Direct CO2 hydrogenation over Na and CeO2-promoted Iron and Cobalt-based Catalysts Supported on MCM-41

This contribution has studied iron or cobalt-based Fischer-Tropsch catalysts, promoted with CeO₂ and Na and supported on MCM-41 mesoporous silica in the direct CO₂ hydrogenation to hydrocarbons. The cobalt-based catalyst is more active in the presence of ceria as a promoter, presenting long-chain hydrocarbons under reaction conditions of 350 °C, 40 bar, H₂/CO₂ = 3, and GHSV = 6000 mL g^-1 h^-1. The characterization of the catalysts suggests that CoCeNa/M exhibits a strong Co-O-Si bond formation, preventing the cobalt oxide reduction to Co²⁺ species, which can be associated with methane production. On the other hand, iron-based catalysts present higher CO and CH₄ concentrations, as shown via in situ DRIFTS, suggesting a possible iron carbide phase, which can be formed by the severe FTS reaction conditions, producing a high concentration of water and competing with Sabatier reaction.