Oxidative dehydrogenation of propane over alumina supported vanadia catalyst – Effect of carbon dioxide and secondary surface metal oxide additive

Abstract

Abstract Oxidative dehydrogenation (ODH) of propane was investigated using CO2 as an oxidant. Thermodynamic equilibrium calculations revealed the beneficial effect of using CO2 on propane conversion. In order to increase the propene selectivity, alumina supported vanadia catalysts modified with secondary metal oxides viz., chromia, molybdena and tungsta were synthesized. The catalyst characterization using temperature programmed reduction (TPR) and X-ray photoelectron spectroscopy confirmed the non-interacting nature of the metal oxides in the mixed oxide form. Additionally, TPR study of reoxidized catalysts indicated that CO2 was able to only partially reoxidize the reduced active sites in contrast to O2. These catalysts showed similar redox property in individual as well as in mixed metal oxide form reconfirming their non-interacting nature in mixed oxides. The synthesized catalysts were examined for propane dehydrogenation in the absence and presence of CO2. Chromia was found to be the best catalyst for dehydrogenation reaction in the absence of CO2. Moreover, no synergy was obtained in mixed oxide catalysts. Feeding CO2 with propane had no beneficial effect on the propene formation rates for the chromia modified supported vanadia catalyst, whereas, the molybdena and tungsta modified vanadia catalyst showed an improved propene formation rate.