Tuning Performance of CO2 hydrogenation over Transition-Metal Promoted Tungsten Carbide Catalysts

Catalyzing CO₂ hydrogenation reactions to create value-added chemicals is a potentially valuable part of closing the carbon cycle to create a net carbon-neutral economy. One proposed pathway is to convert CO₂ to CO via the reverse water gas shift reaction (RWGS) and then hydrogenate effluent CO through the Fischer-Tropsch synthesis within a second reactor. To make this process industrially viable, low-cost, and scalable, active and selective catalysts are required. One promising candidate is tungsten carbide which has been shown to be active for hydrodeoxygenation reactions and has similar electronic properties to the active, selective, and stable Mo-C catalysts. Reactor data demonstrates that platinum and cobalt promotors nearly double CO₂ conversion as compared to control tungsten carbide. Copper and cobalt change product distribution as compared to the control to increase methane production as well as copper promotion leading to methanol production. FTIR data support that these transition metals act as promotors rather than tandem sites as the only CO binding site present can be attributed to linear bound CO on tungsten carbide. Reviewing this data gives insights into the mechanistic pathways of CO₂ hydrogenation and can lead to better-designed catalysts.