Infrared spectroscopic study of the interaction of cations in zeolites with simple molecular probes. Part 1.—Adsorption of molecular hydrogen on alkaline forms of zeolites as a test for localization sites

Abstract

The localization sites for univalent cations in cationic forms of zeolites (A, X, Y, ZSM-5 and mordenite) have been investigated using the low-temperature adsorption of molecular hydrogen as a spectroscopic test. The extent of H—H bond polarization, estimated from the low-frequency shift of the fundamental stretching vibration of perturbed H₂ molecules, was found to be strongly dependent on the basicity of the neighbouring oxygen atoms of the framework.