Question

Write a note on the shape selective catalysis exhibited by zeolites.

Answer 1

Zeolites are microporous aluminosilicates with a porous structure consisting of interconnected channels and cavities of molecular size. This unique structure gives rise to shape selective catalysis. The catalytic action of zeolites depends on the size of these pores and cavities. Only molecules smaller than the pore size can enter and react inside the zeolite, while larger molecules are excluded. This property allows zeolites to act as selective adsorbents and catalysts. For example, the zeolite ZSM-5 can convert alcohols into gasoline-range hydrocarbons, where the product distribution depends on how well molecules fit into the pores. This selective reaction based on molecular shape and size is called shape selective catalysis.