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CRE II Heterogeneous Catalysis

L1-2

Prof. K.K.Pant

Department of Chemical EngineeringIIT Delhi.

kkpant@chemical.iitd.ac.in 

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CRE-II 3  – 1  – 0Prerequisite CHL-122

Course Outline

•Introduction to Catalysis, Classification, Catalyst preparation,

evaluation of Catalyst properties. 5

•Physical and Chemical adsorption, Different types of

adsorption isotherms, determination of surface area and porevolume of the Catalyst 6

•Kinetics of solid catalyzed gas phase reaction, Reaction

mechanism, Laboratory reactors for catalytic gas solidreactions. 8-9

•Mass transfer, Diffusion and Chemical reactions in catalysts.

Effects of external mass transfer and heat transfer,

Effectiveness factors. 8-9

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•Course outline , contd..

•Fixed bed catalytic reactors, reactor models, concept of

heterogeneous models. 4

•Non-catalytic gas-solid reactions, different model for gas-solid

reaction, 4

•Gas liquid reactions, film and penetration theories, enhancefactor in gas-liquid reactions, Concept of Reactor Design 4

•Reactor systems for gas-liquid reactions. Laboratory / design

activity (time permitting). 2-3

Grading: QUIZ : 10 (ONE ONLY), TERM Paper 4, Assignments/

Tut. : 2+4, Minors 2( 40), Major (40)

NO MAKE UP EXAMS

• 

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Books:

•Fogler H.S, ‘Elements of chemical reaction engineering’ IV th

Ed . ( Text Book: MUST be BRING during TUTORIAL

SESSIONs)

•Smith J.M., ‘Chemical engineering kinetics’, Mcgraw Hill,

•Carberry, J ‘Chemical and catalytic reaction engineering’

Mcgraw Hill

•Froment G.F & Bischoff K.B., ‘Chemical reactor analysis and

design’ John Wiley 

•C.G. Hill, ‘An Introduction to Chemical Engineering Kinetics

and Reactor Design’ 

•Levensipiel : Chemical Rexn Engg.

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What is a catalyst ??

•  Alters the rate of reaction with highselectivity

• Does it participate in the reaction ??

• How does it change the rate ?? – Offers an alternate path with low E.

• Does it affect HR, GR, and Eq.

constant ??• Does it affect yield & selectivity ??

• Does it initiate a reaction ??

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-What is Catalyst ?

•  Allow reactions occur under a milder

conditions, e.g. at lower temperatures forthose heat sensitive materials

•  It is important to remember that the use of

catalyst DOES NOT vary DG & K eq values ofthe reaction concerned, it merely change the

PACE of the process.

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Assignment 1Due date: August 6th 

1. Give the Thermodynamic criteria for a ChemicalReaction.

2. Write down an Algorithm for calculation of

product composition in a multiple reaction from

Thermodynamic analysis (case study: Steam

reforming of Ethanol (PRODUCTS: CH4, CO, CO2,

and H2, T= 500-800 C) State other conditions used.

3. Different types of Reactors used in Chemical

Process Industries.

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• The reaction activation energy is altered

• The intermediates formed are different

from those formed in non-catalytic

reaction

• The rates of reactions are altered (both

desired and undesired ones)

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Action of Catalysts

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-Reactions proceed under less demanding

conditions

•  Allow reactions occur under a milder

conditions, e.g. at lower temperatures for

those heat sensitive materials

•  It is important to remember that the use

of catalyst DOES NOT vary DG & K eq 

values of the reaction concerned, it

merely change the PACE of the process.

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• Whether a reaction can proceed or not and to

what extent a reaction can proceed is solely

determined by the reaction thermodynamics,

which is governed by the values of DG & K eq,

NOT by the presence of catalysts.

• The reaction thermodynamics provide the drivingforce for a rxn; the presence of catalysts

changes the way how driving force acts on that

process.

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e.g CH4(g) + CO2(g) = 2CO(g) + 2H2(g)

DG°373=151 kJ/mol (100 °C) & DG°973

=-16 kJ/mol (700 °C)

=>At 100°C, DG°373=151 kJ/mol > 0.There is no thermodynamic driving force,the

reaction won’t proceed with or without a

catalyst

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 At 700°C, DG°373= -16 kJ/mol < 0. The

thermodynamic driving force is there. However,

simply putting CH4 and CO2 together in a

reactor does not mean they will react. Without

a proper catalyst heating the mixture in reactor

results no conversion of CH4 and CO2 at all.

When Pt/ZrO2 or Ni/Al2O3 is present in thereactor at the same temperature, equilibrium

conversion can be achieved (<100%).

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