Zeolites treated with silicon tetrachloride vapour. Part 1.—Preparation and characterisation

Abstract

Crystalline materials with Si/Al ratios ranging from 2.5 to over 100 have been prepared by treating zeolites with silicon tetrachloride vapour at elevated temperatures. Most of the work described involves zeolite Y (synthetic faujasite), but other wide-pore zeolites, such as mordenite, ZSM-5, L, omega (synthetic mazzite) and ferrierite, are also amenable to SiCl₄ treatment. We describe the method of preparation of high-silica zeolites and the application of an array of techniques to monitor the degree of crystallinity, unit-cell parameters, the Si/Al ratio and hydrophobicity of the products. Also described are the effects of treatment of wide-pore zeolites with some other inorganic halides.