Ethane dehydrogenation over CaCO-mediated tandem catalysts.

CO-assisted oxidative dehydrogenation of light alkane is a promising and innovative technology for light olefin production; however, the interference of side reactions and sluggish reactivity of CO limit olefin yields. This paper describes an economically viable tandem catalytic system by coupling alkane dehydrogenation and the reverse water gas shift (RWGS) reaction, employing PtSn/SiO as ethane dehydrogenation (EDH) sites and nano-CaCO as the hydrogen acceptor for sequent RWGS. This tandem catalytic system significantly surpasses commercial CrO- and Pt-based catalytic systems, and breaks the EDH thermodynamic equilibrium limitation, reaching 142% of the nominal equilibrium ethylene yield of non-oxidative EDH process with 96.7% selectivity under industrially relevant conditions. Experimental characterization and theoretical analysis confirm that CaCO mediates the pathway of hydrogen spillover that originates from adjacent PtSn/SiO, which effectively facilitates the RWGS reaction and thus shifts the EDH toward ethylene. This tandem catalytic strategy assisted by carbonates potentially expands the palette of catalytic systems pertaining to hydrogen transfer mechanisms in CO-involved hydrogenation or dehydrogenation reactions.