Role of Oxygen Vacancies in Fe/Ru-Based Catalysts for the Reverse Water Gas Shift Reaction: Performance and Characterization.

The Reverse Water-Gas Shift (RWGS) reaction is a key process for converting carbon dioxide (CO2) into carbon monoxide (CO), enabling downstream synthesis of fuels and chemicals while contributing to CO2 emissions mitigation. This study investigates the performance of several Fe x -Ru y -based catalysts supported on different doped oxide materials (La-Al2O3, Ce-Al2O3, Sm-CeO2, Si-Al2O3), with the goal of identifying a cost-effective and thermally stable alternative to purely noble metal systems. Catalysts were evaluated in atmospheric conditions up to 800 °C and subjected to repeated temperature ramp cycles to assess CO2 conversion, CO selectivity, and long-term stability. Comprehensive characterization was performed using ICP-OES, BET, TPR, XRD, HRTEM, and XPS. The results reveal that optimizing the strength of the metal-support interaction, as well as the active metals ratio can have a significant impact, in terms of available active sites, which influences the catalytic performance, especially at lower temperatures (<500 °C). It was found that a ratio of 75% Fe and 25% Ru on Ce-doped Al2O3 provided this balance of properties. These findings provide insight into the design of robust, economically viable RWGS catalysts for efficient CO2 utilization.