Evaluation of the potassium incorporation method in MgFe catalysts derived from layered double hydroxides in the hydrogenation of CO2

Abstract

This study investigated catalysts derived from layered double hydroxides (LDH) with and without potassium in the Reverse Water Gas-Shift (RWGS) reaction. According to the results, despite the addition of potassium reducing the catalysts´ porosity and altering their morphology, K improved their efficiency by decreasing CH₄ production and increasing selectivity towards CO. An evaluation of the K impregnation method demonstrated when not calcined prior to the impregnation process with 5 wt% of K (MgFe/K), the material showed better catalytic performance in comparison to catalysts calcined at 500 (MgFe500/K) and 800 °C (MgFe500/K). Adjustments in parameters such as temperature, gas flow rates, and H₂:CO₂ ratio offer a pathway for increasing selectivity for CO in the RWGS reaction. In situ DRIFTS analyses revealed changes in bands associated with CO₃^2 − and *HCOO species, offering insights into CO₂ activation and suggesting the involvement of formate-mediated pathways as responsible for CO production.