Class 12 Chemistry Surface Chemistry Mechanism of Catalytic Activity

Mechanism of Catalytic Activity

  1. Diffusion of reactants towards the surface of the catalyst
  2. Adsorption of reactant molecules on the surface of the catalyst
  3. Occurrence of a chemical reaction between the reactants and the catalyst which forms an intermediate
  4. Desorption of product molecule from the surface because of the lack of its affinity to the catalyst’s surface by which the surface is now available for the adsorption of new reactant molecules
  5. Diffusion of product molecules away from the surface of the catalyst

Advantages of This Theory:

  • Only a small quantity of the catalyst is required as it is regenerated again and again
  • The catalyst does take part in the reaction but its mass and composition remain unchanged at the end of the reaction
  • If catalytic poisons are present they preferentially get adsorbed onto the surface of the catalyst. This hinders the adsorption of the reactant molecules

Note- This theory does not satisfactorily explain the action of catalytic promoters

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