On-purpose Ethylene Production via CO2-assisted Ethane Oxidative Dehydrogenation: Selectivity Control of Iron Oxide Catalysts

The potential of on-purpose ethylene production, in parallel with CO2 conversion to CO, is of great interest. Iron oxide-based catalysts supported on mixed oxides zNiO-MgO-ZrO2, z=0-10 wt%, are active for the CO2-assisted oxidative dehydrogenation of ethane at 873 K and 101.3 kPa. Enhanced control of their selectivity towards C-H bond cleavage and not towards C-C bond cleavage can be achieved by adjusting the Ni/Fe ratio. Fine tuning Ni/Fe molar ratio results in stable catalytic performance, with selectivity towards C2H4 >65 % and C2H6 conversion >20 %. Density functional theory (DFT) calculations show a significant enhancement in activity due to decrease in the oxygen-vacancy formation energy and the increase in hydrogen adsorption energy at the Ni oxide-Fe oxide interface. The latter interface is the potential active site responsible for the enhanced performance that was experimentally exemplified for the Fe oxide/zNiO-MgO-ZrO2 catalysts vs Fe oxide/MgO-ZrO2.