CATALYSIS, TYPES OF CATALYSIS FOR CHEMISTRY STUDENTS

TYPES OF CATALYSIS
Pharmaceutical Chemistry
GURUNANAK COLLEGE OF PHARMACY

CONTENTS
• Introduction
• Types of catalysis:-
- Homogenous Catalysis
- Heterogenous Catalysis
• Advantages
• Disadvantages
• Summary
• References
12/2/2019
University Department of Pharmaceutical
Sciences,R.T.M.N.U, Nagpur.
2

INTRODUCTION
• A Catalyst is a substance that affects the rate of chemical reaction but emerges from
the process unchanged.
• Catalysis is the occurrence, study, and use of catalysts and catalytic processes.
• Catalyst is a substance which is not consumed in the reaction but increases the rate of
reaction.
• It provides an alternative reaction mechanism with lower activation energy than the
non-catalyzed mechanism.
• Forms a temporary intermediate, which then generates the original catalyst in a cyclic
process.
• Catalytic activity is usually denoted by symbol 'z' & Measured in mol/s ( katal is SI unit
for Catalytic activity).
• Examples of catalysts-
METALS OXIDES
1.Fe – Haber Process 1. Al2O3 - Dehydration reactions
2.Ni,Pt- Hydrogenation reactions 2. V2O5 - Contact process
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TYPES OF CATALYSIS
CATALYSIS
HOMOGENOUS
CATALYSIS
HETEROGENOUS
CATALYSIS
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HOMOGENOUS CATALYSIS
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EXAMPLES
• Transition metal compounds participate in homogenous
catalysis as they have the ability to change their oxidation
states.
• Other examples include:-
12/2/2019 University Department of Pharmaceutical Sciences,R.T.M.N.U, Nagpur. 6

ADVANTAGES
• Dissolves in reaction medium, hence all
catalytic sites are available for reaction
• Good contact with reactants
• Low cost and widely available
• High specificity
• Low reaction temperatures
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DISADVANTAGES
• Difficult separation
• Reactor corrosion
• Huge waste materials
• Complicated handling
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HETEROGENOUS CATALYSIS
• Catalyst in different physical phase from the reactants.
• It is also called contact catalysis.
• It possesses great industrial importance.
• It works in 3 steps:-
1. Adsorption- Incoming species lands on an active site and forms
bond with catalyst.
It may use some of the bonding electrons in the molecules thus
weakening them and making a subsequent reaction easier.
2. Reaction- Adsorbed gases ay be held on the surface in just right
orientation for a reaction to occur.
This increases the chances of favorable collisions taking place.
3. Desorption- There is a rearrangement of electrons and the
products are then released from active sites.
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EXAMPLES
1. Gas Phase –
2. Liquid Phase-
3. Solid Phase-
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ADVANTAGES
• Stable
• Reusable
• Use as a fixed beds
• Easy separation
• Less corrosive character
• Environment friendly
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DISADVANTAGES
• Difficult to study and hence reaction
mechanism unknown.
• Nonselective to chiral catalysis.
• Energy intensive.
• Complicated catalyst synthesis leads to higher
cost.
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SUMMARY
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REFERENCES
• Available from https://en.wikipedia.org/wiki/Catalysis
• Available from https://www.slideshare.net/
• Available from https://www.researchgate.net/
• Available from https://slideplayer.com/slide/
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CATALYSIS, TYPES OF CATALYSIS FOR CHEMISTRY STUDENTS

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