What do you understand by shape selective catalysis? Why are zeolites good shape selective catalysts?

(N/A) The catalytic reaction that depends upon the pore structure of the catalyst and the size of reactant and product molecules is called shape selective catalysis.
Zeolites are good shape selective catalysts because of their honeycomb-like structure.
Zeolites are microporous aluminosilicates with a three-dimensional network in which some silicon atoms are replaced by aluminium atoms,creating an $Al-O-Si$ framework. The reaction taking place in a zeolite depends upon the size and shape of the reactant and product molecules,as well as the pores and cavities of the zeolites.
Zeolites are widely used as catalysts in petrochemical industries for the cracking of hydrocarbons and isomerisation. For example,the zeolite $ZSM-5$ converts alcohols into gasoline by dehydrating them to produce a mixture of hydrocarbons.