Modification of a phase-inhomogeneous alumina support of a palladium catalyst. Part I: effect of the amorphous phase on the textural and acidic characteristics of alumina and methods for controlling its phase homogeneity

Abstract

© 2020 Elsevier Ltd The contribution of the amorphous phase in aluminum hydroxide and alumina to their properties was investigated in this work. It was shown that the amorphous phase in aluminum hydroxide is stabilized by alumoxanes, and it is a source of a finely porous component and capable of increasing the surface area by ~78%. In γ-Al2O3, amorphous alumina raises the surface area and the acidity. It was established that the method of chemical modification does not change the phase inhomogeneity but allows adjusting the acid properties while maintaining the high specific surface area. It was shown that the amorphous phase is more reactive when processing phase-inhomogeneous aluminum hydroxide with acetic acid. Crystallization of amorphous alumina as a result of high-temperature treatment of phase-inhomogeneous aluminum hydroxide is accompanied by significant decrease in specific surface area and acidity.