Carbon dioxide reduction in tandem with light-alkane dehydrogenation

A greenhouse gas and mild oxidant, CO2 can effect the oxidative dehydrogenation (CO2-ODH) of light alkanes over heterogeneous catalysts. These catalysts are bifunctional in that they mediate CO2 reduction while oxidizing the alkanes, most notably the C2–C4 components in shale gas. In this way, one obtains CO and alkenes as value-added products. Although desirable, this transformation has proven challenging in terms of catalyst design, with most catalysts for the CO2-ODH being metal oxides that typically undergo rapid deactivation. More recently, bimetallic catalysts have been identified as promising systems to activate alkanes by either selectively cleaving C–H bonds to produce alkenes or breaking all the C–C and C–H bonds to produce the dry reforming products CO and H2. This Review describes general trends in the CO2-ODH of light alkanes. We will also outline how to use a combined approach involving flow reactor experiments, in operando characterization and density functional theory to determine whether a catalyst is intrinsically active for CO2-ODH or dry reforming. CO2 reacts with alkanes over heterogeneous catalysts to give CO, H2O and the corresponding alkene. This Review describes catalytic bimetallics and their oxides, as well as experimental and theoretical studies of their mechanisms.