Mechanistic study of CO2 hydrogenation on FeCu-K/Al2O3 and FeCu-K/CeO2 catalysts

Abstract

Atmospheric carbon dioxide concentrations have been rapidly increasing due to fossil fuel combustion and industrial activities, posing a serious threat to the global climate. To address this challenge, catalytic CO2 conversion to valuable chemicals has been widely studied. Reverse water gas shift (RWGS) reactions are a promising strategy for CO2 utilization coupled with downstream hydrocarbon synthesis processes such as the Fischer-Tropsch (FT) reaction. In this study, we investigated the reaction mechanism of the initial stage of olefin formation on FeCu-K catalysts supported by Al2O3 and CeO2 using density functional theory (DFT) calculations, focusing on the key elementary steps of CO2 hydrogenation and subsequent hydrocarbon production. Based on our mechanistic study, we identified the potential-determining step for CO2 hydrogenation and C-C coupling reactions on FeCu/Al2O3 and FeCu/CeO2 catalysts, and the role of the promoter (K) in their catalytic activity and selectivity. Based on our electronic structure analysis, we also proposed electronegativity as a simple descriptor for predicting catalytic activity for CO2 hydrogenation.