Tunable H2/Syngas Production by Chemical Looping Reforming of Methane over La0.6Sr0.4MxM’1‐x(M,M’ = Fe, Mn, Co)O3 Perovskites

The applications of perovskites in chemical looping dry and steam reforming have shown promising results in efficient hydrogen production from hydrocarbons. Notably, LaFeO3 has shown exceptional capabilities in reforming processes, with surface oxygen contributing to the complete oxidation of methane to CO2 and H2O, while bulk lattice oxygen promotes partial methane oxidation to H2 and CO. In this study, the effect of B-site substitution in La0.6Sr0.4BxB’1-xO3 (B, B’ = Fe, CO, Mn) was systematically investigated with the aim to develop a material with enhanced redox properties and selectivity to syngas. Among the synthesized materials, under cyclic operation at 900 °C, La0.6Sr0.4Fe0.6Mn0.4O3 (LSFM) demonstrated improved redox activity, stability, and reproducibility. In addition, an innovative three-step redox cycle is proposed in this study: (i) methane reduction at 900 °C, producing H2-rich syngas and coke deposition, (ii) steam oxidation at 550 °C, producing pure H2 and reoxidation of the material, and (iii) steam oxidation at 900 °C, which gasifies the coke into syngas. Structural characterization indicated increasing perovskite stability with cycling by secondary phases disappearing while redox properties were unaffected. These results highlight the potential of Sr- and Mn-substituted perovskites as efficient and durable oxygen carriers for chemical looping reforming.