Influence of ZrO2 crystal structure on the catalytic performance of Fe-Ni catalysts for CO2-assisted ethane dehydrogenation reaction

The catalytic reaction of ethane with CO2 promotes the value-added conversion of natural gas and the resource utilization of greenhouse gases. In this work, the CO2-assisted ethane dehydrogenation reaction characteristics on Fe1.5Ni0.5/ZrO2(M, T, Mix) catalyst with different crystal plane structure were studied through catalyst activity test, catalytic reaction kinetics study and catalyst characterization analysis. It is found that the exposed crystal faces of the ZrO2-supported catalyst has a significant effect on the CO2-assisted ethane oxidative dehydrogenation reaction. The monoclinic phase Fe1.5Ni0.5/ZrO2-M catalyst exhibits the largest conversion of ethane (21.8%) and CO2 (25.2%) and the maximum selectivity to C2H4 (80.5%). Monoclinic phase of ZrO2 selectively exposes the (-111) and (1 1 1) low-index surfaces with higher oxygen vacancy (Ov) density and stronger metal-support interaction, which leads to the formation of more FexZr1-xO2 structures with high catalytic activity. The reductive oxygen vacancy Ov and Fe2+-O-Zr3+ sites promote the activation of CO2 through the cleavage of C=O bond to supplement O* species. The O* species on the oxidative Fe3+-O-Zr4+ site are captured and combined with H* species derived from the selective cleavage of ethane C-H bond to generate H2O.