A study on Sn-doped SrFeO_3-δ oxygen carriers for chemical looping oxidative dehydrogenation of ethane

This investigation explores the impact of tin (Sn) substitution on the oxygen transfer characteristics and redox selectivity of SrFeO_3-δ within the context of chemical looping oxidative dehydrogenation (CL-ODH) of ethane. The incorporation of Sn^{4 +} as a redox-inactive cation at the B-site contributes to the stabilization of the perovskite lattice during successive reduction–oxidation cycles and modulates the reactivity of oxygen species critical for selective oxidative dehydrogenation. In the absence of Sn doping, SrFeO_3-δ exhibits rapid oxygen release and unstable surface oxygen species, which facilitate deep oxidation reactions and structural degradation. Conversely, moderate Sn substitution, particularly at a composition of X = 0.90, enhances the utilization of lattice oxygen while mitigating the presence of excessive surface oxygen species. This adjustment leads to a reduction in CO₂ formation and an improvement in both ethylene selectivity and yield. However, excessive Sn incorporation reduces the availability of Fe-based active oxygen species and shifts the reaction mechanism toward thermal dehydrogenation. These findings indicate that precise Sn doping serves as an effective approach to modulate oxygen transfer pathways in SrFeO_3-δ, achieving a balance between structural stability and selective oxidative dehydrogenation performance. The results underscore the potential of Sn-modified perovskite materials as efficient oxygen carriers and suggest avenues for further enhancement through targeted control of oxygen species distribution.