CO2-mediated oxidative dehydrogenation of propane enabled by Pt-based bimetallic catalysts

The greenhouse gas CO2 is a promising soft oxidant for the oxida-tive dehydrogenation of light alkanes. However, the occurrence of side reactions including cracking, hydrogenolysis, and reforming results in lower olefin yields compared with direct dehydrogenation. We report that Pt-M (M = Sn/In/Zn) bimetallic catalysts on non-redox-active silica support can break the equilibrium limit of direct propane dehydrogenation using CO2 as a co-reactant to consume the hydrogen formed in propane dehydrogenation. Unlike the commonly postulated direct CO2-assisted dehydrogenation mecha-nism, we confirm that CO2-oxidative dehydrogenation of propane (ODHP) proceeds in two tandem steps on these bimetallic catalysts, i.e., propane dehydrogenation and reverse water-gas shift, with the latter being the rate-determining step. In situ X-ray absorption studies and density functional theory calculations suggest that the PtmMn-MOx (e.g., Pt3Sn-SnOx) interfaces are likely active sites.