Structure - Catalytic Activity Correlation in Aluminium Hydroxide Supported Vanadia Catalysts

Abstract

            Aluminium hydroxide samples containing vanadium in the range 5 - 25 wt % have been prepared by incipient wetness impregnation method. The catalysts have been characterized through % composition of vanadium, BET surface area, FTIR, PXRD, SEM and solid state V-NMR. Liquid phase conversion of benzyl alcohol over the above materials into various products has been used as a chemical probe to investigate the activity of these catalysts. Benzyl alcohol has been converted into benzaldehyde, toluene and 1, 2-diphenyl ethane (dibenzyl). Formation of various products at different loadings of vanadium is found to be related to structural features of vanadium oxo-species. Oxidation- reduction products and 1, 2-diphenyl ethane have been formed selectively, at lower loadings of vanadium, which was in the tetrahedral environment of oxygen and at higher loading when vanadium was in square pyramidal environment catalytic activity increased but with low selectivity. When aluminum hydroxide was used as a support monolayer coverage was completed only at higher loading indicating better dispersion of metal - oxo species over this support.