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 (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. [Display omitted] •The CO2-ODH activity and product selectivity of MoxCy is significantly influenced by the choice of MOx support material.•The ability to activate CO2 by a MoxCy-based catalyst is partly directed by the basic properties of the MOx support.•Al2O3 as a support for MoxCy excels over Ga2O3 and ZrO2 in both CO2-ODH as well as RWGS.•Despite variations in activity, all three catalysts demonstrate remarkable stability under RWGS conditions.•Over-stoichiometric feed of CO2 during CO2-ODH improves catalyst stability but does not prevent deactivation.