Sorption of methanol in alkali exchange zeolites

Metal cation methanol sorption complexes in MFI (ZSM5), MOR and X have been studied by in situ i.r. spectroscopy in order to understand the nature of interactions of methanol in the molecular sieve pores. The results show that (a) a freely vibrating hydroxy and methyl group of methanol exist on Na-ZSM5 and that (b) lateral hydrogen bonding between the hydroxy group of methanol and the framework with additional hydrogen bonding between adsorbed methanol molecules exists on Na-X and Cs-X. Methanol adsorbed on Na-MOR appears to assume an intermediate position as both sorbate structures are observed upon the adsorption of methanol. In addition to the lateral hydrogen bonding on Cs-X also interaction of the methyl group with the framework is observed. The interaction of the hydrogens of methanol with the zeolite framework of zeolites with the highly charged lattice oxygen in e.g., Cs-X, results in a facile abstraction of the hydroxy and methyl hydrogens of methanol at elevated temperatures