Aluminas modified with silica. Part 1.—An X-ray diffraction and secondary-ion mass-spectrometry study of the influence of preparation and thermal treatment on structure and surface composition

Abstract

The surface composition and crystal structure of three series of aluminas, containing 5, 10 and 30 wt% silica, have been studied as a function of preparation and subsequent thermal treatment using secondary-ion mass spectrometry (SIMS) and X-ray diffraction (X.r.d.). A number of modes of preparation have been studied, ranging from various aqueous coprecipitation procedures to mechanical mixtures of silica and alumina. It is shown that the formation of a silica coating is a controlling feature in the thermal reactions of silica and alumina.