A La, Sm co-doped CeO2 support for Fe2O3 to promote chemical looping splitting of CO2 at moderate temperature

Abstract

Moderate temperature chemical looping processes can effectively mitigate the sintering and deterioration of oxygen carriers at elevated temperatures (>800 °C). However, lower temperatures have a degrading effect on reaction activation and oxygen release and uptake, resulting in slow redox kinetics. In this work, we proposed La, Sm co-doped CeO₂ as an active support for Fe₂O₃ to promote CO₂-splitting performance in reverse water-gas shift with chemical looping at 650 °C. Characterization demonstrates that La, Sm co-doping improves the oxygen vacancy content of the support materials. Pulse tests demonstrated much-enhanced oxygen-ion conduction, which determines the overall reaction efficiency, in both reduction and reoxidation reactions. In addition, the solid-state reaction between Fe₂O₃ and CeO₂ to form CeFeO₃ was suppressed by La, Sm co-doping, thus providing more oxygen capacity for CO₂ splitting. As a result, Fe₂O₃/La_0.1Sm_0.1Ce_0.8O_2−δ presents superior CO₂ splitting performance with a CO yield of 8.93 mmol g⁻¹ and an average CO₂ splitting rate of 595.6 μmol g⁻¹ min⁻¹. The performance remains stable over 40 cycles. We hope that the results in this work will have an impact on the rational design of oxygen carriers for mid-temperature applications.