THE EFFECT OF THE PREPARATION METHOD ON THE NATURE AND DISPERSION OF SURFACE SPECIES FORMED UPON REACTION OF MOLYBDENUM TRIOXIDE WITH ALUMINA AND TITANIA

摘要

Titania- and alumina-supported molybdenum-containing systems have been prepared from mechanical mixtures of the support and molybdenum trioxide. The systems have been characterized by X-ray diffraction, temperature-programmed reduction and scanning electron microscopy, and Fourier transform-infrared monitoring of pyridine adsorption has been used to determine surface acidity. Dispersion of the supported phase, and its transformation to well-dispersed species has been attained by mechanical grinding and calcination in air, or by hydrothermal treatment of such mixtures and calcination. In the latter case, a higher dispersion is reached, despite the shorter time of calcination. Also hydrothermally treated samples show a larger concentration of surface Bronsted acid sites. [References: 28]