Oxidative dehydrogenation of propane over low-loaded vanadia catalysts:: Impact of the support material on kinetics and selectivity

The influence of the support material of low-loaded (<2 V nm(-2)) vanadia catalysts on selectivities, activation energies and turn over frequencies in the oxidative dehydrogenation of propane and the combustion of propene was investigated. CeO2, TiO2, Al2O3, ZrO2 and SiO2 supported catalysts were prepared by saturation wetness impregnation in toluene. Characterization with temperature-programmed reduction and Raman spectroscopy revealed a high dispersion of surface vanadia species for all investigated catalysts. The impact of heat and mass transfer limitations on the catalytic performance has been thoroughly excluded. Selectivities towards propene as well as activation energies strongly depend on the support material. For all catalysts, propene selectivity increases with temperature. Deconvolution of the reaction network of oxidative dehydrogenation of propane (ODP) into decoupled reactions of different reactants for at least three of the catalysts is not possible, because of a significant impact of the oxidation state of the catalyst on the reaction. Except for the CeO2 supported catalyst, the contribution of the bare support material on the activity can be neglected. (C) 2008 Elsevier B.V. All rights reserved.