Reactivity of Ca2Fe2O5 oxygen carriers for chemical looping steam methane reforming

Chemical looping steam methane reforming (CL-SMR) can obtain high-quality syngas and pure hydrogen at the same time, with a prerequisite that oxygen carriers possess excellent reactivity. In this work, a composite oxygen carrier, i.e., Ca₂Fe₂O₅, was prepared by the sol-gel method and found to hold remarkable reactivity and syngas selectivity. At the optimal condition, the average CH₄ conversion, CO selectivity, and syngas yield were 36.33%, 78.79%, and 7.81 mmol/g_OCs respectively during the methane reforming stage, while hydrogen yield was 3.72 mmol/g during the water splitting stage. Ten redox-cycle experiments indicate that the syngas yield and H₂ yield were stable at 4.40 and 1.88 mmol/g_OCs. Characterization analysis of oxygen carriers indicates that Fe exsolution favors methane activation and decomposition, therefore enhancing the reaction efficiency.