Characteristics of Catalysts
1 . The catalyst remains unchanged in mass and chemical composition .
2 . In case of reversible reactions , the catalyst does not influence the composition of reaction mixture at equilibrium . It only helps to attain the equilibrium quickly .
Promoters and Poisons
Promoters are chemical substances that enhance the activity of a catalyst while poisons decreases the activity of a catalyst
Adsorption Theory of Heterogeneous Catalysis
The mechanism involves five steps : Diffusion of reactants to the surface of the catalyst
Adsorption of reactant molecules on the surface of the catalyst .
Occurrence of chemical reaction on the catalyst ’ s surface through formation of an intermediate .
Desorption of reaction products from the catalyst surface .
Diffusion of reaction products away from the catalyst ’ s surface