Oxygen desorption behavior of sol-gel derived perovskite-type oxides in a pressurized fixed bed reactor

Abstract

Perovskite-type oxides have been considered to be an effective oxygen carrier for producing O2/CO2 for oxy-fuel combustion application, which is a promising technique for carbon capture and storage. However, the main problem of common perovskite-type oxygen carriers is their relatively low oxygen desorption capacity at atmospheric pressure. Therefore, it is important to develop new oxygen carriers and enhance the reaction pressure to achieve high desorption capacity. In this study, a series of A/B-site substitution Ba1−xSrxCo1−yFeyO3−δ(x=0, 0.5, 1; y=0, 0.2, 1) perovskites were synthesized by sol-gel method, and the oxygen desorption performance of them was investigated in pressurized fixed bed. The perovskite samples were characterized using X-ray diffraction (XRD), X-ray fluorescence (XRF), X-ray photoelectron spectroscopy (XPS) and Transmission electron microscopy (TEM) measurements. The effect of reaction pressure, temperature and flow rate on the oxygen desorption performance were investigated in details. The results indicated that all of the Ba1−xSrxCo1−yFeyO3−δ perovskites showed an obvious improvement on oxygen desorption capacity at pressurized conditions. Besides, BaCoO3−δ showed the best oxygen desorption performance among the Ba1−xSrxCo1−yFeyO3−δ(x=0, 0.5, 1; y=0, 0.2, 1) perovskites. Oxygen desorption amounts of BaCoO3−δ increased by 57.2% and 62.7% under 2MPa and 3MPa conditions respectively, comparing to that of it under atmospheric pressure at 850°C. The optimal temperature and WHSV for BaCoO3−δ are 850°C and 176.78h−1. XRF and XRD results showed that the elemental contents of perovskites remained after reactions and the crystal structure of perovskites could recover after cyclic process under high pressure calcination. XPS results showed the evolution of oxygen species during oxygen desorption process.