(651a) Oxidative Dehydrogenation of Propane Using CO2 over Molybdenum Oxycarbidic Catalysts
Transition metal carbides have been shown to catalyze oxidative dehydrogenation of alkanes using CO2 as a soft oxidant. In this work, we investigate reactive pathways of propane and CO2 including oxidative dehydrogenation to form propylene, reforming to form CO, and hydrogenolysis to form C2 and C1 hydrocarbons over molybdenum oxycarbidic formulations at ambient pressure and 803 â 843 K. Co-feeds of CO2 and H2 can result in an order of magnitude change in steady-state propane dehydrogenation rates at constant propane pressure, and these rate changes are reversible. Product carbon selectivities vary between >95% dehydrogenation, >80% reforming, or >95% hydrogenolysis depending upon reaction conditions and the introduction of co-feeds. CO2 co-feed can produce alkane-derived CO via a reforming pathway, and excess H2 can result in methane produced via propane hydrogenolysis. Product selectivities and rates can be rationalized and quantitatively fit using a proposed kinetic model predicated upon surface site interconversion between oxidized or reduced active sites as functions of H2/CO2 co-feed partial pressures.