1. Catalytic Reaction Engineering Catalysis and Catalytic Reactors
Textbook: Elements of Chemical Reaction Engineering, 4th Edition
CHE 404
Catalytic Reaction Engineering
Chapter 10
Catalysis and Catalytic Reactors
PART 1

2. What is Catalyst? Definition
화학공정 (촉매)
What is Catalyst? Definition
Definition
A catalyst is a substance which increases the thermodynamically feasible
reaction rate while remaining unaltered at the end of the reaction;
A substance which alters the speed of a chemical reaction by its presence
although not being consumed significantly
Catalysis: an act of catalyst (Berzelius, 1936)
The word catalysis comes from two Greek words.
cata - ‘down’ lysein - ‘split or break’
to denote the breaking down of the normal forces
which inhibit the reaction of molecules.
Rxn: A + B  P
(Adsorption)
(Surface reaction)
(Desorption)
What is Catalysis?
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3. Action of Catalysts: Energy Diagram
화학공정 (촉매)
Action of Catalysts: Energy Diagram
-rA = kCAn, k = k0e(-Ea/RT)
-Ea ↓  - rA ↑
ΔG0
A catalyst changes only the rate of a reaction
but cannot change the equilibrium.
ΔG0
The initial and final states are the same by both un-catalyzed and catalyzed process,
 The overall free Gibbs energy, ΔG0 is therefore identical,
 All the thermodynamic parameters, including the equilibrium constant Keq = exp (- ΔG0 /RT) were
not affected and catalysts only permit to attain the equilibrium more quickly.
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4. 화학공정 (촉매)
Action of Catalysts
The use of catalyst DOES NOT vary G & Keq values of the reaction concerned.
 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 G & Keq, NOT by the presence of catalysts.
 In other word, the reaction thermodynamics provide the driving force for a rxn;
the presence of catalysts changes the way how driving force acts on that process.
e.g CH4(g) + CO2(g) = 2CO(g) + 2H2(g) G°373=151 kJ/mol (100 °C)
G°973 =-16 kJ/mol (700 °C)
 - At 100°C, G°373=151 kJ/mol > 0. There is no thermodynamic driving force, the reaction
won’t proceed with or without a catalyst
 - At 700°C, G°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 the reactor at the same temperature, equilibrium
conversion can be achieved (<100%).
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5. Steps in Catalytic Reactions
화학공정 (촉매)
Steps in Catalytic Reactions
A  P
Not limiting if
small cat. particle
high fluid velocity
Limiting steps !
Step-4 >75%
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6. Energy Diagram during Reaction
Step in the overall reaction
Energy level of the system
Er (catalytic)
Er (thermal)
 Hr
Reactant
Product
Adsorption
Reaction
Desorption
A catalyst changes only the rate of a reaction but cannot change the equilibrium.
CHE 404 Chemical Reaction Engineering Chapter 10

7. 화학공정 (촉매)
History of Catalysis
New word "katalysis", breaking down or loosening, was introduced
by J. J. Berzelius
Major breakthrough in industrial catalysis
Synthesis of ammonia from nitrogen and hydrogen gases using osmium
as catalyst, by Frith Harber
The ammonia synthesis was commercialized at BASF as the
Harber-Bosch process. Mittasch at BASF developed iron catalysts.
The synthesis of methanol from CO and H2 over ZnO-Cr2O3.
The cracking of heavier petroleum fractions to gasoline using
acid-activated clay.
The alkylation of isobutane to C3-C4 olefins in the presence of AlCl3,
leading to branched C7-C8 HCs for high quality gasoline by Ipatieff et al,
and commercial process of UOP, USA.
Fischer-Tropsch synthesis of HCs from CO and H2 over iron catalyst.
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8. Industrial Application of Heterogeneous Catalysis
화학공정 (촉매)
Industrial Application of Heterogeneous Catalysis
Quantum developments in industrial application of heterogeneous catalysis
ENERGY & CLEAN TECH
Fuel Cell
xTL(CTL, GTL, BTL )
CO2 Conversion
Batteries (Li-Air)
Photosynthesis
Electrocatalysis
etc
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9. Organization of Catalysts
화학공정 (촉매)
Organization of Catalysts
Main focus
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10. Solid Catalysts: what they contain?
화학공정 (촉매)
Solid Catalysts: what they contain?
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11. Principles and concepts in heterogeneous catalysis
화학공정 (촉매)
Principles and concepts in heterogeneous catalysis
 Sabatier’s Principle
Proposes the existence of an unstable intermediate compound formed between the catalyst surface and at least one of the reactants
This intermediate (surface formate) must
be stable enough to be formed in
sufficient quantities and labile enough to
decompose to yield the final product.
The measure of stability of the
intermediates ~ heat of formation Hf
Au isn’t good catalyst because it doesn’t
form strong enough attachments, W
ins’t a good catalyst because it adsorbs
too strongly.
 A max rate is observed at intermediate Hf over Pt or Ir catalyst.
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12. Possible another reaction:
Porous Catalysts
Typical example: Zeolite
(SEM image of zeolite)
(TEM image of Pd-Pt/Beta)
Possible another reaction:
Ethane cyclization
CHE 404 Chemical Reaction Engineering Chapter 10

13. Shape Selectivities in Zeolites
CHE 404 Chemical Reaction Engineering Chapter 10

14. Catalytic functions for hydrocarbon processing
What do we want to do with hydrocarbons?
1) something with C-H : metals
2) something with C-C : acids
3) something with C-H & C-C : both metals & acids 14
CHE 404 Chemical Reaction Engineering Chapter 10

15. R&D in Catalysis: Multi-discipline approach
화학공정 (촉매)
R&D in Catalysis: Multi-discipline approach
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