Selective CO₂ Hydrogenation to Hydrocarbons on Cu-Promoted Fe-Based Catalysts: Dependence on Cu–Fe Interaction

Conversion of CO₂ to sustainable chemical feedstocks and fuels by reacting with renewable hydrogen is considered to be a promising direction in energy research. The selectivity of desired products, such as C₂–C₄⁼ and C₅₊, is low over unpromoted iron-based catalysts for CO₂ hydrogenation. Therefore, promoters are often used to tailor and optimize the product distribution. In this work, the effect of doping Cu into Fe-based supported catalysts on the catalytic performance for CO₂ hydrogenation to hydrocarbons was studied with a particularly focus on the interaction between Fe and Cu. For this purpose, catalysts with different Fe and Cu distribution were prepared by various impregnation methods. It was found that the selectivity of C₂–C₄⁼ over Cu-promoted catalysts decreased, but a significant improvement was obtained for C₅₊. This promoting behavior is different from that of other promoters (e.g., K, Mn, Zn, etc.). The secondary conversion of produced olefins on Cu-promoted catalysts, which results from the improvement of olefins adsorption, on Cu-promoted catalysts leads to the decrease of C₂–C₄⁼ (hydrogenation) but the increase of C₅₊ (oligomerization). Characterization results demonstrate that the catalytic performance is evidently associated with the strength of the interaction between Fe and Cu in the supported catalysts