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1.  Reference book: Arun Bhaul
Chapter : Catalysis

2.  Promoters
 Catalytic Poisoning
 Auto-catalysis
Negative Catalysis
Activation energy and catalysis

3.  “A substance which, though itself not
a catalyst, promotes the activity of a
catalyst is called a promoter.”
Activity of catalyst can often be increased by addition
of small quantity of a second catalyst
that is :
 either not a catalyst itself
 Or may be a feeble catalyst

4.  Mo promotes the activity of Fe
 Mixture of catalysts are used(ZnO, Cr2O3)

5.  Change of lattice spacing
 Increase of peaks and cracks
 Note: The phenomenon of promotion is a common
feature of heterogeneous catalyst.

6.  A substance which destroys the activity
of the catalyst to accelerate a reaction, is
called a poison and this process is called
catalytic poisoning.
 Note: Presence of small amount of impurities(Heterogenous
catalysis)

7.  Contact Process
SO2+O2 → 2SO3 (Pt, As2O3)
 Haber Process
N2+3H2→2NH3 (Fe, H2S )
 Synthesis of Water
 2H2+O2→2H2O (Pt, CO)

8.  The poison is adsorbed on the catalyst
surface in preference to the reactants
 The catalyst may combine chemically with
impurity

9.  When one of the products of reaction acts
as a catalyst for that reaction, this
phenomenon is called autocatalysis.
Rate of reaction raises, as the catalytic
product is formed, instead of decreasing
steadily.

10.  Hydrolysis of an ester(Acid act as catalyst)
 Decomposition of arsine(As act as catalyst)
AsH3→2As+3H2
 Oxidation of oxalic acid
 (Reference book)

11.  When a catalyst reduces the rate of a
reaction, it is called as negative catalyst
or inhibitor.
 Examples:
 Oxidation of Chloroform(2%Methanol)
 CHCl3+3O2→4COCl2+2H2O+2Cl2
 Decomposition of hydrogen peroxide(Dil.acid)
 2H2O2→2H2O+O2
 Combustion of fuel (Tetraethyl lead)

12.  According to collision theory , a reaction occurs by
the collisions b/w the reactant molecules (or ions).
 At ordinary temperature the molecules do not possess
enough energy and here collisions are not effective
however when temperature of system is raised the
kinetic energy increases.
 But the molecules do not react unless they attain a
minimum amount of energy.
 Catalyst works by alternate route.

13.  The minimum amount of energy required to cause a
chemical reaction is known as the activation energy.
 The activated molecules on collision first form a
activated complex.
 As a result of breaking and forming of new bonds the,
the activated complex dissociated to yield product
molecules.
 So large number of collisions occur in the presence of
catalyst, than would occur at same temperature without
presence of catalyst.

15. 1. Intermediate compound formation
theories
2.The adsorption theory