Hydroxyl groups and acid sites in NaZSM-5 zeolites studied by i.r. spectroscopy

Abstract

The decomposition of TPA (tetrapropylammonium ions) in NaZSM-5 zeolites, the localization of OH groups and acid properties of zeolites were studied by i.r. spectroscopy. NaZSM-5 zeolite in which TPA are not decomposed contain small amount of 3738 cm −1 OH groups. The decomposition of TPA results in the formation of considerable amounts of 3738 cm −1 OH groups situated inside zeolitic channels. These OH groups are not acidic at the reaction with pyridine. NaZSM-5 zeolites contain Brönsted and Lewis acid sites the amounts of which depend on the composition of the zeolite.