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 LaFeO3 was proposed. A series of 5 wt % Ni/LaFeO3 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 H2/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 CH4 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 LaFeO3 and offers new insights into the rational design of highly active and stable perovskite oxygen carriers for CL-DRM.