Enhanced performance of La1-xFeO3-δ oxygen carrier via A-site cation defect engineering for chemical looping dry reforming of methane

Abstract

Chemical looping is a process-intensification tool that focuses on the fields of fossil fuel combustion, CO2 capture, hydrocarbon valorization, energy storage, and other energy-related and environmental-related areas. Perovskite-structured LaFeO3, a typical oxygen storage material, shows great potential for chemical looping partial oxidation and H2O/CO2 splitting. Here, we report a simple and efficient strategy to enhance catalytic activity by tuning A-site cation defects in perovskites via a sol-gel method. Systematically studies show that A-site cation defects affect both the physical and chemical properties. With the A-site cation defect engineering, the crystallite size of the La1-xFeO3-δ perovskites is reduced. The catalytic performance for CH4 oxidation and CO2 splitting is enhanced with increasing oxygen vacancy concentration. The La0.93FeO3-δ oxygen carrier exhibits the highest catalytic performance with 88% CO selectivity and 90% methane conversion at 750 °C. In addition, the La0.93FeO3-δ shows higher stability in the successive CH4 partial oxidation/CO2 splitting redox cycles, with almost unchanged CH4 conversion and CO selectivity. All these results demonstrate that the strategy of adjustment of different molar ratios of A/B site in perovskite metal oxides can effectively regulate the oxygen vacancy concentration.