CaCox Zr1-x O3-δ Perovskites as Oxygen-Selective Sorbents for Air Separation.

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 [ p O 2 ]. 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 p O 2 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.