La0.8Sr0.2Co0.2Fe0.8O3–δ as a potential oxygen carrier in a chemical looping type reactor, an in-situ powder X-ray diffraction study

Abstract

Perovskite type materials which can change oxygen content quickly under changing oxygen partial pressures are believed to be suitable materials for chemical looping of natural gas. In order to investigate the oxidation/reduction of these materials in-situ powder X-ray diffraction was used to study the La1−xSrxCo1−yFeyO3−δ system. It was found that for samples with high iron content a hexagonal/orthorhombic to cubic phase transition was observed upon heating in a reductive atmosphere and that the cationic lattice is maintained upon reduction. On the other hand, the samples with high cobalt content were unstable with respect to heating in a reductive atmosphere as they decomposed to form La2O3, Co and at least one additional phase. Once a suitable candidate had been obtained a chemical looping experiment was carried out using H2 as a model fuel, again using in-situ powder X-ray diffraction.