Oxygen-Vacancies Enriched LaFeO 3 for Efficient Chemical Looping Dry Reforming of Methane

Engineering oxygen vacancies is an effective approach to enhancing the performance of chemical looping dry reforming of methane (CL-DRM). Here, a facile urea-induced strategy to achieve the precise modulation of oxygen vacancies in LaFeO 3 was proposed. A series of 5 wt % Ni/LaFeO 3 oxygen carriers were synthesized via a urea-assisted sol–gel method and evaluated for CL-DRM. Structural and spectroscopic characterization indicate that proper urea modulation increases the oxygen-vacancy concentration within the perovskite structure and concurrently regulates the valence states of Fe. This synergistic effect culminates in improved lattice oxygen mobility, a reduction in onset temperature for methane reduction, and a notable elevation in CO selectivity. Furthermore, a more stable H 2 /CO ratio was achieved, indicating a superior kinetic match between methane activation and oxygen supply. The 5Ni/LFO-U2 (citric acid to urea molar ratio of 1:2) exhibited the best performance, with a CH 4 conversion of 96.2% and CO selectivity of 92.1% at 800 °C, showing no significant degradation after 40 redox cycles. This strategy provides a cost-effective defect engineering route for the precise tuning of oxygen vacancies in LaFeO 3 and offers new insights into the rational design of highly active and stable perovskite oxygen carriers for CL-DRM.