Molybdenum carbide nanowires as efficient heterogeneous catalyst for CO2 hydrogenation

CO 2 hydrogenation is one of the various strategies for CO 2 reduction.Molybdenum carbide is one of the heterogeneous catalysts that have been found catalytically active for CO 2 hydrogenation.From the open literature, catalytic performance of molybdenum carbide catalyst is linked with their crystal structure.However the characteristic properties of different crystal structures still deserve further investigation.In this research, two main phases of molybdenum carbide catalysts, α-MoC 1-x and β-Mo 2 C were synthesized for investigation.The conversion of α-MoC 1-x into active α phase was achieved by slightly elevate the carburization temperature from 700℃ to 720℃.The catalytic activity of these molybdenum carbide nanowires materials was assessed in the hydrogenation of CO 2 .Result showed the apparent activity of active α-MoC 1-x catalyst synthesized at 720℃ were 10% higher than β-Mo 2 C due to its 4 times larger surface area, however the intrinsic activity of active α-MoC 1-x catalyst is still lower than β-Mo 2 C catalyst.With In-situ XPS technique, we discovered the reducibility of β-Mo 2 C was significantly higher than α-MoC 1-x , which corresponded to β-Mo 2 C catalyst high intrinsic activity.We then conclude the reducibility difference, closely linked to crystal structure difference, and strongly affected the catalytic performance.DRIFTS was used to study the adsorption properties of molybdenum carbide nanowires catalyst.We proposed the weak adsorption of CO on molybdenum carbide catalyst explained catalyst's high selectivity behavior.