Support Effects on Mo2C-Based Catalysts in CO2-rich Oxidative Dehydrogenation of Ethane

This study focuses on the use of metal oxide-supported molybdenum carbide (Mo2C) catalysts for the CO2-assisted oxidative dehydrogenation of ethane. The catalysts exhibit a tandem effect, combining Mo2C nanoparticles with a (reducible) metal oxide support materials, aiming to improve both CO2 and C2H6 activation. While Mo2C-based catalysts exhibit promising selectivity towards ethylene, their poor stability, attributed to carbon deposition and oxidation to MoOx, prevents industrial application. CO2- and NH3-TPD reveal distinctive acid-base properties, with MoxCy/Al2O3 showing the largest amount of weak acid-base sites, where MoxCy/ZrO2 predominantly shows the presence of stronger acid sites. On Ga2O3 the lowest population of acid-base sites is observed, with a small signal indicating stronger acid sites. Under RWGS conditions, MoxCy/Al2O3 and MoxCy/ZrO2 outperform MoxCy/Ga2O3, demonstrating higher CO2 conversion and stability. In the CO2-ODH of ethane, MoxCy/Al2O3 exhibits the best stability and highest ethylene selectivity, even with an over-stoichiometric CO2:C2H6 feed ratio. The superior performance of MoxCy/Al2O3 is suggested to be due to the balanced acid-base properties, improving CO2 activation capability as well as dehydrogenation activity.