Perovskite promoted iron oxide for hybrid water-splitting and syngas generation with exceptional conversion

Abstract

We report a perovskite promoted iron oxide as a highly effective redox catalyst in a hybrid solar-redox scheme for partial oxidation and water-splitting of methane. In contrast to previously reported ferrite materials, which typically exhibit 20% or lower steam to hydrogen conversion, La_0.8Sr_0.2FeO_3−δ (LSF) promoted Fe₃O₄ is capable of converting more than 67% steam with high redox stability. Both experiments and a defect model indicate that the synergistic effect of reduced LSF and metallic iron phases is attributable to the exceptional steam conversion. To further enhance such a synergistic effect, a layered reverse-flow reactor concept is proposed. Using this concept, over 77% steam to hydrogen conversion is achieved at 930 °C, which is 15% higher than the maximum conversion predicted by the second law for unpromoted iron (oxides). When applied to the hybrid solar-redox scheme for liquid fuels and hydrogen co-generation, significant improvements in the energy conversion efficiency can be achieved with reduced CO₂ emissions.