Syngas-induced structural evolution and reduction kinetics of Fe₂O₃/Al₂O₃ composite oxygen carrier

Chemical looping gasification (CLG) offers a promising route for efficient fuel conversion, enabling syngas production without the need for additional separation processes. In this study, the interaction between gasification syngas (H₂ and CO) and Fe₂O₃/Al₂O₃ oxygen carrier was systematically investigated using combined experimental and theoretical approaches for the first time. A series of reduction experiments were conducted at temperatures of 700 °C, 800 °C and 900 °C under varying H₂/CO ratios to evaluate the reduction performance and gas conversion behavior of the oxygen carrier. The results revealed distinct reduction characteristics of H₂ and CO, as well as competitive effects when both gases coexisted. Hydrogen exhibits stronger reducibility than CO at high temperature, whereas CO demonstrates superior reduction capability at medium and low temperature. Notably, the temperature of equal conversion ratios between H₂ and CO was determined to be 827.6 °C. The competitive mechanism was further analyzed based on reduction degree, gas conversion ratios and morphological changes of samples. Additionally, density functional theory (DFT) calculations were performed to explore the adsorption behavior and reaction pathway on the surface of Fe₂O₃/Al₂O₃, thereby elucidating the microscopic mechanism governing the gas-solid interactions. This study provides valuable insights into the redox behavior and synergistic effects of H₂ and CO in chemical looping processes, offering theoretical guidance for optimizing oxygen carrier utilization in syngas applications.