Highly Active and Selective Multicomponent Fe–Cu/CeO2–Al2O3 Catalysts for CO2 Upgrading via RWGS: Impact of Fe/Cu Ratio

The reverse water–gas shift reaction (RWGS) reaction represents a direct route for CO2 conversion whose selectivity significantly depends on the selected catalyst. In this work, a new family of bimetallic iron–copper oxide catalysts supported on ceria-alumina with various Fe/Cu oxides ratios were investigated for the RWGS reaction. Additionally, bare Fe-based and Bare Cu-based catalysts were synthesized for comparison. Our results demonstrate that the developed bimetallic Fe–Cu catalysts present a remarkable enhancement of catalytic performance when compared to monometallic systems, especially at the so-called "low-temperature range" for RWGS. Characterization results evidence that Cu species undergo different states on the catalytic surface during the reaction, wherein the formed metallic Cu is linked to the catalytic activity via the strength of the interaction with the multioxide phases, such as Fe3O4/CeO2, while the copper-dopped ceria could contribute to the promotion of CO selectivity. Besides, we identify that the Fe/Cu oxides mass ratio of 0.25/0.75 is an optimal formulation rendering highly commendable CO2 conversion levels at 450 °C with excellent selectivity and stability for long-term runs. Very importantly, without preactivation, our multicomponent materials still display an optimum performance which have a potential realistic application from cost perspective than other Cu-based catalysts. Overall, this work showcases a strategy to design highly effective multicomponent Fe–Cu catalysts for CO2 conversion via RWGS.