Describe some feature of catalysis by Zeolites .

Explanation

(i) Zeolites are microporous, crystalline, hydrated, alumino silicates, made of silicon and aluminium tetrahedra.
(ii) There are about 50 natural zeolites and 150 synthetic zeolites. As silicon is tetravalent and aluminium is trivalent, the zeolite matrix carries extra negative charge.
(iii) To balance the negative charge, there are extra framework cations for example, `H^(+) " or " Na^(+)` ions.
(iv) Zeolites carrying protons are used as solid acids, catalysis and they are extensively used in the petrochemical industry for cracking heavy hydrocarbon fractions into gasoline, diesel, etc., Zeolites carrying `Na^(+)` ions are used as basic catalysis.
(v) One of the most important applications of zeolites is their shape selectivity.
(vi) In zeolites, the active sites namely protons are lying inside their pores.
(vii) So, reactions occur only inside the pores of zeolites.