Structural recognition and preorganization in zeolite catalysis: Direct aromatization of n-hexane on zeolite L-based catalysts

Abstract

It is demonstrated that solid (microporous) catalysts which confine reactants within their intracrystalline free volume can function as “supermolecular catalysts” resembling enzymes in some of their actions. In particular, the unique channel properties of (Ba,K)-exchanged zeolite L may play a role in its unmatched selectivity (>90%) for the dehydrocylization of n-hexane into benzene. Non-binding interaction of n-hexane with the active site environment leads to the preorganization of n-hexane as a pseudo-cycle. The supermolecule is eventually transformed into a metallocycle which can yield cyclic compounds and ultimately benzene. An avenue is opened for new thinking and strategies in the application of zeolite catalysts in organic synthesis.