Features of catalysis by Zeolites :
(i) Zeolites are hydrated alumino silicates which have a three dimensional network structure containing water molecules in their pores.
(ii) To use them as catalysts, they are heated so that water of hydration present in the pores is lost and the pores become vacant.
(iii) The size of the pores varies from 260 to 740 pm. Thus, only those molecules can be adsorbed in these pores and catalyzed whose size is small enough to
enter these pores. Hence, they act as molecular sieves or shape selective catalysts.
An important catalyst used in petroleum industries is ZSM-5. It converts alcohols into petrol by first dehydrating them to form a mixture of hydrocarbons.
