Fe-Cu Bimetallic Catalysts for Selective CO₂ Hydrogenation to Olefin-Rich C₂⁺ Hydrocarbons

This paper reports on Fe-Cu bimetallic catalysts supported on γ-alumina for selective CO₂ hydrogenation to olefin-rich C₂⁺ hydrocarbons. A strong synergetic promoting effect on C₂⁺ hydrocarbon synthesis was observed over Fe-Cu bimetallic catalysts when the Cu/(Cu + Fe) atomic ratio was 0.17. Compared to monometallic Fe catalyst, the Fe-Cu bimetallic catalyst significantly enhances C₂-C₇ hydrocarbon formation and suppresses the formation of undesired CH₄. The addition of K into Fe-Cu bimetallic catalysts inhibits the methanation and further enhances the formation of C₂⁺ hydrocarbons in the meantime. The synthesis of olefin-rich C₂-C₄ hydrocarbons from CO₂/H₂ was achieved by using K-promoted Fe-Cu/Al₂O₃ catalysts with higher K/Fe atomic ratios (e.g., K/Fe ≥ 0.5), where the selectivity of C₂-C₄ olefin contents was even higher than K-promoted Fe-Co catalysts under the same reaction conditions.