Question

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

Answer 1

Hint : Catalysts are the molecule or the atom that catalysis the chemical reactions. Catalysts help in increasing the rate of reaction by decreasing its activation energy. Catalysts in the reactions don't get consumed and can be found as it is after the product formation.

Complete Step By Step Answer:
Shape of the catalysts plays an important role in catalysing a particular reaction, as a particular catalyst reacts with a particular substrate only. The same catalyst cannot be used for all the reactions.
So, shape- selective catalysis is a catalysis reaction that depends on the size and shape of the reactant and product. Also in this type of catalysis reaction the pore size of the catalyst is very important.
One of the good examples of shape selective catalysts is Zeolites.
Zeolites are very good shape selective catalysts because of their structure or you can say shape, size and the pore structure.
So, let’s find out about the structure of the zeolites:
Zeolites are basically the network of silicon, aluminium and oxygen atoms. They can be found as aluminosilicates in the form of $Al - O - Si$ .
Zeolite structure provides it with small pores in which cations, small molecules can take place and this is a very effective qualification for being a good shape- selective catalysts.

Note :
Zeolites are also molecular sieves. Zeolites can be found naturally in nature or are especially synthesized for the catalysis reaction purposes. Other than acting as a shape-selective catalyst, zeolite can act as a drying agent, in the detergents, in air purifiers. Zeolite is also used in treating diseases like cancer.