The Role of CO2 in Oxidative Propane Dehydrogenation over Ga2O3/SiO2 Catalysts

Due to the substantial industrial significance of propylene and the development of shale gas, there is growing interest in propane dehydrogenation (PDH) technology for producing propylene. Gallium-based catalysts have significant potential in PDH technology due to their high activity and low carbon deposition. Additionally, CO2 could reduce carbon deposition and promote reaction equilibrium, thereby enhancing the performance of the catalyst. To investigate the role of CO2 in oxidative propane dehydrogenation, the Ga2O3/SiO2 catalyst was synthesized by incipient wetness impregnation in this study. The activation energy for propane dehydrogenation with and without CO2 was determined between 773 and 923 K, and the reaction orders were determined by varying the partial pressures of CO2 and propane. The activation energies for both reactions were observed to be about 100 kJ·mol–1, with a reaction order of 1 to 0 for propane and 0 for CO2, ruling out competitive adsorption of CO2 and propane on the catalyst. To clarify the reaction mechanism, a relatively simple model system was constructed to systematically and thoroughly investigate the role of CO2 in the propane dehydrogenation process catalyzed by gallium oxide. The results suggest that CO2 does not participate in the β-H elimination of propane or the reoxidation of gallium oxide, but instead, CO2 enhances the PDH performance through coupling with the RWGS reaction.