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8/13/2019 CRE II L1
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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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