Perovskite Sr(Fe1-xCux)O3-δ materials for chemical looping combustion applications

Abstract

This paper presents the results of chemical looping combustion (CLC) research. Nowadays, CLC is one of the best prospective combustion technologies, because it enables the production of a concentrated carbon dioxide (CO2) stream, following water condensation, without any energy penalty for its separation.The objective of this work was to study chemical looping reaction performance with the application of novel perovskite-type oxygen carriers (OCs). Sr(Fe1-xCux)O3-δ family members were tested for hydrogen combustion for power generation purposes. Sr(Fe1-xCux)O3-δ, which is a perovskite-type oxide, was prepared using the calcination method, where x = 0, 0.1 and 0.33. Reactivity tests were performed using a thermogravimetric analyser (TGA, Netzsch STA 409 PG Luxx) under isothermal conditions in multiple reduction–oxidation cycles. Both the temperature (600–800 °C) and number of redox cycles (five cycles) effects on the reaction performance of recently developed OC samples were evaluated in the study. TGA data were used for the assessment of the oxygen transport capacity value, redox reaction rates and stability. Sr(Fe1-xCux)O3-δ showed an excellent stable chemical looping performance. The changing of oxygen content (3.8–4.86 wt%) occurred within approximately 2 min, with the chemical properties of the material maintained during the cycling combustion tests.In addition, new SrFeO3-δ OCs, doped with copper (Cu) perovskite-type materials, were analysed using multiple methods: X-ray powder diffraction (XRD); scanning electron microscopy (SEM); surface area by Brunauer–Emmett–Teller (BET) method; and melting behaviour study. In terms of physical properties, the new OCs can resist both high CLC process temperatures and mechanical forces, which are essentially useful. The analysis showed that Sr(Fe1-xCux)O3-δ carriers performed at extremely high melting temperatures (>1280 °C). Results of crushing strength testing showed that developed materials had a pronounced mechanical resistivity with a crushing strength higher than 1 N and will perform well in fluidized beds (4.31–6.23 N).In this paper, it was demonstrated that known mixed oxygen-ionic and electronic conducting membrane materials such as Sr(Fe1-xCux)O3-δ might also be applied as oxygen carriers. Overall results demonstrated Fe-Cu-based perovskites might be successfully used as OCs in the chemical looping combustion process.