Ethane dehydrogenation over CaCO3-mediated tandem catalysts

CO2-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 CO2 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/SiO2 as ethane dehydrogenation (EDH) sites and nano-CaCO3 as the hydrogen acceptor for sequent RWGS. This tandem catalytic system significantly surpasses commercial CrOx- 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 CaCO3 mediates the pathway of hydrogen spillover that originates from adjacent PtSn/SiO2, 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 CO2-involved hydrogenation or dehydrogenation reactions.