Influence of surface phenomena in oxidative desulfurization with WO_x/ZrO₂ catalysts

Abstract

Oil refinery related catalysis, particularly hydro desulfurization is viewed as a mature technology, but still we view that more efforts have to be made to boost the efficiency of the existing catalysts. So in this article we report the use of WO_x/ZrO₂ catalysts for the oxidation of dibenzothiophene (DBT) as a more effective material in nanometer scales. The WO_x/ZrO₂ samples were prepared by solid impregnation of ZrO_2-x(OH)_2x with ammonium metatungstate solution maintaining the pH at 10. Detailed structural and surface morphological analyses were carried out using Raman spectroscopy and Atomic force microscopy. In order to understand the catalytic activity which is largely influenced by the surface morphology, an interpretation based on the experimental results is given. The results showed an important correlation between the catalytic efficiency with the morphology of the surface which is identified as arrays of planes with steps of around 10 nm with the structures showing faceting with a preferential angle of 90°. It was established that when the number of W atoms in the surface increase the catalytic efficiency also increases. Thus we conclude that the material efficiency as a catalyst is directly related with the surface structure.