range goal of the proposed program is a unique catalyst development tool that can track changes that occur in the kinetic properties of complex metal oxide and supported metal surfaces while they are being formed or modified. The TAP-SPAN (Temporal Analysis of Products – Surface Preparation and Analysis) instrument presents a systematic methodology for modifying the surface metals composition of a complex catalyst in submonolayer amounts that is integrated with intrinsic kinetic characterization. The ability to manipulate the atomic level surface composition of technical catalytic materials and then directly correlate the change in intrinsic kinetic properties will provide rapid feedback for rational catalyst development. To serve as a vehicle for new catalyst design, fundamental kinetic data describing the simple bond breaking/forming reactions of C-C, C-O and C-H bonds can be systematically evaluated with respect to incremental, well-defined changes in catalyst surface composition. This project seeks to further preliminary work at Washington University where pulsed-laser ablation was use generate ultra-sparse loadings of metals on inert supports (Fushimi 2007, 2008) that demonstrated the feasibility of the technique. In these experiments samples of coarse SiO2 particles (250 μm) were enriched with Pd using pulsed-laser atomic beam deposition, Figure 1. The resulting deposits were too sparse and the surface too complex for observation with spectroscopic techniques (TEM, XPS), however, the enrichment was clearly detectable using chemical probes thorough the TAP pulse response technique. In these experiments, the kinetic data was used to describe a unique structure forming process observed on the deposited material (Fushimi 2007). In other experiments samples of the VPO catalyst were enriched with submonolayer amounts of Cu and Te. Figure 2 shows the change in the kinetic response of these materials to produce furan when butene is used as a reactant in the TAP pulse response experimental format. While the total furan production was approximately the same for all samples, a maximum is reached much earlier in the reduction cycle for the Te-enriched sample which indicates this modification led to a catalyst which was more selective at a higher oxidation state.

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The idea to integrate kinetic characterization with a synthesis technique like atomic beam deposition is not novel. What makes the TAP-SPAN system unique is how TAP is distinguished from the more common methods of kinetic characterization and how it is uniquely suited to accommodate technical catalytic materials. The TAP pulse response is performed under vacuum and a very small pulse (10 nanomol) of reacting gas is pulsed into the evacuated reactor. Transport is thus defined by Knudsen diffusion and can be clearly separated from kinetic effects. The time dependence of the exit flow is captured by a mass spectrometer. With submillisecond time resolution, this technique is useful for the identification of reaction intermediates, determination of rate constants of elementary steps and the elucidation of sequences in multi-step reactions. The small pulse size makes possible the sampling of the catalyst kinetic properties without inducing changes in the catalyst itself, i.e. the number of active sites in a typical sample is many times larger than the number of molecules introduced in a pulse. A long series of pulses, however, can be used to incrementally change a sample (e.g. from oxidized to reduced), thus manipulating surface coverage and measuring changes in kinetic properties at each step of the change. In addition, the small pulse size results in a very low adiabatic temperature rise from even highly exothermic reactions and hence minimizes the possibility for surface reconstruction of nanoscale metal domains added from atomic beam deposition. The high signal to noise ratio of the mass spectrometer makes it possible to detect extremely low-level changes in kinetic function; similar to that associated with surface science but without the need to use model catalysts. An independent review that highlights the distinguishing features of TAP from traditional kinetic characterization can be found in Perez-Ramirez 2007. Building on experience from the preliminary work at Washington University the TAP system design has been expanded to integrate a variety of synthesis and spectroscopic techniques with the pulse response characterization, Figure 3. The atomic beam preparation now includes the use of a commercially available EFM electron beam evaporator (Omicron Instruments) which greatly simplifies the design. This is an ideal source for producing beams of a wide range of materials that includes non-conducting materials and semiconductors. Figure 4 demonstrates the new atomic deposition design: catalyst samples are transported in vacuum on a sample carousel, a solenoid in the sample holder vibrates the bottom surface to ensure that particles are randomly exposed to the beam for uniform coverage. After deposition, the sample is directly transferred to the TAP kinetic characterization module without exposure to atmosphere. This is significant since formation of a native oxide layer will likely change the nature of the deposited species and long term exposure of nanoscale metal deposits can lead to agglomeration. If the desire however is to deposit metal clusters or metal oxides, a low inert or oxidizing pressure can be introduced to the deposition chamber. The system is designed to allow cyclical experiments were submonolayer additions of metal atoms are made in the deposition module, changes in catalytic properties are detected in the kinetic module, and the sample returned to the deposition module to increase the loading. In addition, the design includes a sample library so that many prepared samples can be rapidly tested in a combinatorial fashion. By increasing the metal concentration on a single catalyst sample in a series of steps and

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testing the catalytic properties after each step, changes in kinetic performance can be directly related to changes in composition.

References Fushimi, R., J. Gleaves, G. Yablonsky, A. Gaffney, M. Clark, S. Han (2007) “Combining

TAP-2 experiments

with atomic beam deposition on Pd on quartz particles” Catalysis Today 121, 170 – 186.

Fushimi, R., X. Zheng, J. Gleaves, G. Yablonsky, A. Gaffney, M. Clark, S. Han (2008)

“Techniques for

fabricating nanoscale catalytic circuits” Topics in Catalysis 49, 167-177.

Perez-Ramirez, J., E. Kondratenko (2007) “Evolution, achievements, and perspectives of

the TAP

technique” Catalysis Today 121, 160-169.

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Current Staff – 2011-2012

During the period covered by this report (July 1, 2011 through June 30, 2012) the following individuals have been associated with the various projects in CREL.

WU Tenured and Research Faculty Dr. M.P. Dudukovic Dr. J. T. Gleaves Dr. P.A. Ramachandran Dr. G. Yablonsky

Research Collaborators Dr. G. Combes, J. Matthey Dr. R. Mudde, Delft University Dr. M. Kulkarni, MEMC Dr. B. Brennan, Sasol, South Africa Dr. N. Mancini, ENI Dr. F. Podezani, ENI Dr. D. Schanke, Statoil, Norway Dr. P. Mills, Texas A&M University-Kingsville Dr. B. Subramaniam, University of Kansas Dr. F. Larachi, Laval University Dr. J.J. Lerou, Lerou Consulting

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Dr. S. Roy, IIT-New Delhi Dr. H. Stitt, J. Matthey Dr. A. Cornell, Royal Institute of Technology, KTH Sweden Dr. J. Wanngard, EKA Chemicals, Sweden Dr. A. Alexiadis, Warwick University, England

Visiting Researchers Dr. Qiao Congzhen (Visiting Professor), Henan University Yanqing Hou (Research Associate), Kunming University of Science and Technology Yong Luo (Research Associate), Beijing University of Chemical Technology

Graduate Students D. Combest B.W. Lee E. Redekop

V. Havran M. Morali Y. Sun

H. Mohamed O. Manjrekar

Undergraduate Student Researchers CREL 2011/2012 Zachary Bluestein Terry Wang

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Summary of CREL Current Activities

CREL research activities and achievements during 2011/2012 are briefly summarized in this report. These activities encompassed many aspects of multiphase reaction engineering as research continued on the use of various multiphase reactors in energy, chemical and environmental processes (e.g., clean and alternative fuels, energy/bioenergy, benign processes, environmentally beneficial catalytic processes, preparation of new materials, etc.). The following types of multiphase reactors have been the subject of systematic and sustained research:

-Bubble and slurry bubble columns -Stirred reactors -Circulating fluidized beds -Processes in mini- and micro-reactors -Fluidized beds -Aerosol/particulate reactors -Trickle beds -Bioreactors and bioprocesses -Structured beds

-Packed beds

In addition, CREL is a core partner in the Engineering Research Center (ERC) for

Environmentally Beneficial Catalysis Center (CEBC) headquartered at the University of Kansas in Lawrence.

Research described in this report conducted during the 2011-2012 period is focused on:

Multiphase reaction engineering project (MRE) with industrial sponsorship

Slurry bubble column project (SCBR) via the industrial support by the Consortium

for Clean Alternate Energy (CAE)

Environmentally benign processing - CEBC and NSF funded projects

Gas evolution in electrochemical systems - European Commission funded project

via MELPRIN Grant in cooperation with KTH in Sweden

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CREL Achievements By advancing the multi-scale reaction engineering methodology we ensure the needed breadth and depth of new generations of reaction engineers. After graduating from CREL-WUSTL our graduates are well equipped to handle the challenges related to clean sustainable technologies, energy or fuels production, synthesis of chemical and materials, and environmental and human health concerns. We engage these young people in exciting research and provide them with the depth and breadth needed to handle modern technological advances. This ensures a pool of well qualified people for our profession.

Recent Ph.D Graduates We are proud of the following recent PhD graduates: D. Combest, Interstitial-Scale Modeling of Packed-Bed Reactors, PhD 2012. Employed by ENGYS. M. Hamed, Hydrodynamics, Mixing, and Mass Transfer in Bubble Columns with Internals, PhD 2012. Employed by SASOL. E. Redekop, Non-Steady-State Catalyst Characterization with Thin-Zone TAP Experiments, PhD 2011. Postdoctoral Researcher at University Ghent. A. Yousef, Fluid Dynamics and Scale-Up of Bubble Columns with Internals, PhD 2010. Employed by SABIC Innovative Plastics. Z. Kuzeljevic, Hydrodynamics of Trickle Bed Reactors: Measurements and Modeling, PhD, 2010. Employed by SABIC Innovative Plastics. B. Henriques-Thomas, Enhanced Water Removal from Whole Stillage by Enzyme Addition during Fermentation, PhD, 2009. Employed by Confluence Solar, Inc. S. Mueller, Optical Measurements in Gas-Liquid Stirred Tanks, PhD, 2009. Employed by Celanese Chemicals in Houston Texas. S. Nayak, Transport in Nanoporous Zeolites Used in Alkylation Processes, PhD, 2009. Employed as Research Associate at Texas A&M University in College Station, Texas. The theses of these students and other CREL graduates are available on Washington University’s Library’s website. (http://library.wustl.edu/research/finddiss.html)

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Recognition The ACS E.V. Murphree Award in Industrial and Engineering Chemistry received by Professor Dudukovic in 2009 is a tribute to all people in CREL. Clearly, the work in CREL has been recognized as seminal and important for the profession. Professor Dudukovic thus joins the following distinguished group of previous winners:

2009 Milorad (Mike) P. Dudukovic 1996 Eli Ruckenstein

2008 Georges Belfort 1995 Charles A. Eckert

2007 Wolfgang F. Holderich 1994 Edwin N. Lightfoot

2006 Liang-Shih Fan 1993 James J. Carberry

2005 Mark E. Davis 1992 Clarence D. Chang

2004 James E. Lyons 1991 Richard Alkire

2003 Leo E. Manzer 1990 L. E. Scriven

2002 George R. Lester 1989 Warren E. Stewart

2001 John N. Armor 1988 Jule A. Rabo

2000 J. Larry Duda 1987 Wolfgang M. H. Sachtler

1999 Donald R. Paul 1986 John H. Sinfelt

1998 Stanley I. Sandler 1985 Michel Boudart

1997 Arthur W. Westerberg 1984 Robert K. Grasselli

In spring 2010, Professor Dudukovic also received special recognition for his mentoring of graduate students. This recognition was won on a competitive basis in the WUSTL School of Arts and Sciences, he is the first engineering professor to be so recognized. In 2012, he was recognized as best professor by the graduating undergraduate class. In addition, recent CREL graduate Evgeniy Redekop was the recipient of a Marie Curie Outgoing International Fellowship, awarded to outstanding researchers for his proposal entitled "Intrinsic Catalytic Kinetics Analyzed and Reconciled with Industrial Conditions". Currently he is completing his fully-funded project in the Laboratory for Chemical Technology (http://www.lct.ugent.be) at Ghent University under the guidance of Dr. Guy Marin.

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Proposed CREL Future Research We are all aware that the level of reaction engineering research efforts and

innovations in companies across all industrial sectors that deal with manufacture of chemicals, fuels, materials and pharmaceuticals is less than desirable. This is mainly caused by the fact that the old empirical approaches to reactor selection, design and scale up are often still profitable. As a result the giant contracting engineering firms have not introduced more science in their designs and rely on over half a century old correlations to deal with transport problems in multiphase systems. Thus, since the scientific basis for linking the cause and effect in reactor performance is missing, it is difficult to predict what will happen when one ventures outside the current data boundaries. Yet processes with higher mass, atom and energy efficiency will demand performance not achievable by current practice. We are pushed by new environmentally more benign technology to operate well outside the established envelopes. As stated earlier, CREL will continue to provide leadership in two main areas: 1) we will work on increasing the scientific base for treatment of traditional reactor types (e.g. stirred tanks, trickle beds, slurry bubble columns, fluidized beds, risers etc.) for their application in a number of technologies; 2) we will engage in collaborative efforts in selection, scale–up and design of novel rectors (e.g. micro-reactors, etc) for particular more efficient technologies. This should be very useful in estimating the limits of available technologies and in improved assessment of novel technologies. Current economic and environmental impact programs base their estimates on primitive reactor models. More accurate, science based models for these reactors would not only reduce the risk of scale up, allow optimization of operation but also provide more realistic estimates of economic and environmental benefits. To do this effectively we plan to expand our in-house expertise pool and add new faculty. At the same time we plan to address with our industrial partners a number of problems of increasing interest to them and provide them with in-house taught short courses that will expose them to the increasing scientific basis for reactor design and operation.

Expansion of Faculty Expertise Professors Ramachandran and Dudukovic are recognized experts in multiphase

reaction engineering as they cover both modeling and experimental work. The time is right to hire middle aged (or young) individuals with expertise in multi-phase CFD and in sophisticated multi-phase flow and transport experimental techniques. This can provide a smooth transition later when the ‘old guard’ switches to less than full time activities. CREL has had past collaborations with Professor Pratim Biswas and his strong group in aerosol reactors and intends to renew these. There also are already established collaborations with Professors John T Gleaves, G. Yablonski, Cynthia Lo, and Venkat Subramanian. These individuals bring unique strengths in catalyst testing, kinetic modeling, molecular modeling, electrochemical systems and batteries, respectively. We are also working on developing collaborative efforts with Professor Younan Xia

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(departed for Georgia tech recently from our biomedical department) who is a world expert in synthesis of metallic nano particles. Some of his preparations offer significant potential in the energy related field and we would like to use the CREL multi-scale approach in examining this. We also have fruitful collaborative efforts with Professor Jody O’Sullivan from our Electrical Engineering Department on imaging and tomography, and with Professor Renato Ferres from our mathematics department on probabilistic modeling. CREL can field a team of unique strengths on a number of new technology oriented projects. We would be pleased to discuss these with potential sponsors.

CREL – Industry Interactions Our plan within the next few years is to capitalize on the 37 years of the rich

tradition of successful CREL-industrial interactions and get our industrial partners and others involved in a Center for Multiscale Process Engineering for Energy and the Environment (MPE3). This center will involve most of our departmental faculty and many from 27 partner universities. This proposal will be communicated shortly to our industrial partners.. Within this new framework we would like to continue providing the scientific basis for the reactor types of interest to our sponsors under the MRE project and CAE-SBCR consortium, each of which is outlined later in this report. By making our industrial partners aware of our work in the CREL report and during CREL annual meeting we help them identify findings of interest to them and leverage resources. CREL meetings are also excellent places for informal exchange of information with other companies, for finding partners and for keeping an eye on competitors. Short courses that we offer on sponsor premises bring their staff up to date in reaction engineering technology. Such gatherings should be extended to include representatives of engineering contractors. We intend to keep and extend all these modes of interactions that have proven so useful over decades. We would also like to explore a joint research effort with some companies in development of new technologies with federal funding and in formation of a Center for Multiphase Flows and a Center for Scale up of Catalytic Reaction Systems.

Novel Energy Technology CREL will explore potential partnerships in pursuing novel ideas in - Carbon dioxide conversion with methane to syngas and/or chemicals - Reactor–regenerator concept for improved thermal efficiency - Novel chemical looping methods that do not involve fluid beds - Rapid scale up of novel catalysts from TAP to reactor - Photochemical conversion of carbon-dioxide Interested companies should contact us for more details.

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Center for Multiphase Flows CREL is known worldwide for its application of Computer Aided Radioactive Particle Tracking (CARPT) and gamma ray Computed Tomography (CT) to multiphase flows encountered in multiphase reactors. These techniques are essential for validation of multiphase flows on larger scales and are housed in our high bay areas in our old building (Urbauer Hall), while the rest of CREL offices and laboratories have moved to the new Brauer Hall that houses all of our Energy, Environmental and Chemical Engineering Department EECE). This provides us with the opportunity to re-open our CARPT–CT facilities that have been so popular with our sponsors. However, this requires funding beyond that provided by the MRE or CAE-SBCR programs. To run a first rate facility we would need to have: a young faculty member committed to it, a full time technician and, at the start, a good post-doc. We also need new detectors and electronics. Thus, if industrial partners are interested, we must submit a comprehensive proposal to an appropriate government agency in which we will articulate the novel ideas that we will implement in the facility and the benefits to the scientific community. Matching funds would have to come from industrial partners. Please, let us know if your company is willing to support this proposal.

Experimental Facility Most systems of interest are multiphase and opaque and, hence, special

experimental techniques are needed to determine the flow pattern, mixing and phase distribution. CREL currently maintains seven laboratories, including one brand-new laboratory in the new engineering building, Brauer Hall, which is equipped with a walk-in fume hood. This 1052 ft2 laboratory has been operational since the end of summer 2010.

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List of Active Projects The working title of each active project, along with the name of the graduate student or researcher involved, is listed below. The projects are broken into several categories including multiphase reaction engineering (MRE), CAE-SBCR, and general reaction engineering research.

Name Project Title

CREL Projects Funded By Industry MRE Funded Projects

Dan Combest (Graduate Student)

Micro-Scale CFD Modeling of Trickle-Bed Reactors

Evgeniy Redekop (Graduate Student)

Transient Kinetic Characterization of Multicomponent Catalysts with Thin Zone TAP experiments: the Y-Procedure Methodology

CAE-SBCR Funded Projects Mohamed Hamed (Graduate Student)

Mechanism of Gas Phase Mixing in Bubble Columns

Onkar Manjrekar (Graduate Student)

Mass Transfer in Bubble Column with Internals

General Reaction Engineering Research Funded by

Non-Industrial Sources and MRE Vesna Havran (Graduate Student)

Catalytic Conversion of Methane and Carbon Dioxide to Higher Value Products (CCCU)

Boung Wook (Tim) Lee (Graduate Student)

Advancing Optical Probe Measurement Techniques for Multi-Phase Reactors (NSF & MRE)

Mehmet Morali (Graduate Student)

Bubble Induced Liquid Flow in Narrow Channels with Gas Evolution at Electrodes (McDonnell Scholar)

Yujian Sun (Graduate Student)

Optical Fiber Reflectance Probes for Detection of Supercritical Phase Transition (NSF & MRE)

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Projects by Visiting Researchers Dr. Qiao Congzhen

Supported Ionic Liquid Phase Catalysis (SILPC)

Yanqing Hou

Engineering Analysis of Polycrystalline Silicon Deposition from SiHCl3

Yong Luo

Process Intensification: Reactive Distillation in a Rotating Packed Bed

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CREL Individual Reports

CREL Projects Funded By Industry

MRE Funded Projects

Introduction to MRE The multiphase reaction engineering (MRE) project is a continuation of a multiyear on-going effort in CREL to introduce an improved scientific basis into the modeling, design and scale-up of multiphase reactors commonly used in many diverse industries. Industrial partners in the MRE program contribute an annual fee ($20,000/year up to 2012) to ensure the continuity of our work. This work has generated a rich data base for many reactor types that continues to be mined and utilized in validation of improved reactor models in diverse technologies. Our partners benefit by utilizing the data base for their purposes and by implementing our advances into their in-house programs. The full description of the MRE Project can be found in the Appendix. The current individual projects are briefly described below. We invite our sponsors to suggest additional projects for the MRE program and have added some suggestions in this report under the general research category.

Graduate Student Project Title Dan Combest

Micro-Scale CFD Modeling of Trickle-Bed Reactors

Evgeniy Redekop

Transient Kinetic Characterization of Multicomponent Catalysts with Thin Zone TAP experiments: the Y-Procedure Methodology

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Micro-Scale CFD Modeling of Trickle-Bed Reactors

A. Problem Definition The intricate structure of packed beds directly affects heat, mass, and momentum transport across multiple length scales. On a reactor scale, bed geometry strongly influences overall pressure drop, residence time distribution, and dispersion of species. On the interstitial and particle scale, thin film flow, interphase mass transfer, local eddy formation, etc. are also strongly influenced by meso and micro structures. Recently, near particle single phase flow using a unit cell approach has been studied (Gunjal et al., 2005) considering small clusters (less than 20) of pseudo-random particles (Dixon et al., 2006). However, much more work could be done to extend this approach to larger domains with hundreds of randomly packed non-spherical particles. It is the goal of this project to extend these models to larger domains and to improve the fundamental understanding of the effect of bed geometry on transport phenomena on the interstitial and particle scale.

B. Research Objectives The overall objective of this project is to elucidate the phenomena of heat, mass, and momentum transport on the length scale of the catalyst particle that is part of a packed bed. Developing knowledge in this area will improve the fundamental understanding of the effect of bed geometry on the transport phenomena seen in packed beds. In order to achieve this objective, several milestones need to be reached:

1. Domain Generation: A computational domain representing a packed bed of catalyst particles must be created that is both random and industrially relevant/realistic. Randomly packed catalyst particles will be arranged via a Monte Carlo type simulation. The particles present will be realistic (cylinders, trilobes, and quadlobes) and have a distribution of lengths and radii similar to particles seen industrially.

2. Model Development: An interstitial-scale model that captures the phenomena of heat, mass, and momentum transport common to non-isothermal reacting flow through interstitial spaces in a catalytic packed bed will be created. Specifically, single and multiphase flows will be simulated using computational fluid dynamics as a research tool to resolve local transport phenomena.

3. Integration of Advanced Computing Technology: Graphics processing units (GPUs) will be used to increase computational capability through integration into the open source C++ library OpenFOAM. Specifically, task specific sparse matrix solvers (preconditioned conjugate gradient or BiCGStab) using a GPU programming language (CUDA) will be developed. The OpenFOAM library will be used for all other tasks not related to the solving of sparse matrices (discretization, boundary conditions, mesh manipulation, matrix assembly, etc.). This has not been previously achieved and integrated into a standard CFD library, and represents a new feature in the current OpenFOAM library.

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C. Results and Discussion Milestone 1 (Domain Generation): A packing algorithm has been developed to pack both cylinders and more complex cylinder based particles (trilobes and quadlobes). As shown in the 2009-2010 CREL Annual Report, the algorithm is able to generate computational meshes of packed particles on the order of hundreds to less than three thousand particles with bulk bed porosities less than seventy percent. Figure 1 shows typical packing configurations for cylinders and trilobed particles.

Figure 1. (left) 1000 Packed Cylindrical Particles (right) 250 Packed Trilobed Particles

Figure 1 shows a packed domain of 1000 packed cylindrical particles (left) and 250 packed trilobed particles (right). The particle location and orientation are known exactly so that a computational mesh can be generated using meshing software. The procedure for producing the computational meshes involved several steps. First, a face mesh is produced in GAMBIT and then smoothed to reduce the skew cells in the face mesh. Next, the face mesh is imported into TGRID, where a Delaunay tetrahedral mesh is generated and smoothed. Lastly the mesh is converted to an arbitrary to polyhedral cells using FLUENT 13 mesh conversion algorithm. The resulting mesh is imported into OpenFOAM, where the simulations are run to solve the laminar and turbulent flow fields within the interstitial spaces. Typical results for the domains are discussed in the next section. Milestone 2 (Model Development): A model based on the OpenFOAM C++ library has been completed. This CFD model is capable of modeling steady-state laminar and turbulent flows. To model species transport and reaction, a model capturing passive

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scalar transport has been used to investigate coupled convection-diffusion problems within the interstitial spaces of the packed bed. To achieve this, stead-state flow fields for both laminar and turbulent flows were achieved using a Reynolds averaged Navier-Stokes (RANS) formulation with a low Reynolds number turbulent viscosity closure. In particular, the Lam-Bremhorst k-epsilon model, along with a fine mesh near the particle surfaces, was used to resolve near wall boundary layers. Figure 2 shows typical time averaged velocity results from a simulation in a turbulent field.

Figure 2. Turbulent velocity field in packed domain of cylinders

Figure 3. Snapshot of simulated step-tracer cut along the (1, - 1, 0) plane within the packed bed for

laminar flow (left) and a low turbulent flow (right)

Further investigation into the results yields a more detailed portrait of the flow, showing vortex shedding off of particles which inhibits uniform boundary layer formation over downstream particles. From the turbulent flow fields various time dependent and steady-state studies can be performed. Currently, the focus of the work is on boundary layer formation and separation over the surface of particles and the influence of turbulent scalar-flux through these boundary layers to the surface of the particles.

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The second portion of the interstitial-scale modeling involved simulated step-tracer experiments. Figure 3 below shows typical snapshots of the tracer traveling through the packed bed. For laminar flows, the dispersed interface of the tracer traveling through the packed bed was mainly due to “residence-time”, where spread of the tracer was controlled by molecular diffusion. For turbulent flows, the deviation from plug-flow was primarily due to tortuosity and interstitial velocity gradients. Due the short residence time of the fluid in turbulent flows, molecular diffusion (and turbulent diffusion effects) was minimal compared to the convective influences. More detail can be pursued through e-mail and in the dissertation cited below. Milestone 3 (Integration of Advanced Computing Technology): In the previous CREL annual report, it was reported that sparse linear solvers based on CUDA have been developed in house using a CUDA-based BLAS library called CUBLAS. As an improvement, these sparse linear solvers have been converted to another library based on CUDA called CUSP (http://code.google.com/p/cusp-library/). Currently, we have tied in Krylov space solvers for symmetric and asymmetric systems and have seen greater than tenfold increase in linear system solving compared to CPU based solvers of the same type. These results were presented at the 6th OpenFOAM workshop last summer. Currently, the work has been released as an open source library to promote collaboration and improve the code, under the name cufflink. Cufflink can be downloaded at (http://code.google.com/p/cufflink-library/) and is offered under the GPL version 3 license.

D. Future Goals Now that a framework for mesh generation, modeling, and analysis has been developed, more advanced particle shaped can be investigated. In order to achieve this, packing algorithms based on the Discrete Element Method (DEM) along with mesh conversion strategies could be pursued. As an alternative project, a reactor-scale project focused on pseudo-continuum models may yield more industrially important results. The overall goal of a funded project would be to develop more precise pseudo-continuum based reactor models (single and multiphase) for packed beds through:

1. Utilizing a packing algorithm based on Discrete Element method (DEM), to produce three-dimensional representations of complex particle shapes, which are then post-processed to reveal a three dimensional porosity field. This 3D porosity field would then allow for a better approximation of the variability of radial and axial porosity rather than relying solely on a porosity distribution based on Bessel functions (traditional method of approximating geometry).

2. Surveying the literature for single and multiphase pseudo-continuum reactor models (e.g. Eulerian-Eulerian) for packed beds, and comparing the prediction capability of each model against CREL’s trickle-bed data. A comparison of the traditional functional porosity distributions and the new more accurate porosity

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distributions from the DEM packing algorithm should be included. Through understanding the shortcomings of these models, newer models can be developed that capture physical phenomena accurately.

With a more robust and accurate model, industry can gain further confidence in reactor models to predict trends in flow to aid in process scale-up.

E. For Further Information Contact Dan Combest at dcombest@seas.wustl.edu

F. References Daniel P. Combest. “Micro-Scale CFD Modeling of Trickle-Bed Reactors”. CREL Annual

Report 2010-2011, 2011, Pages 28 – 32.

A. Dixon, M. Nijemeisland, and H. Stitt. “Packed Tubular Reactor Modeling and Catalyst

design using CFD”. Advances in Chemical Engineering, 2006, vol 1, 307.

Prashant Gunjal, Vivek V. Ranade, and Raghunath V. Chaudhari, “Computational Study

of a Single-Phase Flow in Packed Bed of Spheres”. AICHE Journal, 2005, 51(2), 365.

L. H. S. Roblee, R. M. Baird, J. W. Tierney. “Radial porosity variations in packed beds”.

AICHE Journal, 1958, vol 4, 460.

Oral Presentations Daniel P. Combest. Interstitial-Scale Modeling of Packed-Bed Reactors. Thesis Defense,

May 23rd, 2012. Washington University.

Daniel P. Combest, Palghat A. Ramachandran, and Milorand P. Dudukovic. Implementing

Fast Parallel Linear System Solvers in OpenFOAM Based on CUDA. 6th OpenFOAM

Workshop, PennState University, USA, June 2011.

Daniel P. Combest, Palghat A. Ramachandran, and Milorand P. Dudukovic. Micro-Scale

Modeling of Packed Bed Reactors: A Conjugate Mass Transfer Model with Turbulence.

6th OpenFOAM Workshop, PennState University, USA, June 2011.

D.P. Combest and P. A. Ramachandran. Micro-Scale CFD Modeling of Packed Beds.

AIChE National Conference, Salt Lake City UT. (November, 2010)

D.P. Combest, P.A. Ramachandran, B. Ram Yadav, and A. Garg. Oxidative Treatment of

Indus-trial Waste Water: Development of Novel Catalysts and Technology Evaluation.

AIChE National Conference, Salt Lake City UT. (November, 2010)

Dan Combest, Multiscale Modeling of Trickle-Bed Reactors: Application to Catalyst

Design and Industrial Catalytic Processes. Thesis Proposal Presented to EECE

Department April, 2009.

Poster Presentations Poster Presentation, (5 Different Posters in total) McDonnell International Scholars

Academy Symposium: Global Energy Future (October 1 - 5, 2010) Washington University

in St. Louis, MO.

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D.P. Combest and P.A. Ramachandran. “Micro-Scale CFD Modeling of Trickle-Bed

Reactors”. ACS Summer School in Green Chemistry, Colorado School of Mines, Golden

CO. July, 2009.

Journal Publications Daniel P. Combest, Palghat A. Ramachandran, and Milorad P. Dudukovic. “On The

Gradient Diffusion Hypothesis and Passive Scalar Transport in Turbulent Flows.” Ind.

Eng. Chem. Res. 2011, 50, 8817-8823.

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Transient Kinetic Characterization of Multicomponent Catalysts with Thin Zone TAP experiments: the Y-Procedure Methodology

A. Problem Definition The heterogeneous catalysis entails complex physico-chemical interactions between solid surfaces and surrounding media across multiple length and time scales. The fundamental understanding of these interactions for an industrial catalyst under working conditions is still a major challenge for chemical engineering science and surface chemistry. The precise kinetic characterization of multicomponent catalysts has to be advanced beyond its current abilities in order to address this challenge. Transient (non-steady-state) characterization methods are among the most effective approaches to the microkinetic analysis of complex reaction networks (Berger et al., 2008). During transient experiments, unlike in the steady-state, rates of various elementary steps comprising the catalytic cycle are not equal. Thus, a better mechanistic hypothesis can be posited and tested based on the interpretation of time-dependent data leading to a more sensible microkinetic model. Historically, atmospheric pressure transient studies of industrial catalysts have been performed in the reactors designed to approach one of the ideal flow patterns (CSTR, PFR, differential PFR). In spite of their simplicity, the non-steady-state experiments in these reactors are burdened by complex hydrodynamics of the time-dependent flow, macroscopic non-uniformities of the catalytic sample, and the low temporal resolution (Gleaves et. al., 2010). The focus of this project is the Temporal Analysis of Products (TAP) reactor system, an advanced kinetic characterization device which can alleviate the limitations of traditional transient methods.

B. Previous Work The signature type of TAP transient measurements is the pulse-response experiment conducted as follows: a very small pulse of gas mixture (1014 molecules) is introduced in to the evacuated (10-6 torr) microreactor by a high-speed pulse valve. The gas travels through the reactor primarily by means of Knudsen diffusion, encounters the catalyst on its way, and then escapes into the vacuum chamber. The kinetic data are then extracted from the exit flows of reactants and products recorded by the Quadrupole Mass Spectrometer (QMS) using the exit flow of inert gas as a transport standard. In a state-defining experiment, the surface composition remains intact or changes insignificantly during the pulse so that observed kinetic characteristics can be related to a single catalytic state. A sequence of state-defining pulses (multipulse) can be used to change the surface gradually and monitor how these changes affect the kinetics. Recent studies (Shekhtman et al., 2005) have been focused on using the Thin Zone (TZ) packing of the TAP reactor in which a narrow catalyst sample is sandwiched by inert zones, as shown in Figure 1(a). The TZ configuration was shown to retain high spatial uniformity of the catalyst during Knudsen flow experiments for conversions up to 80%. Hence, the catalyst sample can be represented as a uniform reactive interface depicted

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in Figure 1(b), and the observed kinetics can be directly related to a specific rather than an averaged catalyst composition. This experimental feature of TZ TAP reactor was used to develop an Interrogative Kinetics (IK) approach for the catalyst characterization which employs a long series of small pulses to gradually alter the catalyst composition while simultaneously sampling the reaction kinetics 'state-by-state' (Shekhtman et al., 2004). The uniformity of TZ also permits the extraction of transient catalytic kinetics (reaction rates, gas concentrations, and surface uptakes) from exit flows via the co-called Y-Procedure algorithm (Yablonsky et al., 2007). The latter is based on solving the inverse diffusion problem for inert zones, and does not require a priori assumptions about the reaction mechanism.

Figure 1. (a) The Thin Zone TAP reactor; (b) The conceptual model of the uniform reactive interface.

C. Research Objectives Specific objectives of this project are: 1) to further develop theory and methodology of Y-Procedure analysis. Particularly, to identify the characteristic patterns in the non-steady-state rate/concentration data corresponding to various model reaction mechanisms; and 2) to start the systematic application of the Y-Procedure analysis to experimental data using CO adsorption/oxidation reaction as an example

D. Results and Discussion We have analyzed several model reactions and identified their characteristic kinetic signatures in rate-composition data which will enable an effective mechanism identification in future practical applications. Novel parameter estimation routines, including the estimation of the number of active sites, were also suggested and tested. In order to implement our theoretical findings, the Pulse Intensity Modulation (PIM) experimental protocol was developed for collecting TAP data specifically intended for analysis using the Y-Procedure. The key idea of a pulse modulation experiment is to precisely control the catalyst composition by changing the amount of molecules sent

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into the microreactor and quantitatively study non-linear kinetic effects caused by increased surface coverage. The protocol also contains instructions on how to account for a noticeable adsorption in the inert material when translating exit flow data into thin-zone kinetic characteristics. The first experimental validation of the Y-Procedure approach was accomplished by employing a well characterized oxygen uptake on polycrystalline platinum (Redekop et al., 2011). The estimated intrinsic kinetic constant and total oxygen storage capacity shown in Figure 2 were in agreement with values previously published for this prototypical reaction. We have also investigated CO adsorption on the same material, and we are currently preparing a manuscript based on these studies.

Figure 2. Oxygen adsorption on platinum. The main 3D plot shows experimental kinetic trajectories (adsorption rate vs. oxygen gas concentration vs oxygen surface uptake) recorded in a multipulse

experiment, and the inset shows a single trajectory (in modified coordinates) used to estimate the total fraction of active sites (0.8) and the intrinsic adsorption constant (1.09•106 m3/mol/s).

Finally, The Y-Procedure methodology was utilized to investigate CO oxidation kinetics on the Au/SiO2 catalyst prepared by the method of magnetron sputtering (Zheng et al., 2010). The observed kinetic behavior was explained by a mechanism involving an additional oxygen reservoir on the catalyst that was filled during pretreatment and from which active surface oxygen was replenished between consecutive pulses in the plateau region of the combined kinetic curve. Once this additional reservoir was exhausted, the apparent kinetic constant decreased as a result of oxygen depletion. This mechanistic hypothesis was corroborated by the intra-pulse evolution of the catalyst composition extracted from exit flow data via the Y-Procedure.

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E. Future Goals More elaborate mechanisms will be analyzed using ‘kinetically model free’ Y-Procedure approach with the emphasis on partial oxidation of hydrocarbons and dry reforming of methane. The developed procedures for mechanism decoding will be systematically applied to the experimental data.

F. For Further Information Contact Evgeniy Redekop at eredekop@go.wustl.edu

G. References Berger, R.J., Kapteijn, F., Moulijn, J.A., Marin, G.B., Wilde, J.D., Olea, M., Chen, D.,

Holmen, A., Lietti, L., Tronconi, E., Schuurman, Y. “Dynamic methods for catalytic

kinetics”. Applied Catalysis A: General,2008, 342, 3-28.

Gleaves, J.T., Yablonsky, G., Zheng, X., Fushimi, R., Mills, P.L.”Temporal analysis of

products (TAP) - Recent advances in technology for kinetic analysis of multi-component

catalysts”. Journal of Molecular Catalysis A: Chemical, 2010, 315, 108-134.

Shekhtman, S.O., Yablonsky, G.S., Gleaves, J.T., Fushimi, R.R. “Thin Zone TAP reactor as a

basis of "state-by-state transient screening". Chemical Engineering Science, 2004, 59,

5493-5500.

Shekhtman, S.O., Yablonsky, G.S. “Thin-Zone TAP reactor versus differential PFR:

analysis of concentration nonuniformity for GasSolid systems”. Industrial & Engineering

Chemistry Research, 2005, 44, 6518-6522.

Yablonsky, G., Constales, D., Shekhtman, S., Gleaves, J. “The yprocedure: How to extract

the chemical transformation rate from reaction-diffusion data with no assumption on

the kinetic model”. Chemical Engineering Science, 2007, 62, 6754{6767.

Redekop E. A., Yablonsky G.S., Constales D., Ramachandran P. A., Pherigo C., Gleaves J.

T. “The Y-Procedure methodology for the interpretation of transient kinetic data:

Analysis of irreversible adsorption”. Chemical Engineering Science, 2011, 66, 6441–6452

Zheng, X., Veith, G.M., Redekop, E., Lo, C.S., Yablonsky, G.S., Gleaves, J.T., “Oxygen and

CO adsorption on Au/SiO2 catalysts prepared by magnetron sputtering: The role of

oxygen storage”. Industrial & Engineering Chemistry Research, 2010, 49, 10428–10437.

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Goals for MRE Projects in 2011/2012 The current two projects, supported for the last few years by MRE sponsors, namely: 1. Micro –scale Modeling of Packed Beds, and 2. Non-steady State Catalyst Characterization with TAP Experiments have culminated in Ph.D. theses by Dan Combest and Evgeniy Redekop, respectively. Both are available on the CREL web-site starting July 1, 2012. Each study contributed valuable tools to interested practitioners. The former enables computation of flow, transport and reaction on assembly of catalytic particles of various configurations which are typically encountered in packed beds. The later provides an unsurpassed tool for understanding catalytic mechanisms on real catalysts and allows readily for mechanism discrimination. Both open the doors for future important research. In studies of packed and trickle beds, the very dangerous hot spot phenomenon is known to be triggered by the growing disturbance and instability on the scale of a particle cluster. Computation of this phenomenon now becomes possible using Combest developed algorithms for packing particles. An improved insight for how to avoid hot spots can now be sought. In addition, a method for extending CFD on the scale of clusters of particles to large bed structures is worthy of investigation. TAP studies are increasingly used in Europe. Our recent alumnus Evgeniy Redekop received the prestigious Marie Curie post-graduate fellowship to pursue them at Ghent in Belgium. TAP opens the door for providing essential information in developing and testing catalysts in the energy and environmental sector. To pursue them with renewed vigor we need to refurbish our laboratory first and for that we need to develop a new TAP system at EECE. A proposal along this line is enclosed in this report. Thus, both packed bed and TAP studies will be placed on hold during 2012/2013 until new projects in this filed are defined in agreement with sponsors. In 2012/2013 the selection projects in which MRE funding was already involved this year, as described in other research in this report, will be pursued. This includes: 1. Use of optical probes in quantifying multiphase systems 2. Mass transfer and mixing in slurry bubble columns 3. Quantification of electrochemical systems with gas evolution at the electrode 4. Methane and carbon dioxide reactions on supported nano-catalysts. 5. Quantification of gas dissolution rate and mass transport in expanded solvents. 6. Review papers on trickle beds and fluidized beds. The final selection will be made after the MPE3 meeting on June 13, 2012 in consultation with sponsors and depending on availability of funds.

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PROPOSAL FOR MRE PROJECT IN CATALYSIS to be initiated in 2012/2013:

Addressing Challenges in Catalysis for Energy and Environment.

John Gleaves, Associate Professor, EECE, Washington University Gregory Yablonsky, Research Professor, Department of Chemistry, Saint Louis University Rebecca Fushimi, Executive Director, The Langmuir Research Institute

Vision: Establishing a comprehensive scientific methodology for design and fabrication of technical catalysts for industrial processes.

Mission: Continuous development of kinetic pulse response techniques that describe the effect of a catalyst’s composition (surface composition, oxidation state, phase composition, etc.) on it’s kinetic performance. Validation of molecular modeling predictions with kinetic data over real and model systems. Education of the next generation for catalyst design.

Tools: The TAP (Temporal Analysis of Products) Reactor System provides unique information on heterogeneous catalytic processes and the materials’ properties that offer the best performance. The TAP technique provides researchers with intrinsic kinetic data of complex multiphase commercial catalysts and the ability to manipulate surface oxidation state and understand its effect of kinetic properties (Shekhtman 2003b). The TAP system coupled with atomic beam deposition and atomic layer deposition makes it possible to manipulate the surface metals composition in precise submonolayer quantities with direct correlation to changes in kinetic properties (Fushimi 2007, 2008). Among kinetic techniques, the theory underpinning TAP pulse response experiments is the most fully developed and well defined (Yablonsky 2007). Key advantages of the TAP technique compared with other kinetic techniques as recently reviewed in Perez-Ramirez (2007) include:

- Millisecond time resolution which enables one to identify reaction intermediates and

distinguishing sequences in a multi-step reaction,

- The absence of mass transfer limitations and well-defined transport in the Knudsen or

molecular regime,

- The use of both model and practical catalytic materials,

- A small pulse size (10 nanomols) which results in a low adiabatic temperature rise

during a reaction, hence an isothermal reaction zone and minimal reconstruction of the

catalyst surface from temperature effects,

- The ability to manipulate and understand the effects of changing oxidation state.

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Some of the detailed kinetic quantities available from the pulse response technique include rate constants of elementary steps, surface residence times, number of active sites, surface to bulk migration rates and porous diffusivity. Research Focus: The TAP technique provides a new methodology for probing the catalyst surface. A few examples of catalytic solutions to environmental and energy related challenges that can be addressed with TAP include:

- Carbon dioxide and methane utilization: dry reforming of methane with CO2, low-

temperature methane activation

- Bimetallic catalysts for direct ethanol fuel cells

- NOx reduction in lean-burn engines

- Oxygen-assisted catalytic coupling.

Although the TAP technique is generally applicable to the gas-solid reactions of heterogeneous catalysis it is most commonly used to study metal oxides and supported metal catalysts as well as microporous materials.

Metal Oxides and Supported Metals: Characterizing the relationship between a catalyst’s surface composition and its kinetic properties will enable the rational design of high performance materials. The TAP technique allows quantitative calculation of intrinsic catalyst properties as they depend on the surface oxygen composition (Shekhtman 2003b). By combining TAP experiments with atomic deposition techniques we can now include the description of intrinsic catalyst properties as they depend on surface metal composition (Fushimi 2007, 2008). The TAP technique also makes it possible to understand how adsorbed species and products influence the catalyst surface and kinetic properties. While most industrial catalytic processes operate at atmospheric and higher pressures, the TAP experiment is performed under vacuum conditions. The experimental configuration of the TAP system allows the researcher to perform both vacuum pulse response and high pressure flow experiments on the same catalyst sample. The key difference between the two regimes is surface coverage and only the TAP system allows one to manipulate surface coverage. A recent example showed a correlation between a reaction rate controlled by a balance between the surface coverage of two species under both vacuum and pressure conditions (Zheng 2008). In another example, the TAP system was used to reveal how secondary reactions in the fast and highly exothermic ammonia oxidation process are dependent on surface coverage (Perez-Ramirez 2007).

Zeolites: The TAP technique offers several key advantages when studying transport and reaction in microporous materials:

- the diffusing species is only in contact with the microporous material for a short time,

- external transport limitations are eliminated,

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- one may decouple the adsorption process from the external surface with the diffusion in

the porous interior,

- a small quantity of sorbent is used and the transport/kinetic data is obtained at low pore

occupancy.

TAP experiments offer an efficient means to capture diffusivity and residence time in pores (Keipert 1998, Shekhtman 2003a) and also to understand the effects of carbon deposition on the kinetic interaction with the external surface and the diffusivity in the porous interior (Schuurman 2005).

Strategy: Develop synthetic techniques to develop new catalysts that incorporate atomic beam deposition, atomic layer deposition and chemical vapor deposition into the TAP kinetic analysis framework. This will include the use of model supports and working catalysts. Graduate students will develop a new methodology for cyclic surface modification and kinetic analysis to yield a fundamental description of the composition/activity relationship which is key to improving catalytic materials.

References

• Fushimi, R., J. Gleaves, G. Yablonsky, A. Gaffney, M. Clark, S. Han (2007) “Combining TAP-2 experiments with atomic beam deposition of Pd on quartz particles” Catalysis Today 121 170-186.

• Fushimi, R., X. Zheng, J. Gleaves, G. Yablonsky, A. Gaffney, M. Clark, S. Han (2008) “Techniques for fabricating nanoscale catalytic circuits” Topics in Catalysis 49 167-177.

• Keipert, O., M. Baerns (1998) “Determination of the intracrystalline diffusion coefficients of alkanes in H-ZSM-5 zeolite by transient technique using the tempoeral-analysis-of-products (TAP) reactor” Chemical Engineering Science 53 3623-3634.

• Olsbye, U., Moen, O., Slagtern, A., and Dahl, I. M., Applied Catalysis A: General 228 (2002) 289–303.

• Perez-Ramirez, J., E. Kondratenko (2007) “Evolution, achievements and perspectives of the TAP technique” Catalysis Today 121 160-169.

• Schuurman, Y., C. Delattre, I. Pitault, J. Reymond, M. Forissier (2005) “Effect of coke deposition on transport and sorption in FCC catalysts studied by temporal analysis of products” Chemical Engineering Science 60 1007-1017.

• Shekhtman, S., (2003a) “A new methodology for catalyst characterization” Doctoral Thesis, Washington University, Saint Louis, Missouri.

• Shekhtman, S., G. Yablonsky, J. Gleaves, R. Fushimi (2003b) “’State defining’ experiment in chemical kinetics – primary characterization of catalyst activity in a TAP experiment” Chemical Engineering Science 58 4843-4859.

• Yablonsky, G., D. Constales, S. Shekhtman, J. Gleaves (2007) “The Y-Procedure: How to extract the chemical transformation rate from reaction-diffusion data with no assumption on the kinetic model” Chemical Engineering Science 62 6754-6767.

• Zheng, X., J. Gleaves, G. Yablonsky, T. Brownscombe, A. Gaffney, M. Clark, S. Han (2008) “Needle in a haystack catalysis” Applied Catalysis A: General 341 86-92.

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CAE-SBCR Funded Projects

Introduction to CAE-SBCR The Consortium for Clean Alternative Energy (CAE) via Slurry Bubble Column Reactor (SBCR) is based on research established by the CREL 10 year effort with the Department of Energy (DOE) sponsorship in this area, followed up by the industrially sponsored cooperative project which was renewed several times. The goal is to improve the scientific basis for design, scale-up and operation of slurry bubble column reactors used in gas to liquid fuel conversion. The emphasis recently has been on the Fischer Tropsch slurry reactors with either cobalt or iron catalysts. This project illustrates the additional avenue open for CREL partnerships with industry. In this arrangement, companies interested in advancing the scientific basis of a particular reactor type or technology fund a multi-year project at the level needed to accommodate the goals that are set. Data and information gathered is first shared with them to allow patent applications, if desired. Ultimately main findings are shared by other CREL partners and the public via open literature. We invite our current SBCR sponsors to expand the current scope and allow solicitation of other interested partners. This type of arrangement does require a separate contract. A general outline of it is available upon request.

Graduate Student Project Title Mohamed Hamed Mechanism of Gas Phase Mixing in Bubble columns Onkar Manjrekar Mass Transfer in Bubble Column with Internals

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Mechanism of Gas Phase Mixing in Bubble Columns

A. Problem Definition The popularity of bubble columns as industrial reactors is growing as evidenced by their increased use in many important chemical applications like oxidation, absorption, fermentation, waste water treatment, methanol synthesis, and Fischer-Tropsch process. Due to their excellent mixing and transport characteristics, bubble column reactors are well suited for handling highly exothermic reactions. Gas phase mixing is one important hydrodynamic parameter to consider in the scale-up of bubble columns, as it can significantly affect the reaction rates and product selectivity. The most common model used in simulating gas mixing is the 1-D axial dispersion model (ADM). In the ADM, all the mechanisms leading to the overall axial gas mixing are lumped into a single coefficient: the axial dispersion coefficient (Dg). This causes Dg to become sensitive to the reactor scale and operating conditions, and hence very difficult to scale up. The popularity of the model stems from its simplicity and ease of use, although its ability to describe two-phase flows with large degrees of back-mixing, such as those encountered in bubble columns, is questionable. It is the lack of better alternatives that makes the ADM predominantly used to scale up bubble columns.

B. Research Objectives Despite the various attempts to develop theoretical or semi-theoretical expressions for Dg, there still exists no relationship that quantifies the contributions of the different mixing mechanisms to the overall axial gas mixing in bubble columns. The present work attempts such quantification. The main objective is to better understand the relation between the axial dispersion coefficient and the key fluid dynamic parameters and turbulent dispersion coefficients. In the light of the development of such an expression, one should be able to:

1. Better understand the effects of different process conditions and column scale on Dg.

2. Define the key parameters that should be used to predict Dg. 3. Determine the dominant gas mixing mechanism.

These objectives were accomplished by measuring simultaneously the axial dispersion coefficient, and axial and radial turbulent diffusivities using a well-developed tracer technique.

C. Results and Discussion In this work, gas mixing experiments were performed to measure the RTD of the gas phase at different conditions summarized in Table C.1. The experimentally measured RTD of the gas phase was analyzed by a 2-D convection-diffusion model to estimate

and

values, while a 1-D axial dispersion model was used to estimate the axial dispersion coefficient (Dg). The details of the gas mixing experiments and of the 2-D

42

model development are given in Hamed (2012). In order to determine the convective effects on the overall mixing, the 4-point optical probe was used to measure the gas holdup profile and gas velocity profiles.

Dc (cm) Ug (cm/s) HD (cm)

19.00 20,25,30,35,40,45 190

45.80 20,25,30,35,40,45 266

Table C.1. Experimental conditions

The contribution of the turbulent dispersion and convective mixing to the overall axial mixing was analyzed by Wilkinson (1991) and Degalesaan and Dudukovic (1998). Wilkinson (1991) developed a mechanistic model and used it to calculate the axial liquid

dispersion coefficient from the average axial turbulent diffusivity , recirculation velocity ( , overall gas holdup ( and a radial exchange term ( ).

√

.

(C.1)

Degaleesan and Dudukovic (1998) developed a 2-D convection diffusion model and reduced it to a 1-D model, from which the axial liquid dispersion coefficient was calculated from the recirculation liquid velocity, cross-section averaged turbulent axial diffusivities, and cross-section averaged radial diffusivities (equation C.2).

(C.1)

where is an empirical constant. Both models indicate that the overall axial dispersion coefficient conceptually can be divided into two parts: a turbulent diffusivity term which accounts for the contribution of the turbulent dispersion in the axial direction, and a Taylor-type ‘diffusivity’ term which accounts for the contribution of convection to the overall axial mixing and of radial turbulent diffusivity. Both studies showed that the turbulent diffusivity term is equal to the cross-sectional averaged axial turbulent

diffusivity ( , while the Taylor diffusivity term is a function of the recirculation phase

velocity and the cross sectional averaged radial turbulent diffusivity ( . Based on these models, it is evident that the overall axial mixing will increase with an increase in the axial turbulent diffusivity and the recirculation velocity, and will decrease with an increase in the radial turbulent diffusivity. It is also evident that the contribution of convection (recirculation velocity) to the overall axial mixing decreases at high values of radial turbulent diffusivities.

The predicted values of ,

, and Dg were analyzed using the models discussed above (equations C.1 and C.2) to understand the effect of different operating conditions and the contribution of convective mixing and turbulent dispersion on the overall axial gas mixing . The contribution of the axial mixing was quantified by dividing the axial

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turbulent diffusivity by the overall axial mixing coefficient (Dg). Figure C.1 shows the variation of the ratio of

to Dg with the superficial gas velocities in 8-inch and 18-inch bubble columns. Figure C.2 shows the variation of Dg,

, and with the superficial

gas velocity in the 8-inch and 18-inch columns. values were calculated from Equation

(C.2) by subtracting from Dg.

Figure C.1. The ratio the axial turbulent diffusivity to the axial dispersion coefficient (Dzz/Dg) at different superficial gas velocities in the 8-inch and 18-inch columns

Figure C.2. Effect of column scale on the axial turbulent diffusivity and Taylor-type diffusivity

The data shows that in the lab-scale 8-inch column, the overall axial gas mixing is mainly controlled by the axial turbulent dispersion, since it accounts for ~85% of the total axial mixing. The contribution of the convective mixing increases with increase in the column

0.4

0.5

0.6

0.7

0.8

0.9

1

15 20 25 30 35 40 45 50

Dzz

/D

g

Superficial gas velocity, cm/s

Dzz/Dg - No Internals- 8 inch

Dzz/Dg - No Internals- 18 inch

0

2000

4000

6000

8000

10000

12000

14000

15 20 25 30 35 40 45 50

Dis

per

sio

n c

oef

fici

ents

, cm

2/

s

Superficial gas velocity, cm/s

Dzz, 8 inch, No Internals

Dg, 8 inch, no internals

DTaylor, 8 inch, no internals

Dzz, 18 inch, No Internals

Dg, 18 inch, no internals

DTaylor,18 inch, no internals

44

diameter, mainly due to the significant increase in the gas circulation with the increase in column diameter. This was also reflected in the values of the Taylor diffusivities in the 18-inch column, shown in Figure C.2, which were larger than those in the 8-inch column.

D. Conclusion Generally, the reported data showed that the overall axial gas mixing is mainly controlled by turbulent dispersion under the operating conditions of this study (20-45 cm/s in 8 and 18 inch columns). This indicates that operating conditions leading to the increase in the turbulent intensity will cause an increase in the overall axial gas mixing. This has been described in detail in Hamed (2012). It should be noted that the change in the operating conditions and scale was found to affect the contribution of different mechanisms due to the change in turbulent intensity and circulation rates under these different conditions. It is therefore important to consider the contribution of both the convective mixing and turbulent dispersion in the modeling of gas mixing or in the development of axial gas dispersion coefficient correlations. More focus should be directed towards studying parameters that affect the circulation rates and turbulent intensity in bubble columns including pressure, solids, and the presence of internals. The doctoral thesis of Hamed (2012) provides the tools for assessing the effect of operating conditions on axial gas mixing via physical based models.

E. Future Work Although this work presented a detailed description of the mechanism of gas phase mixing in bubble columns, more research is needed to enhance this understanding at different operating conditions. This requires the implementation of novel experimental techniques to measure the gas concentration locally. The absence of axial gas concentration data hinders our ability to estimate the local turbulent parameters of the gas phase. Such techniques can be coupled with a 2-D model, similar to the one used in this study, to achieve more confident estimation of the axial and radial profiles of Dzz and Drr. In addition, these techniques will help us to understand how the relative magnitudes of different mixing mechanisms change with the column height. This can lead to a better prediction of the developing axial profile of the lumped axial gas dispersion coefficient.

F. For Further Information Contact Mohamed Hamed at mea2@cec.wustl.edu

G. References Degaleesan, S. and Duduković, M. P., 1998. Liquid back-mixing in bubble columns and

the axial dispersion coefficient, AIChE Journal, 44, 2369–2378.

Wilkinson, P.M., 1991. Physical aspects and scale-up of high pressure bubble columns,

Ph.D. Thesis, University of Groningen, Rijksuniversiteit Groningen, the Netherlands.

45

Hamed, .M., 2012. Hydrodynamics,Mixing, and Mass Transfer in Bubble Columns with

Internals, Ph.D. Thesis, Washington University in St. Louis, Saint Louis, USA.

Pulications and Presentations Hamed, M, Dudukovic, M. and Al-Dahhan, M., 2009.On Bubble Columns with internals,

GLS9 (8th World Congress of Chemical Engineering 2009, Montreal, Canada.

Hamed, M, Dudukovic, M. and Al-Dahhan M., 2009.Gas Phase back-mixing in bubble

column with internals - BIOENERGY II: FUELS AND CHEMICALS FROM RENEWABLE

RESOURCES - Rio de Janeiro, Brazil.

Youssef, A., Hamed, M., Dudukovic, M. and Al-Dahhan, M., 2009. Novel scale-up

methodology for bubble column reactors, International Journal of Chemical Reactor

Engineering (accepted).

46

Mass Transfer in Bubble Column with Internals

A. Problem Definition Multiphase reactions are very common in chemical industry. They are frequently encountered in many petrochemical processes, biochemical processes, waste water treatment, and in production of various organic compounds. Bubble column reactors are used for Fischer Tropsch synthesis. Fischer Tropsch reaction has become subject of renewed interest due to its ability to convert synthesis gas derived from natural gas or from biomass sources to liquid transportation fuels. The main incentive for this conversion is increased availability of natural gas in remote locations and increased demand for transportation fuels (Krishna and van Baten, 2003). For economic reasons F-T conversions are carried out on large scale, hence it is important to have a fundamental understanding of these. One of the important issues in F-T reactions is their strong exothermicity, huge amount of heat is released per mole of feed. Internals are used in order provide cooling for the system and keep the temperature under control. Despite the large amount of kLa data and correlations reported in the literature, none is available in presence of vertical cooling internals. Also most of the work in this area is focused on low superficial gas velocities. Ho Nam Chang et.al (1998), Nedeltchev S. et al. (2008), and many other workers have focused on superficial gas velocities less than 15 cm/s. Only R. Krishna and co-workers have studied mass transfer at high superficial gas velocities. There is limited literature on mass transfer in presence of internals at high superficial gas velocities. When bubble column reactors are operated in churn-turbulent regime increase in mass transfer is observed, hence it is beneficial to operate in this regime.

B. Research Objectives 1. Investigate the effect of superficial gas velocity and internals on volumetric mass

transfer coefficient, kLa, in a pilot scale bubble column. 2. Study variation in kLa along the axis and radial positions.

C. Experimental Procedure Experiments were carried out in a poly-acrylate column of 0.45 m diameter. Air-water system was used for all the mass transfer measurements at ambient temperature and pressure. Semi-batch mode operation was used with liquid as stationary phase. The oxygen enriched method was used to measure the step response of oxygen in the liquid phase. This method involves adding a small oxygen flow, while maintaining the main air flow, as a step change to achieve a switch between air and oxygen-enriched air. An optical oxygen probe was used to measure the dissolved oxygen concentration in the liquid phase.

D. Results and Discussion Mass Transfer without Internals: Results were analyzed using CSTR model. The values of kLa (volumetric mass transfer coefficient per unit volume of liquid in bubble column)

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obtained at various axial positions are reported in Figure-1. The values of kLa were found to be independent of axial position.

Figure 1. kla Values at different axial Positions

Also values of kLa were found independent of the radial position as shown in Figure-2. According to experimental results we have found that there is no significant effect of internals on volumetric mass transfer coefficient. The comparison of mass transfer coefficients is shown in the Figure-3.

Figure 2. kla Values at different radial Positions

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

20 25 30 35 40 45 50

kla

s-1

Superficial Gas Velocity cm.s-1

X-1 1.75 m

X-2 1.39 m

X-3 0.736 m

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

20 25 30 35 40 45 50

kla

s-1

Superficial Gas velocity cm.s-1

R-1, X-1

R-2, X-1

R-3, X-1

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Figure 3. kla Values with and without internals (Position X-1)

All of the above figures point out that at these very high superficial gas velocities the volumetric mass transfer coefficient is not a strong function of gas velocity.

E. Conclusion From the obtained experimental results it follows that in the churn-turbulent regime bubble column behaves as a CSTR, the liquid phase concentration is uniform through the reactor. There are no liquid phase concentration gradients in the reactor. Due to high turbulence at high gas velocities there is no significant effect of superficial gas velocity on volumetric mass transfer coefficient. In presence of internals the values of volumetric mass transfer coefficient are slightly lower than without internals but the reduction in the values is not significant. The values of mass transfer coefficients were also calculated by using axial dispersion model [Mohamed 2012] the values using this model are little higher compared to CSTR model. From the evidence that concentration profiles in the reactor and simplicity CSTR model which is very commonly used in literature was used in this study.

F. Future Goals We are planning to study the effect of solids on mass transfer coefficients under these conditions.

G. For Further Information Please contact Onkar Manjrekar at onkar.manjrekar@wustl.edu

H. References R. Krishna, J.M. van Baten. A strategy for scaling up the Fischer–Tropsch bubble column

slurry reactor, Topics in Catalysis Vol. 26, (2003),21-28.

0

0.02

0.04

0.06

0.08

0.1

0.12

15 20 25 30 35 40 45 50

kla

s-1

Superfecial Gas Velocity cm/s

Internals

No Internal

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Ho Nam Chang, Benoit Halard and Murrary Moo-young. “Measurements of kla by a

gassing in method with oxygen enriched air”. Biotechnology and Bioengineering, 34

(1988) 1147-1157.

Nedeltchev S. Theoretical prediction of mass transfer coefficients in a slurry bubble

column operated in the homogeneous regime , Chemical and Biochemical Engineering

quarterly,21-4 (2007), 327-334.

C.O Vandu, R.Krishna. “Influence of scale on the volumetric mass transfer coefficients in

bubble column”. Chemical Engineering and Processing 43 (2004) 575-579.

Mohamed H. “Hydrodynamics, Mixing, and Mass Transfer in Bubble Columns with

Internals”. PhD Thesis, 2012.

* This work was done as part of rotation project in fall 2011 and continued in spring 2012.

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General Reaction Engineering Research Funded by Non-Industrial Sources

Introduction to General Research This section contains projects funded primarily by non-industrial sources which the university has the right to publish. These projects add significantly to CREL growth and expand the horizons of our sponsors. Of the projects described below some are candidates for becoming an MRE project or becoming a basis for separate consortium funding. Sean Mueller’s thesis grew into the current project (Advancing Green Reactor Engineering by Fundamental Characterization of Multiphase Flows) for which he received NSF funding. We strongly recommend that the readers take a good look as to how this technique could be used to improve the monitoring and control of your reaction systems, or how it can be expanded to other applications. The technique has been implemented at our partners at CEBC, University of Kansas, and two probes have been sent to two MRE sponsors. Two individuals Boung Wook Lee and Yujian Sun are continuing these studies. Alessio Alexiadis’s work and Mehmet Morali’s work described below represent a foundation for introducing more fundamentally based understanding not only for chlorate producers but in other electrochemical cells and batteries. It could lead to collaborations with Professor Subramanian and to a consortium of interested companies. Vesna Havran’s work represents a pioneering effort in attempting to relate molecular dynamics modeling results (done by professor C. Lo’s group) to experimental observations in catalytic low temperature activation of methane and carbon dioxide on platinum nano-clusters on different oxide supports. The work was supported by the Consortium for Clean Coal Utilization at Washington University.

Graduate Student Project Title Vesna Havran

Catalytic Conversion of Methane and Carbon Dioxide to Higher Value Products

Boung Wook (Tim) Lee

Advancing Optical Probe Measurement Techniques for Multi-Phase Reactors.

Mehmet Morali

Bubble Induced Liquid Flow in Narrow Channels with Gas Evolution at Electrodes

Yujian Sun

Optical Fiber Reflectance Probe for Detection of Supercritical Transition

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Catalytic Conversion of Methane and Carbon Dioxide to Higher Value Products

A. Problem Definition The goal of this research is to develop a rationally designed catalytic system for direct conversion of methane and carbon dioxide at mild temperatures (< 400°C). Although the abundance of these two greenhouse gases makes them attractive raw materials for fuels and chemical synthesis, most of their reactions require significant energy inputs as well as properly designed catalytic systems that lower kinetic barriers in their direct conversion. Generally, it has been considered that there are two limiting steps in this reaction (Ding et al., 2007):

1. Methane dehydrogenation over metal active center 2. Carbon dioxide activation on the support.

The carbonaceous species from adsorbed methane by reaction with activated carbon dioxide may then serve as building blocks for the production of chemicals and fuels. Based on molecular modeling analysis, Density Functional Theory (DFT) calculations have been used as a tool to determine the optimized structure of a bifunctional catalytic system that would supposedly enhance catalyst performance in each of these two reaction steps. Well-shaped Pt nanoclusters deposited on ceria support, known for its high oxygen storage capacity, have been chosen as a potential candidate for this study. It has been shown previously that the numerous low-coordinated sites on metal active center, such as surface steps, edges and kinks, can stabilize reaction intermediates and in that way facilitate the methane conversion (Wei and Iglesia, 2004). Certain shapes of these metal nanoparticles, depending on their size, can contain higher percentage of these under-coordinated atoms when compared to conventional round shaped nanoparticles (Figure 1 and Table 2). Distribution of specific sites shown in Table 2 has been determined according to the method described in Hardeveld and Hartog (1969) and under the assumption that the sites on the bottom of these clusters are not available as surface sites upon deposition onto supports.

Figure 2. Different sites on hemispherical and tetrahedral Pt nanoclusters

4 Table 2. Energies of adsorption (eV) for CHx (x = 0 - 4)

4

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Molecular modeling analysis of the thermodynamics of methane dehydrogenation over two different clusters, shown in Figure 1, showed that the energy barriers for methane dehydrogenation on the tetrahedral cluster are lower than the corresponding barriers on the hemispherical cluster. In particular, the dissociation of the methyl group to form methylene and hydrogen has the activation barrier of only 0.2 eV (Zhuo et al., 2012) indicating that the shape of the nanocluster, by affecting the distribution of these intermediate carbonaceous species on the surface, may enhance the selectivity of the catalyst. Also, it has been found that the methane adsorbs more strongly on the corner sites of the tetrahedral cluster that on the hemispherical one (Table 1) (Zhuo et al., 2012). Thus, we expect that hydrogen production from methane would proceed at a higher rate and conversion on tetrahedral clusters than on hemispherical clusters (Zhuo et al., 2012). There are no experimental studies of the effect of different metal nanocluster shapes on the methane dehydrogenation and their interaction with the support yet. Considering carbon dioxide interactions with solid surfaces, molecular modeling studies indicate that the carbon dioxide bonds more strongly on the oxygen vacancies of reduced ceria (Zhuo et al.) than on stoichiometric ceria surface. Ceria has the capability to easily cycle between two different oxidation states (+3/+4) depending on the surrounding conditions. Certain facets of ceria ({110} and {100}) are more easily reducible and hence might contain, under reducing conditions, higher concentration of oxygen vacancies that are active centers for carbon dioxide reduction (Zhou et al., 2005). Our study will investigate the role of these vacancies on the carbon dioxide adsorption as well as their interaction with different metal clusters. The obtained results should advance the fundamental understanding of the CH4 dissociative adsorption mechanisms on different cluster morphologies as catalytic active centers as well as elucidate the involvement of the support. This integrated approach including theoretical considerations, catalyst synthesis and characterization, and finally - its testing in a lab scale reactor should help in determining the key features needed for design of a good catalyst system.

B. Research Objectives The main focus of this project is to develop a catalytic system that will enhance methane activation and its reaction with the carbon dioxide to obtain higher value products. To meet this goal, the following objectives are set:

1. Synthesize and characterize the bifunctional catalysts that have been selected on the basis of molecular modeling studies as potential candidates: tetrahedral and conventional (round) Pt nanoparticles deposited onto three different supports: silica powder, ceria powder and ceria nanorods.

2. Study the effect of different sizes and shapes of Pt nanoparticles on methane dehydrogenation at low temperatures (< 400°C) and compare the activation energies for C-H bond scission with those obtained by molecular modeling.

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3. Investigate the presence of metal-support interaction and involvement of the

support in the activation of carbon dioxide and its reaction with adsorbed methane.

4. Examine the effect of metal cluster shapes and the role of different metal oxide supports on catalyst activity and selectivity in the reaction of methane with carbon dioxide in a small laboratory reactor at mild temperatures.

C. Results and Discussion Catalyst synthesis and characterization: Well-defined tetrahedral shape of Pt nanoparticles was achieved by mixing the metal precursor (H2PtCl6∙6H2O) and a capping agent (polyvinyl pyrolydone - PVP) in a specific concentration ratio according to protocol described in Lee et al. (2008). Argon, Ar, was bubbled first through the mixture to remove air from solution and then H2 was introduced to reduce the Pt anions. Colloidal nanoparticles are deposited onto different supports (silica, ceria powders) by simple impregnation at room temperature. Conventional catalysts with approximately round shape of Pt nanoparticles were synthesized by modified polyol method where H2PtCl6∙6H2O was mixed with ethylene glycol, as described in Tang et al. (2004). Ceria powder was prepared by precipitation from Ce(NO3)3∙H2O. The platinum loading of each of the catalysts was determined by Inductively Coupled Plasma Mass Spectrometer (Agilent 7500ce ICP-MS) and was around 1% wt.

Resulting tetrahedral Pt nanoparticles are shown in Figure 2. Size and shape distribution of both colloidal and deposited metal nanoparticles was determined by transmission electron microscope (TEM, FEI Tecnai G2 Spirit) operated at 120 kV (Figures 1-4). The shape distribution analysis showed that 65 ± 8 % colloidal nanoparticles have tetrahedral shape and the remaining ones have the shape of distorted tetrahedrons. The average size of these experimental tetrahedral Pt nanoclusters is 7.0 ± 1.3 nm and of the round ones is 2.2 ± 0.4 nm Both are larger than the model clusters (1 nm as shown in Figure 1). Consequently, the fraction of specific sites is different as shown in Table 2.

Figure 3. TEM images of a) tetrahedral Pt nanoparticles in solution, b) tetrahedral Pt on ceria support, c) hemispherical Pt on ceria support

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Theoretical clusters Experimental clusters

Hemispherical Pt

Tetrahedral Pt Hemispherical Pt

Tetrahedral Pt

Cluster size 1.0 nm 1.0 nm 2.2 nm 7.0 nm

Total number of atoms

21 20 274 2925

Number of surface atoms

16 19 130 865

Percentage of edge and corner atoms in total atoms

57% 80% 17% 5%

Percentage of edge and corner atoms in surface atoms

75% 84% 36% 16%

Table 3. Statistics of atoms on different Pt clusters3

Methane dehydrogenation in a lab scale packed bed reactor: The effect of Pt nanocluster shape on the reaction of methane dehydrogenation (Eq. 1) was studied in a laboratory scale quartz packed bed reactor (6 mm i.d.). Around 0.4 g of a catalyst sample was placed between two quartz wools and exposed for 20 minutes to the flow of methane (100 ml/min). Hydrogen evolution was tracked on the gas chromatograph (SRI 8610C) equipped with the TCD detector. CH4 → C +2H2 (1) The results in the form of the turn-over-frequency at four different temperatures: 150, 200, 250 and 300°C are shown in Figure 3. It can be observed that the tetrahedral Pt nanoparticles perform better than the hemispherical ones at two lower temperatures (150 and 200°C), while at the higher temperatures their activity decreases. This can be explained by loss of the well-defined tetrahedral shape at these higher temperatures which has been observed earlier by Lee and al. (2008). Although tetrahedral nanoclusters are bigger (7.0 nm vs 2.2 nm) and contain a smaller amount of low coordinated sites, it seems that their corner sites bind the methane more strongly at lower temperatures then the sites of hemispherical clusters. This indicates that those low coordinated sites indeed can reduce the barriers for C-H bond cleavage as the DFT analysis has suggested. As our experimental results showed, in the case of both clusters, hydrogen evolution increased with the temperature. Thermo-gravimetric experiment confirmed that there has not been any detectible carbon deposition on tested samples at such low temperatures.

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D. Future Goals Currently, possible modifications of the synthesis protocol for the tetrahedral Pt nanoparticles in solution that would result in different sizes of nanoclusters are being investigated. In that way, the effect of cluster size on C-H bond activation could be explored. Furthermore, the adsorption of carbon dioxide over different supports (silica and ceria powders, ceria nanorods) will be studied in a TGA experiment (Q5000 IR Thermogravimetric Analyzer) in order to clarify the role of the support as well as the presence of any metal-support interactions. The effect of different reduction temperatures on the creation of oxygen vacancies on ceria supports and the capacity for carbon dioxide adsorption will also be examined. This work that constitutes the part of my thesis will be finished in Fall 2012 which is the intended graduation time.

E. For Further Information Contact Vesna Havran at vhavran@wustl.edu

Figure 4. Turn-over-frequencies for H2 during the exposure to the methane flow

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F. Follow up project Developing an effective process for conversion of methane and carbon dioxide into highly valuable chemicals and/or clean fuels, would help not only address environmental issues by lowering the levels of carbon dioxide, but would also reduce the need for indirect routes of fuel production from methane via syngas. Despite the considerable research effort in this area, no readily applicable solution has emerged that results in satisfactory yields and/or selectivities. Development of an effective catalytic process that could be scaled up for industrial purposes remains a great challenge for catalysis. Deeper understanding of the reaction mechanisms and the effects of the structure of catalytic materials on their performance is needed. The main focus of this project would be to develop a predictive tool for rational catalyst design that will be guided by theoretical and computational studies using ab initio modeling, which will explore the activation of C-H bonds on various metal clusters as well as the possibilities for carbon dioxide adsorption on transition metal oxide supports. The theoretical studies will provide estimates of kinetic parameters for adsorption of carbon dioxide and methane on different nanostructures, which will then be tested and “tuned” in an iterative process based on experimental kinetic adsorption data on different nanoparticles, obtained via nonsteady-state experiments using the temporal analysis of products (TAP) reactor. The most promising catalyst configurations will be tested in small laboratory scale reactor, and optimal reaction conditions for maximum yield will be determined. Relating the structure of selected nanomaterials with their activity under both high-vacuum (molecular modeling and TAP) and atmospheric conditions (lab scale reactor) is of crucial importance in attempting to overcome the “pressure and material gap”. Unique integration of theoretical, computational and experimental approaches will serve as a foundation for presenting a strategy on industrial-scale catalyst development with improved yield and selectivity.

G. References Ding, Y.; Huang, W.; Wang, Y. “Direct Synthesis of Acetic Acid from CH4 and CO2 by Step-

Wise Route over Pd/SiO2 and Rh/SiO2 Catalysts”. Fuel Processing Technology, 2007, vol

88, 319-324.

Gleaves, J. T., Yablonsky, G., Zheng, X., Fushimi, R., Mills, P. L. “Temporal Analysis of

Products (TAP)—Recent Advances in Technology for Kinetic Analysis of Multi-

component Catalysts”, J. Mol. Cat. A: Chem., 2010, 315, 108–134

Havran, V., Duduković, M., Lo, C. Conversion of Methane and Carbon Dioxide to Higher

Value Products, Ind. Eng. Chem. Res, 2011, vol. 50 (12) 7089–7100.

Lee, I., Morales, R., Zaera, F. “Synthesis of Heterogeneous Catalysts with Well Shaped

Platinum Particles to Control Reaction Selectivity”. Proceedings of the National Academy

of Sciences of the United States of America, 2008, vol. 105(40), 15241-15246.

Lo, C. Integrated Nanoscale Catalysts for the Conversion of CO2 to Chemicals and Fuels.

Project proposal, 2009

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Tang, X., Zhang, B., Li, Y., Xu, Y., Xin, Q., Shen, W. “Structural features and catalytic

properties of Pt/CeO2 catalysts prepared by modified reduction-deposition techniques”.

Catalysis Letters, 2004, Nos. 3–4, 97, 163-169.

Van Hardeveld, R. and Hartog, F. “The Statistics of Surface Atoms and Surface Sites on

Metal Crystals”. Surface Science, 1969, 189-230.

Wei, J., Iglesia, E. “Mechanism and Site Requirements for Activation and Chemical

Conversion of Methane on Supported Pt Clusters and Turnover Rate Comparisons

among Noble Metals”. The Journal of Physical Chemistry B, 2004, vol 108(13), 4094-

4103.

Zhuo, C. and al. “Platinum Nanoclusters Exhibit Enhanced Catalytic Activity for Methane

Dehydrogenation”. Topics in Catalysis (accepted)

Zhuo, C. and al. Adsorption of Carbon Dioxide on Stoichiometric and Reduced Ceria

Catalyst. In preparation

Zhou, K., Wang, X., Sun, X., Peng, Q., Li, Y. “Enhanced Catalytic Activity of Ceria

Nanorods from Well-defined Reactive Crystal Planes”. Journal of Catalysis, 2005, vol.

229, 206-212.

Presentations Havran, V., Duduković, M., Lo, C. Catalyst Development for Direct Conversion of

Methane and Carbon Dioxide to Higher Value Products. Oral presentation at the 2012

ACS Annual Meeting, San Diego, CA, 2012.

Havran, V., Duduković, M., Lo, C. Catalytic Conversion of Methane and Carbon Dioxide

to Higher Value Products. Oral presentation at the 2011 AIChE Annual Meeting,

Minneapolis, MN, 2011.

Havran, V., Duduković, M., Lo, C. Catalytic Conversion of Methane and Carbon Dioxide

to Higher Value Products. Thesis Proposal Presented to EECE Department in April, 2011.

Havran, V., Duduković, M., Lo, C. Catalyst Development for Direct Conversion of CH4 and

CO2 to higher value products. Poster presentation at the 22nd North American Catalysis

Society Meeting, Detroit, MI, 2011.

Havran, V., Duduković, M., Lo, C. Catalyst development for direct conversion of CH4 and

CO2 to higher value products. Poster presentation at the Catalysis Club of Chicago

Symposium, Naperville, Il, 2011.

Havran, V., Duduković, M., Gleaves, J., Lo, C. Multiscale Analysis of CH4 and CO2

Conversion, 3rd International Symposium on Energy and Environment, St. Louis, MO,

2010.

Journal Publications Havran, V., Duduković, M., Lo, C. Conversion of Methane and Carbon Dioxide to Higher

Value Products, Ind. Eng. Chem. Res, 2011, vol. 50 (12) 7089–7100.

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Advancing Optical Probe Measurement Techniques for Multi-Phase Reactors

A. Problem Definition Since most reactors both at laboratory and industrial scale involve multiple phases, accurately measuring key parameters within them is crucial for scale up, design and optimization purpose. Of several methods, optical probe measurement technique developed by Xue et al. (2003) at CREL has significant advantage as this method is both inexpensive and durable under harsh conditions (Mueller and Dudukovic, 2010; Mueller et al., 2007) as described by Lee et al. (2011). To exploit this technique even further and use it in a wide variety of multiphase systems, a fiber box responsible for both emitting and detecting light signals must be built to be simple but with high sensitivity. The art of doing this has been mastered in our CREL.

B. Research Objectives Overall goal of this research is to advance the optical probe technique even further for utilization in a variety of multiphase systems, e.g. liquid-liquid systems. New correlations and models are to be developed upon determination/validation of key parameters.

C. Accomplishments Since the amount of light emitted at the end of the optical fiber that is transmitted back to the fiber box depends on: 1) the type of probe being used, and 2) the multiphase system in which the measurement is being made, having a box with the highest light sensitivity is highly desirable. As demand for optical probe technique continues to rise in both CREL and industry, a simpler way of constructing the fiber box was developed. The guidelines outlined by Mueller (2009) were updated. New appropriate parts and required steps for machining are detailed.

Figure 1. Optical Fiber Box and fiber-optic coupling (Mueller, 2009)

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Via procedure given in the guidelines, an optical fiber box was assembled and shipped to one of the CREL industrial sponsors (along with 4-point probes and other required opto-electric parts). Each of the four photodiodes in the box has an adjustable gain (directly related to sensitivity of the measurement) and is capable of measuring wide range of multiphase systems. Also, due to its simple schematics, sub-parts can easily be removed or replaced.

Figure 2. New optical fiber box (left) in comparison to the old one (right)

D. Future Goals 1. Probe data acquired via flow regime transition/4-point probe data on aerated

stirred tank will be analyzed using time series analysis (Diks et al., 1996;

Grassberger and Procaccia, 1983; van Ommen et al., 2011).

2. Flow regime transition, 4-point mini-probe, and reflectance probes will be tested

on other complex multiphase systems for development of new correlations and

models.

3. The probes will be modified/improved to better detection in other multiphase

systems e.g. liquid-liquid system.

E. For Further Information Please contact Boung Wook (Tim) Lee at leeb@seas.wustl.edu

F. References Diks, C., van Zwet, W.R., Takens, F., DeGoede, J., 1996. Detecting differences between

delay vector distributions. Physical Review E 53, 2169-2176.

Grassberger, P., Procaccia, I., 1983. Characterization of Strange Attractors. Physical

Review Letters 50, 346-349.

Lee, B.W., Ramachandran, P.A., Dudukovic, M.P., 2011. Advancing Optical Probe

Measurement Techniques for Multi-Phase Reactors, CREL Annual Report, pp. 55-61.

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Mueller, S.G., 2009. OPTICAL MEASUREMENTS IN GAS-LIQUID STIRRED TANKS,

Department of Energy, Environmental, and Chemical Engineering. Washington

University in St. Louis, Saint Louis, Missouri

Mueller, S.G., Dudukovic, M.P., 2010. Gas Holdup in Gas−Liquid Stirred Tanks. Industrial

& Engineering Chemistry Research 49, 10744-10750.

Mueller, S.G., Werber, J.R., Al-Dahhan, M.H., Dudukovic, M.P., 2007. Using a Fiber-Optic

Probe for the Measurement of Volumetric Expansion of Liquids. Industrial & Engineering

Chemistry Research 46, 4330-4334.

van Ommen, J.R., Sasic, S., van der Schaaf, J., Gheorghiu, S., Johnsson, F., Coppens, M.-

O., 2011. Time-series analysis of pressure fluctuations in gas–solid fluidized beds – A

review. International Journal of Multiphase Flow 37, 403-428.

Xue, J., Al-Dahhan, M., Dudukovic, M.P., Mudde, R.F., 2003. Bubble Dynamics

Measurements Using Four-Point Optical Probe. The Canadian Journal of Chemical

Engineering 81, 375-381.

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Bubble Induced Liquid Flow Field in Narrow Channels with Gas Evolution at Electrodes

A. Motivation Electrochemical reactors are used on variety of applications. Some common examples include electrolysis of water, chlorine production and aluminum electrolysis. These rather different three electrochemical processes have one thing in common; at least one of the products is gaseous. The presence of gas phase hinders the transport of ions to the electrode surface as well as creates resistance to current flow through the bulk of the reactor (Ohmic potential drop). Both phenomena dictate an increase in the cell voltage to sustain the electrochemical reaction at desired rate, which results in increased energy consumption. To minimize the energy consumption in an electrochemical system with gas evolving electrode a comprehensive multiscale analysis of underlying phenomena is necessary. This can be achieved by investigation of individual components such as: formation of bubbles, departure of bubbles from the surface, size distribution of bubbles, phase hold-up, bubble-liquid flow field interactions, coverage of electrode surface by bubbles, ionic species transport, etc. The current work focuses on developing the better understanding of two major contributors of potential drop: Formation of bubbles on the electrode surface and bubble-liquid flow field interactions with a special focus on the effect of gas phase hold-up on Ohmic potential drop. This will eventually lead to development of better modeling approaches for gas evolving electrodes.

B. Research Objectives Current work has two main objectives: Developing better tools to predict Ohmic potential drop and developing a novel model of bubble formation. Details of individual objectives are as follows:

1. Ohmic potential drop: The reactor scale phenomena (Ohmic potential drop) will be investigated in a chlorate cell. A typical cell has two vertical electrodes 3mm apart with high aspect ratio (400 mm x 3 mm). The electrolyte hinders bubbles coalescence and the system sustains small bubble sizes [1]. Bubbles are evolved on one of the electrodes. Once they are formed they vacate the system in a region close to the wall. The thickness of this region (bubbly layer) and the gas hold-up profile in it are two essential components of the effort to predict the potential drop. For this purpose a model will be developed to predict the thickness of the bubbly layer. This will be achieved following the outline below:

1. Experimentally observe a simplified system 2. Develop a Lagrangian model based on the experimental observations 3. Test the accuracy of the effective medium approximations used in the

above model to ensure the applicability in the conditions of interest.

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2. Formation of bubbles on electrode surface: Another important contributor to cell potential drop is the resistance that develops due to the presence of bubbles on the electrode surface. Bubbles are formed on nucleation site and grow larger until their departure. Bubbles on the surface reduce the available area for electrochemical reaction, which causes an increase in potential [2-3]. Reducing the average residence time of bubbles on the electrode surface or increasing the mass transfer of ions to the surface can reduce energy consumption. To achieve this bubble formation, detachment and mass transfer relationships should better understood. The objective of this part is to develop a novel model for bubble growth to better understand the mechanism of bubble formation. For this purpose these steps need to be followed:

1. Develop a model, which accounts for expansion of bubble boundaries on the electrode surface.

2. Create a model surface with random and structured nucleation sites to investigate the interaction of multiple bubbles.

C. Accomplishment and Future Work

1. Ohmic potential drop: To clearly see the formation of bubbly layer a single wire is used. A single aluminum wire is immersed in a caustic solution and the resulting rises of bubbles are observed with a high speed camera system. Figure 1 shows a snapshot of such a bubble layer formation.

Figure 5. A thin aluminum wire is in caustic solution.

Visual observations of the bubble layer formation show that the bubble formed at the lowest part of the wire tends to stay at the outer edge of the bubbly layer as it moves outwards. This observation gives rise to the idea that tracking a single bubble from the lowest end of the electrode can provide information on the evolution of the shape of the bubbly layer. A Lagrangian model based on tracking of a single bubble has been developed to predict the edge of the envelope of the bubbly layer. The model seems

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capable of predicting observed trends. A sample result showing the effect of average bubble diameter on bubbly layer thickness can be found in Figure 2. The model is described in Morali (2012) [4-5].

Figure 6. Effect of bubble diameter on bubbly layer thickness

The model to predict the thickness of the bubbly layer relies on approximations of effective conductivity for gas-liquid mixture. To validate the applicability of effective medium approximations Monte-Carlo simulations have been performed. For this purpose, first spheres at a desired volume fraction are packed (Figure 3). The resulting domain between the spheres has been used to calculate the potential field via finite volume method. Simulation results have been compared to available correlations, such as Bruggeman’s relationship [6-7]. Preliminary results show that variations in bubble size distribution at constant overall bubble holdup do not have a substantial effect on the accuracy of the effective medium approximation [5].

0 0.5 1 1.5 2 2.5 30

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bub

[mm]

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mm

]

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Figure 7. Domain used in calculation of effective conductivity. Domain packed at gas phase volume

fraction of 40% for bubbles with an average bubble size of 76 microns.

As described above, a model based on tracking of single bubble has been developed. This model can predict the trends in the bubbly layer with great accuracy based on a given gas phase hold-up distribution. As next step, the model will be extended to track multiple bubbles, which will remove the need for assumed gas hold-up profile.

2. Formation of bubbles on electrode surface: A model based on the movement of the bubble-liquid interphase has been developed. The model takes into account the movement of the gas liquid interphase for a single bubble in a unit cell. The model for a single bubble will be extended to investigate the interaction of multiple bubbles on an electrode surface.

D. For Further Information Contact Mehmet Moralı at morali@wustl.edu

E. References [1] P. Boissonneau and P. Byrne, “An Experimental Investigation of Bubble-Induced

Free Convection in A Small Electrochemical Cell,” Journal of Applied Electrochemistry, vol. 30, no. 7, pp. 767–775, Jul. 2000.

[2] R. J. Balzer and H. Vogt, “Effect of Electrolyte Flow on the Bubble Coverage of Vertical Gas-Evolving Electrodes,” J. Electrochem. Soc., vol. 150, no. 1, pp. E11–E16, Jan. 2003.

[3] H. Vogt and R. Balzer, “The Bubble Coverage of Gas-Evolving Electrodes in Stagnant Electrolytes,” Electrochimica Acta, vol. 50, no. 10, pp. 2073–2079, Mar. 2005.

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[4] E. M. Moralı, P. A. Ramachandran and M. P. Duduković, “Prediction of Gas Phase Hold-up in a Narrow Electrochemical Channel”, in Preperation

[5] E. M. Moralı, “Gas-Liquid interaction in a Narrow Electrochemical Channel”, St. Louis, Fall 2012, Dissertation in Preparation

[6] D. A. G. Bruggeman, “Berechnung verschiedener physikalischer Konstanten von heterogenen Substanzen. I. Dielektrizitätskonstanten und Leitfähigkeiten der Mischkörper aus isotropen Substanzen,” Ann. Phys., vol. 416, no. 7, pp. 636–664, 1935.

[7] D. A. G. Bruggeman, “Berechnung verschiedener physikalischer Konstanten von heterogenen Substanzen. II. Dielektrizitätskonstanten und Leitfähigkeiten von Vielkristallen der nichtregulären Systeme,” Ann. Phys., vol. 417, no. 7, pp. 645– 672, 1936.

F. Acknowledgments This work was initiated by MELPRIN grand of the European Research Consul (ERP). We would like acknowledge the assistance and collaboration with Dr. A. Alexiadis and Dr. J. Wanngård.

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Optical Fiber Reflectance Probe for Detection of Supercritical Transition

A. Research Objective Making use of the fact that a transition from subcritical to supercritical state coincides with the change of the fluid from heterogeneous opalescent to homogeneous transparent state, we are able to design and manufacture an optical fiber probe to detect the reflected light which travels a certain known distance in the mixture and therefore carries information related to the transition. We can capture the changes in the light signal during in-situ detection in the methanol-cyclohexane (liquid-liquid) mixture as the system temperature is raised from below to above critical temperature at fixed pressure. Similarly, we can also capture the signal changes with pressure in the CO2-methanol (gas-liquid) system at different temperatures. These examples illustrate the applicability of the optical fiber probe in the detection of critical phase transition for multiple types of mixtures.

B. Research Progress The optical probe system used in this work consists of three optical fibers, as shown in Fig. 1. Fiber III (ø1035 µm) is coupled closely with fibers I and II (ø630 µm), which are connected to the laser source and the light detector, respectively. The other end of fiber III, with a small piece of mirror attached about 1~2mm away, is immersed in the mixture being studied. In this way, the light coming from the laser source can be transmitted to the mixture through fiber I and III, and then reflected back by the mirror to fiber III and sent back to the light detector through fiber II. The light signal can be converted to an analog signal by the detector, which can then be transferred to the data acquisition system and recorded by the computer.

Figure 1. Schematic for the optical fiber probe system

The light signal acquired by the detector consists of two parts, one reflected by the mirror and the other scattered by the mixture. The mirror is attached sufficiently close to the probe end ensuring that the reflected part dominates in the total signal. The “noisy” part of the signal due to contribution of scattered light is negligible compared to the intensity of the reflected light from the mirror. When a mixture is at subcritical state, there exist distinct interface boundaries between the two immiscible distinctly different phases. Under sufficient stirring, the interface boundaries are broken down into small pieces and distributed randomly throughout the heterogeneous mixture, resulting in strong fluctuation of light signals. During supercritical transition, when

67

interphase boundaries cease to exist, the mixture turns to homogeneous transparent state, thus the fluctuation of the light signal is greatly reduced at the same stirring rate. This disappearance of the fluctuations distinguishes the supercritical state from the subcritical state, and helps in determining the critical conditions.

C. Results and Discussion As the liquid mixture of methanol and cyclohexane is heated up to reach its critical temperature, the stirred mixture turns to homogeneous supercritical state, and thus a light signal change can be clearly captured. Fig. 2 shows in-situ data collected with 50% mole fraction of methanol. In the same way, critical temperatures of methanol-cyclohexane mixtures are determined at different compositions, and all agree well with previously obtained data, as shown in Fig. 3. At transition point we always find an abrupt rise in the signal. The reason for this change is as follows. In the subcritical methanol-cyclohexane mixture, the heterogeneity results in opalescence as shown in the left photo in Fig. 2. This opalescence increases the light scattering in the liquid, and this greatly reduces the reflectance since it blocks the path of reflected light and scatters it also. During supercritical transition, the mixture turns from heterogeneous opalescent to homogeneous transparent state, thus the reflected part of the light is enhanced while the scattered part is reduced. Since reflectance dominates in the signal, the entire signal increases sharply at transition. Critical pressure for CO2-methanol at different temperatures is determined similarly by the same reflectance probe. Fig. 4 shows a set of data collected at 25.2 oC. We can still see the disappearance of light intensity fluctuations during supercritical transition. However, the abrupt rise in the signal at transition, which was evident in Fig. 2 for the methanol-cyclohexane mixture, is clearly missing in Fig. 4 for the carbon dioxide-methanol mixture. The reason is that this initially heterogeneous gas liquid mixture consisting of small bubbles dispersed in the liquid has different optical properties and opalescence character than the methanol-cyclohexane mixture. Our probe can withstand high pressures as shown in Fig. 5, which suggests its applicability in many processes.

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Figure 2. In-situ light signal for methanol-cyclohexane mixture during supercritical transition

0.0 0.2 0.4 0.6 0.8 1.0

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Cri

tica

l T

em

pera

ture

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Our Experimental data (2011)

Original Data of Jones and Amstell (1930)

Figure 3. Critical temperatures for methanol-cyclohexane at different compositions

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Figure 4. In-situ light signal for CO2-methanol mixture during supercritical transition

24 28 32 36 4055

60

65

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tical P

ressure

, bar

Temperature, oC

Figure 5. Critical pressures for CO2-methanol at different temperatures

D. Conclusion A reflectance probe is developed in this work to detect the reflected light signal change during supercritical transitions of both methanol-cyclohexane and CO2-methanol system. This signal change can be coupled to the temperature or pressure recorder to determine the critical condition at interest.

E. Future Goals The reflectance probe has been proven effective for detecting in-situ supercritical transitions. It can be utilized in future work in real multiphase systems where phase transition is relevant, such as reactions enhanced by CO2 expanded liquids.

F. For Further Information Contact Yujian Sun at yujian.sun@wustl.edu

0 20 40 60 80 100 1200

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G. Reference Mueller S. G., “Optical Measurements in Gas-Liquid Stirred Tanks”. Doctorate

Dissertation, Washington University in St. Louis, 2009

McHugh M. and Krukonis V. J., “Supercritical Fluid Extraction”. Butterworth-Heinemann,

Boston, 1994

Subramaniam B. and McHugh M., “Reactions in Supercritical Fluids - A Review”. Ind.

Eng. Chem. Process Res. Dev., 1986, 25, pp. 1-12

Jessop P. G. and Subramanian B., “Gas - Expanded Liquids”. Chemical Reviews, 2007,

107, pp. 2666-2694.

Publication and Presentation Sun Y., Lee B. W., Mueller S. G. and Dudukovic M. P., Optical Fiber Reflectance Probe for

Detection of Supercritical Transition. AIChE Spring Meeting Proceedings, 2012

Sun Y., Optical Fiber Reflectance Probe for Detection of Supercritical Transition. AIChE

Spring Meeting, Houston, 2012

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Projects by Visiting Researchers

Researcher Project Title Dr. Qiao Congzhen

Supported Ionic Liquid Phase Catalysis (SILPC)

Yanqing Hou

Engineering Analysis of Polycrystalline Silicon Deposition from SiHCL3

Yong Luo

Process Intensification: Reactive Distillation in a Rotating Packed Bed

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Supported Ionic Liquid Phase Catalysis (SILPC)

A. Problem Definition Ionic liquids (ILs), as neoteric media of unique properties, have gained tremendous attention in development of clean processes and catalytic technologies in recent years. The homogeneous (or bi-phase) catalysis involved in ILs usually offers the advantages of high catalytic activity and good selectivity. However, their widespread use in catalytic processes is still hampered by several practical drawbacks, such as the large amounts of expensive ILs being needed, product isolation and catalyst recovery. The Supported Ionic Liquid Phase Catalysis (SILPC), combines the benefits of ILs and heterogeneous catalysis, such as the design ability, good “solubility” of the catalytically active species, ease of handling, separation and recycling, and is expected to overcome drawbacks of ILs.

B. Research Objectives The overall objective of this project is to construct shape selective catalytic systems by composite formation of transition metal complexes as catalyst in ionic liquids itself which are covalently anchored on the surface of selected solid carriers. The reaction performances will be investigated in a fixed-bed reactor in continuous gas flow operation mode. This set-up can also be used for the determination of intrinsic kinetics on different catalysts. Simultaneously, multi-scale modeling of reaction and transport will be carried out to interpret the micro mechanisms of the intrinsic kinetic process and the specific shape selective catalysis, to probe the relationship between the textural properties of catalysts and the products formation rate, to establish the macro kinetic models for the catalyst pellets and for the whole packed bed.

1. Supported Ionic Liquid Composite Preparation: First, selected functional ionic liquids are synthesized. Appropriate carriers are selected (such as SBA, ZSM, MCM series, SiO2 gelatin, C-nanotube and polymers) to support functional ionic liquids by immersion, covalent anchoring or physical confinement or by encapsulation method. Those result in the so-called Supported Ionic Liquid Phase (SILP). Then, different catalytic active components targeting the desired reaction can be introduced into SILP.

2. Performance Test: Textural properties of carriers before and after the immobilization are characterized and the effect of their structure on desired reaction is examined.

3. Multi-scale Modeling: Generally, the SILPC materials are composed of three different parts, i.e. the porous support, the ILs (always a thin layer on the support surface), and the immobilized liquid phase complex catalyst. For scale-up of this heterogeneous application, both “thermodynamic” methods and Interstitial-scale modeling are needed to fully quantify the behavior of a single pore, single pellet and fixed bed reactor, thus requiring the multi-scale approach.

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C. Results and Discussion Complex of Magnetic ionic liquid and C-nanotube: Since C-nanotubes are of great interest in both academia and industry, here we show research performed on modification effect of magnetic ionic liquid to C-nanotube. Figure 1 shows the typical procedures for Magnetic ionic liquid and C-nanotube Complex preparation.

Figure 1. Preparation Procedures for Complex of Magnetic Ionic Liquid and C-nanotube

Figure 2 shows the characterization results of Magnetic ionic liquid and C-nanotube Complex. IR and TGA demonstrate the combination of C-nanotube with poly-IL. Raman indicates that [FeCl4]- may enter into the inner parts of the C-nanotube. And SEM investigation shows that the C-nanotube surfaces are smoother after the modifying of the poly-ILs.

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Figure 2. Characterization of Magnetic Ionic Liquid and C-nanotube Complex

Shape-selective propylene dimerization catalysis processes: Supported ionic liquid and Ni-based composite catalysts were used to investigate propylene dimerization performance in the heterogeneous semi-batch operation mode. Preliminary results show that various supported ionic liquid- Ni-based complexes of acetylacetone nickel on composite catalysts improve selectivity of 4-methylpentene and 2,3-dimethylbutene isomer. For example, using MCM-41 as support, improved selectivity of 4-methylpentene is 8.2 % and 2,3-dimethylbutene is 10.0% with respect to the homogeneous catalyst. As to SBA-15 as support, net increased selectivity of 4-methylpentene is 18.0 %. These results indicate that MCM-41 and SBA-15 support materials play the so-called shape-selective roles in the heterogeneous propylene dimerization catalysis process. Figure 3 shows the chemical mechanism for immobilization of ionic liquid on silica surface.

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Figure 3. Immobilization of ionic liquid on the silica surface

D. Future Goals The future work on this project will involve further investigation on surface species detection and the reaction mechanism analysis based on the intrinsic kinetic process. The micro-mechanism will be modeled, as well as transport and reacting flow in a catalytic packed bed, to provide the prediction for the macro-scale performance.

E. For Further Information Contact QIAO CONGZHEN at congzhenq@seas.wustl.edu or qiaocongzhen@163.com

F. References • E Yoda. Shape-selective dissociative adsorption of alcohols on 1-butyl-3-

methylimidazolium-exchanged mordenite zeolite. App Catal A: General, 2010, 375:230-235.

Immobilized ionic liquid

Cl-containing silicon alkyl N-methyl- imidazole

abundant hydroxide radicals

Support material

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• M Eichmann, W Keim, M Haumann, B U Melcher, P Wasserscheid. Nickel catalyzed dimerization of propene in chloroaluminate ionic liquids: Detailed kinetic studies in a

batch reactor. J Mol Catal A: Chemical, 2009, 314：42-48.

• Q Zhang，Y Deng. Recent advances in ionic liquid catalysis. Green Chem, 2011, 13:2619-2637.

• E öhsner, M J Schneider, C Meyer, M Haumann, P Wasserscheid. Challenging the scope of continuous, gas-phase reactions with supported ionic liquid phase (SILP) catalysts-Asymmetric hydrogenation of methyl acetoacetate. Appl Catal A: General, 2011,399: 35–41.

• N Y Chen, T F Degnan, C M Smith. Molecular Transport and Reaction in Zeolites-Design and Application of Shape Selective Catalysis. VCH Publishers Inc., New York, Weinheim 1994, ISBN 0-89573-765-5. 173~193.

G. Future research together with CREL members Ionic liquids phase droplets sizes distribution in bi-phase operation: such as ILs phase droplets dispersed in reactant phase in agitated tank reactor or in static mixer reactor, using laser and fiber optic probe techniques developed by CREL. This should provide the information on the evolution of the phase interfacial area with progress of reaction. Surface species detection for propylene catalytic dimerization on Supported Ionic Liquid Phase Composite Catalyst: the surface species of reaction involved are essential to judge chemical reaction mechanism and to establish intrinsic kinetic model, TAP, or TPA/D/R/O techniques of CREL can be adopted.

(Note: The experimental results reported in Part C come from the project conducted at Henan University, China. Correspondence to QIAO CONGZHEN, School of Chemistry and Chemical Engineering, Institute of Fine Chemistry and Engineering, Henan University, Kaifeng, China. 475001. E-mail: qiaocongzhen@henu.edu.cn)

H. Acknowledgment Financial support from Science and Technology Office of Henan Province is gratefully acknowledged.

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Engineering Analysis of Polycrystalline Silicon Deposition from SiHCl3

A. Problem Definition In response to the ever-increasing cost and diminishing supply of petroleum fuels, high-efficiency solar energy conversion to electricity has become the subject of intense attention because this process is environmentally friendly and is sustainable. Polycrystalline silicon is presently one of the best materials for solar cell applications in photovoltaic energy conversion (Hou et al., 2010). The Siemens process is the primary technology in production of polycrystalline silicon at present (Mukashev et al., 2009). A fundamentally based model is desirable to investigate the effect of operating variables on volumetric productivity and yield in order to minimize costs and compare the Siemens decomposer to other reactors. Recently, some researchers investigated the thermodynamics based on the minimum Gibbs free energy method (Chernyavsky and Ritov, 2009) and others suggested a transport phenomena model (del Coso et al, 2008). Improved fundamental models are always needed. The aim, therefore, of this project is on elucidating, based on fundamentals, the effect of temperature, pressure and feed Cl/H ratio on the silicon deposition yield and silicon deposition rate. We start with the thermodynamic equilibrium model, coupled with ideal flow assumptions, and add additional refinements as needed for quantification of the effect of various process variables on productivity and yield.

B. Research Objectives The objective of this project is to investigate the Si-Cl-H system thermodynamics and elucidate, as needed, the phenomena of heat, mass, and momentum transport in the Siemens reactor that affect the growth rate and yield. Quantitative knowledge is needed to assess the effect of temperature, pressure and feed Cl/H ratio on the silicon yield. Appropriate flow and transport models are needed to improve the fundamental understanding of the effect of velocity, pressure, temperature on the silicon surface, temperature on the wall, hydrogen feed molar fraction, rod diameter etc. on the silicon deposition rate. In order to achieve this objective, models are constructed sequentially in increased order of complexity as needed.

1. Thermodynamic Analysis: Equilibrium calculations are performed for a wide range of temperatures (1000K-1500K), pressure (0.1-0.6MPa) and flow ratios of H2 to SiHCl3 (1-50), (i. e. the range of Cl/H is from 0.03 to 3).

2. Well Mixed Gas Phase Model: The thermodynamic model can now be used to predict the maximum yield and best achievable deposition rate by assuming that the gas phase is well mixed, and that equilibrium is established at the surface temperature of the rods for each given rod temperature, Cl/H feed ratio and Si/Cl inlet and equilibrium ratio.

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3. Transport Phenomena Based Model: More sophisticated model that properly accounts for fluid flow, mass transfer to rods and heat transfer to rods and bell jar surfaces is needed if the Siemens decomposer’s ‘best performance’ based on model 2 above is superior to that of other reactors and/or is not being achieved in practice.

C. Results and Discussion Milestone 1 (Thermodynamic Analysis): The thermodynamics of Si-Cl-H system has been studied and the equilibrium phase composition and the parameters (temperature, pressure and feed Cl/H ratio) have been investigated. The silicon yield (x),(i. e. the fraction of incoming silicon that is deposited), is given by:

Here the subscript o and eq indicate feed conditions and equilibrium conditions respectively. The temperature, pressure and Cl/H ratio of the system determine the yield as illustrated in Figures 1 and 2. It is obvious that the silicon yield increases significantly with the deposition temperature up to 1400K and deceases with pressure. However the silicon yield begins to decrease when the temperature is higher than 1400K at 0.1MPa as evident from Figure 1.

Figure 2 provides the dependence of the equilibrium silicon yield on the feed molar ratio of H2 to SiHCl3 and pressure. It is evident that the silicon yield increases significantly when the pressure in the reactor decreases and the feed molar ratio of H2 to SiHCl3 increases. However, excessive big feed molar ratios increase the costs of separation. Moreover, the silicon deposition rate decreases because the process is limited by TCS at large hydrogen excess.

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Figure 8. Silicon yield vs. temperature at 0.1Mpa (1), 0.2MPa (2) at input molar ratio of 15

Figure 2. Silicon yield vs. input molar ratio at 0.1MPa (1), 0.2MPa (2) at 1400K

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Milestone 2 (Well Mixed Gas Phase Model): Siemens reactor has been the workhorse for the semiconductor grade silicon. The process uses a bell jar reactor containing pure silicon rods which are heated to about 1150 deg C by electrical heating through the rods (Figure 3). It is noted that the vessel walls are quartz and air cooled or stainless steel and water cooled. A mixture of TCS and hydrogen is introduced into the bell jar reactor and the gases react to deposit Si on the rods, which causes the rod diameter to grow from the initial "slim rod" diameter. The rods must be taken out by stopping the operation when the rod diameter grows to the final desired rod size. It is, therefore, semi-continuous process.

Figure. 3 Schematic of a Siemens Reactor

Maximum productivity can be obtained at the surface temperature of the rods. For any given flow-rate into the bell jar, that gives the maximum amount of silicon deposited per unit time. Divided by surface area of all silicon rods at that time provides the linear growth rate in micrometers per hour or minute. The growth rate is, therefore, a strong function of silicon rods external surface. At fixed temperature the growth rate will decay because silicon surface area grows unless flow rate is increased. To keep the growth rate up to the maximum as the rods grow one must increase the flow rate of the feed. The maximum deposition rate depends on the Cl/H ratio in the feed. A proper model for heating the rods electrically, and for radiation and convection of heat from the rods, needs to be established to assess the thermal efficiency of the process. Comparison of the predicted performance based on this model and actual data is essential to point out which additional effects should be modeled in more detail. Poorer performance indicates that full flow pattern, including forced jet induced and temperature gradients induced natural convection must be accounted for. This may also require accounting for full radiation heat transfer in the enclosure including absorption by the gas medium and mass transfer effects. Also heating and cooling of rods must be modeled to properly account for the ways in which temperature can be controlled.

Milestone 3 (Transport Phenomena Based Model): A transport phenomena based model based on COMSOL can be developed. A simplified model that illustrates the capability of this approach to assess the effect of fluid flow, transport and kinetics on reactor performance has been developed (Hou et al. 2012). The current CFD model is

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capable of modeling steady-state laminar flows for Reynolds numbers smaller than 3600. The transport parameters and the surface kinetics have been taken into account to illustrate their effect on the silicon growth rate in the model. The effect of parameters (velocity, hydrogen molar fraction etc.) on silicon growth rate has been examined. Attempts to tie the simplified model to the actual flow dynamics in the Siemens decomposer are in progress.

D. Future Goals The future work on this project will involve developing a fluid dynamic model of a fluidized bed reactor fed both with silane and chlorosilane and validate it through comparison with experimental data.

E. For Further Information Yanqing Hou houy@seas.wustl.edu or hhouyanqing@163.com

F. References • Y. Q. Hou, G. Xieet. al, "Production Technology of Solar-grade Polycrystalline Silicon"

Material Review,2010,24, 31-34.

• B. N. Mukashevet. al, "A metallurgical route to produce upgraded silicon and

monosilane",Solar Energy Materials & Solar Cells,2009, 93, 1785-1791.

• L. I. Chernyavsky and V.A. Ritov, "Thermodynamic Simulation of Silicon Deposition from

the Gas Phase of Si-H-Cl system", Inorganic Material, 2009, 45, 463.

• G. delCoso, C. delCanizo et. al. "Chemical Vapor Deposition Model of Polysilicon in a

Trichlorosilane and Hydrogen system", Jounal of the Electrochemical Society,2008,

155(6): D485-D491

• Yanqing Hou, Gang Xie, P. A. Ramachandran et. al. Transport Phenomena Model of

Polysilicon CVD from Trichlorosilane. Recently submitted.

Oral Presentations • Yanqing Hou, Gang Xie, P. A. Ramachandran et. al. Thermodynamics of Si-H-Cl

System and SiCl4 Recovery, CPTIC_2012 International conference, Shanghai, China. (March, 2012).

Journal Publications • Yanqing Hou, Gang Xie, P. A. Ramachandran et. al. Thermodynamics of Si-H-Cl

System in Siemens Process for manufacturing Polysilicon. Recently submitted. • Yanqing Hou, Gang Xie, P. A. Ramachandran et. al. Transport Phenomena Model of

Polysilicon CVD from Trichlorosilane. Recently submitted.

G. Acknowledgment Financial support from China Scholarship Council (No. 2011853026) is gratefully

acknowledged.

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Process Intensification: Reactive Distillation in a Rotating Packed Bed

A. Problem Definition The concept of process intensification (PI) was first defined by Ramshaw in 1995 at the 1st International Conference on Process Intensification in the Chemical Industry (Ramshaw C., 1995). The goal of PI is to make industrial processes faster, more efficient and better for the environment and achieve simultaneous reduction in capital cost as well as operating costs through reduced energy and raw materials consumption. Process intensification is achievable in general by equipment designed for PI and methods for PI which often involves multi-functionality, as shown in Fig. 1 (Stankiewicz et al., 2000).

Figure 1. Process intensification equipment and methods (Stankiewicz et al., 2000)

Recently, it was suggested to further enhance process intensification by combining the PI methods in the PI equipment. Reactive distillation in a rotating packed bed (RPB) is a good example of this idea. Reactive distillation combines chemical reaction and distillation in a single vessel to reduce capital and production costs. In a RPB, the gravitational field, which drives liquid flow in conventional packed bed, is replaced with a centrifugal field produced by a high speed rotor driven by a motor in a static casing. A RPB can achieve high volumetric mass transfer coefficients within a small volume of the contactor. Considerable size and investment reductions make it very desirable for space-limited and plant upgrade applications. A feasibility study of reactive distillation in a novel RPB for n-butyl acetate synthesis was conducted and it demonstrated that the RPB can be used effectively for reactive distillation (Chen et al., 2011). However, modeling work for this new technology is rare. It is the goal of this project to extend the fundamentally based mathematical models to improve the understanding of the effect of high gravity field in the RPB on the reaction rate and separation efficiency.

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B. Research Objectives The overall objective of this project is to establish the fundamentally based equations for modeling reactive distillation in a RPB.

C. Accomplishments and Future Work RPBs can be used for distillation with wire mesh packing in the rotor. It can also be used for reactive distillation (catalytic distillation) with both wire mesh packing and solid catalysts in the rotor instead of in tray columns. In this work, the catalytic reaction is assumed to occur on the outside surface of the catalysts.

1. Assumptions for Non-equilibrium Model (Rate- based model)

Figure 2. Schematic diagram of the RPB system

Schematic of the operation is shown above. The model is based on fundamental mass, species mass and energy balances. The current model is based on the well mixed compartments with counter-current vapor and liquid flow. Additional assumptions used are:

Packing is represented with the number of equivalent trays. Operation reaches steady state and system reaches mechanical equilibrium. The vapor-liquid interface in a given stage is assumed to be in thermodynamic equilibrium. The vapor and liquid bulk on each side of the interface are mixed perfectly. The reaction takes place only in the liquid phase between liquid reactants and dissolved gas reactants. Variation of temperature, concentration, velocity and holdup in the rotor the axial direction is negligible compared to the variation in the radial direction.

2. Selected Reaction System

The model is being tested on the following reaction system:

CH3COOH + C4H9OH CH3COOC4H9 + H2O 1 2 3(desired) 4

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Assumed that the number of NT =10 (Rectifying section: 2; RD section: 5; stripping section:1; condenser:1; reboiler:1) (According to the distillation experiment with an acetone–water system, the RPB has a NT of 4.94–11.57 with a packing thickness of 200 mm (Chen et al., 2012)); Number of components is 4.

3. Needed Conservation Equations:

Vapor and liquid phase material balance. Energy balance for vapor and liquid phase. Transfer rate model from vapor to interface and from liquid to interface. Phase equilibrium equations at each interface. Rate form in the liquid phase.

4. Fortran Code Used to Solve Non-linear Model Equations

Figure 3. Flow chart of algorithm

In this modeling work, a fully rate-based model for reactive distillation in a RPB which reflects the coupling of the kinetics and transport phenomena has been implemented. The benefit of this work is to provide a fundamental approach for the design work of a promising system. For future work, there is a need to provide some experiments to verify these simulation results. An additional model based on application of differential mass balances will be developed for execution of catalytic distillation when reaction occurs on the catalyst surface.

D. For Further Information Contact Yong Luo at luoyong980@gmail.com

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E. References Stankiewicz, A. Process Intensification: Transforming Chemical Engineering. Chem. Eng.

Progress. 2000, 1, 22.

Lee, JK-H., Dudukovic, M.P. A Comparison of the Equilibrium and Nonequilibrium

Models for a Multicomponent Reactive Distillation Column. Comput. Chem. Eng.1998,

23, 159.

Taylor, R.; Krishna, R. Modelling Reactive Distillation. Chem. Eng. Sci. 2000, 55, 5183.

Shi, Q.; Zhang, P. Y.; Chu, G. W.; Chen, J. F.A New High Gravity Catalytic Reactive

Distillation Process for n-butyl Acetate Synthesis. J. Beijing. Univ. Chem. Technol. 2011,

38, 5.

Luo, Y.; Chu, G. W.; Zou, H. K.; Xiang, Y.; Shao, L.; Chen, J. F. Characteristics of a Two-

stage Counter-current Rotating Packed Bed for Continuous Distillation. Chem. Eng.

Process. 2012, 52, 55.

F. Acknowledgment The financial support from China Scholarship Council (NO. 2011688017) is gratefully

acknowledged.

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Appendix A:

Multiphase Reaction Engineering (MRE) Project: CREL Industrial Participation Plan

We created our Chemical Reaction Engineering Laboratory (CREL) about forty years ago to bridge academic research in reaction engineering and its industrial practice. Reaction engineering is the cornerstone of the chemical and process engineering field and is a required course everywhere. Multiphase reactors are used over all industrial sectors. Thus, it is necessary to educate new reaction engineers well in fundamentals as well as make them aware of the breadth of applications in different industries. The best way to accomplish this is by getting industrial practitioners involved in our academic efforts. CREL was created for that purpose as a unique entity for industry/academia interactions. CREL pools industrial and governmental resources for needed long-term fundamental research in reaction engineering, conducts such fundamental research, transfers the results to tools for industrial practice, and enriches the profession by new tools. This provides broad and in depth reaction engineering education and training both to students and industrial practitioners. Also it makes it possible for industrial participants to take a long term view and be actively involved in the development of new ideas, methods, techniques and tools. In the last few decades market globalization paradoxically reduced the need for

innovation in capital intensive process industries, as it almost guaranteed to those who were entrenched in the business increased profitability at low risk with old technology. As a result the in-house R&D effort in reaction engineering in process technology oriented companies has decreased. Yet, the scientific understanding of the phenomena that govern the performance of the reactors used in these technologies is still primitive, but the heuristics developed over decades provided some comfort that repeating the old designs for similar conditions will be successful and will not involve much risk. This resulted in a spurt of global licensing of “spruced up world war II technologies”. Unfortunately, this approach fails when new more active and selective processes need to be scaled-up. The reality is that the barrier to transferring any new bench scale observations to improved technologies lies most often in our incomplete understanding of transport-kinetic interactions which prevents a rational approach to reactor selection, design and operation. Only advances in the science of the multi-scale approach to reaction engineering can overcome these difficulties. Actually, reactors currently in operation are still not understood in terms of the quantitative description of the phenomena that govern their performance. Thus, they are ill-suited to deal with systems that are offering higher volumetric productivity and selectivity, which are the two key performance indices vital for proper implementation of green chemistry to environmentally friendly technologies. Research on improved quantification of transport –kinetic interactions is needed more than ever to achieve various means of process intensification.

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Forward looking companies strive to maintain a leading edge in their reaction engineering expertise and ensure a stable and reliable supply of expertise in the field. It is these companies that find our Multiphase Reaction Engineering (MRE) Project attractive and helpful.

The Project on Multiphase Reaction Engineering (MRE) represents an open ended multi-year research commitment to advancing the methodology for quantification, modeling, scale-up and design of multiphase reaction engineering systems. This increased knowledge base is used then to generate novel tools for specific reactor type or specific technology. This research is pursued with faculty, research associates (post-doctoral candidates), Ph.D. graduate students, and undergraduates and with the involvement of industrial members when appropriate.

Advantages of MRE membership that CREL offers to industrial partners: The following are some of the benefits of MRE to industrial sponsors.

Continued access to and development of science based tools for multiscale analysis,

scale up and design of reaction systems

Interactions with new generation of reaction engineers educated to provide leadership

in the field over a broad sector of technologies.

Unique facilities for quantification of phase distributions flow and mixing in various

multi-phase contactors and development of improved fundamentally based multi-phase

reactor models; validation of CFD codes for multiphase opaque systems.

Strong basis in gas to liquid fuels, renewable biomass to energy schemes, coal

conversion technologies; strong basis in silicon manufacture.

Continuous development of general reaction engineering expertise.

MRE PROJECT OBJECTIVES The objectives of the Project on Multiphase Reaction Engineering (MRE) are:

1) To advance the fundamental understanding and quantification of multi-scale-transport-kinetic interactions in various multiphase systems via graduate research and education. 2) To use this improved knowledge base in developing science based tools for scale up and design in order to ensure environmentally benign, energy and material efficient transformation of renewable and non-renewable resources to fuels, chemicals and materials over a wide spectrum of industries. 3) To facilitate the use of improved tools in industrial practice and reduce the risk of adopting novel technologies.

MRE PROJECT INDUSTRIAL PARTICIPATION PROGRAM Industrial organizations become members of the MRE Project through CREL by

signing the MRE Project Agreement for the yearly participation, from July 1 of each year to June 30 of the following year, and pay the annual membership fee of $25,000. (Sample agreement is available upon request)

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Becoming a participant in the MRE Project of CREL entitles the company to appoint one technical representative (advisor) who serves on the CREL advisory board for the MRE Project.

To advance the MRE Project objectives listed above the CREL faculty identifies critical areas in multiphase reaction engineering related to specific reactor types (e.g. bubble columns, trickle beds, fluidized beds, risers, etc.), specific processes (e.g. alkylation, oxidation, hydrogenation, enzyme reactions, gas to liquid conversion, etc.) and/or novel reactors (e.g. catalytic distillation, micro/mini-reactors, etc.) in which methodical application of scientific principles, as advocated by CREL, can have a significant impact on the technology. In addition, industrial members pass to CREL faculty ideas for needed long term research projects and these augment the list prepared by CREL faculty. All these topics form the pool from which student research projects are selected annually in discussion with the advisory board. Continuity of the chosen research projects is maintained via Ph.D. theses work. A specific research project is selected for direct support from the industrial funds committed to the MRE Project based on intellectual merit, aptitude and capabilities of the available graduate students, interest of the faculty, and opportunity for future government funding or other leveraging of resources. The suggestions are made by the CREL director and discussed and approved by the advisory board.

The MRE Project general membership industrial funds are used to support the graduate students working on the specific agreed upon topics. In addition, they support the key CREL infrastructure related to the Project. These funds are also used to support the work that complements studies done with other funding on related topics.

Topics of specific interest to a participating company are funded by a separate research agreement between that company and WUSTL and the terms are negotiated separately from the agreement for the MRE Project. All research products remain the intellectual property of CREL.

Other involvements of MRE technical advisors and benefits to sponsors are: i) Technical advisors act as liaisons between their company and CREL. They

review CREL’s activities semi-annually, attend its annual meeting, and distribute its annual technical research results and reports to their colleagues. They pass to CREL faculty their company’s ideas to be considered for long term research projects. The technical advisors and members from the companies may become the students’ theses co-advisors or the students' theses committee members. The MRE research topics supported by the MRE Project through CREL members and by the federal agencies produce research results which are shared immediately with all the sponsors and then later on via theses and publications with the general public. Participating companies have the option of having students execute part of their research on their premises and certainly have the best opportunity to hire these individuals upon completion of their degrees.

ii) Graduate students involved on MRE research projects are encouraged to seek industrial internships at sponsor companies in the areas of their research.

iii) CREL does provide consulting and research contract work only for participating companies. The nature and results of this work are kept proprietary, and

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the reports are only given to the sponsoring company. It is the task of technical advisors to identify areas in which CREL can contribute to their company via research contract work. CREL’s unique experimental facilities are accessible only to participating companies.

iii) CREL also provides education and training in various aspects of reaction engineering for industrial sponsors, either at Washington University or on companies’ premises.

iv) CREL is always prepared to undertake joint research projects with a consortium of industrial sponsors with or without federal funding.

Supporting Specific Doctoral (or Master) Theses A company may fund a specific research topic of interest as a doctoral (or a

Master) thesis by signing a separate research agreement from that of MRE Project agreement. A separate budget is agreed upon, depending on the scope of work, with three year guaranteed minimum. In this case, in addition to the interaction avenues described in i) through iv) above, this avenue guarantees a Doctoral (or Master) thesis on the topic of direct interest to the sponsor. Proprietary information received form the sponsors can be protected by NDA signed by university personnel involved. Some selected results based on proprietary sponsor information can remain. The representative of the company is appointed as graduate student co-advisor or graduate student committee member. Research can be conducted at CREL or at company premises.

Also a group of companies may support and fund a specific project that generates a number of theses for in-depth study of special topics of interest to them. The needed funding varies and is determined in consultation with companies’ representatives and depends on the scope and magnitude of the project and work to be done.

Relationship of Industry, Government and MRE-CREL Since CREL’s major products are research results, technical and scientific consultations, recommendations and well trained graduates, and industry is the main customer for these products, the MRE industrial participation plan provides a unique opportunity for industry to affect the products it is about to receive. Benefits to participating companies are many and are not limited to:

leveraging of industrial resources,

networking with universities, national laboratories and companies,

providing long term research goals for MRE project,

early review of MRE research results and graduates,

opportunity to gain rights to MRE results, expertise and discoveries,

having an input for selection for CREL future theses projects,

opportunity to co-advise graduate students and serve on graduate theses committees as

adjunct faculty,

opportunity to subcontract work to proven university personnel at CREL,

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having CREL personnel available for short and long term contract work and consultation

for projects distinct from MRE goals,

opportunity to do joint research with CREL,

having access to unique facilities,

educational and training courses provided by CREL,

access and recruitment of high quality graduates.

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Appendix B: CREL List of Publications (2005-2012) (2005-Present, 102 published to date) (225 Publications since 1997) 1. Comparison between CFD calculations of the flow in a rotating disk cell and

Cochran/Levich equations. Alexiadis, A., Cornell, A., Dudukovic, M.P., J. Electroanal. Chem. Mar 2012;669:55-66.

2. The Flow Pattern in Single and Multiple Submerged Channels with Gas Evolution at the Electrodes. Alexiadis, A., Dudukovic, M.P., Ramachandran, P., Cornell, A., Wanngard, J., Bokkers, A., Int. J. Chem. Eng. 2012.

3. On the measurement of gas holdup distribution near the region of impeller in a gas-liquid stirred Rushton tank by means of gamma-CT. Kong, L.N., Li, W., Han, L.C., Liu, Y.J., Luo, H.A., Al Dahhan, M., Dudukovic, M.P., Chemical Engineering Journal. Apt 2012;188:191-198.

4. Computational Modeling of Trickle Bed Reactors. Kuzeljevic, Z., Dudukovic, M.P., Ind. Eng. Chem. Res., 51(4), 1663-1671, 2012.

5. TAP Study of Adsorption and Diffusion of 2,2,4-Trimenthylpentane and 2,5-Dimethylhexane on beta and USY Zeolites. Nayak, S.V., Ramachandran, P.A., Dudukovic, M.P., Ind. Eng. Chem. Res., 51(4), 1570-1578,2012

6. From Laboratory to Field Tomography: Data Collection and Performance Assessment. Kuzeljevic, Z., Dudukovic, M.P., Stitt, H., Ind. Eng. Chem. Res., 50(17), 9890-9900, 2011.

7. Axial gas and solids mixing in a down flow circulating fluidized bed reactor based on CFD simulation. Khongprom, P., Aimdilokwong, A., Limtrakul, S., Vatanatham, T., Ramachandran, P.A., Chem. Eng. Sci., 73, 8-19, 2012.

8. Relationship between size of oil droplet generated during chemical dispersion of crude oil and energy dissipation rate: Dimensionless, scaling, and experimental analysis. Mukherjee, B., Wrenn, B.A., Ramachandran, P., Chem. Eng. Sci., 68(1), 432-442, 2012.

9. The Y-Procedure methodology for the interpretation of transient kinetic data: Analysis of irreversible adsorption. Redekop, E., Yablonsky, G., Constales, D., Ramachandran, P., Pherigo, C., Gleaves, J., Chem. Eng. Sci., 66(24), 6441-6452, 2011

10. Conversion of Methane and Carbon Dioxide to Higher Value Products. Vesna Havran, Milorad P. Dudukovic, and Cynthia S. Lo. Ind. Eng. Chem. Res., 50(12), 7089-7100, 2011.

11. On the Gradient Diffusion Hypothesis and Passive Scalar Transport in Turbulent Flows. Daniel P. Combest, Palghat A. Ramachandran, and Milorad P. Dudukovic. Ind. Eng. Chem. Res., Articles ASAP (As Soon As Published), May 4th 2011.

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12. Liquid–gas flow patterns in a narrow electrochemical channel. Alexiadis A., Dudukovic M.P., Ramachandran P., Cornell A.,Wanngård J., Bokkers A., Chem. Eng. Sci., 66(10), 2252-2260, 2011.

13. On the electrode boundary conditions in the simulation of two phase flow in electrochemical cells. Alexiadis A., Dudukovic M.P., Ramachandran P. A., Cornell A., Wanngård J., Bokkers A., International Journal of Hydrogen Energy, 36(14), 8557-8559, 2011.

14. γ-CT measurement and CFD simulation of cross section gas holdup distribution in a gas–liquid stirred standard Rushton tank. Liu Y., Li W., Han L., Cao Y., Luo H., Al-Dahhan M., Dudukovic M.P., Chem. Eng. Sci., In Press, Corrected Proof, Available online, 2011.

15. Gas holdup in gas−liquid stirred tanks. Mueller, S.G., Dudukovic M.P., Ind. Eng. Chem. Res., 49 (21), 10744-10750, 2010.

16. Development of fluidized bed reactors for silicon production. Filvedt W.O., Javidi M., Holt A., Melaaen M.C., Marstein E., Tathgar H., Ramachandran P.A., Solar Energy Materials & Solar Cells, 94, 1980-1995, 2010.

17. Tapered Element Oscillating Microbalance (TEOM) Studies of Isobutane, n-Butane and Propane Sorption in β- and Y-zeolies, Gong, K., Subramaniam, B., Ramachandran, P. A., Hutchenson, K. W., AIChE J., 56(5), 1285-1296, 2010.

18. Solution Strategy for film model for non-isothermal gas-liquid reactions. Limtrakul S., Kongo A., Ramachandran P.A., Chem. Eng. Sci., 65, 4420-4431, 2010.

19. Tailoring oxygen distribution in 300mm Czochralski crystal of pure silicon using CUSP magnetic field. Gunjal P. R. and Ramachandran P. A., Progress in Computational Fluid Dynamics, 5(6), 307-318, 2010.

20. Reaction engineering: Status and future challenges. Dudukovic, M.P., Chem. Eng. Sci.

65(1). 3–11, 2010. 21. Solids flow models for gas-flowing solids-fixed bed contactors. Nikacevic, N. M,

Dudukovic, M.P., Int. J. Chem. Reactor Eng. 8(8), 55, 2010. 22. Capillary reactor for cyclohexane oxidation with oxygen. Jevtic, R., Ramachandran, P.A.,

Dudukovic, M.P., Chem. Eng. Res. Des. 88(3), 255–262, 2010. 23. Frontiers in Reactor Engineering. Dudukovic, M.P., Science 325(5941), 698–701, 2009. 24. Adsorption/desorption studies of 224-trimethylpentane in beta-zeolite and mesoporous

materials using a tapered element oscillating microbalance (TEOM). Gong, K., Shi, T., Ramachandran, P.A., Hutchenson, K.W., Subramaniam B., Ind. Eng. Chem. Res. 48(21), 9490–9497, 2009.

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25. Effect of oxygen on cyclohexane oxidation: a stirred tank study. Jevtic, R., Ramachandran, P.A., Dudukovic, M.P., Ind. Eng. Chem. Res. 48(17), 7986–7993, 2009.

26. Tortuosity model for fixed beds randomly packed with identical particles. Lanfrey, P.Y.,

Kuzeljevic, Z.V., Dudukovic, M.P., Chem. Eng. Sci. 65(5), 1891-1896, 2009. 27. Transport and sorption studies in beta and USY zeolites via temporal analysis of

products (TAP). Nayak, S.V., Morali, M., Ramachandran, P.A., Dudukovic, M.P., J.Cat., 266(2), 169–181, 2009.

28. Modeling of key reaction pathways: zeolite catalyzed alkylation processes. Nayak, S.V.,

Ramachandran, P.A., Dudukovic, M.P., Chem. Eng. Sci. 65(1), 335-342. 2009. 29. Polysilicon production: reaction engineering and scaleup issues, Ramachandran, P.A.,

ECS Trans., 18(1) 915-924, 2009. 30. Comparison of boundary collocation methods for singular and non-singular

axisymmetric heat transfer problems. Ramachandran, P.A., Gunjal, P.R., Eng. Analysis with Boundary Elements, 33(5), 704–716, 2009.

31. Impact of internals on the gas holdup and bubble properties of a bubble column.

Youssef, A.A., Al-Dahhan, M.H., Ind. Eng. Chem. Res., 48(17) 8007-8013, 2009. 32. Challenges and innovations in reaction engineering. Dudukovic, M.P., Chem. Eng.

Comm., 196, 152-266, 2009. 33. Solids flow pattern in gas-flowing solids-fixed bed contactors: part I experimental.

Nikacevic, N.M., Petkovska, M., Dudukovic, M.P., Chem. Eng. Sci., 64(10), 2501-2509, 2009.

34. Solids flow pattern in gas-flowing solids-fixed bed contactors: part I mathematical

modeling. Nikacevic, N.M., Petkovska, M., Dudukovic, M.P. Chem. Eng. Sci., 64(10), 2491-2500, 2009.

35. Computed tomographic investigation of the influence of gas sparger design on gas

holdup distribution in a bubble column. Ong. B.C., Gupta, P., Youssef, A., Al-Dahhan, M.H., Dudukovic, M.P. Ind. Eng. Chem. Res., 48(1), 58-68, 2009.

36. Evaluation of large eddy simulation and Euler-Euler CFD models for solids flow dynamics

in a stirred tank reactor. Guha, D., Ramachandran, P.A., Dudukovic, M.P., Derksen, J.J. AIChE J., 54(3), 766-778, 2008.

37. Effect of operating pressure on the extent of hysteresis in a trickle bed reactor.

Kuzeljevic, Z.V., Merwe, W., Al-Dahhan, M.H., Dudukovic, M.P. Ind. Eng. Chem. Res. 47(20), 7593-7599, 2008.

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38. Comparison of boundary collocation methods for singular and non-singular axisymmetric heat transfer problems, Ramachandran, P.A., Gunjal, P.R., Eng. Analysis with Boundary Elements, 33(15), 704-716, 2008.

39. A comparison of alternating minimization and expectation maximization. Varma, R.,

Bhusarapu, S., O’Sullivan, J.A., Al-Dahhan, M.H., Meas. Sci. and Tech., 19, 1-13, 2008.

40. Modeling of trickle-bed reactors with exothermic reactions using cell network approach. Guo, J., Jiang, Y., Al-Dahhan, M.H., Chem. Eng. Sci., 63(3), 751-764, 2008.

41. Local characteristics of hydrodynamics in draft tube airlift bioreactor. Luo, H.P., Al-

Dahhan, M.H., Chem. Eng. Sci., 63(11), 3057-3068, 2008.

42. Bubble velocity, size, and interfacial area measurements in a bubble column by four-point optical probe. Xue, J., Al-Dahhan, M.H., Dudukovic, M.P., Mudde, R.F., AIChE J., 54(2), 350-363, 2008.

43. Effect of hydrodynamic multiplicity on trickle bed reactor performance. van der Merwe,

W., Nicol, W., Al-Dahhan, M.H., AIChE, J., 54(1), 249-257, 2008.

44. Effect of shear on performance and microbial ecology of continuously stirred anaerobic digesters treating animal manure. Hoffman, R., Garcia, M.L., Vesvikar, M., Karim, K., Al-Dahhan, M.H., Angenent, L.T., Biotech. and Bioeng., 100(1), 38-48, 2008.

45. Enhancing water removal from whole stillage by enzyme addition during fermentation.

Henriques, A.B., Johnston, D.B., Al-Dahhan, M.H., Cereal Chem., 85(5), 685-688, 2008.

46. Bubble dynamics investigation in a slurry bubble column. Wu, C., Suddard, K., Al-Dahhan, M.H., AIChE J., 54(2), 1203-1212, 2008.

47. Digestion of sand-laden manure slurry in an upflow anaerobic solids removal (UASR)

digester. Karim, K., Hoffman, R., Al-Dahhan, M.H., Biodegradation, 19(1), 21-26, 2008.

48. Four-point optical probe for measurement of bubble dynamics: Validation of the technique. Junli Xue, Muthanna Al-Dahhan, M.P. Dudukovic, R.F. Mudde, Flow Measurement and Instrumentation, 19(5), 293-300, 2008.

49. Coupling exothermic and endothermic reactions in adiabatic reactors. R.C.

Ramaswamy,P.A. Ramachandran, M.P. Duduković, Chemical Engineering Science, 63(6), 1654-1667, 2008.

50. An internet-based distributed laboratory for interactive ChE education. Guo, J., Kettler,

D.J., Al-Dahhan, M.H., Chem. Eng. Ed., 41(1), 24-30, 2007.

51. Dynamical features of the solid motion in gas-solid risers. Bhusarapu, S., Cassanello, M., Al-Dahhan, M., Dudukovic, M., Trujillo, S., O’Hern, T.J., Int. J. of Multiphase Flow, 33(2), 164-181, 2007.

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52. Flow field of suspended solids in a stirred tank reactor by Lagrangian tracking. Debangshu Guha, P.A. Ramachandran, M.P. Dudukovic, Chemical Engineering Science, 62(22), 6143-6154, 2007.

53. Gas-lift digester configuration effects on mixing effectiveness, Karim, K., Thoma, G., Al-

Dahhan, M.H., Martin, R.E., Water Research, 41(14), 3051-3060, 2007.

54. Mass transfer effects during homogeneous 1-octene hydroformylation in CO2-expanded solvent: Modeling and experiments. Hong Jin, M.P. Dudukovic, P.A. Ramachandran, Bala Subramaniam, Chemical Engineering Science, 62(18-20), 4967-4975, 2007.

55. Measuring gas-liquid distribution in a pilot scale monolith reactor via an industrial

tomography scanner (ITS), Al-Dahhan, M.H., Kemoun, A., Cartolano, A.R., Roy, S., Dobson, R., Williams, J., Chem. Eng. J., 130(2-3), 147-152, 2007.

56. Using a fiber-optic probe for the measurement of volumetric expansion of liquids,

Mueller, S., Werber, J., Al-Dahhan, M., Dudukovic, M., I&EC Res., 46(12), 4330-4334, 2007.

57. Activity and stability of iron-containing pillared clay catalyst for wet air oxidation of

phenol, Guo, J., Al-Dahhan, M.H., Applied Catalysis, 299, 175-184 (2006). 58. CFD-based compartmental modeling of single phase stirred-tank reactors. Guha, D.,

Dudukovic, M. P., Ramachandran, P. A., Mehta, S., Alvare, J., AIChE Journal, 52(5), 1836-1846 (2006).

59. Gas adsorption in slurries containing fine particles: Review of models and recent

advances, Nedeltchev, S., Shaikh, A., Al-Dahhan, M., Chem. Eng. Tech., 29(9), 1054-1060 (2006).

60. Gas holdup in trayed bubble column reactors, Alvare, J., Al-Dahhan, M.H., I&EC

Research, 45(9), 3320-3326 (2006).

61. Gas-liquid mass transfer in a high pressure bubble column reactor with different sparger designs, Chem. Eng. Sci., 62(102), 131-139 (2006).

62. Heat transfer coefficients in a high-pressure bubble. Wu, C., Al-Dahhan, M.H., Prakash,

A., Chem. Eng. Scil, 62(1-2), 140-147 (2006).

63. Hydrodynamics of slurry bubble column during dimethyl ether (DME) synthesis: gas-liquid recirculation model and radioactive tracer studies. Chen, P., Gupta, P., Dudukovic, M.P., Toseland, B.A., Chem. Eng. Sci., 61(19), 6553-6570 (2006).

64. Identification of flow regimes in a bubble column based on chaos analysis of g-ray

computed tomography data, Nedeltechev, S., Shaikh, A., Al-Dahhan, M., Chem. Eng. Tech., 29(9), 1 (2006).

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65. Influence of different closures on the hydrodynamics of bubble column flows. Rafique, M.; Dudukovic, M. P., Chemical Engineering Communications, 193(1), 1-23 (2006).

66. Liquid phase mixing in trayed bubble column reactors, Alvare, J., Al-Dahhan, M.H.,

Chemical Engineering Science, 61(6), 1819-1835 (2006).

67. Liquid-phase tracer responses in a cold-flow counter-current trayed bubble column from conductivity prove measurements, Al-Dahhan, M.H., Mills, P.L., Gupta, P., Han, L., Dudukovic, M.P., Leib, T.M., Lerou, J.J., Chem. Eng. and Processing, 45(11), 945-953 (2006).

68. Measurement of gas hold-up distribution and digital color image reconstruction for

standard gas-liquid Rushton stirred tank with Cs-137 γ-CT, Liu, Y., Han. L., Lu, H., Al-Dahhan, M., Dudukovic, M.P., Gaoxiao Huaxue Gongcheng Xuebao, 20(4), 648-652 (2006).

69. Melt flow simulations of Czochralski crystal growth process of silicon for large crystals,

Gunjal, P., Kulkarni, S., Ramachandran, P.A., ECS Transactions, 3(4, High Purity Silicon 9), 41-52 (2006).

70. Mesophilic digestion kinetics of manure slurry, Borole, A.P., Klasson, K.T., Ridenour, W.,

Holland, J., Karim, K., Al-Dahhan, M.H., App. Biochem. Biotech., vol. 129-132, 887-896 (2006).

71. Methane production in a 100-L upflow bioreactor by anaerobic digestion of farm waste.

Borole, A.P., Klasson, K.T., Ridenour, W., Holland, J., Karim, K., Al-Dahhan, M.H. Applied Biochemistry and Biotechnology 129-132 887-896, (2006).

72. Phase distribution in an upflow monolith reactor using computed tomography, Al-

Dahhan, M.H., Kemoun, A., Cartolano, A.R., AIChE J 52(2), 745-753, (2006).

73. Recuperative coupling of exothermic and endothermic reactions, R.C. Ramaswamy, P.A. Ramachandran, M.P. Duduković, Chemical Engineering Science, 459-472, 61(2), 2006.

74. Solids flow mapping in a gas-solid riser: Mean holdup and velocity fields. Bhusarapu,

Satish; Al-Dahhan, Muthanna H.; Dudukovic, Milorad P., Powder Technology, 163(1-2), 98-123 (2006).

75. Anaerobic digestion of animal waste: Effect of mixing, K. Karim, K. Klasson, Thomas, R.

Hoffmann, S.R. Drescher, D.W. DePaoli, M.H. Al-Dahhan, Bioresource Technology, 96(14), 1607-1612 (2005).

76. Anaerobic digestion of animal waste: Effect of mode of mixing, K. Karim, R. Hoffmann, K.

Klasson, Thomas, M.H. Al-Dahhan, Water Res., 39(15), 3597-3606 (2005).

77. Boundary Element Method for Solution of Dispersion Models for Packed Bed Reactors. Ramachandran, P.A.. I&EC Res., 44(14), 5364-5372 (2005).

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78. Catalytic wet air oxidation of phenol in concurrent downflow and upflow packed-bed reactors over pillared clay catalyst, J. Guo, M.H. Al-Dahhan, Chemical Engineering Science, 60(3), 735-746 (2005).

79. Characterization of the hydrodynamic flow regime in bubble columns via computed

tomography, A. Shaikh, M.H. Al-Dahhan, Flow Measurement and Instrumentation, 16(2-3), 91-98 (2005).

80. Dynamic Modeling of Slurry Bubble Column Reactors, N. Rados, M.H. Al-Dahhan,M.P.

Dudukovic, Industrial & Engineering Chemistry Research, 44(16), 6086-6094 (2005).

81. Experimental investigation of the hydrodynamics in a liquid-solid riser, S. Roy, A. Kemoun, M.H. Al-Dahhan, M.P. Dudukovic, AIChE Journal, 51(3), 802-835 (2005).

82. Exothermic and endothermic reactions in simultaneous and sequential directly coupled

adiabatic reactors. Ramaswamy, R. C.; Ramachandran, P. A.; Dudukovic, M. P., World Congress of Chemical Engineering, 7th, Glasgow, United Kingdom, July 10-14, 2005.

83. Experimental Study of the Solids Velocity Field in Gas-Solid Risers. Bhusarapu, Satish; Al-

Dahhan, Muthanna H.; Dudukovic, Milorad P.; Trujillo, Steven; O'Hern, Timothy J., Industrial & Engineering Chemistry Research, 44(25), 9739-9749 (2005).

84. Flow distribution characteristics of a gas-liquid monolith reactor. Roy, S., Al-Dahhan,

M.H., Catalysis Today, 105(3-4), 396-400 (2005).

85. Flow pattern visualization in a mimic anaerobic digester using CFD, M. Vesvikar, M.H. Al-Dahhan, Biotechnology and Bioengineering, 89(6), 719-732 (2005).

86. Gas-lift reactor for hydrogen sulfide removal, Limtrakul, S., Rojanamatin, S.,

Vatanatham, T., Ramachandran, P.A., I&EC Research, 44(16), 6115-6122 (2005).

87. Gas-liquid flow generated by a Rushton turbine in stirred vessel: CARPT/CT measurements and CFD simulations, A.R. Khopkar, A.R. Rammohan, V.V. Ranade, M.P. Dudukovic, Chemical Engineering Science, 60(8-9), 2215-2229 (2005).

88. Laboratory experience in a bench-scale fermentor to produce bioethanol, a renewable

source of energy, A.B. Henriques, K. Karim, F. Mei, M.H. Al-Dahhan, Abstracts of Papers, 229th ACS National Meeting, San Diego, CA, United States, March 13-17, 2005.

89. Liquid saturation and gas-liquid distribution in multiphase monolithic reactors, T. Bauer,

S. Roy, R. Lange, M.H. Al-Dahhan, Chemical Engineering Science, 60(11), 3101-3106 (2005).

90. Mathematical modeling and simulation for gas-liquid reactors, Kongto, A., Limtrakul, S.,

Ngaowsuwan, K., Ramachandran, P.A., Vatanathan, T., Comp. & Chem. Eng., 29(11-12), 2461-2473 (2005).

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91. Modeling and simulation of the monolithic reactor for gas-liquid-solid reactions, Bauer, T., Guettel, R., Roy, S., Schubert, M., Al-Dahhan, M., Lange, R., Chem. Eng. Res. Des., 83(A7), 811-819 (2005).

92. Modeling Catalytic Trickle-Bed and Upflow Packed-Bed Reactors for Wet Air Oxidation

of Phenol with Phase Change, J. Guo, M.H. Al-Dahhan, Industrial & Engineering Chemistry Research, 44(17), 6634-6642 (2005).

93. Modeling of solid acid catalyzed alkylation reactors. Ramaswamy, R.C. Ramachandran, P.

A.; Dudukovic, M. P., International Journal of Chemical Reactor Engineering, 3 (2005).

94. Multicomponent Flow-Transport-Reaction Modeling of Trickle Bed Reactors: Application to Unsteady State Liquid Flow Modulation, M.R. Khadilkar, M.H. Al- Dahhan, M.P. Dudukovic, Industrial & Engineering Chemistry Research, 44(16), 6354- 6370 (2005).

95. Multiphase Flow Packed-Bed Reactor Modeling: Combining CFD and Cell Network

Model, Y. Jiang, J. Guo, M.H. Al-Dahhan, Industrial & Engineering Chemistry Research, 44(14), 4940-4948 (2005).

96. Numerical simulation of bubble columns flows: effect of different breakup and

coalescence closures, P. Chen, J. Sanyal, M.P. Dudukovic, Chemical Engineering Science, 60(4), 1085-1101 (2005).

97. Phase distribution in a high pressure slurry bubble column via a single source computed

tomography, N. Rados, A. Shaikh, M.H. Al-Dahhan, Canadian Journal of Chemical Engineering, 83(1), 104-112 (2005).

98. Recuperative coupling of exothermic and endothermic reactions. Ramaswamy, R. C.;

Ramachandran, P. A.; Dudukovic, M. P, Chemical Engineering Science, 61(2), 459-472 (2005).

99. Solids flow mapping in a high pressure slurry bubble column, Rados, N., Shaikh, A., Al-

Dahhan, M.H., Chem. Eng. Sci., 60(22), 6067-6072 (2005).

100. Solids motion and holdup profiles in liquid fluidized beds, S. Limtrakul, J. Chen, P.A. Ramachandran, M.P. Dudukovic, Chemical Engineering Science, 60(7), 1889-1900 (2005).

101. Study of liquid spreading from a point source in a trickle bed via gamma-ray tomography

and CFD simulation. Boyer, C.; Koudil, A.; Chen, P.; Dudukovic, M. P., Chemical Engineering Science, 60(22), 6279-6288 (2005).

102. Three-dimensional simulation of bubble column flows with bubble coalescence and breakup, P. Chen, M.P. Dudukovic, J. Sanyal, AIChE Journal, 51(3), 696-712 (2005).

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Appendix C: Doctoral and Masters Degrees Granted (1995 - present)

D. Combest, Interstitial-Scale Modeling of Packed-Bed Reactors, PhD 2012. M. Hamed, Hydrodynamics, Mixing, and Mass Transfer in Bubble Columns with Internals, PhD 2012. E. Redekop, Non-Steady-State Catalyst Characterization with Thin-Zone TAP Experiments, PhD 2011. Z. Kuzeljevic, Hydrodynamics of Trickle Bed Reactors: Measurements and Modeling, PhD, 2010 A. Yousef, Fluid Dynamics and Scale-Up of Bubble Columns with Internals, PhD 2010 B. Henriques-Thomas, Enhanced Water Removal from Whole Stillage by Enzyme Addition during Fermentation, PhD, 2009 S. Mueller, Optical Measurements in Gas-Liquid Stirred Tanks, PhD, 2009 S. Nayak, Transport in Nanoporous Zeolites Used in Alkylation Processes, PhD, 2009 R. Jevtic, The Effect of Oxygen on the Oxidation of Cyclohexane, PhD, 2008 R. Varma, Characterization of Anaerobic Bioreactors for Bioenergy Generation Using a Novel Tomography Technique, PhD, 2008 D. Guha, Hydrodynamics and Mixing in Single Phase and Liquid-Solid Stirred Tank Reactors, DSc, 2007 C. Wu, Heat Transfer and Bubble Dynamics in a Slurry Bubble Column for Fischer-Tropsch Alternative Fuels, PhD, 2007 L. Han, Hydrodynamics and Mass Transfer in a Slurry Bubble Column Reactor, DSc, 2007. A. Shaikh, Bubble and Slurry Bubble Column Reactors for Syngas to Liquid Fuel Conversion: Mixing, Flow Regime Transition, and Scale-Up, DSc, 2007. M. Vesvikar, Understanding the hydrodynamics and performance of anaerobic digesters, DSc, 2006. S. Roy, Phase distribution and performance studies of gas-liquid monolith reactor, DSc, 2006. F. Mei, Mass and energy balance for a corn-to-ethanol plant, MS, 2006. R. Ramaswamy, Steady state and dynamic reactor models for coupling exothermic and endothermic reactions, DSc, 2006. P. Kumar, Aerosol routes for synthesis of nanostructured magnetic oxides: characterization and transport behavior, DSc, 2005. S. Bhusarapu, Solids flow mapping in gas-solid riser, DSc, 2005. J. Guo, Catalytic wet oxidation over pillared clay catalyst in packed-bed reactors: Experiments and modeling, DSc, 2005. R. Hoffman, Effect of modeling on the performance of anaerobic digesters, MS, 2005. H. Luo, Analyzing and modeling of airlift photobioreactors for microalgal and cyanobacteria cultures, DSc, 2005. P. Chen, Fluid dynamic modeling of bubble column flows. DSc, 2004.

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B. Ong, Experimental investigation of bubble column hydrodynamics: Effect of elevated pressure and superficial gas velocity, DSc, 2003. E. Palmisano, Wetting efficiency of complex shape catalyst in trickle bed reactors, MS, 2003. N. Rados, Slurry bubble column hydrodynamics: Experimentation and modeling, DSc, 2003. P. Gupta, Churn-turbulent bubble columns: Experiments and modeling, DSc, 2002. J. Alvare, Gas holdup and liquid phase mixing in trayed bubble column reactors, MS, 2002. K. Balakrishnan, Singularity methods in trickle bed reactors, DSc, 2001. G. Bhatia, A reaction engineering analysis of charcoal formation in batch kilns, DSc, 2001. Y. Jiang, Flow distribution and its impact on performance of packed-bed reactors, DSc, 2000. A. Rammohan, Characterization of Flow Patterns in Stirred Tank Reactors, DSc, 2000. S. Roy, Quantification of Two-Phase Flow in Liquid Solid Risers, DSc, 2000. M. Roveda, Brominated Disinfection By-Product Formation During Ozonation of Bromide-Containing Waters, MS, 1999. Z. Xu, Toluene to benzyl chloride, DSc, 1998. M. Khadilkar, Performance studies of trickle bed reactors, DSc, 1998. S. Highfill, Liquid-solid mass transfer coefficient in high pressure trickle-bed reactor, MS, 1998. S. Degaleesan, Fluid dynamic measurements and modeling of liquid mixing in bubble columns, DSc, 1997. B. Sannaes, Slurry Bubble Columns, DSc, Trondheim Institute of Technology of the University of Norway Trondheim, 1997. R. Shepard, Carbon fibers for affordable polymeric composites, DSc, 1996. M. Kulkarni, Dynamics of asymmetric fixed-bed reactors: Coupling of exothermic and endothermic reactions, DSc, 1996. Q. Wang, Modeling of gas and liquid phase mixing with reaction in bubble column reactors, DSc, 1996. K. Ng, Gas Purification by Rotofilter, MS, 1996. S. Karur, Boundary Element and Dual Reciprocity Methods in Reaction Engineering, DSc, 1996. K. Kumar, Evaluation of Oxygen Releasing Materials for In Situ Bioremedial Processes, MS, 1996. M. Thomas, Quality control of batch chemical processes with application of autoclave curing of composite laminate materials, DSc, 1995.

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Appendix D: Experimental Facilities Most systems of interest are multiphase and opaque and, hence, special experimental techniques are needed to determine the flow pattern, mixing and phase distribution. CREL currently maintains seven laboratories, including one brand-new laboratory in the new engineering building, Brauer Hall, which is equipped with a walk-in fume hood. This 1052 ft2 laboratory will be operational at the end of summer 2010.

Below is a list of the available unique experimental facilities at CREL. For more details, please refer to the CREL website: http://crelonweb.eec.wustl.edu. Computer Automated Radioactive Particle Tracking (CARPT) Monitors velocity profiles and turbulent parameters of solids and/or liquids in gas-liquid, gas-solid, liquid-solid and gas-liquid-solid systems. (Temporarily not operational in anticipation of the move) Computed Tomographic Scanner (CT) Evaluates three dimensional density profiles in composites and in three phase reactors. Optical Probes for Bubble Dynamics and Phase Distribution Measurements Measures liquid level, phase transition, flow regime transition, local gas holdup, bubble size distribution, specific interfacial area, and bubble velocity in multiphase reactors over a range of pressures and temperatures. Borescopes & High Speed Photography Images the local dynamic processes occurring in a multiphase reactor to determine sizes and velocities of particles or bubbles within a reactor. Dynamic Pressure Transducers Monitors pressure fluctuations measurements for flow regime identification in different reactor types. Determines overall gas holdup via pressure difference measurements in bubble/slurry columns over a wide range of pressures. Heat Transfer Probes Measures both the local heat flux and the surface temperature of the probe simultaneously. Can be used in a variety of multiphase systems. Optical Oxygen Probe System for Mass Transfer Measurements Measures the dissolved oxygen concentration in a liquid phase for determination of the oxygen gas-liquid mass transfer coefficient. Gaseous Tracer Technique for Gas Dynamics and Overall Mass Transfer Coefficient Measurements

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Measures the gas phase mixing, the residence time distribution of the gas phase, and the mixing or dispersion parameter in a reactor model in multiphase reactors. Low Pressure Bubble /Slurry Bubble Column Laboratory Available in different acrylic column sizes (1 inch to 18 inch diameters), distributors, and internals High Pressure Bubble /Slurry Bubble Column Operates up to 175 psig at air superficial velocity of up to 50 cm/s, is 6 inches in diameter and 9 ft tall, and equipped with ports and windows along its height (9 ft) for probes (e.g., optical probes, conductivity probes, heat transfer probes, etc.) and pressure transducer measurements 2D Bubble Column Available for monitoring 2D flows with optical probes and cameras Liquid-Solid Riser Facility Available at 6 inch diameter and 9 ft high Gas-Solid Riser Available at 6 inch diameter and 30 ft high. Fluidized Bed Available at 18 inch diameter Trickle-Bed Reactor (TBR) Laboratory Consists of high pressure (1000 psig), atmospheric and high temperature facilities for studies of reactions and hydrodynamic parameters, such as liquid holdup, liquid-solid mass transfer, flow regime transition, pressure drop, and catalyst wetting efficiency in multiple sized pressure trickle-bed reactors Anaerobic Digesters Available in many different configurations that are mixed by different means such as biogas recirculation as air-lift type bioreactor, mechanical agitation slurry recirculation and liquid recirculation. Rotating Packed Bed (RPB) Employs centrifugal force as an adjustable drive for flow of liquid through a porous medium counter-currently to gas which is driven by pressure difference. High Pressure (up to 6000 psig) Slurry and Basket Reactors Available autoclave (1 liter) and atmospheric/high temperature (2 liters) slurry and basket reactors system for kinetics studies and catalyst evaluation.

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Mini Packed Bed Reactor System Available in 5 and 50 ml using titanium alloy to withstand the corrosion effects equipped with a gas chromatograph for reactor effluent analysis and HPLC pump, ISCO pump, and back pressure regulator for high pressure operation. Tubular Capillary Reactor Available in D=0.762 mm and D=2.159 mm with L~30 m at gas and liquid flow rates are in 0-100 cc/min and 0.001-12ml/min, respectively and pressures up to 10,000 psi. Parr® Stirred Tank Reactor Available in Hastalloy C and volume of 25 ml with a maximum pressure of 3,000 psi and temperature up to 350ºC. Remspec Reaction View and High Pressure Parr Autoclave Reactor Equipped with ATR-IR probe to identify the species present in the reactor and is 300 ml and made of Hastelloy to withstand corrosion effects. Chem-BET 3000 with TPD and TPR Features five flow methods of analysis: three temperature program analyses (TPR. TPO and TPD), pulse titration and physioadorption (BET surface area). Ozonation Reactor Set-Up Equipped with ozone generator for studies of waste water oxidation. LOR (Liquid Phase Oxidation Reactors) The equipment for this unique laboratory has been received and awaits installation. Virtual Control Laboratory Available HYSYS, Superpro and Aspen Plus based virtual control software for development of reactor control protocols. Analytical Equipment Gas Chromatographs (TCD, FID, PID and ELCD detectors) with auto sampling, Differential Refractometer, Mass Spectrometer, Atomic Absorption Spectrophotometry, Heat Pulse Anemometry, UV/VIS Spectrometer, FI-IR Infrared Spectrometer, Ph meter, Dissolved Oxygen meter, Ozonator, Fume Hoods, Shaking Table, Magnetic Stirrers, High Accuracy Electronic Scale, Ovens, Refrigerator.