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 Reference book: Arun Bhaul
Chapter : Catalysis
 Promoters
 Catalytic Poisoning
 Auto-catalysis
Negative Catalysis
Activation energy and catalysis
 “A substance which, though itself not
a catalyst, promotes the activity of a
catalyst is called a promoter.”
Activity of...
 Mo promotes the activity of Fe
 Mixture of catalysts are used(ZnO, Cr2O3)
 Change of lattice spacing
 Increase of peaks and cracks
 Note: The phenomenon of promotion is a common
feature of hete...
 A substance which destroys the activity
of the catalyst to accelerate a reaction, is
called a poison and this process is...
 Contact Process
SO2+O2 → 2SO3 (Pt, As2O3)
 Haber Process
N2+3H2→2NH3 (Fe, H2S )
 Synthesis of Water
 2H2+O2→2H2O (Pt,...
 The poison is adsorbed on the catalyst
surface in preference to the reactants
 The catalyst may combine chemically with...
 When one of the products of reaction acts
as a catalyst for that reaction, this
phenomenon is called autocatalysis.
Rate...
 Hydrolysis of an ester(Acid act as catalyst)
 Decomposition of arsine(As act as catalyst)
AsH3→2As+3H2
 Oxidation of o...
 When a catalyst reduces the rate of a
reaction, it is called as negative catalyst
or inhibitor.
 Examples:
 Oxidation ...
 According to collision theory , a reaction occurs by
the collisions b/w the reactant molecules (or ions).
 At ordinary ...
 The minimum amount of energy required to cause a
chemical reaction is known as the activation energy.
 The activated mo...
1. Intermediate compound formation
theories
2.The adsorption theory
Catalysis
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Catalysis

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Catalysis

  1. 1.  Reference book: Arun Bhaul Chapter : Catalysis
  2. 2.  Promoters  Catalytic Poisoning  Auto-catalysis Negative Catalysis Activation energy and catalysis
  3. 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. 4.  Mo promotes the activity of Fe  Mixture of catalysts are used(ZnO, Cr2O3)
  5. 5.  Change of lattice spacing  Increase of peaks and cracks  Note: The phenomenon of promotion is a common feature of heterogeneous catalyst.
  6. 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. 7.  Contact Process SO2+O2 → 2SO3 (Pt, As2O3)  Haber Process N2+3H2→2NH3 (Fe, H2S )  Synthesis of Water  2H2+O2→2H2O (Pt, CO)
  8. 8.  The poison is adsorbed on the catalyst surface in preference to the reactants  The catalyst may combine chemically with impurity
  9. 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. 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. 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. 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. 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.
  14. 14. 1. Intermediate compound formation theories 2.The adsorption theory

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