CO2 conversion to CO by LaCo1−xFexO3 (x = 0, 0.25, 0.5, 0.75, 1) perovskite phases at low temperature

Abstract

This paper reports conversion of CO2 to CO via reverse water-gas shift chemical looping process on LaCo1−xFeO3 perovskites at low temperature as a potential solution for CO2 mitigation. Reactions of LaCo1−xFexO3 phases with x = 0, 0.25, 0.5, 0.75, 1 under hydrogen atmospheres, and subsequently, carbon dioxide, were investigated by in-situ high-temperature X-ray powder diffraction and thermogravimetry. The perovskites show linear thermal expansion up to around 250 ºC under hydrogen atmosphere, followed by a phase change due to formation of oxygen vacancies, and finally, the materials decompose into La2O3 and metallic Co/Fe. Incorporating Fe improves the stability of the reduced phase. Partial reduction and decomposition temperatures under hydrogen were determined. After reduction of the perovskite samples, reactions with CO2 were analyzed. CO2 conversion increases with Fe loading, with LaCo0.50Fe0.50O3 being the material with optimal balance between RWGS-CL activity and long-term stability during five cycles. It reaches a maximum CO yield of 0.25 mol(molperovskite·cycle)−1 and a maximum rate of 3.9 mmol(molperovskite·min)−1 at 550 °C.