Hexagonal mesoporous titanosilicates as support for vanadium oxide-Promising catalysts for the oxidative dehydrogenation of n-butane

Abstract

The comparative study of structural properties and catalytic performance of V-containing high-surface mesoporous silica and mesoporous titanosilicate materials (HMS, Ti-HMS) in oxidative dehydrogenation of n-butane (C-4-ODH) was carried out. The aim of the study was to investigate effect of different titanium amount incorporated into silica support on the texture, speciation of vanadium complexes and its impact on catalytic performance. Prepared catalysts were characterized by XRF for determination of vanadium content, DTA/TG for thermal stability of matrix, XRD, SEM and N-2-adsorption for study of morphology and texture, FT-IR and DR UV-vis spectroscopy for verification of successful incorporation of Ti to the matrix and H-2-TPR and DR UV-vis spectroscopy for determination of vanadium complex speciation. All prepared materials were tested in n-butane ODH reaction at 460 degrees C. We conclude that titanium was successfully incorporated into mesoporous structure, which was preserved at least up to 600 degrees C. Catalytic activities of V-Ti-HMS catalysts were approximately four times higher than activity of V-HMS catalyst in spite of the fact that all samples exhibit the same amount of vanadium species with similar distribution. The selectivity to desired products was comparable for all catalysts. Enhanced catalytic activity of V-Ti-HMS materials allows activating of n-butane at significantly lower temperature (by 100 degrees C) compare with V-HMS materials.