Solution

Shape selective catalysis is the catalysis by zeolites. The catalytic reaction depends on the pore structure of the catalyst and the size of the reactant and product molecules. Zeolites have honeycomb-like structures due to which, they are good shape-selective catalysts. Zeolites have an enormous surface area which is largely on the inside of the solid. The zeolites can permit the entry and exit of molecules of a certain size into the active regions within holes. Pore size range in zeolites is 260 pm to 740 pm.

For example, zeolite catalyst ZSM-5 converts alcohol to gasoline The dehydration of alcohols in cavities forms hydrocarbons. The shape selectivity can be judged from the conversion of methanol and 1-heptanol to hydrocarbon mixtures. The composition of the product mixture depends upon the ability of the pores to accommodate linear and isoalkanes as well as benzene derivatives.