Additional Formation of Brønsted Acid Sites on Silica–Alumina Catalyst Surfaces by Depositing Silica Component

Abstract

Abstract The chemical vapor deposition (CVD) of silica onto an amorphous silica–alumina was investigated using tetraethoxysilane in order to create Brønsted acid sites on the surface of original silica-alumina. Silica loading could be readily controlled by the CVD time at 160 °C; the silica covered an internal wall of mesopore of the support of silica–alumina. The resulting CVD silica–alumina was catalytically more active than the original silica–alumina support for such test reactions as the cracking of cumene and the isomerization of 1-butene. The characteristic changes in the amount of Brønsted acid sites were clarified by means of the temperature-programmed desorption of adsorbed 2,6-dimethylpyridine. Strong Lewis acid sites of the original silica–alumina were converted into strong Brønsted acid sites upon depositing the silica component.