The Evaluation of Cu and K Metals' Functions over Fe-Based Systems for Low-Temperature Reverse Water-Gas Shift Reaction

Abstract The reverse water-gas shift (RWGS) reaction is widely regarded as a platform reaction for the conversion of CO2 into value-added products. In this study, Fe-based catalysts modified with Cu and K were systematically investigated to elucidate the roles of metal promoters in regulating RWGS performance. The results demonstrate that a K-promoted Fe–Cu(2/3)/Al2O3 catalyst exhibits enhanced CO2 conversion together with nearly 100% selectivity toward CO. A combination of ex situ and in situ characterization techniques reveals that the introduction of Cu can enhance CO2 conversion by modifying the surface structure and redox properties of Fe species. Subsequent K promotion also alters the surface reaction pathway by favoring the carboxylate-related route while suppressing the accumulation of formate species, which further suppresses methane formation and improves CO selectivity. These findings highlight the critical role of Cu–K synergy in tuning catalyst structure and reaction pathways for efficient RWGS reactions.