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 C-2-C-4(=) 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 C-2-C-4(=) 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 C-2-C-4(=) (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.