isolation n-butane
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RREEPPUUPPLLIICC OOFF IIRRAAQQ MMIINNIISSTTRRYY OOFF HHIIGGHHEERR EEDDUUCCAATTIIOONN AANNDD SSCCIIEENNTTIIFFIICC RREESSEEAARRCCHH UUNNIIVVEERRSSIITTYY OOFF TTEECCHHNNOOLLOOGGYY BBAAGGHHDDAADD-- IIRRAAQQ
IIMMPPRROOVVEEMMEENNTT OOFF CCAATTAALLYYSSTTSS FFOORR HHYYDDRROOIISSOOMMEERRIIZZAATTIIOONN OOFF IIRRAAQQII LLIIGGHHTT NNAAPPHHTTHHAA
A THESIS SUBMITED TO THE DEPARTMENT OF CHEMICAL
ENGINEERING OF THE UNIVERSITY OF TECHNOLOGY IN A PARTIAL FULFILMENT OF THE REQUIREMENTS FOR
THE DEGREE OF MASTER OF SCIENCE IN CHEMICAL ENGINEERING
BY Muayad Mohammed Hasan
B.Sc. in CHEMICAL ENGINEERING
March, 2010
قـالوا سبحانك ال علم لنـا إال ما علمتنـا إنك
أنت العليم الحكيم
العظيم صدق اهللا
)32(سورة البقرة االية
CERTIFICATE
We certify that we have read this thesis entitled "Improvement of Catalysts for
Hydroisomerization of Iraqi Light Naphtha" by Muayad Mohammed
Hasan and as on Examining Committee examined the student in its contents and
that in our opinion it meets the standard of a thesis for the degree of Master of
Science in Chemical Engineering.
Signature: Signature:
Asst. Prof. Dr. Khalid A. Sukkar Asst. Prof. Dr. Shahrazad R. Raouf
(Supervisor) (Chairman)
Date: / / 2010 Date: / / 2010
Signature: Signature:
Asst. Prof. Dr. Wadood T. Mohammed Asst. Prof. Dr. Saba A. Ghani
(Member) (Member)
Date: / / 2010 Date: / / 2010
Approved for the University of Technology – Baghdad
Signature:
Prof. Dr. Mumtaz A. Zablouk
Head of Chemical Engineering Department
Date: / / 2010
SUPERVISOR CERTIFICATION
I certify that this thesis entitled:- "Improvement of Catalysts for
Hydroisomerization of Iraqi Light Naphtha" Presented by Muayad
Mohammed Hasan, was prepared under my supervision in a partial fulfillment
of the requirements for the degree of Master of Science in Chemical Engineering
at the Chemical Engineering Department, University of Technology.
Signature:
Name: Asst. Prof. Dr. Khalid Ajmi Sukkar
(Supervisor)
Date: / / 2010
In view of the available recommendations I forward this thesis for debate by the
Examination Committee.
Signature:
Name: Asst. Prof. Dr. Khalid Ajmi Sukkar
Deputy Head of Department of Chemical Engineering
Date: / / 2010
CERTIFICATION
This is to certify that I have read the thesis titled "Improvement of
Hydroisomerization Process to Produce High Octane Gasoline using
Modified Catalysts" and corrected any grammatical mistake I found.
The thesis is therefore qualified for debate.
Signature:
Name:
Date: / / 2010
Acknowledgment
I
Acknowledgment
First of all praise be to god Who give me patience, strength and the most
important thing: faith to continue...
I wish to present my sincere appreciation with deep respect to my
supervisor Dr. Khalid Ajmee Sukkar for his helpful efforts and advice
during my work.
My great gratitude is due to the Head and the staff of Chemical
Engineering Department of the University of Technology for their help
and assistance in providing facilities throughout this work.
My respectful regards to Mr. Bushier Yosuf Sharhan for his kindness and helpful efforts to making the characterization of my work.
Finally my grateful thanks are due to my wife for her encouragement and
support.
Summary
II
Summary
In the presented work hydroisomerization of Iraqi light naphtha (produced in Al-
Dura Refinery) has been investigated to produce isomers. Three types of catalysts
were prepared Pt/HY, Pt/BaY, and Pt/Al2O3 with
0.5wt% by impregnation with
hexachloroplatinic acid.
The catalytic unit was constructed from stainless steel and designed to carry out the hydroisomerization process. The fixed bed reactor dimensions were O.D 3cm, I.D 2cm, and 21cm high. All experiments were made at atmospheric pressure and reaction temperature of 230, 250, 270, 290, and 310°C, WHSV 1.5, 3, and 4.5h-1, under constant H2
/HC mole ratio of 4.
The results show that the conversion of the main light naphtha components (n-pentane, n-hexane, 2-methylpentane, and 3-methylpentane) increases with increase in reaction temperature and decreases with increase in weight hour space velocity. Also, it was noted that the selectivity to isomers increase with Pt/HY, Pt/BaY catalysts at low temperature and decrease at high temperature, while with Pt/AlR2ROR3R catalyst the aromatics products increase with increase in reaction temperature. Pt/HY catalyst gives higher selective isomerization than Pt/BaY catalyst which is
(95%) and (89%) respectively at 270°C, and (1.5 hr P
-1P). While, Pt/AlR2ROR3R catalyst
gives 64.7% as total conversion where 18% as aromatic products. The total
conversion for Pt/HY and Pt/BaY were about 50%. The following sequence for
isomerization selectivity was concluded as:
Pt/HY > Pt/BaY > Pt/AlR2ROR3R
Summary
III
A kinetic model was derived based on the present work results. Then, the kinetic
parameters such as K1, K2, Ko
, and activation energy (E) are calculated depending
on the present experimental work results.
The results of model show that the values of apparent activation energy
vary within a range of 22 and 23 kJ/mol for n-pentane, 20 to 24 kJ/mol for
n-hexane, and 15 to 17 kJ/mol for 3mp isomerization reactions. On the
other hand, the model pointed the reactivity order behaves as follows.
3-methylpentane > n-hexane > n-pentane
Derive an equations which are calculating the reaction rate constants (k1 and k2
)
parameters as follows:
k1= [(1+ Є) Ln – Єx]
Ciso = CA° [1- exp (- k1t) - [exp(-kR1Rt) – exp(-kR2Rt)]
Contents
IV
CONTENTS
Pages Subject
I Acknowledgments
II Summary
IV
Contents
VIII
Nomenclature
CHAPTER ONE : INTRODUCTION
1 1. 1 Introduction
3 1. 2 Aims of the Work
CHAPTER TWO: LITERATURE SURVEY
4 2. 1 Scope
5 2. 2 Gasoline Fuel and its Specifications
9 2. 3 Hydroisomerization Process
14
16 17
2. 3. 1 Catalysts for Hydroisomerization Process 2.3.1.1 Alumina 2.3.1.2 Zeolite
20 2.4 Previous Work
Contents
V
27 2.5 Catalysts Preparation
28 2.5.1 Impregnation
30 2.5.2 Calcination
30 2.5.3 Reduction
31 2.6 Catalysts Characterization
32 2.6.1 X-ray Diffraction (XRD)
32 2.6.2 Surface Area
33 2.6.3 Scanning Electron Microscopy (SEM)
CHAPTER THREE: EXPERIMENTAL WORK
34 3.1 Materials
37 3.2 Preparation of Modified Zeolites by Ion Exchange
37 3.2.1 Preparation of Barium- Zeolite
37 3.2.2 Preparation of HY- Zeolite
38 3.3 Catalysts Preparation
38 3.3.1 Preparation of Pt/ BaY and Pt/HY
38 3.3.2 Preparation of Pt/ ALR2ROR3
39
42
45
3.4 Experimental Unit
3.5 Procedure
3.6 Catalysts Characterization
Contents
VI
45
45 45 45
3.6.1 X-Ray Diffraction Analysis
3.6.2 Surface Area
3.6.3 Scanning Electron Microscopy (SEM) 3.6.4 Energy Dispersive X-Ray (EDAX) Analysis
CHAPTER FOUR: KINETIC ANALYSIS
46 4.1 Introduction
48 4.2 Model Development
51 4.3 Reactor Model
CHAPTER FIVE: RESULTS AND DISCUSSION
56 5.1 Characterization of Catalysts
56 5.1.1 X-ray Diffraction
57 5.1.2 Scanning Electron Microscopy (SEM) Analysis
58 5.1.3 Energy Dispersive X-ray (EDAX) Analysis
60 5.1.4 Surface Area
61 5.2 Effect of Operating Conditions
61
61
66
5.2.1 Effect of Temperature
5.2.1.1 Effect of Temperature on Conversion of light naphtha
5.2.1.2 Effect of Temperature on Total Conversion of light naphtha and Selectivity
Contents
VII
75
78
82
5.2.2 Effects of WHSV
5.2.3 Effect of Time
5.3 Results of Kinetic Study
CHAPTER SIX: CONCLUSIONS AND
RECOMMENDATIONS
90 6. 1 Conclusions
91 6. 2 Recommendations
92 REFERENCES
106 APPENDIX A (Volume Percent of Components)
118 APPENDIX B (Concentration of Components)
121 APPENDIX C (Conversion of Light Naphtha)
123 APPENDIX D (Reaction Rate Constants)
125 APPENDIX E (Percentage Selectivity and Conversion)
126 APPENDIX F (Sample of Calculation)
Nomenclature
VIII
Nomenclature Units
Definition Symbols
gm-mol/lit Concentration of Normal
Paraffins at any Time CRA
gm-mol/lit Initial Concentration of
Normal Paraffins CRARP
o
gm-mol/lit Concentration of iso-Paraffins CRiso
gm-mol/lit Concentration of Olefin CRN
( - ) integration constant A
mole/gcat. hr rate of reaction -rRA
hr Time T
K Temperature T
K Initial Temperature TP
o
hrP
-1 Weight Hour Space Velocity WHSV
( - ) Pre-Exponential Factor kRo
hrP
-1 Rate Constant for Paraffins kR1R
hrP
-1 Rate Constant for Olefins kR2
kJ/mole Activation Energy E
mole/hr Molar Flow Rate of
Component A FRA
mole/hr
Initial Molar Flow Rate of
Component A FRARP
o
Nomenclature
IX
atm-lit/gm-mol-K Gas Constant R
cmP
3 Volume of Reactor VRA
( - ) Conversion RX
cm Length of Reactor Zt
( - )
Integration Step for the Reactor
Length ∆z
Nomenclature
X
Abbreviations
Research Octane Number RON
Motor Octane Number MON
Reid Vapor Pressure RVP
American Society for Testing Materials ASTM
Methyl Tertiary-Butyl Ether MTBE
Universal Oil Product Company UOP
Butane Isomerization Unit BUTAMER
Mordenite MOR
iso-Pentane i-CR5
n-Pentane CR5
n-Hexane CR6
2-Methylpentane 2MP
3-Methylpentane 3MP
2,2-Dimethylbutane 2,2DMB
2,3-Dimethylbutane 2,3DMB
2,2-Dimethylpentane 2,2DMP
2,4-Dimethylpentane 2,4DMP
Chapter One Introduction
1
Chapter One Introduction
1.1
Introduction
The interest in improving the efficiency of the automotive motors
encourages the formulation of new catalysts and the development of
processes for gasoline.
Due to the environmental restrictions a reduction in allowable of lead
compounds levels and toxic compounds such as aromatics, in particular
benzene, olefin, sulfur-containing components in automobile gasoline
were imposed, as a result it forced refineries to implement new octane
enhancement projects.
Considering that branched-chain alkanes posses the greatest octane
numbers, the normal alkane's hydroisomerization is one of the most
effective project decisions in a direction favoring the least initial
investment approach as opposed to the best overall payout. The use of
gasoline containing higher content of these compounds is one alternative
to obtain clean fuel with high antiknock characteristics.
In order to increase the gasoline octane number, major petroleum
refineries used different units such as catalytic reforming, cracking,
alkylation, oligomerization, polymerization and isomerization
(hydroisomerization) [Benadda et al., 2003, Nattaporn and James, 2007].
It is important to mention here that the petroleum industry is looking for
economical solutions to meet new regulatory specifications for producing
environmentally clean fuels. Most of the implemented legislations require
Chapter One Introduction
2
a reduction and a limitation on the concentration of benzene in the
gasoline pool. This has increased the demand for high performance C5
and C6
naphtha isomerization technology because of its ability to reduce
the benzene concentration in the gasoline pool while maintaining or
increasing the pool octane.
Light paraffin isomerization has been used historically to offset octane
loss from lead-phase out and to provide a cost-effective solution to
manage benzene in motor fuels. In the current refining environment,
isomerate octane can be used to offset octane loss from MTBE phase-out
[Anderson et al., 2004]. Therefore, the hydroisomerization of light
naphtha (C5-C6
fractions) is an industrially important process and is used
in the production of high octane gasoline blend stocks. The process
involves the transformation (with minimal cracking) of the low octane
normal (and less branched) paraffin components into the high octane
isomers with greater branching of the carbon chain [Ravishankar and
Sivasanker, 1996, Andreas, 2003, Rachid et al., 2006, María et al., 2008].
In Iraq there is no clear strategies to reduce the demand for leaded
gasoline and aromatics (Benzene). Therefore, the hydroisomerization
units are regarded a good solution and a good start point strategy in
direction of clean fuels.
The metal– acid bifunctional catalysts, such as alumina or zeolite
supported Pt catalysts, are used in hydroisomerization of light paraffins
(n-pentane and n-hexane). It shows high efficiency in the isomerization of
alkanes. The isomerization of pentane and hexane is successfully carried
out using noble metals such as Pt- or Pd- supported on Al2O3, mordenite,
beta zeolite, and silicon catalyst. However, difficulties are encountered
with hydrocarbons larger than heptane because the cracking reaction
Chapter One Introduction
3
becomes more significant over these isomerization catalysts as the chain
length increases. So, some modification and pretreatment processes are
required to increase the catalyst activity, selectivity and life time [Takeshi
et al., 2003, Ping et al., 2009].
The literature mentions many studies which were focused to investigate
the hydroisomerization of n-paraffins [Liu et al., 1996, Chica and Corma,
1999, Yunqi et al., 2004, Salwa et al., 2007]. Few investigations have
used light naphtha as a feedstock for the process. On the other hand, many
authors made a kinetic study on the hydroisomerization unit for n-hexane
and n-heptane [Runstraat et al., 1997, Annemieke et al., 1997, Franciscus,
2002, Toshio, 2004, Matthew, 2008]. But only few studies dealling with
the hydroisomerization of light naphtha were published [Holló et al.,
2002, Carsten, 2006].
1.2
The main aims of the present work are:
Aims of the Work
1- Preparation of modified zeolites (BaY and HY) by ion exchange
method.
2- Preparation of Pt/ BaY and Pt/HY by impregnation method.
3- Study the hydroisomerization of Iraqi light naphtha over
bifunctional zeolite catalysts and test of the prepared catalysts
activity and selectivity under different operating conditions of
temperature, and WHSV.
4- To make a mathematical model to describe the reaction kinetics of
the hydroisomerization process.
5- To estimate kinetics parameters under different operating conditions
depending on the results of present experimental work.
Chapter Two Literature Survey
4
Chapter Two
Literature Survey 2.1 UScope
The hydroisomerization of light paraffins is an important industrial process to
obtain branched alkanes which are used as octane boosters in gasoline. Thus,
isoparaffins are considered an alternative to the use of oxygenate and aromatic
compounds, whose maximum contents are subjected to strict regulations in
order to protect the environment [Holló et al., 2002, Satoshi, 2003, Rafael et al.,
2005].
Hydroisomerization reactions are generally carried out over bifunctional
catalysts, often containing platinum. The metal component aids in increasing
the rate of isomerization, besides lowering catalyst deactivation.
The interest in the isomerization process is heightened with the phase out of
tetraethyl lead in 1970's, following the phase out of leaded gasoline due to the
introduction of clean air act amendments of 1990 in the USA and similar
legislation in other countries. Aromatics and olefin react with NORXR emission to
form ozone, thus contributing to smog formation [Maloncy et al., 2005].
Therefore, in many plants refineries have to minimize benzene yield. In Europe,
the aromatics content is limited since 2005 to content 35 vol% instead of 42
vol% and benzene to approximately zero level [Liu et al., 1996, Goodarz et al.,
2008].
There are various approaches in petroleum refineries to obtain high octane
number components, which include processes of cracking, reforming and
Chapter Two Literature Survey
5
isomerization. Catalytic cracking is the process for converting heavy oils into
more valuable gasoline and lighter products. The cracking process produces
carbon (coke) which remains on the catalyst particle and rapidly lowers its
activity. On the other hand, the catalytic naphtha reforming is the chemical
process which converts low octane compound in heavy naphtha to high-octane
gasoline components, without changing carbon numbers in the molecule. This
is achieved mainly by conversion of straight chain naphtha to iso-paraffins and
aromatics over a solid catalyst. The isomerisation (hydroisomerization) is the
chemical process which converts low octane compound in light naphtha to high
octane number components via rearrangement of the molecular structure of a
hydrocarbon without gain or loss of any of its components. [Ulla, 2003,
Northrop et al., 2007 ].
The most widely applied alkane isomerization catalysts are chlorinated alumina
supported platinum and zeolite supported Pt or Pd. Also there are many of
different catalysts in which the selectivity isomerization increases and the
cracking decreases [Rachid et al., 2006].
A comprehensive literature review is shown in this chapter to include: gasoline
specification, hydroisomerization process catalysts and characterization.
UGasoline Fuel and Its Specefications U 2.2 Gasoline is one of petroleum fuels that consists of 5 carbons to 11 carbons in
the hydrocarbon compounds. Actually, gasoline contains up to 500
hydrocarbons, either saturated or unsaturated hydrocarbons and other
compounds. Saturated hydrocarbon known as paraffin or alkane forms the
major component of low octane number gasoline. Unsaturated hydrocarbon
includes olefins or alkenes, isoparaffins or alkyl alkane, arenes or aromatics.
Chapter Two Literature Survey
6
Other compounds consist of alcohols and ethers [Lovasic et al., 1990, Carey,
1992].
Although there are several important properties of gasoline, the three that have
the greatest effects on engine performance are the Reid vapor pressure, boiling
range, and antiknock characteristics.
The Reid vapor pressure (RVP) and boiling range of gasoline govern ease of
starting, engine warm-up, rate of acceleration, loss by crankcase dilution,
mileage economy, and tendency toward vapor lock. Engine warm-up time is
affected by the percent distilled at 158°F (70°C) and the 90% ASTM distillation
temperature. Warm-up is expressed in terms of the distance covered to develop
full power without excessive use of the choke. Crankcase dilution is controlled
by the 90% ASTM distillation temperature and is also a function of outside
temperature [Takao, 2003].
The octane number of the gasoline depends on the number of branch carbon
atoms and the length of carbon atom chain. Octane number is a ratio of n-
heptane to iso-octane part by volume and commercially is between 60:40 and
40:60. n-heptane has octane number of zero while iso-octane has octane number
of 100. Higher octane rating is obtained by decreasing normal alkanes while
increasing iso-alkanes and cyclic hydrocarbons. Although unsaturated
hydrocarbons have desirable octane rating, for example acetylene, benzene and
toluene, they are toxic and their content in the gasoline should be reduced.
The octane number represents the ability of gasoline to resist knocking during
combustion of the air-gasoline mixture in the engine cylinder. Gasoline must
have a number of the other properties in order to function properly and to avoid
damage to the environment [Antos et al., 1995, Tore et al., 2007].
Chapter Two Literature Survey
7
Octane ratings in gasoline are conventionally boosted by addition of aromatic
and oxygenated compounds. However, as a result of increasingly stringent
environmental legislation, the content of these compounds in gasoline is being
restricted and thus industry has been forced to investigate alternative processes
to reach the required octane levels [Rafael et al., 2008].
There are several types of octane numbers for spark ignition engines with the
two determined by laboratory tests considered most common: those determined
by the ‘‘motor method’’ (MON) and those determined by the ‘‘research
method’’ (RON). Both methods use the same basic type of test engine but
operate under different conditions. The RON (ASTM D-908) represents the
performance during city driving when acceleration is relatively frequent, and
the MON (ASTM D-357) is a guide to engine performance on the highway or
under heavy load conditions.
The difference between the research and motor octane is an indicator of the
sensitivity of the performance of the fuel to the two types of driving conditions
and is known as the ‘‘sensitivity’’ of the fuel. On the other hand, the mean
average of RON and MON is named rating. [Chica et al., 2001, Goodarz et al.,
2008]. An overview of octane numbers of different hydrocarbons, given in
Table (2.1).
In the oil industry CR5R and CR6 Rparaffins are typically used in hydroisomerization
units to obtain high octane number components. Paraffins larger thanCR6R, such
as heptane are usually present in catalytic reforming feed streams and converted
into aromatic compounds [Maloncy et al., 2005] .
Chapter Two Literature Survey
8
Table (2.1): Octane number for different hydrocarbons [Goodarz et al.,
2008].
Compound
MON
RON
n-butane 89.6 93.8
Iso-butane 97.5 98.6
n-pentane 62.6 61.7
Iso-pentane 90.3 92.3
n-hexane 26 24.8
2-methyl pentane 73.5 73.4
3-methyl pentane 74.3 74.5
2,3-dimethyl butane 94.3 94.6
n-heptane 0 0
2-methyl hexane 46.4 42.4
3-methyl hexane 55.8 52
3-ethyl pentane 69.3 65
2,2-dimethyl pentane 95.6 92.8
2,4-dimethyl pentane 83.8 83.1
3,3-dimethyl pentane 86.6 80.8
Iso-octane 100 100
Chapter Two Literature Survey
9
UHydroisomerization ProcessU 2.3
One of the important targets in the petroleum industry is the production of
branched alkanes by skeletal isomerisation of n-alkanes using solid acid
catalysts. Environmental concerns are now promoting clean gasoline with high
research octane number (RON) and low content of aromatics such as benzene.
Isomerization of light straight run naphtha has the potential to satisfy these
requirements.
The isomerisation process is catalytic reactions that involve rearrangement of
the molecular structure of a hydrocarbon without gain or loss of any of its
components. This process uses light naphtha (CR5R-CR6R fractions) in the production
of high octane gasoline blend stocks. The process involves the transformation
(with minimal cracking) of low octane normal (and less branched) paraffin
components into high octane isomers with greater branching of the carbon
chain. These types of processes are usually accomplished by bifunctional
catalysts that have both metallic and acidic function [Ravishankar and
Sivasanker, 1996, Maha, 2007].
The refineries of petroleum in the world include hydroisomerization unit.
Figure (2.1) shows the position of hydroisomerization unit in a petroleum
refinery. It is important to mention here that many petroleum companies
designed hydroisomerization processes to produce high octane gasoline.
Chapter Two Literature Survey
10
Fig. (2.1) Location of hydroizomerization process in a modern petroleum
refinery [Ivanov et al.,2002].
Chapter Two Literature Survey
11
Figure (2.2) shows a representative flow scheme hydroisomerization unit for the
the Penex™ process which provides highly isomerized light naphtha products.
Figure (2.2) Penex Process Flow Scheme [Gary, 2001].
Figure (2.3) shows the other flow scheme hydroisomerization unit for the the
Penex DIH process. On the other hand, the Butamer™ process that is shown in
Figure (2.4) provides highly isomerized butane products.
Chapter Two Literature Survey
12
Figure (2.3) Penex DIH Process [Mikhail et al., 2001].
Figure (2.4) The Butamer™ process [Mikhail et al., 2001].
Chapter Two Literature Survey
13
The dual-functional catalysts used in these processes are platinum on chlorided-
alumina support. These types of catalysts offer the highest activity to take
advantage of higher thermodynamic equilibrium iso- to normal ratios
achievable at lower temperatures. In order to improve the performance of these
processes.
If the normal pentane in the reactor product is separated and recycled, the
product RON can be increased by about 3 numbers (83 to 86 RON) . If both
normal pentane and normal hexane are recycled the product clear RON can be
improved to about 87 to 90. Separation of the normals from the isomers can be
accomplished by fractionation or by vapor phase adsorption of the normals on a
molecular sieve bed. The adsorption process is well developed in several large
units.
On the other hand, it is important to mention here that the isomerization process
is called hydroisomerization because its reaction requires HR2R gas to prevent
deactivation of catalysts. In hydroisomerization process, some hydrocracking
occurs during the reactions resulting in a loss of gasoline and the production of
light gas. The amount of gas formed varies with the catalyst type and age and is
sometimes a significant economic factor. The light gas produced is typically in
the range of 1.0 to 4.0 wt% of the hydrocarbon feed to the reactor. The main
composition of these gases is methane, ethane and propane [Gary, 2001, Shi et
al., 2008].
Two types of hydroisomerization processes of alkanes were developed, having
different objectives and technologies [Satoshi, 2003]:
1. The isomerization of lower n-alkanes (CR5R-CR7R) for the production of high-
octane components and of n-CR4R to i-CR4R as feed for the production of
alkylate.
Chapter Two Literature Survey
14
2. The isomerization of the n-alkanes contained in paraffinic oils in
order to produce a significant decrease in the freezing temperature
and thus eliminate the need for dewaxing.
2.3.1 Catalysts of Hydroisomerization Process The first hydro- isomerization unit was introduced in 1953 by UOP, followed in
1965 by the first BP unit, while in 1970 the first Shell Co. hydro-isomerization
(HYSOMER) unit was started up. All these processes take place in the gas
phase on a fixed bed catalyst containing platinum on a solid carrier. In the late
1950s and early 1960s, chlorinated platinum loaded alumina was used as a
catalyst. The major advantage of this catalyst was its low temperature activity
(T< 200°C) due to its high acidity. However the catalysts were sensitive
towards water and oxygenates and in addition had corrosive properties.
Furthermore, chlorine addition during the reaction is necessary to guarantee
catalyst stability [Gary, 2001, Maciej et al., 2002, Yunqi et al., 2004].
In the Hysomer process zeolite based catalysts were used which had the major
advantage of resistance to feed impurities. Industrially applied zeolites used
today are Pt-containing, modified synthetic (large-port) mordernite e.g. HS10 of
UOP, or HYSOPAR from Süd- Chemie. As higher hydrogen to hydrocarbon
ratios are needed recycle compressors and separators are required for this
technology [Jens, 1982, Corma et al., 1995, Christian, 2005].
The isomerization of hydrocarbons < CR6R is currently carried out very
successfully using bifunctional supported platinum catalysts. However,
difficulties are encountered with hydrocarbons larger than hexane since the
cracking reactions become more significant over platinum catalysts as the chain
length increases [Cuong et al., 1995]. Catalysts used in state of the art
Chapter Two Literature Survey
15
isomerization-cracking reactors are bifunctional. They have a metal function
providing de-hydrogenation and hydrogen activation properties that are usually
supplied by group VIII noble metals like Pt, Pd, Ni or Co. The acid function is
the support itself and some examples include acid zeolites, chlorided alumina
and amorphous silica alumina. Noble metals have a positive effect on the
activity and stability of the catalyst. However they have a low resistance to
poisoning by sulfur and nitrogen compounds present in the processed cuts
[Busto et al., 2008].
In order to prepare a suitable catalyst for hydroconversion of alkanes, good
balance between the metal and acid functions must be obtained. Rapid
molecular transfer between the metal and acid sites is necessary for selective
conversion of alkanes into desirable products [Vagif et al., 2003].
Two of the attractive features of zeolite are that the catalysts are tolerant of
contaminants and that they are regenerable. The chlorinated alumina catalysts
are very sensitive to contaminants such as water, carbon oxides, oxygenates,
and sulfur. Thus, feeds and hydrogen must be hydrotreated and dried to remove
water and sulfur. Furthermore, the chlorinated alumina catalysts require the
addition of organic chloride to the feed in order to maintain their activities. This
causes contamination in the waste gas of hydrogen chloride, a scrubber is
needed to remove such contamination [Satoshi, 2003].
The UOP BenSat process uses a commercially proven noble metal catalyst,
which has been used for many years for the production of petrochemical-grade
cyclohexane. The catalyst is selective and has no measurable side reactions.
Because no cracking occurs, no appreciable coke forms on the catalyst to
reduce activity. Sulfur contamination in the feed reduces catalyst activity, but
the effect is not permanent. Catalyst activity recovers when the sulfur is
removed from the system [Meyers, 2004].
Chapter Two Literature Survey
16
2.3.1.1 Alumina Alumina or aluminum oxide (AlR2ROR3R) is a chemical compound with melting
point of about 2000°C and sp. gr. of about 4.0. It is insoluble in water and
organic liquids and very slightly soluble in strong acids and alkalies. Alumina
occurs in two crystalline forms. Alpha alumina is composed of colorless
hexagonal crystals with the properties given above; gamma alumina is
composed of minute colorless cubic crystals with sp. gr. of about 3.6 that are
transformed to the alpha form at high temperatures. Figure (2.5) shows the
shape of AlR2ROR3R [Ulla, 2003].
The most common form of crystalline alumina, α-aluminium oxide, is known as
corundum. If a trace of the element is present it appears red, it is known as
ruby, but all other colorations fall under the designation sapphire. The primitive
cell contains two formula units of aluminium oxide. The oxygen ions nearly
form a hexagonal close-packed structure with aluminium ions filling two-thirds
of the octahedral interstices.
Identifiers Aluminium oxide
Figure (2.5) The shape of aluminium oxide
Chapter Two Literature Survey
17
Typical alumina characteristics include:
Good strength and stiffness
Good hardness and wear resistance
Good corrosion resistance
Good thermal stability
Excellent dielectric properties (from DC to GHz frequencies)
Low dielectric constant
Low loss tangent
2.3.1.2 Zeolite Zeolites are microporous crystalline solids with well-defined structures.
Generally they contain silicon, aluminium and oxygen in their framework and
cations, water and/or other molecules wthin their pores. Zeolites occur naturally
as minerals or synthetic, Figure (2.6) shows the shape of different types of
zeolites [Matthew, 2008].
Because of their unique porous properties, zeolites are used in a variety of
applications with a global market of several milliion tonnes per annum. In the
western world, major uses are in petrochemical cracking, ion-exchange (water
softening and purification), and in the separation and removal of gases and
solvents. Other applications are in agriculture, animal husbandry and
construction. They are often also referred to as molecular sieves [Danny, 2002].
Zeolites have the ability to act as catalysts for chemical reactions which take
place within the internal cavities. An important class of reactions is that
catalysed by hydrogen-exchanged zeolites, whose framework-bound protons
give rise to very high acidity. This is exploited in many organic reactions,
including crude oil cracking, isomerisation and fuel synthesis [Jirong, 1990].
Chapter Two Literature Survey
18
Figure (2.6) Structures and dimensions of different types
of zeolite [Tirena, 2005].
Underpinning all these types of reaction is the unique microporous nature of
zeolites, where the shape and size of a particular pore system exert a steric
influence on the reaction, controlling the access of reactants and products. Thus
zeolites are often said to act as shape-selective catalysts. Increasingly, attention
has focused on fine-tuning the properties of zeolite catalysts in order to carry
out very specific syntheses of high-value chemicals e.g. pharmaceuticals and
cosmetics [Eisuke et al., 2005].
The following properties make zeolites attractive as catalysts, sorbents,
and ion-exchangers [Jirong, 1990, Liu et al., 1996, Danny, 2002].
Chapter Two Literature Survey
19
(1) well-defined crystalline structure.
(2) high internal surface areas (>600 mP
2P/g).
(3) uniform pores with one or more discrete sizes.
(4) good thermal stability.
(5) highly acidic sites when ion is exchanged with protons.
(6) ability to sorb and concentrate hydrocarbons.
The tetrahedral arrangements of [SiOR4R]P
-4P and [AlOR4R]P
-5P coordination polyhedra
create numerous lattices where the oxygen atoms are shared with another unit
cell. The net negative charge is then balanced by cations (e.g. K P
+P or
NHR4RP
+P). Small recurring units can be defined for zeolites named, ‘secondary
building units [Tirena, 2005].
The primary building blocks of all zeolites are silicon Si P
+4P and
aluminum Al P
+3P cations that are surrounded by four oxygen anions O P
-2P.
This occurs in a way that periodic three dimensional framework
structures are formed, with net neutral SiOR2R and negatively charged
AlOR2R.
The negative framework charge is compensated by cation (often NaR
+R)
or by proton (HP
+P) that forms bond with negatively charged oxygen
anion of zeolite.
The secondary building blocks differ between different types of
zeolites. In the top line of Figure (2.6) the structure of a faujasite type
zeolite is shown. The secondary building block of this zeolite is a
sodalite cage, which consists of 24 tetrahedra in the geometrical form of
a cubo-octahedron. The sodalite cages are linked to each other via a
hexagonal prism.
Chapter Two Literature Survey
20
2.4 UPrevious Work Numerous researchers which have dealt with hydroisomerization using
different types of catalysts as follows:
Diaz et al., [1983] studied the isomerization and hydrogenolysis of hexanes on
an alumina-supported Pt-Ru catalyst. On ruthenium/ alumina catalysts, no
isomer products were detected in CR6R hydrocarbon reactions.
Methylcyclopentane hydrogenolysis was selective as confirmed by the high 3-
methylpentane/n-hexane ratios. Isomerization reactions on Pt(9.6 at.%)-Ru (0.4
at.%)/AlR2ROR3R were studied between 220 and 300°C. Skeletal rearrangements
proceeded from 220°C where Pt is inactive for this type of reactions, Very low
apparent activation energies in isomerization reactions of Cs-labeled
hydrocarbons were found for selective and nonselective cyclic mechanisms: 2-
methylpentane 3- methylpentane and 2-methylpentane n-
hexane, respectively. The results were explained using a bimolecular kinetic
model which can take into account the phenomenon as an increase either in
hydrocarbon coverage or in hydrocarbon adsorption strength on the catalyst
surface.
Raouf, [1994] investigated hydroconversion (isomerization, cracking and
cyclization of n-heptane) using three types of a crystalline zeolites as supports.
It was noted platinum supported zeolite catalyst vary in their activity and
selectivity towards n-heptane hydroconversion. Support types were found to
behave differently when impregnated with hexachloroplatinic acid. Applying
HR2RPtClR6R on acidic decationized and cationic zeolite type Y produce most active
catalyst toward isomerization at lower temperature and for hydrocrackingat
higher temperature. On the other hand, applying HR2RPtClR6 Ron zeolite type X
produce an active catalyst. The isomerizing activity is, however, lower than Y
type with moderate hydroisomerization and hydrocracking selectivity. While
Chapter Two Literature Survey
21
for A type produces an active catalyst with low isomerizayion activity and a
higher cracking ability. catalytic activity of all types of Pt-zeolite catalysts
strongly depends on the Si/Al ratio. The order of the catalytic activity for the
catalysts is type Y > type X > Y type A.
Ravishankar and Sivasanker [1996] studied the hydroisomerization of n-hexane
was carried out at atmospheric pressure in the temperature range 473-573 K
over Pt-MCM-22. The influence of Pt content, the SiOR2R/A1R2ROR3R ratio of
thezeolite and the reaction parameters on the isomerization efficiency of the
catalyst was investigated. The optimum Pt content for the reaction was found to
be around 0.5 wt.%. At a constant Pt content of 0.5 wt.%, increasing the A1
content of the zeolite increased the catalytic activities and
isomerization/cracking ratios. The studies suggest that the reaction proceeds by
a bifunctional mechanism. Preliminary activity comparisons between Pt-H-
MCM-22, Pt-H-β and Pt-Hmordenite are reported.
Chica and Corma, [1999] tested The hydroisomerization of n-heptane to
dibranched and tribranched products for producing high octane gasoline has
been studied using unidirectional 12 Membered Ring (MR) zeolites with
different pore diameters, and zeolites with other pore topologies including one
with connected 12×10MRpores and two tridirectional 12 MR zeolites. Besides
the pore topology, the crystallite size of the zeolite was seen to be of paramount
importance for improving activity and selectivity. In a second part of the work,
a Light Straight Run naphtha including n-pentane and n-hexane and another
feed containing n-pentane, n-hexane, and n-heptane have been successfully
isomerized using a nanocrystalline Beta (BEA) zeolite. This can be a favorable
alternative to the commercial zeolite catalyst based on mordenite (MOR),
especially when n-heptane is present in the feed. They found, that with
Chapter Two Literature Survey
22
increasing of reaction temperature within the range 240-380 P
ºPC, the conversion
of n-parafins increased. Also, the results clearly show that regardless of the
zeolite used the reactivity follows the order n-heptane> n-hexane> n-pentane.
Mordenite cracks n-heptane products very quickly, giving low selectivities to
branched products. While a larger unidirectional pore zeolite (SSZ-24) gives
better results than H-mordenite, the 12 MR tridirectional zeolites are the best
catalysts for the branching isomerization of n-heptane, owing to the faster
diffusion rates of reactants and products through the micropores. The zeolite
crystal size has been found to be of paramount importance, because the catalytic
activity and selectivity of a nanocrystalline Beta zeolite was better than that of
Beta zeolites with larger crystallites.
Shuguang et al., [2000] investigated the hydroisomerization of normal
hexadecane using three Pt/WOR3R/ZrOR2R catalysts prepared by different methods.
They found that preparation of the catalyst by impregnation with HR2RPtClR6R.6HR2RO
solution and another calcinations at 500°C results in a highly active and
selective platinum-promoted tungstate-modified zirconia catalyst
(Pt/WOR3R/ZrOR2R) for the hydroisomerization of n-hexadecane. The optimum
range of tungsten loading to achieve high isomerization selectivity at high n-
hexadecane conversion is between 6.5 and 8 wt%.
Falco et al. [2000] studied the effect of platinum concentration on tungsten
oxide-promoted zirconia over the catalytic activity for n-hexane isomerization
was studied. Catalysts were prepared by impregnation of tungsten oxide
promoted zirconia reaching up to 1.50% platinum, followed by calcination at
500℃. The n-hexane reaction was studied at 200℃, 5.9 bar, WHSV 4 and HR2R:
n-hexane (molar) ratio 7. It was found that catalytic activity and stability
increase for platinum concentrations above 0.05% because of higher hydrogen
Chapter Two Literature Survey
23
availability at the surface, measured as a function of the methylcyclopentane/CR6R
isomers ratio. Further increments in platinum concentration do not produce
important modifications in catalytic activity or hydrogen availability.
Srikant and Panagiotis, [2003] used Pt/H-ZSM-12 as a catalyst for the
hydroisomerization of CR5R–CR7R n-alkanes and simultaneous saturation of benzene.
The performance of a Pt/H-ZSM-12 catalyst was compared with a Pt/H-beta
and a Pt/H-mordenite catalysts having a similar Si/Al ratio. It was concluded
that both the paraffin conversion and benzene conversion activity of all the
three catalysts remain stable even in the presence of sulfur. However, the results
showed that the conversion levels over the Pt/H-ZSM-12 and Pt/H-Mor catalyst
are lower compared to the levels obtained in the absence of sulfur at the same
temperature.
Abbass [2004], studied the transformation of n-hexane over
0.5wt%Pt/HY-Zeolite at 250-325˚C and WHSV=1.6hr P
-1P. The pressure
and hydrogen to feed mole ratio were kept constant at 1 bar and 2,
respectively. He use three type of promoter to study the activity of
isomerization catalyst Sn, Ni and Ti .The comparison between prepared
catalysts shows that the total isomer yield during the process with Sn-
Pt/HY-Zeolite catalyst was higher than the others and the total isomer
yield reach 63.95% vol. He found that adding a 0.5 wt% of W and Zr to
Sn-Pt/HY-zeolite catalyst obtains co-metal promoters catalysts, and the
total isomer yield reached to 81.14% vol. and 79.07% vol. respectively.
The results show that the co-metal promoters enhanced the yield of the
product more than that obtained by other types of promoters
Wong et al., [2005] Skeletal isomerization of npentane over Pt/HZSM5 and
Pt/WP/HZSM5 has been studied. Platinum (Pt) and Tungstophosphoric acid
Chapter Two Literature Survey
24
(WP) have been immobilized on protonated ZSM5 by impregnation method
followed by calcinations at 823K. The state of WP on the zeolite surface was
characterized by XRD, FTIR, pyridine adsorption FTIR, TG/DTA and BET
surface area techniques. Catalytic testing in npentane isomerization was
performed in a continuous flow microreactor at 523K under hydrogen flow.
Prior to the reaction, catalyst was treated by heating at 573K under oxygen (30
min), nitrogen (10 min) and hydrogen (180 min) flow. Both of Pt/HZSM5 and
Pt/WP/HZSM5 shows high conversion of npentane and stable catalysts towards
the deactivation compare to those of HZSM5. Although, Pt/HZSM5 and
Pt/WP/HZSM5 exhibit high catalytic activity, Pt/WP/HZSM5 catalyzed the
isomerization of npentane more selectively compare to those of Pt/HZSM5due
to the presence of a strong acid.
Jafar et al., [2006] investigated CR5R-CR6R isomerization in light straight run
gasoline over platinum/mordenite zeolite. They studied effects of hydrogen
partial pressure on catalyst activity and n-paraffins conversions at T=260°C and
P=7-7.3 bar. They concluded that the activity increases with relatively sharp
slope for n-pentane, n-hexane and n-heptane which show the positive effect of
hydrogen on decreasing deactivation. The behavior of the curves in the
mentioned pressure range shows that the activity is constant while increasing
PHR2R. At T=270°C it seems as if the deactivation phenomenon takes place in
the pressure less than PHR2R. Also, at this temperature and while PHR2R>8.5, the
activity decreases evidently. By increasing the temperature, the slop of the
initial activity curve decreases but activity reduction is more evident in higher
pressures.
Rachid et al. [2006] investigated the present work is an evaluation of 1 wt.%
Pd/sulfated zirconium pillared montmorillonite catalyst in the
hydroisomerization reaction of two mfractions of light naphtha composed
Chapter Two Literature Survey
25
mainly of CR5R and CR6R paraffins (feeds 1 and 2). Catalyst activity test was carried
out in a fixed-bed flow reactor at reaction temperature of 300 8C, under
atmospheric hydrogen pressure and weight hourly space velocity of 0.825 h P
-1P.
The reaction products showed high isomer and cyclane selectivity.
Monobranched and multibranched isomers were formed as well as C5 and C6
cyclane products. After the catalytic reaction, the total amount of benzene and
cyclohexane decreased by 30% for the ‘‘feed 1’’ and by 40% for the ‘‘feed 2’’
leading to methylcyclopentane formation in the products. A long-term
performance test catalyst for the two light naphtha fractions was also performed
and we observed an improving of the research octane number (RON) by 15–17
for, respectively, feeds 1 and 2.
Rachid et al., [2006] the present work is an evaluation of 1 wt.% Pd/sulfated
zirconium pillared montmorillonite catalyst in the hydroisomerization reaction
of two fractions of light naphtha composed mainly of CR5R and CR6R paraffins
(feeds 1 and 2). Catalyst activity test was carried out in a fixed-bed flow reactor
at reaction temperature of 300 8C, under atmospheric hydrogen pressure and
weight hourly space velocity of 0.825 h P
-1P. The reaction products showed high
isomer and cyclane selectivity. Monobranched and multibranched isomers were
formed as well as CR5R and CR6R cyclane products. After the catalytic reaction, the
total amount of benzene and cyclohexane decreased by 30% for the ‘‘feed 1’’
and by 40% for the ‘‘feed 2’’ leading to methylcyclopentane formation in the
products. A long-term performance test catalyst for the two light naphtha
fractions was also performed and we observed an improving of the research
octane number (RON) by 15–17 for, respectively, feeds 1 and 2.
Hadi [2007], studied the transformation of n-hexane over 0.3wt%
Pt/HY-zeolite, 0.5wt% Pt/HY-zeolite, 1wt% Pt/HY-zeolite and
Chapter Two Literature Survey
26
0.3wt%Pt/Zr/W/HY-zeolite catalysts at 240-270˚C and LHSV=1-3hr P
-1P.
The pressure and hydrogen to feed mole ratio were kept atmospheric
and 1-4, respectively. She concluded that the n-hexane conversion
increases with increasing temperature, decreasing LHSV and increasing
Pt content. Also isomerization rate is independent of the Pt loading this
lead to the conclusion that dehydrogenation step is not rate limiting.
The effect of the PRH2R and PRnC6R orders on the overall reaction rate was
also studied by the author. She conclude that the value of hydrogen
order varies between -0.388 to -0.342, while the values of n-hexane
order were 0.262 to 0.219. The values of ERact, isomR were also obtained
and found to be equal to 119.7 kJ/mole.
Hadi also study the n-Hexane conversion enhancement by adding TCE
and by co-impregnation with Zr and W using 0.3wt%Pt/HY-zeolite
catalyst, and found that by adding 435ppm of TCE a 49.5mol.%
conversion was achieved at LHSV 1 h P
-1P, temperature 270°C and HR2R/nCR6R
mole ratio= 4, while the conversion was 32.4mol.% on
0.3wt%Pt/Zr/W/HY-zeolite at the same condition.
María et al. [2008] studied Three different distillatednaphthas streamsprovided
by REPSOLYPF, being formed by n-paraffins, iso-paraffins, aromatics and
naphthenes, were isomerized using an agglomerated catalyst based on beta
zeolite.Methane and ethane were not observed as final products revealing that
hydrogenolysis did not contribute to the cracking reaction. The highest overall
paraffin conversion value was obtained when feed A was introduced to the
process, due to its high molar composition of linear paraffins. It was observed
the presence of aromatic compounds (benzene and toluene) in the three feeds. A
total hydrogenation of benzene was achieved, keeping the rest of the aromatic
Chapter Two Literature Survey
27
compounds under the limit imposed by legislation. Different naphthenic
compounds were obtained as a result of the hydrogenation of aromatic ones.
Goodarz et al. [2008] investigated two types of beta zeolites, different amounts
of platinum (0.2%, 0.5% and 1.2%) were loaded on the protonated form of
zeolite by incipient wet impregnation method applying hexachloroplatinic acid
in 0.2N Cl P
-P progressive ion solutions. Catalytic hydroisomerization reactions
were carried out at atmospheric pressure in a fixed bed reactor with vertical
placing and downward flow at three different temperatures, various WHSV
(weight hourly space velocity) and n-HR2R/n-HC (molar hydrogen/hydrocarbon)
ratio. Increase in Si/Al ratio in zeolites structures from 11.7 to 24.5 promoted
selectivity and yield. It was found that optimum platinum content depends on
the Si/Al ratio (zeolite acidity) in catalysts. Monobranched to dibranched
isomers ratio were correlated with a linear function of n-heptane conversion.
Such a correlation was found to be valid for various Si/Al ratios, metal content,
processing temperature and pressure, WHSV and hydrogen to hydrocarbon
ratio. Increase in WHSV, decreased n-heptane conversion, but enhanced
isomers selectivity. On the other hand, increasing the ratio of hydrogen to
hydrocarbon in the feed decreased conversion, while promoted isomers
selectivity.
2.5 UCatalysts Preperation A typical catalyst comprises one or more catalytically active components
supported on a catalyst support. Typically, the catalytically active components
are metals and/or metal-containing compounds. The support materials are
generally high surface area materials with specific pore volumes and
Chapter Two Literature Survey
28
distribution [Lovasic et al., 1990, Raouf 1994, Novaro et al., 2000, Ramze,
2008].
Various methods for depositing catalytically active components on catalyst
supports are known, the catalyst support may be impregnated with an aqueous
solution of the catalytically active components. The impregnated support may
then be dried and calcined. The catalytically active component may also be
deposited onto the catalyst support by precipitation, a catalyst support is first
impregnated in an aqueous solution of a noble metal. The metal is then
precipitated on to the support by contacting the impregnated support with an
aqueous solution of an alkali metal salt [Iker, 2004].
Many factors influence catalysts preparation, such as solution concentration,
contact time, washing, temperature and method of reduction. Figure (2.7)
illustrates the general procedure for catalysts preparation [Shuguang et al.,
2000, Sergio et al., 2005].
2.5.1 Impregnation The manner in which a metal is introduced to a support will influence its
dispersion as well as the nature of the metal-support interaction. Supported
catalysts with low concentration of metal are generally prepared by
impregnation (or in some cases by ion exchanging). The choice of precursor salt
is made both for its solubility in water, and preferred solvent, and for its ability
to disperse throughout the support. Impregnation of pore supported catalyst is
achieved by filling the pores of support with solution of active species of metal
salt from which solvent is evaporated. The concentration of the metal content
can be increased by successive impregnation with intermediate precipitation
and thermal activation to isolubilize the supported species [Jensen et al., 1997,
Shuguang et al., 2000].
Chapter Two Literature Survey
29
Figure (2.7): Typical arrangement of the catalysts
preparation [Anderson, 1975]
Impregnation with interaction occurs when the solute to be deposited
establishes a bond with the surface of the support at the time of wetting. Such
interaction results in a near-atomic dispersion of the active species precursor.
The interaction can be an ion exchange, an adsorption, or a chemical reaction
since ion exchanges occur much more frequently than the others [Lepage,
1987].
Chapter Two Literature Survey
30
2.5.2 Calcination Calcination means any thermal treatment carried out with the purpose of
decomposing precursor compounds (usually with the evolution of gaseous
product) and / or allowing solid-state reactions to occur among different catalyst
components and / or making the catalyst sinter. The calcination temperature is
usually not lower than that of operation at the industrial plant [Thomas, 2004].
The type of calcination is assumed to be calcination in air, typically at a
temperature higher than the anticipated temperatures of the catalytic reaction
and catalyst regeneration.
The objectives of calcination are to obtain:
1- A well determined structure for the active agents or supports.
2- The parallel adjustment of the texture with respect to the surface and pore
volume.
3- A good mechanical resistance if it does not already exist
Among the various types of chemical or physico-chemical transformations that
occur during calcination, the following are the most important:
A- The creation of a generally macroporous texture through decomposition
and volatilization of substances previously added to the solid at the
moment of its shaping.
B- Modifications of texture through sintering: small crystals or particles will
turn into bigger ones.
C- Modifications of structure through sintering.
2.5.3 Reduction Reduction process is the final step in activation of supported metal catalyst,
which consists of the transformation of the metal precursor compound or its
oxide into the metallic state (metal atoms, small metal clusters).
Chapter Two Literature Survey
31
Reduction involves reaction where the initiation process proceeds at distinct
sites (potential centers) on the surface of solid, followed by propagation of the
reaction zone from such a center through the solid, until complete conversion is
achieved upon contact of a metal oxide with hydrogen, oxygen ions are created.
The reaction process of oxides and halides can be represented by the following
equations [Vanden and Rijnten, 1979, Anderson et al., 1984]
MOR(s)R + HR2 RMR(s)R + HR2ROR(g) 2MXR(s)R +HR2(g) R2MR(s)R +2HXR(g) There are many factors affecting the reduction step, calcination of the deposited
precursor might cause several transformation and solid state reaction. Water
vapor inhibits reduction by blocking nucleus forming sites.
2.6 UCatalysts CharacterizationU Characterization of the catalyst is a predominate step in every catalyst study and
at every stage of the catalyst development. Critical parameters are measured not
only to check the effectiveness of each operation but also to provide
specification for future products. Characterization might be studied or
controlled in terms of support properties, metal dispersion and location and
surface morphology [Tirena, 2005].
In general, the quality of any catalyst is determined by a number of factors,
such as activity, selectivity for certain product, and stability. These parameters
are themselves functions of pretreatment conditions of the catalyst preparation
and reaction conditions. The interpretation of catalytic performance through the
mechanism of catalytic action depends on the study of the intrinsic chemical
and physical characteristics of the solid and a recognition of correlations
Chapter Two Literature Survey
32
between some of these characteristics and catalytic performance [Sergio et
al., 2005]. Table (2.4) offer presents the general physcochemical properties of
catalysts and methods of measuring them.
2.6.1 X-ray Diffraction (XRD)
X-ray diffraction is a technique to identify the crystallinity of catalysts. This
technique is based on the knowledge that each compound in catalyst has a
different diffraction pattern. The crystallinity can be determined by comparing
the intensity of a number of particular peaks to the intensity of the same peaks
obtained by standard samples [Marı´a et al., 1997, Benitez et al., 2006].
The diffraction pattern is plotted based on the intensity of the diffracted beams.
These beams represent a map of reciprocal lattice parameter, known as Miller
index (hkl) as a function of 2θ, which satisfies Bragg equation:
nλ = 2d sin θ -------------------------(2.1)
where n is an integer number, λ is the wavelength of the beam d is interplanar
spacing and θ is a diffraction angle. Equation (2.1) is obtained from Bragg
diffraction as shown in Figure (2.8).
2.6.2 Surface Area In practice, the surface area is calculated from the Brunauer-Emmett-Teller
(BET) equation based on the physical adsorption of an inert gas at constant
temperature, usually nitrogen at the temperature of liquid nitrogen. The
principle of measurement consists in determining the point when a mono-
molecular layer of gas covers the surface of the catalyst [Antonio et al., 2006].
Chapter Two Literature Survey
33
Figure (2.8) Bragg diffraction [Tirena, 2005].
2.6.3 Scanning Electron Microscopy (SEM)
Scanning electron microscopy is an extremely powerful technique for obtaining
information on the morphology and structural characteristics of catalysts. There
are some advantages in this technique, which are great depth of focus, the
possibility of direct observation of external form of real objects, and the ability
to switch over a wide range of magnification, so as to zoom down to fine detail
on some part identified in position on the whole object [Shuguang et al., 2000].
Chapter Three Experimental Work
34
Chapter Three
Experimental Work
3.1 UMaterials
In the present work, different materials and compounds are used as
follows:
• Iraqi-Light-Naphtha
Iraqi light-naphtha is used as a feedstock in the present investigation. It was
supplied by Al-Dura Refinery (Baghdad). Table (3.1) shows the specifications
of Iraqi-light naphtha.
• Hydrogen
Hydrogen gas was obtained from Al-Mansour Factory/Baghdad with
a high purity of (99.9%).
• Zeolite
NaY-zeolite was supplied from Zeolyst International UWE Ohlrogge (VF)
as an extrudate (2mm×4mm). The chemical analysis of this zeolite was done
by the General Establishment of Geological Survey and Mining, and the
results are shown in Table (3.2).
• Alumina Alumina support (γ-AlR2ROR3R) with spherical shape and average size of 3mm
was supplied by FLUKA AG company.
• Hexachloroplatinic Acid
Hexachloroplatinic acid (HR2RPtClR6R.6HR2RO) was supplied by REIDEL- DE
HAEN AG SEELZE -HANNOVER chemicals Ltd.This hexachloroplatinic
acid contains 40 wt% of Pt and has a molecular weight of 517.92 g/mol. On
Chapter Three Experimental Work
35
the other hand, other chemicals used such as Barium Chloride (BaClR2R),
Ammonium Chloride (NHR4RCl) and Hydrochloric acid (HCl) were supplied
from FLUKA AG Company.
In the present work the Iraqi light naphtha are used as a feedstock in
hydroisomerization process to produce high octane gasoline. Table (3.3)
shows the chemical composition of light naphtha. It is important to mention
here that the main products of hydroisomerization process are i-pentane, 2,2-
DMB, and 2,3-DMB.
Table (3. 1) The propetries of Iraqi light naphtha.
Property Data
Sp.gr. at 15.6℃ 0.702
API 80.5
Distillation I.B.P. 5 Vol.% distillated 10 Vol.% distillated 20 Vol.% distillated 30 Vol.% distillated 40 Vol.% distillated 50 Vol.% distillated 60 Vol.% distillated 70 Vol.% distillated 80 Vol.% distillated 90 Vol.% distillated 95 Vol.% distillated E.B.P. Total distillate Total recovery residue Loss
37℃ 42℃ 48℃ 52℃ 56℃ 60℃ 65℃ 68℃ 76℃ 82℃ 86℃ 92℃ 124℃ 96 Vol.% 0.7 Vol.% 3.3 Vol.%
Octane Number 68.2
Sulfur Content < 3ppm (Desulfurized)
Kinematic Viscosity at 25℃ 5.4 10P
-7 PmP
2P/s
Chapter Three Experimental Work
36
Table (3.2): Chemical composition of zeolite
Table (3.3) The composition of Iraqi light naphtha.
Compound SiOR2 ALR2ROR3 NaR2RO CaO FeR2ROR3 MgO TiOR2 L.O.I
Percentage 45.85 20.50 12.00 0.140 0.060 0.120 0.010 19.14
Composition Vol.%
n-Butane 0.20
iso-Pentane 3.80
n-Pentane 15.27
2,2DMB 7.20
2,3DMB 7.98
2MP 12.47
3MP 10.50
n-Hexane 12.74
2,2DMP 3.37
Cyclohexane 2.87
2,4DMP 5.65
Methylcyclopentane 3.34
Benzene 3.88
n-Heptane 1.85
Toluene 2.47
CR7RP
+ 3.14
Chapter Three Experimental Work
37
3.2 UPreparation of Modified Zeolites by Ion Exchange: 3.2.1 Preparation of Barium- Zeolite: BaY form was prepared by ion exchanging of the parent zeolite NaY with
(3N) barium chloride solution. Thus, 36.642 gm of barium chloride in 100
ml distilled water was contacted with 20 gm of zeolite with stirring for 1 hr
at 50℃. The batch of zeolite was left in the solution for 72 hr at 25 . The
exchanged barium zeolite was then filtered off, washed with deionized water
to be free of chloride ions and dried at 110℃ over night. The dried samples
were then calcined at 550℃ for 5 hr in the presence of OR2R. Then the
temperature was increased to 550 ℃ at a rate of 10°C/min. The chemical
analysis showed that a 82% of Na was exchanged by Ba in zeolite Y. It was
done by the General Establishment of Geological Survey and Mining.
3.2.2 Preparation of HY- Zeolite: HY form was prepared by ion exchanging of the parent NaY zeolite with
(3N) ammonium chloride solution. Thus, 16.047 gm of ammonium chloride
in 100 ml distilled water was contacted with 20 gm of zeolite with stirring
for 1 hr at 50℃. The batch of zeolite was left in the solution for 72 hr at
25℃. The exchanged ammonium zeolite were then filtered off, washed with
deionized water to be free of chloride ions and dried at 110℃ over night.
The dried samples was then calcined at 500℃ for 7 hr in presence of OR2R.
Then the temperature was increased to 500 ℃ at a rate of 10°C/min. The
chemical analysis showed that a 87% of Na was exchanged by ammonium
chloride to form HY. It was done by the General Establishment of
Geological Survey and Mining
Chapter Three Experimental Work
38
3.3 UCatalysts Preparation 3.3.1 Preparation of Pt/ BaY and Pt/HY The barium and hydrogen exchanged zeolites were loaded with 0.5 wt % Pt
by impregnation with aqueous solution of hexachloroplatinc acid
(HR2RPtClR6R.6HR2RO). The platinum content of the catalyst was calculated from
the weight of the support and the amount of the metal in impregnation
solution.
Thus, 0.25 gm of hexachloroplatinc acid (40 wt % Pt) was dissolved in 25 ml
of distilled water. Then the solution was added for 20 gm of the zeolite
sample as drop wise with mixing for 2 hr at 25℃. The mixture was left at
room temperature for 24 hr, it was stirred intermediately during this time.
The mixture was then slowly evaporated to dryness over a period of 8 hr by
heating on a heat mantle. The resulting catalyst was dried in air at 110℃ for
additional 24 hr. Then the dried catalyst was calcined at 400 ℃ for 3 hr and
reduced with hydrogen at 350℃ for 2 hr [Satoshi, 2003, Goodarz, 2008,
Dhanapalan et al., 2008].
The prepared catalysts at this time is called Pt/BaY and Pt/HY. 3.3.2 Preparation of Pt/ ALR2ROR3 The γ-AlR2ROR3R (spherical shape with an average size of 3mm) was loaded with
0.5 wt % Pt by impregnation with aqueous solution of hexachloroplatinc acid
(40% Pt). Thus, 0.25 gm of hexachloroplatinc acid (40 wt % Pt) was
dissolved in 25 ml of distilled water. Then, the solution was added 20 gm of
γ-AlR2ROR3R sample as drop wise with mixing for 4 hr at 25℃. The mixture was
left at room temperature for 24 hr, The mixture was stirred intermediately
during this time. The resulting catalyst was dried in air at 110℃ for
additional 24 hr. Then, the dried catalyst was calcined at 400℃ for 3 hr and
reduced with hydrogen at 350℃ for 3 hr.
Chapter Three Experimental Work
39
3.4 UExperimental Unit U The experiments were carried out in a continuous catalytic unit. Figure (3.1)
shows the general view of pilot plant for light naphtha hydroisomerization
process, and Figure (3.2) shows a schematic diagram of the apparatus. The
reaction was carried out in catalytic fixed bed tubular reactor, which is made
of stainless steel. The reactor dimensions were 2cm internal diameter, 3cm
external diameter and 21cm height (reactor volume 66 cmP
3P). The reactor was
charged for each experiment with 20g of catalyst located in the middle zone,
while, the upper and lower zones were filled with glass beads.
The reactor was heated and controlled automatically using an electrical
furnace type Heraeushan (Germany) with maximum temperature of 1000 P
°PC,
it was possible to measure the temperature of the catalyst bed using
calibrated thermocouple sensor type K (iron-constantan) inserted into the
middle of the catalyst bed in order to measure and the control reaction
temperature.
The reactor was fitted with accurate means for control of pressure, gas and
liquid flow rate. The liquid (light naphtha) was pumped with a dosing pump
type Prominent (Beta/4- Germany). The liquid hydrocarbons were stored in a
QVF storage tank with capacity of 2000cmP
3P. The liquid flow was passed
through calibrated burette of 52cmP
3P.
Chapter Three Experimental Work
40
Figu
re (3
.1):
Gen
eral
vie
w o
f pilo
t pla
nt fo
r lig
ht n
apht
ha h
ydro
isom
eriz
atio
n pr
oces
s.
Chapter Three Experimental Work
41
Figu
re (3
.2):
Sch
emat
ic d
iagr
am o
f the
exp
erim
enta
l app
arat
us.
Chapter Three Experimental Work
42
3.5 UProcedure
Twenty grams of fresh catalyst was charged into the middle zone of the
reactor. Iraqi light naphtha was fed to the dosing pump from a glass burette
supplied from a feed tank. Feed was pumped at atmospheric pressure. The
hydrogen gas flow to the unit was controlled by a calibrated gas hydrogen
flowmeter. Downstream pressure was controlled with a back pressure valve.
The hydrogen gas before it passed to the reactor passed through molecular
sieve (5A) type to remove any impurities or moisture. The hydrogen gas was
mixed with hydrocarbon before the reactor inlet. The mixture was preheated
before entering the reactor to 150 P
°PC, and then passed through the catalyst
bed.
The performance of catalysts was tested under different operating
temperatures of (230, 250, 270, 290, and P
P310 P
°PC). The hydrogen to
hydrocarbon molar ratio was kept constant at 4. The weight hourly space
velocities (WHSV) was (1.5, 3, and 4.5hr P
-1P). All types of catalysts were
activated in the catalytic reactor before each run for 2 hr in a flow of
hydrogen. A pre-test period of one hour was used before each run to adjust
the feed rates and temperature to the desired values.
The reaction products was cooled by cooling system and collected in the
separator in order to separate the non-condensed gases from the top of the
separator and the condensed liquid hydrocarbons from bottom of the
separator. Then, the products samples were analyzed using Gas
Chromatograph type Shumids 2014 GC using flame ionization detector
(FID). The column dimensions are 0.22mm internal diameter and length 25m
and film thickness 0.2μm. The analyses were carried out under the
conditions shown in Table (3.3), and the retentions time for the
Chapter Three Experimental Work
43
hydrocarbons are shown in Table (3.4). It is important to mention here that,
the calibration of gas chromatography was carried by injection the same
amount of a standard into the Gas Chromatography.
Table (3.3): Gas chromatograph analysis conditions
Temperature program for the column
Initial temperature 50 °C
Final temperature 120 °C
Hold time 5 min
Rate of temperature 5 °C/min
Total time 20 min
Other variables
Pressure at the inlet column 1atm
Pressure of hydrogen 55 KPa
Injection temperature 180 °C
Pressure of carrier gas NR2 5 atm
Linear velocity 31.3 cm/min
Split ratio 100
Chapter Three Experimental Work
44
Table (3.4): Retention times of hydrocarbons in the catalytic
isomerization of light naphtha reaction.
Components Retention times (Sec)
iso-pentane 1.676
n-pentane 1.724
2,2- dimethyl butane 1.924
2,3- dimethyl butane 1.927
2-methylpentane 1.954
3-methelpentane 1.994
n-hexane 2.037
2,2-dimethelpentane 2.580
Cyclohexane 2.699
2,4-dimethelpentane 2.815
Methylcyclpentane 2.983
Benzene 3.096
n-heptane 3.212
Toluene 4.884
Chapter Three Experimental Work
45
3.6 UCatalysts Characterization 3.6.1 X-Ray Diffraction Analysis. X-Ray diffraction analysis was done in the Lab of University of Manchester
in United Kendom. Analysis was carried out using Phillips X" Pert Pro PW
3719 X-ray diffractometer with Cu KαR1R and Cu KαR2 Rradiation source
(λ=1.54056 Å and 1.54439 Å) respectively. Slits width 1/8 and 1/4 have
been applied. Tension=40 kV, Current=30 mA. The range of angles scanned
was (0 to 80) on 2θ.
3.6.2 Surface Area and Pore Volume
The catalysts surface areas and pore volume were determined using (BET)
method, the apparatus used was Micromeritics ASAP 2400 located in
Petroleum Research Center / Ministry of Oil (Baghdad).
The surface area and pore volume of the catalysts was determined by
measuring the volume of nitrogen gas adsorbed at the liquid nitrogen
temperature (- 196 °C). The volume of gas adsorbed was measured from the
pressure decrease that results from the adsorption of a dose of known volume
of gas.
3.6.3 Scanning Electron Microscopy (SEM) Scanning electron microscopy (SEM) measurements were carried out using a
Phillips SEM equipped with a XL30 Field Emission Gun, available at the
Lab of University of Manchester in UK.
3.6.4 Energy Dispersive X-Ray (EDAX) Analysis The modified zeolite catalyst was subjected to the EDAX analyzer that was
done in the Lab of University of Manchester in United Kendom and
connected with the SEM to measure the composition of the zeolite.
Chapter Four Kinetic Analysis
46
Chapter Four
Kinetic Analysis
4.1 Introduction The main aim of the present study is to analyze the kinetics of hydroisomerization
process by assessing the effect of reaction time and reaction temperature on the
performance of the catalysts. The process feed involves light naphtha which
contains many reactions. Therefore, the hydroisomerization reaction has three
stages as follows: [Sergio et al., 2003, Antonio et al., 2006, Pitz et al., 2007,
Marios et al., 2009]:
1- Adsorption of n- paraffin molecule on dehydrogenation- hydrogenation site
followed by dehydrogenation to n- olefins.
2- Desorption of n- olefin from the dehydrogenation sites and diffusion to a
skeletal rearranged site, which converts n- olefin into iso- olefin.
3- Hydrogenation of iso- olefin into iso- paraffin molecule.
In general, the hydroisomerization of n- paraffin can occur through the bifunctional
scheme shown below:
n-Paraffin n-Olefin i- Olefin i- Parffin
Chapter Four Kinetic Analysis
47
The hydroisomerization process of light naphtha is regarded as one of the
complex chemical reactions network, where such types of reactions take on a
metal and acid sites of catalysts [Antonio et al., 2006, Eric et al., 2007 ].
Therefore, the mathematical modeling of the hydroisomerization process is a
very important tool in petroleum refining industries. It translates experimental
data into parameters used as the basis of commercial reactor process optimaization.
In the hydroisomerization of alkanes it is supposed that the alkane is
dehydrogenated to an alkene on the metal site. The alkene is then protonated on the
acid site to a carbenium ion, which is subsequently isomerized to a branched
carbenium ion. The branched carbenium ion gives the proton back to the acid site,
the resulting branched alkene is hydrogenated on the metallic site. The branched
alkane is formed, and can be desorbed from the catalyst surface. The reaction
mechanism scheme is shown in Figure (4.1) [Franciscus, 2002, Maha, 2007,
Matthew, 2008].
Figure (4.1) The general reactions mechanism for isomerization of n-alkane [Franciscus, 2002].
Chapter Four Kinetic Analysis
48
4.2 Model Development In developing the model of the catalytic hydroisomerization kinetic the following
assumptions are taken into account:
1. The system is isothermal and in steady state operation with first order
reactions.
2. The reaction is carried out in the gas phase with constant physical properties
and without pressure drop.
3. The temperature and concentration gradients in the radial direction can be
neglected.
The objective of kinetic study is to construct from the experimental results of the
process, a mathematical formulation that can be used to predict the kinetic
parameters of the hydroisomerization process. Therefore, the main aim of the
present work is to estimate the reaction parameters (reaction rate constant,
activation energy and pre-exponential factor) depending on the experimental work
results under real isomerization conditions.
In present work, it is suggested kinetic model for the reactions of
hydroisomerizayion for light naphtha (n-paraffin) can be considered by the
following scheme depending on the present model assumptions which can be
formulated to the following equations:
Figure (4.1) The suggested reactions of light naphtha isomerization of the present work.
Chapter Four Kinetic Analysis
49
Let CRAR denotes the mole fraction of n-paraffin present at any time t,
CRN R the mole fraction of n-olefin, CRisoR the mole fraction of i-paraffin.
Then, the mole balance can be formulated mathematically as follows:
--------------------------------(4.2)R
-------------------------------(4.3)
By integration of equation (4.2) CRAR = CRARP
°P at t= 0 we get
CRAR = CRARP
° Pexp (- kR1Rt) -------------------------------------
(4.4)
Substituting the equation (4.4) in equation (4.3) yield:
= kR1RCRARP
° Pexp (- kR1Rt) - kR2RCRN R--------------------------------------
(4.5)R
Rearrangement of equation (4.5) gives:
= kR1RCRA
= kR1RCRAR-kR2RCRN
Chapter Four Kinetic Analysis
50
R R+R RkR2RCRN R= kR1RCRARP
° Pexp (- kR1Rt)
This is a linear first order differential equation as follows:
+ Py =Q where P = kR2 R, Q = kR1RCRARP
° Pexp (- kR1Rt)
Then, can be solving this differential equation as follows:
yρ = Q dx + c where ρ integration factor which can be calculated from:
ρ =
where integration factor is exp (kR2Rt).
Then by integrate of differential equation will give:
exp (kR2R-kR1R) t + A ----------------------------------(4.6) CRNR exp (kR2Rt) =
where A is the integration constant, and it can be determined using the following
conditions:
t = 0 , CRNR = 0 Thus :
--------------------------------- (4.7)
Then:
CRNR exp (kR2Rt) = [exp (kR2R-kR1R)t – 1]. Then
A = -
Chapter Four Kinetic Analysis
51
CRNR = [exp(-kR1Rt) – exp(-kR2Rt)] -----------------------------------(4.8)
But, all products come from initial n-paraffin in the light naphtha feed, then, CRAR° = CRAR + CRNR + CRisoR -----------------------------------(4.9)
Then substituting the equations (4.4) and (4.8) in equation (4.9), will give:
CRAR° = CRARP
° Pexp (- kR1Rt) + [exp(-kR1Rt) – exp(-kR2Rt)] + CRiso R-------(4.10)
Rearrangement of equation (4.10) gives:
CRisoR = CRAR° - CRARP
° Pexp (- kR1Rt) - [exp(-kR1Rt) – exp(-kR2Rt)]
-------(4.11)
4.3 Reactor Model To develop a reaction model for an integral reactor, a material balance is made
over the cross section of a very short segment of the tubular catalyst bed, as shown
in Figure (4.2):
CRisoR = CRAR° [1- exp (- kR1Rt) - [exp(-kR1Rt) – exp(-kR2Rt)]
Chapter Four Kinetic Analysis
52
Figure (4.2) Segment of packed bed reactor.
A stady- state mole balance on reactant P gives:
[ flow rate] – [flow rate] + [ rate of ] = [ rate of ] in out generation accumulation Then, the resulting equation is:-
R RVRAR (-rRAR)=0 [Mole Balance] -----------(4.12) FRAR
FRAR
Z+∆Z Z
Chapter Four Kinetic Analysis
53
0, the differential material balance reduces to :- As: ∆Z
AA r
dVdF
−= -------------------------------------------------------- (4.13)
For a flow system, FA has previously been given in terms of the entering
molar flow rate FA and the conversion X:
----------------------------------(4.14)
Substituting equation (4.13) into (4.12), gives differential form of the design
equation for a plug flow reactor:
-----------------------------------(4.15) = rA FAP
ο
Integration with the limit V=0 when X=0 gives:
------------------------------- (4.16)
But, the rate of reaction for first order is:
First order reaction --------------------------------(4.17)
Substituting equation (4.17) in equation (4.16), will give:
- FAP
οP X FA= FAP
ο
V= FAP
οP
rA= k1 CA
Chapter Four Kinetic Analysis
54
----------------------------(4.18) V= FAP
οP
----------------------------(4.19) CA= CA◦
----------------------------(4.20) V=
By integration will give
[(1+ є)Ln – Єx] ---------------------------(4.21) V=
k1= [(1+ є)Ln – Єx] ------------------------------(4.22)
From equation (4.22), the values of k1 are calculated for any component
From Arrhenius equation plot Ln k1 vs 1/T, the slope represents –E/RT to
calculate the activity energy (E) and the intercept represents Ln k◦ as shown in
Figure (4.3).
Lnk1=Ln k◦ - -----------------------------(4.23)
Substitute values of k1 in equation (4.11) to calculate values of k2 .
Chapter Four Kinetic Analysis
55
Figure (4.3) The relationship between Lnk1 vs 1/T using
Arrhenius equation.
Chapter Five Results & Discussion
56
Chapter Five Results & Discussion
5.1 UCharacterization of Catalysts
5.1.1 X-ray Diffraction
X-ray diffraction analysis was used to determine the crystalline structure
of Y zeolite on 2θ scale. From this pattern different phases and average
crystalline sizes were determined, as shown in Figure (5.1). These results
clearly point to standard specification of Y zeolite [Novaro et al., 2000].
From the point of view of analysis, this step of characterization will give
us real identification of used zeolite specification and its crystalline
structure.
Figure (5.1): XRD spectrum of the Na/Y catalyst.
Chapter Five Results & Discussion
57
5.1.2 Scanning Electron Microscopy (SEM) Analysis
Scanning electron microscopy (SEM) was used to determine the morphology and
average crystallite size of the catalysts. Figures (5.2) and (5.3) show the SEM
monograph of Pt/HY and Pt/BaY respectively. As can be seen, platinum particles
were homogeneously distributed, where the white spots represent a platinum
particles and black zone represent the supported, with the average diameter of the
Pt/HY catalyst is 4µm, while for Pt/BaY catalyst is 3.5µm. These results are in
accord with that the faujasite crystallite size range (2 -5)µm. SEM is used ensue
good impregnation of active component.
Figure (5.2): A SEM-picture of Pt/HY 0.5 wt% Pt catalyst used in pilot experiments.
Chapter Five Results & Discussion
58
Figure (5.3): A SEM-picture of monograph Pt/BaY.
5.1.3 Energy Dispersive X-ray (EDAX) Analysis
Figure (5.4) shows the EDAX of the Y zeolite. This test is equipped with
SEM measurements.The pattern of the analysis indicates that the zeolite
composition is in accord with standard Y zeolite and agrees well with X-
ray diffraction measurement of Figure (5.1) for the same catalyst type
[Novaro et al., 2000, Somyod et al., 2004].
Chapter Five Results & Discussion
59
Figure (5.4): Energy Dispersive X-ray (EDAX) of zeolite NaY.
Also, from Figure (5.4) it is clear that the Si and Al are the main
components of zeolite structure where the Si/Al ratio is equal to
approximately 1.58. This ratio is calculated depending on the composition
measurement inside the zeolite structure and pores at different positions in
the structure. Such measurements give more accurate results for Si/Al
ratio.
Chapter Five Results & Discussion
60
5.1.4 Surface Area
Surface areas of catalysts were determined by phisorption method (BET). The
results of surface area tests tabulated in Table (5.1). It is noted, the platinum
/zeolite catalysts give the highest values of the surface area and pore volume as
compared with the platinum/alumina catalyst. It is seen there that high surface area
and large pore volume Pt/BaY and Pt/HY catalysts are more selective to isomers
than Pt/Al2O3
catalyst which have low surface area and pore volume.
Table (5.1) Physical characteristics of the catalysts.
Catalysts Surface Area m2 Pore Volume cm/gm 3/gm
Pt/Al2O 288.86 3 0.3307
Pt/BaY 421.3 0.65
Pt/HY 425 0.67
Chapter Five Results & Discussion
61
5.2 The hydroisomerization process is affected by different parameters such as catalyst
type, WHSV, and reaction temperature.
Effect of Operating Conditions
5.2.1 Effect of Temperature
5.2.1.1 Effect of Temperature on Conversion of Light Naphtha
Figures (5.5) to (5.13) and Appendix C show the effect of temperarure on
conversion of light naphtha For the catalysts examined (Pt/BaY, Pt/HY,
and Pt/Al2O3). It can be seen that (n-pentane, n-hexane, 2MP, 3MP) are
the most common. From the general behavior of these figures, it was noted
that with increasing of reaction temperature within the range 230-310ºC,
the conversion of light naphtha increased, that is due to the increasing of
sites that can be contribute in the reaction when the temperature increases.
It was concluded that the catalytic activity of different catalysts for
hydroisomerization of light naphtha decreases in the following order:
Pt/Al2O3 > Pt/HY > Pt/BaY, as an example, the conversion of light
naphtha using 0.5wt% Pt/Al2O3 and WHSV of 1.5h-1 increases from
31.2% at 230ºC to 64.7% at 310º
C. These results are in agreement with the
works of Ravishankar and Sivasanker [1996], Chica and Corma, [1999],
Rachid et al. [2006].
Chapter Five Results & Discussion
62
Figure (5.5): Influence of reaction temperature on conversion ■n-C6 , ♦n-C5
, ▲Total, ●3MP, ×2MP.
Figure (5.6): Influence of reaction temperature on conversion ■ n-C6 , ♦ n-C5
, ▲Total, ●3MP, ×2MP.
Chapter Five Results & Discussion
63
Figure (5.7): Influence of reaction temperature on conversion ■ n-C6 , ♦ n-C5
, ▲Total, ●3MP, ×2MP.
Figure (5.8): Influence of reaction temperature on conversion ■ n-C6 , ♦ n-C5 , ▲Total, ●3MP, ×2MP.
Chapter Five Results & Discussion
64
Figure (5.9): Influence of reaction temperature on conversion ■ n-C6 , ♦ n-C5
, ▲Total, ●3MP, ×2MP.
Figure (5.10): Influence of reaction temperature on conversion ■ n-C6 , ♦ n-C5
, ▲Total, ●3MP, ×2MP.
Chapter Five Results & Discussion
65
Figure (5.11): Influence of reaction temperature on conversion ■ n-C6 , ♦ n-C5
, ▲Total, ●3MP, ×2MP.
Figure (5.12): Influence of reaction temperature on conversion ■ n-C6 , ♦ n-C5 , ▲Total, ●3MP, ×2MP.
Chapter Five Results & Discussion
66
Figure (5.13): Influence of reaction temperature on conversion ■ n-C6 , ♦ n-C5
, ▲Total, ●3MP, ×2MP.
5.2.1.2 Effect of Temperature on Total Conversion of Light Naphtha and Selectivity
Figures (5.14) to (5.22) and appendix A show the effect of reaction
temperature on the conversion of light naphtha and hydroisomerization
selectivity toward branched isomers hydrocarbons over different catalysts
and WHSV. According to the results of G.C. analysis, the isomerization of
light naphtha leads to the formation of mainly mono-branched and di-
branched molecules. Also, a very small amount of aromatic products is
detected. It was noted that, the total conversion of light naphtha for all
types of catalysts is increased with increase in reaction temperature. At
reaction temperatures of 230, 250, 270℃ for Pt/BaY and Pt/HY catalysts,
the selectivity to isomers is increased with no aromatics (51, 74, and 89)
Chapter Five Results & Discussion
67
for Pt/BaY and (63,81, and 95) for Pt/HY, while, at 290 and 310℃
selectivity to isomers is decreased and with formation of few aromatics
products (67 and 46) for Pt/BaY and (89 and 73) for Pt/HY. On the other
hand, for Pt/AlR2ROR3R catalyst it was found as temperature increase, the
selectivity to isomerization reaction decreases gradually because of
creating of more and more aromatic products. It shows that for Pt/AlR2ROR3R
catalyst at 230℃ is the best temperature of increasing isomerization
selectivity. It is important to mention here that for hydroisomerization
process over Pt/AlR2ROR3R catalyst it is necessary to use low temperatures in
order to get good results of isomerization selectivity and to prevent
aromatic formation. This is in agreement with the investigation of [Falco
et al. [2000], and María et al. [2008].
Moreover, it is important to say that the aromatization of alkanes must be avoided
because of new regulations requiring the reduction of aromatic compounds because
of their detrimental environmental effects. The environmental concerns have
prompted legislation to limit the amount of total aromatics, particularly benzene, in
gasoline. The specifications allow no more than 35% (v/v) of aromatic
compounds. The reduction of aromatics will have a negative impact on gasoline
octane ratings. To satisfy the environmental specifications, the total hydrogenation
of benzene could be achieved, keeping the rest of the aromatic compounds under
the limit imposed by legislation [Chica et al., 2001, Marı´a et al., 2005].
On the other hand, the acidity of the catalyst has a major influence on the
hydroisomerization and hydrocracking yields. The pore opening of the molecular
sieve can also have a major effect on the selectivity of these catalysts. If the pore
opening is small enough to restrict the larger iso-paraffins from reacting at the
acidic sites inside the pore, the catalyst will show good selectivity for converting n-
Chapter Five Results & Discussion
68
paraffins. Therefore, the ideal catalyst for selective hydroisomerization of n-
paraffins should have both selectivity for isomerization, which comes from the
proper balance of acidity and hydrogenation activity, and selectivity for reacting
only with n-paraffins, which comes from the size of the pore openings of the
molecular sieve used. [Deldari, 2005, Christian, 2005].
Figure (5.14): Influence of reaction temperature on Vol.% ♦ Aromatic , ■ Isomer
, ▲Conversion.
Chapter Five Results & Discussion
69
Figure (5.15): Influence of reaction temperature on Vol.% ♦ Aromatic , ■ Isomer
, ▲Conversion.
Figure (5.16): Influence of reaction temperature on Vol.% ♦ Aromatic , ■ Isomer
, ▲Conversion.
Chapter Five Results & Discussion
70
Figure (5.17): Influence of reaction temperature on Vol.% ♦ Aromatic , ■ Isomer
, ▲Conversion.
Figure (5.18): Influence of reaction temperature on Vol.% ♦ Aromatic , ■ Isomer
, ▲Conversion.
Chapter Five Results & Discussion
71
Figure (5.19): Influence of reaction temperature on Vol.% ♦ Aromatic , ■ Isomer
, ▲Conversion.
Figure (5.20): Influence of reaction temperature on Vol.% ♦ Aromatic , ■ Isomer
, ▲Conversion.
Chapter Five Results & Discussion
72
Figure (5.21): Influence of reaction temperature on Vol.% ♦ Aromatic , ■ Isomer
, ▲Conversion.
Figure (5.22): Influence of reaction temperature on Vol.% ♦ Aromatic , ■ Isomer
, ▲Conversion.
Chapter Five Results & Discussion
73
The same results also show that the Pt/HY catalyst is the most suitable catalyst for
hydroisomerization process because it reduces the aromatic content with high
selectivity toward isomers. It was concluded that the Pt/HY catalyst is more active
than Pt/BaY because it gives high conversion and selectivity to hydroisomerization
reaction as shown in Figures (5.23) to (5.25). On the other hand, Pt/Al2O3
catalyst
is the most active for light naphtha conversion at 230℃. But, under reaction
temperature greater than 230℃ the reaction selectivity goes toward aromatic and
hydrocracking products. Therefore, according to these results the optimum
reaction temperature for isomerization is at 270℃ for all catalysts where such
temperature gives the highest catalyst selectivity toward isomers. On the other
hand, it is indicated that the Pt/HY catalyst gives higher selectivity toward isomers
than Pt/BaY. This is attributed to the effect of cation type that forms the final
catalyst, because the hydrogen atom is larger than the barium atom and its high
acidity.
Figure (5.23): Influence of reaction temperature on isomerization selectivity ♦ Pt/BaY, ■ Pt/HY , ▲Pt/Al2O3
.
Chapter Five Results & Discussion
74
Figure (5.24): Influence of reaction temperature on isomerization selectivity ♦ Pt/BaY, ■ Pt/HY , ▲Pt/Al2O3
.
Figure (5.25): Influence of reaction temperature on isomerization selectivity ♦ Pt/BaY, ■ Pt/HY , ▲Pt/Al2O3
.
Chapter Five Results & Discussion
75
5.2.2 Effects of WHSV Figures (5.26) to (5.30) show the effects of WHSV on light naphtha conversion
for different catalysts at different reaction temperatures. According to many
references [Goodarz et al., 2008, Ping et al. 2009] the WHSV is a very important
factor that determines the performance of hydroisomerization process of light
naphtha. The WHSV was varied by changing the flow of liquid hydrocarbon feed
and H2 gas so that the molar ratio of hydrogen to hydrocarbon remained
unchanged at a value of 4. This value represents the best ratio for isomerization
reaction [Novaro et al., 2000, Ivanov et al., 2002, Rafael et al., 2008]. It was noted
that the conversion of the light naphtha decreases with increase in WHSV. The
results show, that when WHSV equal 1.5hr-1 gives the highest conversion for all
catalyst types. While, at 4.5hr-1
value of WHSV gives the lowest conversion.
Therefore, it is concluded that there is a inverse relationship between conversion
and WHSV, where the increase in WHSV decreases the residence time, which
leads to a plenty of contact time of feedstock with the catalyst inside reactor, and
the latter means effective conversion for n-paraffins. This is in agreement with the
explanation of Goodarz et al. [2008].
Chapter Five Results & Discussion
76
Figure (5.26): Effect of WHSV on light naphtha conversion ♦ Pt/BaY, ■ Pt/HY, ▲Pt/Al2O3
.
Figure (5.27): Effect of WHSV on light naphtha conversion ♦ Pt/BaY, ■ Pt/HY, ▲Pt/Al2O3.
Chapter Five Results & Discussion
77
Figure (5.28): Effect of WHSV on light naphtha conversion ♦ Pt/BaY, ■ Pt/HY, ▲Pt/Al2O3
.
Figure (5.29): Effect of WHSV on light naphtha conversion ♦ Pt/BaY, ■ Pt/HY, ▲Pt/Al2O3
.
Chapter Five Results & Discussion
78
Figure (5.30): Effect of WHSV on light naphtha conversion ♦ Pt/BaY, ■ Pt/HY, ▲Pt/Al2O3
.
5.2.3 Effect of Time
Figures (5.31) to (5.35) illustrate the change in conversion with time in the light
naphtha conversion into various products over Pt/HY catalyst at (230 to 310℃),
WHSV (1.5hr P
-1P) and atmospheric pressure. These figures are regarded as samples
for groups of figures of the change in conversion with time for Pt/BaY, Pt/HY, and
Pt/AlR2ROR3R catalysts at (230 to 310℃),WHSV (1.5 to 4.5hr P
-1P) at atmospheric
pressure which have the same behavior for the all catalyst types. The major
reaction products are iso- pentane, 2,2- DMB, and 2,3-DMB. Additionally, there
is another component that has low percentage in light naphtha and has not a clear
effect on conversion of hydroisomerization process and yield distribution, such as,
the methylcyclopentane fraction which increases while the cyclohexane and
benzene fractions decrease [Rashed et al., 2006].
Chapter Five Results & Discussion
79
The results indicate that the catalysts have high activity at initial period. It is
noted, that the conversion of light naphtha increases with increase in time, while,
the selectivity of isomerization decreases with time. This conclusion is based on
catalyst deactivation because of formation of coke precursors over the acid sites.
Catalyst deactivation is a result of a number of unwanted chemical and physical
changes. The three major categories of deactivation mechanisms are sintering,
poisoning, and coke formation or fouling. They may occur separately or in
combination, but the net effect is always the removal of active sites from the
catalytic surface. On the other hand, fouling (coking) formation is the most
important type of catalyst deactivation in hydroisonerization process . The
catalytic coke is gradually formed on both metal and supports by different
mechanisms. When the operation is extended, the coke precursors will
predominantly accumulate on the supports and continually polymerize through
acid catalyzed reactions [Novaro et al., 2000, Andreas, 2003, Khalid et al., 2007].
Chapter Five Results & Discussion
80
Figure (5.31) Effect of time on conversion and selectivity for hydroisomerization of light naphtha ♦ n-C5, ■n-C6, ▲3MP, ×i-C5
, +2,2-DMP, ●2,3DMP.
Figure (5.32) Effect of time on conversion and selectivity for hydroisomerization of light naphtha ♦ n-C5, ■n-C6 ▲3MP, ×i-C5
, +2,2-DMP, ●2,3DMP.
Chapter Five Results & Discussion
81
Figure (5.33) Effect of time on conversion and selectivity for hydroisomerization of light naphtha ♦ n-C5, ■n-C6, ▲3MP, ×i-C5
, +2,2-DMP, ●2,3DMP.
Figure (5.34) Effect of time on conversion and selectivity for hydroisomerization of light naphtha ♦ n-C5, ■n-C6, ▲3MP, ×i-C5
, +2,2-DMP, ●2,3DMP.
Chapter Five Results & Discussion
82
Figure (5.35) Effect of time on conversion and selectivity for hydroisomerization of light naphtha ♦ n-C5, ■n-C6, ▲3MP, ×i-C5
, +2,2-DMP, ●2,3DMP.
5.3
According to our approach that shown in chapter 4 in which explained the kinetic
behavior of hydroisomerization process of light naphtha as shown in Figure (4.1).
The present study has calculate the kinetic parameters such as K
Results of Kinetic Study
1, K2, Ko
, and
activation energy (E) depending on present experimental work results.
n-Paraffin Olefin iso-Paraffin
Chapter Five Results & Discussion
83
The classical mechanism proceeds via an olefin intermediate that is formed
through a dehydrogenation step on the metal site. As the olefin concentration under
hydroisomerization conditions is rather low, due to the equilibrium position of the
strongly endothermic dehydrogenation step, it has to be guaranteed that a sufficient
number of olefins is present to be converted to form a carbon on the acidic sites of
zeolite which is rather low as well. It was observed that the rate for the
isomerization reaction strongly depends on the chain length of the involved
alkanes. The longer the chain length, the more stabilized the associated carbenium
ion and the faster the isomerization reaction [Sergio et al., 2003, Christian, 2005].
The activation energies of the isomerization reaction was determined over the
temperature of 230, 250, 270, 290, and 310℃ at a atmospheric pressure and a
WHSV of 1.5, 3, and 4.5h-1 for conversion levels of up to15% where a linear
correlation between the logarithmic isomerization of reaction rate constant (Lnk1)
and the inverse temperature (1/T) is observed as shown in Figures (5.36) to (5.44),
where the slope represents the (-E/R) and the intercepts represent the pre-
exponential factor (Lnko
). The apparent activation energies for the different
catalysts are in the range between (15 – 24 kJ/mol) and are given in the summary
of the characterization data in Table (5.2) which are calculated from Arrhenius
equation. It is noted, that there are a simple differences among its value. In general,
the values of apparent activation energies are small and that the reduction values
indicate the selectivity of hydroisomerization.
Ln k1=Ln ko - Arrhenius equation
Chapter Five Results & Discussion
84
On the other hand, the reaction rate constant (k1
) can be calculated via equation
(4.22) as follows:
Also, in our approach that is given shown in chapter 4, the equation which
describes the behavior of hydroisomerization process of light naphtha is derived.
Also, the reaction rate constant (k2
) parameter can be calculated from this equation
as follows. The results of the kinetic parameters tabulated in Appendix D.
Table (5.2) Apparent activation energies (kJ/mol) for C5, C6
, and 3MP.
Catalysts n-C n-C5 3MP 6
Pt/BaY 22 21 15
Pt/HY 23 20 16
Pt/Al2O 22 3 24 17
k1= [(1+ Є) Ln – Єx]
Ciso = CA° [1- exp (- k1t) - [exp(-kR1Rt) – exp(-kR2Rt)]
Chapter Five Results & Discussion
85
Figure (5.36) Arrhenius plot ♦WHSV=1.5hr-1, ■WHSV=3hr-1, ▲WHSV=4.5hr-1
.
Figure (5.37) Arrhenius plot ♦WHSV=1.5hr-1, ■WHSV=3hr-1, ▲WHSV=4.5hr-1.
Chapter Five Results & Discussion
86
Figure (5.38) Arrhenius plot ♦WHSV=1.5hr-1, ■WHSV=3hr-1, ▲WHSV=4.5hr-1
.
Figure (5.39) Arrhenius plot ♦WHSV=1.5hr-1, ■WHSV=3hr-1, ▲WHSV=4.5hr-1
.
Chapter Five Results & Discussion
87
Figure (5.40) Arrhenius plot ♦WHSV=1.5hr-1, ■WHSV=3hr-1, ▲WHSV=4.5hr-1
.
Figure (5.41) Arrhenius plot ♦WHSV=1.5hr-1, ■WHSV=3hr-1, ▲WHSV=4.5hr-1.
Chapter Five Results & Discussion
88
Figure (5.42) Arrhenius plot ♦WHSV=1.5hr-1, ■WHSV=3hr-1, ▲WHSV=4.5hr-1
.
Figure (5.43) Arrhenius plot ♦WHSV=1.5hr-1, ■WHSV=3hr-1, ▲WHSV=4.5hr-1.
Chapter Five Results & Discussion
89
Figure (5.44) Arrhenius plot ♦WHSV=1.5hr-1, ■WHSV=3hr-1, ▲WHSV=4.5hr-1.
Chapter Six Conclusions & Recommendations
90
Chapter Six
Conclusions & Recommendations
6.1 ConclusionsThe following major conclusions can be drawn from the present study:
1. The hydroisomerization of Iraqi light naphtha was carried out to give high
selectivity toward isomers. Therefore, the results of the present work can be
applicable to the design of hydroisomerization unit in Iraq.
2. The results show that the best operating temperature for the
hydroisomerization process (with high selectivity toward isomerization) is
270°C.
3. The results obtained in this work show high selectivity with Pt/HY and
Pt/BaY catalysts, while, Pt/Al2O3
Pt/HY > Pt/BaY > Pt/Al
has the low selectivity to the isomers.
Therefore, the prepared catalysts follows the following sequence: 2O3
which, are 95%, 89%, and 30% respectively.
4. The total conversion of light naphtha was achieved to be 64.7% over
Pt/Al2O3 catalyst at 310℃ and WHSV1.5hr-1
Pt/Al
, with high aromatic formation,
while, at the same conditions with Pt/HY and Pt/BaY catalysts it was 52 %,
50% respectively. Therefore, the following sequence for the catalysts
conversion is concluded at 310℃: 2O3 > Pt/HY > Pt/BaY
Chapter Six Conclusions & Recommendations
91
and this sequence applicable for all temperatures range.
5. In the present work, a kinetic model was developed to describe the
hydroisomerization of light naphtha. This model was developed depending
on our experimental data results and approach. Then, the kinetic parameters
(k°, k1, and E) are estimated, while, k2
can be calculated from the derived
equation as follows:
6. It was observed that the values of apparent activation energy for
hydroisomerization of light naphtha (n-pentane, n-hexane, and 3MP) over
the prepared catalyst takes the following order:
E of 3MP < E of n-Hexane < E of n-Pentane
7. The conversion of light naphtha and selectivity of hydroisomerization
increase with a decrease in WHSV. 1.5hr-1
is the best which give high rate of
isomers.
6-2
1- The investigation can be extended to study the influence of varying the
pressure on activity and selectivity.
Recommendetions
2- An extension of theoretical work can be done by assuming a higher order of
reaction rate for hydroisomerization reactions (not first order).
Ci-P = CP° [1- exp (- k1t) - [exp(-kR1Rt) – exp(-kR2Rt)]
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Appendix A
106
Appendix A
The volume percent of component in product Table(A1) The volume percent of component in product
using Pt/Ba-Y Zeolite(WHSV=1.5h-1
)
Volume%
Tim
e m
in.
Tem
per
ature
℃
2-4 DMP
2-2DMP
2-3 DMB
2-2DMB
n-C6
3-MP
2-MP
n-C5
i-C5
6.86
4.25
9.49
8.69
14.6
9.31
11.20
14.25
5.49
60
230
6.77
4.20
9.43
8.65
14.5
9.17
11.18
14.18
5.32
90
6.75
4.20
9.38
8.51
14.3
9.11
11.10
14.06
5.24
120
6.75
4.15
9.33
8.38
14.2
9.0
11.00
13.85
5.11
150
6.94
4.32
10.14
9.86
13.77
9.10
10.91
14.00
7.25
60
250
6.88
4.25
10.10
9.82
13.63
9.00
10.89
13.81
7.15
90
6.84
4.18
9.96
9.77
13.28
8.81
10.55
13.77
7.00
120
6.70
4.18
9.88
9.75
13.00
8.62
10.42
13.70
6.87
150
7.17
5.56
11.25
10.12
12.21
8.70
9.90
11.72
9.22
60
270
7.15
5.48
11.18
10.10
12.17
8.49
9.87
11.53
9.14
90
7.13
5.45
11.15
10.07
11.95
8.31
9.38
11.38
8.09
120
7.12
5.38
11.11
9.95
11.91
8..24
9.31
11.21
8.94
150
7.15
5.55
11.18
9.84
11.54
8.28
9.30
11.15
9.00
60
290
7.08
5.43
11.11
9.73
11.52
8.17
9.25
11.08
8.97
90
6.95
5.38
10.96
9.68
11.42
7.96
9.23
10.85
8.89
120
6.81
5.15
10.87
9.35
10.87
7.88
9.19
10.75
8.70
150
6.83
5.21
10.66
9.85
11.32
8.44
8.79
10.22
8.93
60
310
6.79
5.18
10.45
9.71
10.87
8.14
8.50
10.13
8.85
90
6.77
5.14
10.22
9.54
10.61
7.87
8.45
10.87
8.41
120
6.49
5.08
9.88
9.45
10.42
7.65
8.23
10.67
8.33
150
Appendix A
107
Table(A2) The volume percent of component in product
using Pt/Ba-Y Zeolite (WHSV=3h-1
)
Component Vol.%
Tim
e m
in.
Tem
per
ature
℃
2-4 DMP
2-2DMP
2-3 DMB
2-2DMB
n-C6
3-MP
2-MP
n-C5
i-C5
6.15
3.95
9.12
8.00
15
9.57
11.86
14.73
5.20
60
230
6.11
3.94
9.00
7.98
14.94
9.51
11.79
14.70
5.17
90
5.95
3.90
8.95
7.95
14.80
9.43
11.75
14.66
5.05
120
5.89
3.76
8.91
7.86
14.61
9.41
11.63
14.57
4.97
150
6.25
4.27
9.82
8.79
14.73
9.28
11.49
14.29
6.51
60
250
6.18
4.25
9.80
8.70
14.54
9.17
11.35
14.25
6.48
90
6.15
4.16
9.75
8.68
14.46
9.00
11.25
14.18
6.36
120
6.00
4.00
9.61
8.62
14.37
8.91
11.19
14.00
6.27
150
6.65
5.21
10.64
9.34
14.26
9.17
11.00
14
7.53
60
270
6.63
5.15
10.60
9.33
14.15
9.15
10.84
13.93
7.49
90
6.60
4.97
10.68
9.28
14.00
9.00
10.76
13.85
7.45
120
6.45
4.81
10.59
9.22
13.77
8.72
10.51
13.76
7.35
150
6.55
4.98
10.31
9.24
13.81
8.93
10.78
13.88
7.23
60
290
6.45
4.94
10.25
9.15
13.61
8.82
10.44
13.78
7.15
90
6.37
4.86
10.16
8.88
13.53
8.77
10.33
13.53
7.14
120
6.28
4.82
10.00
8.73
13.50
8.66
10.00
13.18
6.89
150
6.36
4.76
10.17
7.95
13.21
8.83
9.64
13.32
6.89
60
310
6.25
4.67
10.15
7.90
13.00
8.80
9.60
13.16
6.86
90
6.13
4.62
9.93
7.81
12.97
8.73
9.52
12.87
6.73
120
5.97
4.60
9.66
7.72
12.83
8.68
9.33
12.55
6.62
150
Appendix A
108
Table(A3) The volume percent of component in product
using Pt/Ba-Y Zeolite(WHSV=4.5h-1
)
Component Vol.%
Tim
e m
in.
Tem
per
ature
℃
2-4 DMP
2-2DMP
2-3 DMB
2-2DMB
n-C6
3-MP
2-MP
n-C5
i-C5
5.78
3.65
8.45
7.43
15.61
10.20
12.00
15
4.50
0
230 5.76
3.64
8.42
7.37
15.59
10.08
11.90
14.8
4.46
15
5.71
3.59
8.37
7.32
15.45
9.91
11.89
14.6
4.40
30
5.68
3.57
8.34
7.31
15.36
9.85
11.67
14.5
4.35
5.95
4.18
9.61
7.87
15.20
9.87
11.70
14.70
4.81
0
250 5.89
4.00
9.55
7.69
14.84
9.82
11.62
14.60
4.77
15
5.85
3.88
9.54
7.65
14.73
9.76
11.55
14.45
4.63
30
5.79
3.83
9.33
7.64
14.66
9.53
11.31
14.38
4.43
6.65
5.00
10.70
8.97
14.86
9.83
11.35
14
5.59
0
270 6.63
4.95
10.68
8.96
14.65
9.62
11.12
13.84
5.55
15
6.60
4.87
10.64
8.91
14.61
9.53
10.84
13.75
5.54
30
5.96
4.79
10.51
8.83
14.50
9.47
10.64
13.69
5.47
6.61
4.88
10.42
8.94
14.53
9.55
10.79
13.92
5.23
0
290 6.60
4.84
10.33
8.83
14.21
9.35
10.63
13.88
5.15
15
5.85
4.61
10.25
8.78
14.13
9.16
10.27
13.73
5.06
30
5.77
4.58
10.12
8.56
13.91
8.94
10.18
13.33
5.00
6.57
4.66
10.17
8.22
13.83
9.31
10.23
13.42
5.17
310
6.45
4.57
9.89
8.00
13.65
9.15
10.17
13.25
4.98
6.30
4.40
9.75
7.81
13.25
8.90
9.87
13.10
4.94
6.25
4.33
9.55
7.66
13.00
8.75
9.45
12.96
4.72
Appendix A
109
Table(A4) The volume percent of component in product
using Pt/H-Y Zeolite(WHSV=1.5h-1
)
Component Vol.%
Tim
e m
in.
Tem
per
ature
℃
2-4 DMP
2-2DMP
2-3DMB
2-2DMB
n-C6
3-MP
2-MP
n-C5
i-C5
7.00
4.67
10.37
10.00
13.23
9.00
10.70
12.75
7.56
60
230
6.97
4.65
10.33
9.94
13.15
8.88
10.69
12.70
7.50
90
6.88
4.65
10.32
9.90
12.97
8.79
10.65
12.62
7.48
120
6.79
4.60
10.22
9.78
12.80
8.76
10.45
12.44
7.45
150
6.85
4.80
11.65
10.65
12.65
8.75
10.52
11.00
8.65
60
250
6.80
4.79
11.60
10.60
12.63
8.70
10.50
10.61
8.59
90
6.81
4.73
11.59
10.59
12.18
8.51
10.44
10.55
8.55
120
6.76
4.70
11.56
10.55
11.87
8.43
10.40
10.40
8.54
150
8.10
6.22
13.18
11.12
11.10
8.70
9.75
8.71
9.22
60
270
7.95
6.20
13.15
11.11
11.00
8.44
9.70
8.34
9.19
90
7.87
6.14
13.10
11.00
10.91
8.39
9.40
8.33
9.12
120
7.80
6.00
12.96
10.97
10.60
8..00
9.15
8.25
9.11
150
8.00
5.98
12.87
10.76
9.95
8.18
9.12
8.60
9.77
60
290
7.88
5.96
12.45
10.75
9.91
8.13
9.10
8.47
9.68
90
7.84
5.95
12.32
10.69
9.88
7.92
9.00
8.37
9.65
120
7.81
5.90
12.25
10.49
9.56
7.89
9.00
8.13
9.63
150
7.62
5.70
12.66
10.45
9.33
8.10
8.60
8.48
9.55
60
310
7.55
5.65
12.44
10.33
9.12
7.90
8.47
8.45
9.46
90
7.43
5.59
12.42
10.30
9.00
7.81
8.45
8.36
9.41
120
7.40
5.58
12.30
10.18
8.88
7.50
8.19
8.22
9.40
150
Appendix A
110
Table(A5) The volume percent of component in product
using Pt/HY Zeolite(WHSV=3h-1
)
Component Vol.%
Tim
e m
in.
Tem
per
ature
℃
2-4 DMP
2-2DMP
2-3 DMB
2-2DMB
n-C6
3-MP
2-MP
n-C5
i-C5
6.25
4.00
10.77
9.00
13.55
9.49
11.34
13.33
6.00
0
230 6.24
3.98
10.75
8.98
13.48
9.45
11.25
13.10
5.98
15
6.20
3.98
10.70
8.97
13.40
9.35
11.11
12.85
5.93
30
6.18
3.95
10.55
8.89
13.32
9.30
10.97
12.70
5.93
6.33
4.60
11.00
9.80
13.37
9.09
11.22
13.00
7.44
0
250 6.33
4.56
10.89
8.76
13.34
8.96
11.10
12.75
7.38
15
6.32
4.49
10.79
9.75
13.29
8.87
10.65
12.66
7.37
30
6.16
4.47
10.75
9.60
13.11
8.81
10.48
12.50
7.29
7.00
5.44
12.26
10.54
13.00
9.00
11.00
10.00
8.66
0
270 6.94
5.43
12.16
10.48
12.85
9.95
10.66
9.93
8.64
15
6.91
5.40
12.08
10.40
12.66
8.74
10.45
9.86
8.60
30
6.85
5.33
11.90
10.40
12.45
8.70
10.00
9.79
8.55
6.75
5.37
11.89
10.33
12.65
8.50
10.27
9.84
8.60
0
290 6.74
5.25
11.85
10.27
12.50
8.46
10.14
9.83
8.45
15
6.66
5.14
11.78
10.15
12.44
8.35
10.00
9.33
8.44
30
6.62
5.11
11.70
10.10
12.39
8.29
9.76
9.20
8.32
6.69
5.34
11.57
10.14
12.00
8.33
9.84
9.36
8.36
310
6.65
5.33
11.55
10.00
12.77
8.20
9.44
9.16
8.30
6.60
5.26
11.47
9.88
11.45
9.12
9.23
8.88
8.23
5.54
6.20
11.44
9.82
11.19
8.80
9.12
8.80
8.13
Appendix A
111
Table(A6) The volume percent of component in product
using Pt/H-Y Zeolite(WHSV=4.5h-1
)
Component Vol.%
Tim
e m
in.
Tem
per
ature
℃
2-4 DMP
2-2DMP
2-3 DMB
2-2DMB
n-C6
3-MP
2-MP
n-C5
i-C5
5.80
3.68
8.60
7.45
15.42
10.00
11.34
14.84
4.80
0
230 5.79
3.66
8.59
7.44
15.33
9.88
11.30
14.66
4.76
15
5.74
3.62
8.53
7.41
15.25
9.82
11.17
14.56
4.75
30
5.73
3.59
8.44
7.36
15.17
9.66
11.10
14.35
4.68
6.00
4.18
9.82
8.00
15.17
9.71
11.11
14.45
4.91
0
250 5.95
4.10
9.78
7.89
14.74
9.63
10.92
14.44
4.89
15
5.91
4.00
9.78
7.87
14.64
9.45
10.85
14.31
4.83
30
5.90
4.00
9.65
7.77
14.54
9.34
10.79
14.30
4.76
6.85
5.14
10.77
9.18
14.75
9.55
11.00
13.77
5.80
0
270 6.83
5.12
10.76
9.16
14.61
9.47
10.88
13.74
5.79
15
6.83
5.09
10.70
9.11
14.57
9.38
10.76
13.62
5.74
30
6.70
5.10
10.67
9.10
14.43
9.27
10.55
13.49
5.69
6.79
5.00
10.60
9.12
14.53
9.51
10.56
13.62
5.73
0
290 6.67
4.93
10.57
9.06
14.40
9.24
10.34
13.57
5.70
15
6.61
4.92
10.55
8.98
14.00
9.10
10.12
13.50
5.63
30
6.57
4.75
10.49
8.87
13.80
8.78
10.00
13.30
5.50
6.74
4.70
10.48
8.93
13.73
9.20
10.22
13.37
5.48
310
6.70
4.69
10.40
8.85
13.60
9.15
9.97
13.16
5.44
6.65
4.69
10.33
8.81
13.19
8.60
9.77
13.00
5.38
6.53
4.50
10.20
8.67
13.00
8.33
9.33
12.90
5.22
Appendix A
112
Table(A7) The volume percent of component in product
using Pt/Al2O3(WHSV=1.5h-1
)
Component Vol.%
Tim
e m
in.
Tem
per
ature
℃
Tolu.
Benz.
2-4 DMP
2-
2DMP
2-3DMB
2-
2DMB
n-C6
3-MP
2-MP
n-C5
i-C5
3.44
3.78
7.56
5.84
11.14
9.97
12.68
9.78
10.30
11.75
6.33
0
230
3.12
3.77
7.45
5.80
10.85
9.75
12.67
9.77
10.27
11.71
6.15
15
3.12
3.65
7.38
5.78
10.62
9.74
12.60
9.74
10.22
11.69
5.89
30
3.10
3.45
7.35
5.70
10.55
9.74
12.56
9.66
10.17
11.56
5.85
4.5
4.95
7.44
5.27
10.87
9.41
10.87
9.60
10.26
8.00
5.45
0
250
4.29
4.93
7.39
5.22
10.67
9.00
10.82
9.59
10.15
7.54
5.12
15
4.26
4.88
7.38
5.20
10.61
8.87
10.65
9.35
9.97
7.53
5.10
30
4.23
4.85
7.33
5.18
10.44
8.66
10.33
9.11
9.92
7.47
5.08
6.47
5.80
7.37
5.16
10.22
9.22
9.80
9.35
10.17
6.90
5.33
0
270
6.37
5.78
7.34
5.08
10.19
8.97
9.71
9.29
10.00
6.79
5.25
15
6.29
5.75
7.23
4.95
9.98
8.57
9.45
9.15
9.89
6.76
5.12
30
6.18
5.73
7.18
4.88
9.84
8.23
9.32
8..97
9.76
6.55
5.00
9.21
7.57
6.86
5.00
9.76
8.57
8.54
8.83
9.83
6.86
5.11
0
290
9.13
7.46
6.78
4.93
9.54
8.28
8.44
8.79
9.75
6.72
4.94
15
9.10
7.42
6.66
4.88
9.52
7.98
8.36
8.65
9.60
6.64
4.88
30
8.97
7.34
6.45
4.85
9.48
7.90
8.18
8.46
9.58
6.44
4.80
10.00
7.80
6.32
4.87
9.42
8.44
7.35
8.72
9.65
5.98 4.80
310
9.81
7.74
6.25
4.78
9.36
8.21
7.21
8.64
9.58
5.97 4.75
9.72
7.65
6.15
4.74
9.30
8.13
6.93
8.53
9.45
5.84 4.63
9.44
7.62
6.11
4.68
9.28
8.00
6.74
8.49
9.36
5.33 4.55
Appendix A
113
Table(A8) The volume percent of component in product
using Pt/Al2O3(WHSV=3h-1
)
Component Vol.%
Tim
e m
in.
Tem
per
ature
℃
Tolu.
Benz.
2-4 DMP
2-2 DMP
2-3DMB
2-2DMB
n-C6
3-MP
2-MP
n-C5
i-C5
3.32
3.18
7.38
5.61
10.87
9.45
13.32
9.88
11.22
12.90
5.89
0
230
3.28
3.15
7.36
5.60
10.54
9.39
13.26
9.86
11.17
12.84
5.88
15
3.16
3.15
7.36
5.55
10.46
9.34
13.12
9.82
11.09
12.80
5.79
30
3.11
3.12
7.25
5.49
10.39
9.33
13.00
9.80
10.92
12.66
5.55
5.20
4.79
7.35
5.00
10.65
9.38 11.15
9.65
10.88
10.23
5.65
0
250
5.11
4.64
7.38
4.93
10.59
9.17 11.08
9.57
10.84
10.14
5.60
15
5.09
4.50
7.33
4.91
10.51
8.55 10.95
9.55
10.77
10.11
5.47
30
4.98
4.50
7.29
4.86
10.42
8.43 10.87
9.49
10.68
9.98
5.37
6.54
4.84
7.28
4.98
10.10
8.96 11.00
9.46
10.63
8.34
5.22
0
270
6.22
4.67
7.27
4.96
10.00
8.86
10.78
9.34
10.57
8.32
5.13
15
6.13
4.57
7.25
4.89
9.87
8.63
10.65
9.33
10.48
8.25
4.96
30
6.00
4.44
7.00
4.81
9.79
8.60
10.49
9..20
10.25
8.19
4.89
8.98
5.57
6.70
4.90
9.66
8.38
9.74
9.40
10.33
8.45
5.15
0
290
8.86
5.54
6.65
4.83
9.48
8.19
9.61
9.24
10.26
8.44
5.08
15
8.42
5.50
6.52
4.81
9.37
8.17
9.55
9.11
10.13
8.38
4.93
30
8.33
5.40
6.41
4.77
9.22
8.05
9.42
9.00
10.10
8.34
4.86
9.00
6.34
6.48
4.75
9.31
7.97
9.10
9.23
10.25
7.98 4.90
310
9.10
6.25
6.43
4.73
9.25
7.95
8.85
9.19
10.17
7.86 4.85
9.12
6.19
6.42
4.69
9.12
7.85
8.78
8.88
9.95
7.80 4.73
9.23
6.16
6.28
4.50
8.95
7.77
8.75
8.65
9.90
7.72 4.68
Appendix A
114
Table(A9) The volume percent of component in product
using Pt/Al2O3(WHSV=4.5h-1
)
Component Vol.%
Tim
e m
in.
Tem
per
ature
℃
Tolu.
Benz.
2-4 DMP
2-2 DMP
2-
3DMB
2-
2DMB
n-C6
3-MP
2-MP
n-C5
i-C5
3.22
3.15
7.12
5.45
8.98
8.20
13.80
10.20
11.80
13.10
5.39
0
230
3.20
3.12
6.94
5.31
8.98
8.10
13.77
10.10
11.77
13.00
5.20
15
3.16
3.11
6.86
5.30
8.88
8.00
13.67 9.96
11.67
12.97
5.00
30
3.14 3.11 6.79 5.22 8.76 7.95 13.60 9.87 11.50
12.95 500
4.80
4.49
6.97
4.88
8.87
8.10
13.00 10.00 11.60
11.65
5.16
0
250
4.77
4.44
6.85
4.76
8.68
8.00
12.88
9.88
11.53
11.44
5.12
15
4.69
4.30
6.84
4.72
8.54
7.89
12.60
9.85
11.36
11.37
4.98
30
4.61 4.18 6.82 4.68 8.43 7.85 12.43 9.83 11.24
11.15 4.96
7.54
4.64
7.92
4.68
8.78
8.00
12.36 9.89 11.30
10.32
5.10
0
270
7.44
4.60
6.77
4.56
8.63
7.87
12.20
9.84
11.24
10.29
5.00
15
7.23
4.53
6.68
4.51
8.57
7.66
12.10
9.76
11.18
10.19
4.87
30
7.12 4.43 6.67 4.47 8.34 7.54 12.00 9.74 10.92
10.25 4.65
8.66
4.71
6.44
4.50
8.22
7.84
11.00
9.65
11.00
10.15
5.00
0
290
8.58
4.62
6.35
4.47
8.12
7.70
10.85
9.59
10.93
9.89
4.80
15
8.42
4.50
6.31
4.40
7.98
7.65
10.78
9.48
10.89
9.76
4.77
30
8.35 4.46 6.22 4.31 7.92 7.58 10.60 9.41 10.77
9.69 4.59
8.87 5.87 6.12 4.47 7.86 7.76 10.88 9.30 10.87
9.78 4.78
310
8.76 5.78 6.10 4.35 7.77 7.64 10.82 9.23 10.78
9.73 4.60
8.72 5.69 6.09 4.25 7.73 7.59 10.72 9.18 10.63
9.65 4.35
8.53 5.65 6.00 4.13 7.66 7.40 10.65 9.00 10.57
9.45 4.22
Appendix A
115
Table(A10) The average volume percent of component in product
using Pt/BaY.
WHSV=1.5hr-1
T℃
C7+
2,4DMP 2,2DMP 2,3DMB 2,2DMB 3MP 2MP n-C6 n-C5 i-C5
14.04 6.50 4.20 10.40 10.55 9.14 11.12 14.40 14.08 5.29 230
13.65 6.84 4.23 10.80 10.60 8.88 10.69 13.42 13.84 7.05 250
13.82 7.14 5.46 11.20 11.36 8.43 9.61 12.06 12.46 8.82 270
17.42 7.00 5.37 11.13 10.65 8.07 9.24 11.33 10.95 8.69 290
20.41 6.72 5.15 10.80 10.51 8.02 8.49 10.80 9.97 8.63 310
WHSV=3hr-1 T℃
15.36 6.02 3.88 9.99 8.94 9.48 11.75 14.83 14.66 5.09 230
15.70 6.30 4.17 10.74 9.69 9.09 11.32 14.52 14.18 6.40 250
13.53 6.58 5.03 11.42 10.29 9.01 10.77 14.04 13.88 7.45 270
16.07 6.41 4.90 10.15 9.00 8.79 10.38 13.61 13.59 7.10 290
20.26 6.15 4.66 9.97 7.84 8.76 9.52 13.00 12.97 6.87 310
WHSV=4.5hr-1 T℃
16.39 5.73 3.61 9.39 8.37 10.01 11.86 15.50 14.72 4.42 230
15.62 5.87 3.97 10.50 8.71 9.74 11.55 14.85 14.53 4.66 250
14.23 6.61 4.90 10.40 9.00 9.61 10.98 14.65 13.82 5.53 270
15.86 6.55 4.77 10.28 8.77 9.25 10.46 14.19 13.71 5.11 290
20.86 6.38 4.49 9.84 7.92 9.02 9.93 13.43 13.18 4.95 310
Appendix A
116
Table(A11) The average volume percent of component in product
using Pt/HY.
WHSV=1.5hr-1
T℃
C7+
2,4DMP 2,2DMP 2,3DMB 2,2DMB 3MP 2MP n-C6 n-C5 i-C5
13.76 6.91 4.64 11.31 10.90 8.85 11.21 13.90 13.62 5.49 230
15.16 7.39 4.75 12.00 11.10 8.59 10.46 13.33 11.64 7.58 250
14.37 7.93 6.14 12.10 11.70 8.38 10.19 10.90 9.40 8.89 270
15.05 7.88 5.94 12.07 11.67 8.03 9.07 10.82 9.39 8.68 290
17.75 7.50 5.63 12.00 11.51 7.92 8.92 10.78 9.39 8.60 310
WHSV=3hr-1 T℃
14.95 6.21 3.97 10.69 9.96 9.39 11.16 14.42 14.00 5.25 230
13.50 6.60 4.53 10.85 10.13 8.93 10.86 14.23 13.72 7.37 250
13.22 6.89 4.65 11.10 10.45 8.84 10.61 13.74 11.89 8.61
270
16.92 6.69 4.51 10.80 10.21 8.40 10.08 13.39 10.55 8.45 290
19.07 6.62 4.45 10.50 10.00 8.11 9.80 13.15 10.05 8.25 310
WHSV=4.5hr-1 T℃
15.07 5.75 3.63 9.54 8.41 9.84 11.22 15.29 14.60 4.90 230
14.70 6.10 4.07 10.75 8.88 9.53 10.91 14.77 14.37 5.84 250
13.19 6.80 5.11 10.85 9.30 9.41 10.79 14.59 13.65 6.75 270
16.18 6.66 4.90 10.55 9.00 9.15 10.25 13.48 13.19 6.64 290
18.16 6.64 4.64 10.27 8.81 8.82 9.82 13.38 13.10 6.36 310
Appendix A
117
Table(A12) The average volume percent of component in product
using Pt/Al2O3.
WHSV=1.5hr-1
T℃
C7+ Tolu. Benz. 2,4DMP 2,2DMP 2,3DMB 2,2DMB 3MP 2MP n-C6 n-C5 i-C5
8.06 3.19 4.66 7.43 5.78 10.79 9.78 9.73 10.24 12.62 11.67 6.05 230
9.85 6.34 6.90 7.38 5.21 10.64 8.98 8.68 9.55 11.66 10.63 5.18 250
9.28 9.23 8.77 7.28 5.02 10.05 8.74 8.66 9.48 10.57 8.75 5.17 270
9.94 12.35 10.44 6.69 4.91 9.57 8.18 8.50 9.44 8.38 6.67 4.93 290
9.16 14.74 12.70 6.20 4.76 9.34 8.06 8.36 9.17 7.05 5.78 4.68 310
WHSV=3hr-1 T℃
7.24 3.31 3.94 7.33 5.56 10.56 9.37 9.84 11.10 13.17 12.80 5.78 230
9.66 6.09 6.60 7.32 4.92 10.54 8.88 9.56 10.79 11.01 10.11 5.52 250
7.35 9.22 8.63 7.20 4.91 9.94 8.76 9.33 10.48 10.73 8.40 5.05 270
7.61 11.64 9.50 6.57 4.83 9.43 8.19 9.18 10.20 9.58 8.27 5.00 290
7.00 13.11 11.23 6.40 4.66 9.15 7.91 8.98 10.06 8.87 7.84 4.79 310
WHSV=4.5hr-1 T℃
10.15 3.18 3.91 6.92 5.32 8.90 8.06 10.03 11.68 13.71 13.00 5.14 230
10.26 5.71 5.35 6.86 4.76 8.63 7.96 9.89 11.43 12.72 11.40 5.03 250
7.19 8.33 8.55 6.76 4.55 8.58 7.76 9.81 11.16 12.16 10.26 4.89 270
8.55 10.50 8.57 6.33 4.42 8.06 7.69 9.53 10.89 10.80 9.87 4.79 290
8.82 10.71 10.00 6.07 4.29 7.75 7.59 9.17 10.71 10.76 9.65 4.48 310
Appendix B
118
Appendix B The concentration (C×10P
-3P) of light naphtha.
Table (B1): The concentration of components in products using catalyst Pt/ BaY.
WHSV=1.5hrP
-1
T℃ 2,4DMP 2,2DMP 2,3DMB 2,2DMB 3MP 2MP n-CR6 n-CR5 i-CR5
1.57 0.97 2.52 2.46 2.21 2.69 3.49 3.41 1.28 230
1.59 0.98 2.56 2.47 2.07 2.49 3.12 3.22 1.64 250
1.60 1.22 2.73 2.55 1.89 2.15 2.70 2.79 1.98 270
1.51 1.16 2.60 2.36 1.74 2.00 2.45 2.37 1.92 290
1.40 1.07 2.36 2.19 1.67 1.77 2.25 2.08 1.80 310
WHSV=3hrP
-1 T℃
1.45 0.94 2.42 2.16 2.29 2.84 3.59 3.55 1.23 230
1.46 0.97 2.50 2.25 2.11 2.63 3.38 3.30 1.49 250
1.47 1.12 2.56 2.31 2.02 2.41 3.15 3.11 1.67 270
1.38 1.06 2.19 1.94 1.90 2.24 2.94 2.94 1.53 290
1.28 0.97 2.08 1.63 1.83 1.99 2.71 2.71 1.43 310
WHSV=4.5hrP
-1 T℃
1.38 0.87 2.27 2.02 2.42 2.87 3.75 3.56 1.07 230
1.39 0.92 2.44 2.03 2.27 2.69 3.46 3.38 1.08 250
1.48 1.10 2.61 2.10 2.15 2.46 3.29 3.10 1.24 270
1.41 1.03 2.22 1.89 2.00 2.26 3.07 2.96 1.10 290
1.33 0.93 2.05 1.65 1.88 2.07 2.80 2.75 1.03 310
Appendix B
119
Table (B2): The concentration of components in products using catalyst Pt/ HY.
WHSV=1.5hrP
-1
T℃ 2,4DMP 2,2DMP 2,3DMB 2,2DMB 3MP 2MP n-CR6 n-CR5 i-CR5
1.67 1.12 2.74 2.64 2.14 2.72 3.37 3.30 1.33 230
1.72 1.10 2.79 2.68 2.00 2.43 3.10 2.71 1.76 250
1.78 1.37 3.57 2.93 1.88 2.29 2.44 2.11 2.39 270
1.70 1.28 3.13 2.74 1.73 1.96 2.34 2.03 2.09 290
1.56 1.17 2.80 2.57 1.63 1.76 2.10 1.96 1.97 310
WHSV=3hrP
-1 T℃
1.50 0.96 2.42 2.41 2.27 2.70 3.49 3.39 1.27 230
1.53 1.05 2.52 2.36 2.08 2.53 3.31 3.19 1.71 250
1.54 1.21 2.71 2.34 1.98 2.38 3.08 2.67 1.93 270
1.44 1.12 2.55 2.21 1.81 2.18 2.90 2.28 1.83 290
1.38 1.07 2.40 2.07 1.69 1.96 2.63 2.10 1.72 310
WHSV=4.5hrP
-1 T℃
1.39 0.88 2.31 2.03 2.38 2.72 3.70 3.53 1.18 230
1.42 0.94 2.50 2.07 2.22 2.54 3.44 3.35 1.36 250
1.52 1.14 2.63 2.08 2.11 2.42 3.27 3.06 1.51 270
1.44 1.06 2.28 1.94 1.98 2.22 3.07 2.92 1.43 290
1.38 0.97 2.14 1.84 1.84 2.05 2.79 2.74 1.33 310
Appendix B
120
Table (B3): The concentration of components in products using catalyst Pt/ AlR2ROR3R.
WHSV=1.5hrP
-1
T℃ Tolu. Benz. 2,4DMP 2,2DMP 2,3DMB 2,2DMB 3MP 2MP n-CR6 n-CR5 i-CR5
0.77 0.88 1.80 1.40 2.61 1.37 2.35 2.48 3.05 2.82 1.46 230
1.01 0.90 1.72 1.21 2.48 2.09 2.02 2.22 2.48 1.77 1.20 250
1.39 1.07 1.63 1.12 2.25 1.96 1.72 1.95 2.15 1.51 1.16 270
2.09 1.67 1.50 1.10 2.14 1.83 1.62 1.89 1.88 1.49 1.10 290
2.03 1.61 1.29 0.99 1.95 1.68 1.54 1.70 1.47 1.20 0.97 310
WHSV=3hrP
-1 T℃
0.80 0.95 1.77 1.34 2.56 2.27 2.38 2.69 3.19 3.10 1.40 230
1.18 1.07 1.70 1.14 2.45 2.07 2.22 2.51 2.56 2.35 1.28 250
1.39 1.03 1.61 1.10 2.23 1.96 2.09 2.35 2.40 1.88 1.13 270
1.87 1.19 1.42 1.04 2.04 1.77 1.98 2.20 2.07 1.79 1.08 290
1.90 1.30 1.33 0.97 1.91 1.65 1.87 2.10 1.85 1.63 1.00 310
WHSV=4.5hrP
-1 T℃
0.77 0.94 1.67 1.28 2.15 1.95 2.43 2.83 3.32 3.15 1.24 230
1.09 1.01 1.59 1.10 2.01 1.85 2.30 2.66 2.96 2.65 1.17 250
1.19 1.02 1.51 1.02 1.92 1.74 2.20 2.50 2.73 2.30 1.09 270
1.62 0.98 1.37 0.95 1.74 1.66 2.06 2.35 2.33 2.13 1.03 290
1.82 1.20 1.26 0.89 1.62 1.58 1.91 2.24 2.25 2.01 0.93 310
Appendix C
121
Appendix C The conversion percent of light naphtha.
Table(C1) The Conversion percent of light naphtha using Pt/BaY
Conversion %
Tem
pera
ture
℃
WHSV=4.5 hr P
-1 WHSV=3 hr P
-1 WHSV=1.5 hr P
-1
Total 3MP 2MP n-CR6
n-CR5 Total 3MP 2MP n-
CR6 n-CR5 Total 3MP 2MP n-
CR6 n-CR5
18.9 19.8 20.0 17.2 19.0 21.0 24.1 20.8 20.7 19.3 24.0 26.8 25.0 22.9 22.5 230
24.0 24.8 25.0 23.6 23.1 26.5 30.1 26.7 25.3 25.0 29.8 31.4 30.6 31.1 26.8 250
29.2 29.8 31.4 27.3 29.5 31.2 33.1 32.8 30.4 29.3 40.0 37.6 40.1 40.3 41.5 270
33.7 33.7 37.0 32.2 32.7 35.5 37.0 37.6 35.0 33.1 44.9 42.3 44.2 45.9 46.1 290
38.8 37.3 42.3 38.1 37.5 40.5 39.3 44.5 40.1 38.4 50.0 44.7 50.6 50.3 52.7 310
Appendix C
122
Table(C2) The conversion percent of light naphtha using Pt/HY.
Conversion % Te
mpe
ratu
re
℃
WHSV=4.5 hr P
-1 WHSV=3 hr P
-1 WHSV=1.5 hr P
-1
Total 3MP 2MP n-CR6 n-CR5 Total 3MP 2MP n-CR6 n-CR5 Total 3MP 2MP n-CR6 n-CR5
20.6 21.1 24.2 18.3 19.7 23.7 24.8 24.7 22.9 22.9 26.5 29.1 24.2 24.9 25.0 230
25.6 26.4 29.2 24.0 23.8 28.5 31.1 29.5 26.9 27.5 34.1 33.7 32.3 31.5 38.4 250
30.1 30.1 32.5 27.8 30.4 34.9 34.4 33.7 32.0 39.3 44.9 37.7 36.0 46.1 52.0 270
34.4 34.4 38.1 32.2 33.6 40.9 40.0 39.2 35.9 48.1 48.1 42.7 39.5 48.3 53.8 290
39.3 39.0 42.8 38.4 37.7 46.0 44.0 45.4 41.9 52.2 52.0 46.0 43.3 53.6 55.4 310
Table(C3) The conversion percent of light naphtha using Pt/AlR2ROR3R.
Conversion %
Tem
pera
ture
℃
WHSV=4.5 hr P
-1 WHSV=3 hr P
-1 WHSV=1.5 hr P
-1
Total 3MP 2MP n-CR6 n-CR5 Total 3MP 2MP n-CR6 n-CR5 Total 3MP 2MP n-CR6 n-CR5
25.5 19.5 21.1 26.7 28.4 27.4 21.1 25.0 27.5 29.5 31.2 22.1 30.9 33.6 35.9 230
33.8 23.8 25.9 34.6 39.7 40.3 26.4 30.0 43.4 46.5 47.5 33.1 38.1 45.2 59.7 250
39.4 27.1 30.3 39.7 47.7 46.6 30.7 34.5 47.0 57.2 54.9 43.0 45.6 52.5 65.6 270
45.4 31.7 34.5 48.5 51.5 51.1 34.4 38.7 54.3 59.3 58.2 46.3 47.3 58.4 66.1 290
48.3 36.7 37.6 50.3 54.3 55.2 38.0 41.5 59.1 62.9 64.7 49.0 52.6 67.5 72.7 310
Appendix D
123
Appendix D
Table (D1):The reaction rate constant for n-pentane, n-hexane,
and 3MP at WHSV of 1.5hr P
-1P over Pt/BaY and Pt/HY catalysts.
n-pentane
Temperature℃
Pt/HY Pt/BaY
kR2 kR1 kR2 kR1
0.198 0.179 0.200 0.159 230
0.310 0.287 0.400 0.187 250
0.511 0.413 0.350 0.329 270
0.360 0.419 0.318 0.338 290
0.300 0.422 0.250 0.392 310
n-Hexane
1.0 0.182 0.258 0.156 230
0.775 0.231 0.400 0.228 250
1.8 0.364 0.388 0.304 270
0.658 0.375 0.215 0.349 290
0.330 0.422 0.09 0.384 310
3MP
2.3 0.219 0.370 0.198 230
2.0 0.251 0.680 0.230 250
2.87 0.282 0.735 0.278 270
3.5 0.316 0.400 0.313 290
0.761 0.350 0.122 0.325 310
Appendix D
124
Table (D2):The pre-exponential (kRoR) factor for n-pentane, n-hexane, and 3MP at WHSV of 1.5hrP
-1P over Pt/BaY and Pt/HY
catalysts.
3MP n-hexane n-pentane Catalysts
0.227 0.179 0.259 Pt/BaY
0.386 0.275 0.272 Pt/HY
Appendix E
125
Appendix E
Table (E1): The percentage selectivity and conversion products.
Pt/Ba-Y
Tem
pera
ture
℃
WHSV=4.5hrP
-1 WHSV=3hrP
-1 WHSV=1.5hrP
-1
Conversion Isomers Aromatic Conversion Isomers
Aromatic Conversion Isomers Aromatic
18.9 19 0.69 21.0 33 0 24.0 51 0 230
24.0 31 0 26.5 49 0 29.8 74 0 250
29.2 42 0 31.2 75 0 40.0 89 0 270
33.7 32 0.16 35.5 45 0.37 44.9 67 1.72 290
38.8 17 5.16 40.5 44 4.56 50.0 46 4.71 310
Pt/H-Y ℃ T
20.6 25 0 23.7 46 0 26.5 63 0 230
25.6 44 0 28.5 69 0 34.1 81 0 250
30.1 60 0 34.9 84 0 44.9 95 0 270
34.4 44 0.48 40.9 61 1.22 48.1 89 0 290
39.3 35 2.46 46.0 50 3.37 52.0 73 2.05 310
Pt/ALR2ROR3 ℃ T
25.5 0.17 0.74 27.4 43 0.9 31.2 48 1.5 230
33.8 0 3.71 40.3 17 5.34 47.5 26 6.89 250
39.4 0 10.53 46.6 .18 11.5 54.9 12 11.65 270
45.4 0 12.72 51.1 0 14.79 58.2 0.11 16.44 290
48.3 0 14.36 55.2 0 18 64.7 0.08 21.09 310
Appendix F Sample of Calculation
126
Appendix F
Sample of Calculation
1. Calculation of amount of H2PtCl6
in each catalyst samples :
0.5% Wt of Pt must be added to each sample catalysts
0.5 100
w=20 (0.5/100) = 0.1 g of Pt
w 20
but H2PtCl6
contain 40% of Pt
WH2PtCl6 = 0.1/0.4 = 0.25 g of H2PtCl
6
2-
Calculation of amount of Ba (in BaY catalyst
wt (gm)= N × eq. wt × V/1000
wt (gm)= 3 × 122.14 × 100/1000
wt (gm)= 36.642 gm
Appendix F Sample of Calculation
127
3-Calculation of amount of H as (NH4
wt (gm)= 3 × 53.49 × 100/1000
Cl) in HY catalyst
wt (gm)= 16.047 gm
4-
Calculation of the conversion of the light naphtha (X).
X =
CAo = × yA
C
o
A = × y
Where P Pressure, (atmospheric pressure)
A
R Gas Constant, 0.0821 atm-liter/g-mole-K
yAo
y
Initial Mole Fraction of n- Paraffin
A
T
Mole Fraction of n- Paraffin at any Time o
T Second Temperature at any Time
Initial Temperature
5-Calculation of the reaction rate constants (k1, k2
).
A- The calculation of the reaction rate constant (k1) can be achieved according to equation (4.22)
Appendix F Sample of Calculation
128
k1= [(1+ є)Ln – Єx] ------------------------------(4.22)
where X Percentage Conversion
FAo:
V: Volume of Reactor cm
Mass Flow Rate gm/hr
3
B- The calculation of the reaction rate constant (k2
) can be achieved according to equation (4.11) by trial and error.
Ciso = CA° [1- exp (- k1t) - [exp(-k1t) – exp(-k2
t)]
6-
According to equation (4.23) the calculation of the apparent
activation energy may be achieved by plotting Lnk
Calculation of the apparent activation energy (E).
1
Lnk
vs. 1/T as shown
in Figures (5.36) to (5.44).
1=Ln k◦ - -----------------------------(4.23)
Where the slope is represent –E/R, the intercept is represent pre-exponential factor (ko
where R Gas Constant 8.314 joules/g-mole-K
).
الخالصة
النتاج األيزومرات ) في مصفى الدورة المنتجة(البحث ازمرة مادة النفثا الخفيفة العراقية عملية تضمن ت
Pt/AlR2ROR3 هي خالل العملية تم تحضير ثالثة عوامل مساعدة. قابلة والتي لها عدد اوكتاني عاليمال
%0.5 .وزنا من البالتين والمحضر بطريقة الترطيب Pt/BaY, Pt/HY , وية على نسبة والحا
مصنوع من مادة تم اجـــــراء التجارب في منظومة مختبريــــــة تحتوي على مفاعل ذو حشــــــــــوة ثابتة
سم 3سم والقطر الخارجي 2القطر الداخلي للمفاعل . األستيل المقاوم للصدأ والمصمم لعملية األزمرة
، 250، 230وبدرجـــات حرارة حت الضغط الجوي األعتياديتالتجارب جميع تمت. سم 21واألرتفاع
Pساعة 4.5و 3، 1.5 وزنية م وباستخدام سرع فراغية˚310و 290، 270
-1P ثابتة مولية ةوبنســـب
.4 النفثا الخفيفةللهيدروجين الى
، البنتان األعتيادي(تي تعاني عملية التحول هي أظهرت النتائج بان المركبات الرئيسية في النفثا الخفيفة ال
والتي تزداد بزيادة درجة حرارة التفاعل وتقليل السرع) مثيل بنتان 3و ، مثيل بنتان 2، الهكسان األعتيادي
تزداد عمليات التحولاأليزومرات الناتجة من وتشير نتائج التحليل بان . والمحمل عليهما البالتين الفراغية
. كعوامل مساعدة Pt/BaY, Pt/HYعند درجات الحرارة المنخفضة و بوجود
بينما نالحظ المركبات األروماتية في النواتج تزداد بزيادة درجة حرارة التفاعل وبوجود األلومينا كعامل .مساعد
اكبر من % 95اعطى انتقائية باتجاه األزمرة وهي Pt/HY من خالل النتائج بان العامل المساعد نالحظ
تحت نفس الظروف من% 89والتي كانت Pt/BaY األنتقائية التي حصلنا عليها باستخدام العامل المساعد
ساعة1.5وسرعة فراغية م ˚270درجة حرارة من جانب اخر تم الحصول على اعلى نسبة تحول. P
-1
كانت .%18 حيث تشكل نسبة المواد األروماتية منها حوالي %64.7مساعد وهي باستخدام األلومينا كعامل
% .50تقريبا Pt/BaY, Pt/HYنسبة التحول الكلي للعوامل المساعدة
:كما يلي األنتقائيةالكفاءة بأتجاه ترتيب العوامل المساعدة حسب يكون
Pt/HY > Pt/BaY > Pt/AlR2ROR3R
من خالل الميكانيكية المقترحة باألعتماد على الميكانيكية الكالسيكية في عمليات تم دراسة حركية التفاعالت األزمرة ومن خاللها تم حساب المتغيرات kR1R, kR2R, kRoR, E . باألعتماد على النتائج العملية )
)
، األعتيادي بنتانمول بالنسبة لل/كيلوجول 23و 22تتراوح بين بانها تم دراسة قيم طاقات التنشيط و وجدت
3الى ال مول بالنسبة/كيلوجول 17و 15و بين ، مول بالنسبة للهكسان األعتيادي /كيلوجول 24و 20و بين
أللكانات األعتيادية المستخدمة في هذه الدراسة تسير كما ل درجة التفاعليةالى ان كما تشير النتائج، مثيل بنتان
:يلي
3-methylpentane > n-hexane > n-pentane
باألعتماد على الميكانيكية المقترحة ومن خالل النتائج العملية التي تم الحصول عليها في تم اشتقاق معادلتين :من خاللهما وكما يلي ) kR1R, kR2R (ثوابت معدل التفاعل حيث تم حساب ، عملية األزمرة
kR1R= [(1+ Є) Ln – Єx]
CRisoR = CRA°R [1- exp (- kR1Rt) - [exp(-kR1Rt) – exp(-kR2Rt)]