NANOCATALYSIS AND PROSPECTUS OF GREEN CHEMISTRY

Prepared and represented by:Ankit groverMsc.(h .s)chem.2nd year

Higher activity,

Higher selectivity,

Efficient recovery

Cost-effectiveness.

Durability

Overview

Refernces

Introduction Nanoparticles Catalysis

Gold nanocatalysis: oxidation reactions

Magnetically separable nanocatalysts

Applications of Nanocatalysts Hydrogen storage for fuel cell applications

Intoduction

Factor Prefix Symbolo 10-1 deci d o 10-2 centi co 10-3 milli mo 10-6 micro µo 10-9 nano n o 10-12 pico po 10-15 femto f

Actually the nanoparticles are particles with sized between 100 and 1 nanometers

What Is The Meaning Of Nanoparticles?

GOLD NANOPARTICLES

5

Catalysis

• Catalyst - a substance that initiates or accelerates a chemical reaction without itself being affected

A + B C + DActivation energy

catalyst

oil refining petrochem polymersfine chemicals pharma environmental

Traditional catalyst markets

Annual catalyst market $12 - 15 Billion

25 °C0% yield100% yield!!

What is the meaning of nano for catalysis?

Cubic (7.2 nm)(More active)

Spherical(4.8)(Less active)

Nanosize imparts special properties to the material by its structural and electronic changes.Bcz in case of nanoparticles activity is the function of electronic and structural function.

Activity of a catalyst Surface area of catalyst∝For conventional catalyst’s .There is direct relation between activity and area of the catalyst

Big picture: Sustainable Development

Waste prevention

Atom economy

Less hazardous chemistry

DesigningOf safer chemicals

Safer solventsAnd auxillries

Energy efficiency

Reduce the use Of chemical derivatives

catalysis

Design fordegradation

Real time Analysis forPollution prevention

Safer chemistry

Green chemistry is a philosophy that puts forward sustainable concepts, which are designed to reduce or eliminate chemicals and chemical processes that have negative environmental impacts and it based on 12 principle’s.

RenewableFeedstock

Waste prevention

Atom economy

Less hazardous chemistry

DesigningOf safer chemicals

Safer solventsAnd auxillries

Energy efficiency

Reduce the use Of chemical derivatives

catalysis

Design fordegradation

Real time Analysis forPollution prevention

Safer chemistry

Green chemistry is a philosophy that puts forward sustainable concepts, which are designed to reduce or eliminate chemicals and chemical processes that have negative environmental impacts and it based on 12 principle’s.

RenewableFeedstock

catalysis

Designing and developing ideal catalysts paves the way to green chemistry.

Green and sustainable catalyst should posses:

higher activity,

higher selectivity,

cost-effectiveness.

efficient recovery from reaction medium

durability or recyclability, and

Gold nanocatalysis: oxidation reactions

The pt/pd catalysts that are currently used in cars for CO oxidationWork only at temperatures above 200C, so most of COPollution occurs in the initial minutes after starting theEngine.

Au catalyst could solve this problem because of the complexity involved in Au/metal oxide catalysts.

History:

The bare Au6

Adsorbs molecular oxygen In the superoxo form

SubsequentCo-adsorption of CO may initially yield an au6co3

Species

Rearranges to produce the very stable CO3

-

Adsorbate

Elimination ofCO2 yields the Au6O- form

Adsorption of a second CO yields theAu6CO2

Mechanism:

Efficient recovery of the catalyst from the reaction medium after the completion of reaction is the key factor that determines its usage for practical applications

Magnetically separable nanocatalysts :

Anchoring colloidal particles or homogeneous catalysts on magnetic supports (nanoparticles) is an ideal solution to this problem.

Nanoparticles catalyst

Hetrogeneous catalyst’s

Homogeneous catalyst’s

Anchoring of homogeneous catalystschiral Ru-based complex was anchored successfully on Fe3O4 nanoparticles

Ru(II) complex [Ru(BINAP-PO3H2)(DPEN)Cl2]

Phosphonic acid group attached to the BINAP ligand acts as a linker and binds to the surface of Fe3O4 nanocrystal surface.

Anchoring of homogeneous catalystschiral Ru-based complex was anchored successfully on Fe3O4 nanoparticles

This catalyst was successfully used for the hydrogenation of a range of aromatic ketonesto the corresponding secondary alcohols with high enantioselectivity.

catalyst was tested up to 14 cycles without loss of activity, and high enantiomeric excess (ee) values.Ru(II) complex [Ru(BINAP-PO3H2)(DPEN)Cl2]

Phosphonic acid group attached to the BINAP ligand acts as a linker and binds to the surface of Fe3O4 nanocrystal surface.

Nanocatalysts for Clean Energy Applications

H2 +O2 H2O+Energy

Totally green reaction and hydrogen has3 times more chalorific value than L.P.GExcept the problem of storage H2 is seems As good energy source.

(=-150 kJ/mol).

H2 can be preapred by 2 methods:

1)By hydrolysis of H2O

(G=237 kJ/mol).

2) from coal and natural gasby the steam reforming reactionleads to large CO2 emission as shown in picture.

Water splitting in the presence of a semiconducting photocatalyst(e.g., TiO2, TaON, and LaTiO2N). The nanotubular architecture allows for more efficient absorptionof incident photons as well as decreased bulk recombination.

It has been established that the presence of a cocatalyst greatly enhances the efficiency of the overall process. Noble metal- or transition metal-oxide nanoparticles are often used as cocatalysts to facilitate water reduction. These nanoparticles are dispersed on active photocatalysts by applying in situ photodeposition methods to produce activesites and reduce the activation energy for gas evolution

HRTEM image of Rh-GaN:ZnO catalyst:

Rh-GaN:ZnO photo-catalyst surface

Rh nanoparticles

Cr2O3 cocatalyst

HRTEM image of Rh-GaN:ZnO catalyst:

Rh core facilitates the transfer of photo-generated electrons from the bulk(GaN:ZnO) to the surface (Cr2O3). The Cr2O3 layer is permeable to protons and the evolved H2 molecules, but not to oxygen.Therefore, the backward reaction over the noble metal is prevented by the Cr2O3 shell

Applications of Nanocatalysts:Hydrogen storage

Being the lightest element Storing H2 at high pressures or at very low temperaturesis not economically viable. Chemical H2 storage involves storing H2 in the form ofchemical bonds. A number of materials with a high gravimetric .H2 content are explored as H2 storage materials.

Boron hydrides with a high gravimetric content of H2 havebeen widely studied as H2 storage materials; however, their regenerationprocess is energy intensive.Most of these materialsare stable at room temperature and do not react at a sufficientrate to warrant their application

Conclusions and Outlook:

Rational design for environmentally benign catalysts is possible.

nanocatalysts are widely applicable.For hydrogen storageFor fuel cell applicationsFor industrial manufacturing procesessIn pharma. industries

Academic application areas are limitless

References:

[1] a) R. P. Goodman, I. A. T. Schaap, C. F. Tardin, C. M. Erben, R. M. Berry,C. F. Schmidt, A. J. Turberfield, Science 2005, 310, 1661 –1665; b) B. C.Regan, S. Aloni, K. Jensen, R. O. Ritchie, A. Zettl, Nano Lett. 2005, 5,1730 –1733.

[2] a) J. Grunes, J. Zhu, G. A. Somorjai, Chem. Commun. 2003, 2257– 2260;b) G. A. Somorjai, K. McCrea, Appl. Catal. A: Gen. 2001, 222, 3 – 18

[3] a) G. Ertl, D. Prigge, R. Schloegl, M. Weiss, J. Catal. 1983, 79, 359– 377;b) G. Ertl, Angew. Chem. 2008, 120, 3578– 3590; Angew. Chem. Int. Ed.2008, 47, 3524 –3535.

[4] M. Haruta, N. Yamada, T. Kobayashi, S. Iijima, J. Catal. 1989, 115, 301

[5] R. Narayanan, M. A. El-Sayed, Nano Lett. 2004, 4, 1343 – 1348.

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