ABO3-δ perovskites are ideal for high-temperature thermochemical air separation for oxygen production because their oxygen nonstoichiometry δ can be varied in response to changes in temperature and oxygen partial pressure [ ]. Herein, the outstanding oxygen-sorption performance of CaCox Zr1-x O3-δ perovskites and their potential application as oxygen-selective sorbents for air separation is reported. In situ thermal X-ray diffraction was used to study the materials' structural changes in response to temperature variations in air and inert atmosphere. Temperature-programmed reduction was employed to elucidate the relationship between perovskite composition and redox property. O2 sorption performance was evaluated by isothermal analyses at various temperature and along with long-term absorption-desorption cycle tests. The high oxygen-sorption capacity was mainly attributed to Co at B-site, whereas partial substitution of Co by Zr enhanced the structural crystallinity and thermal stability of the perovskite. A stable oxygen production of 2.87 wt % was observed at 900 °C during 5 min-sorption cycles for 100 cycles.
Keywords: air separation; oxygen sorbent; oxygen storage material; perovskite; redox cycle.
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