Reversible change in crystal structure of Ba(or Sr)FeO3−δ associated with oxygen sorption/desorption by pressure variation

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Oxygen-enriched air has been expected to be used in several industrial processes for the purpose of less energy consumption as well as less CO2 emission. Thus, an innovative and economical oxygen-separation method is eagerly needed for a large-scale production of oxygen-enriched air. Pressure-swing adsorption (PSA) method is considered to be effective for this purpose, if the high-performance oxygen adsorbents can be developed. It has been lately reported that La–Sr–Co–Fe-based perovskite-type oxide is a good candidate as a potential oxygen adsorbent for PSA. However, its cost is still relatively high, because the oxide is composed of relatively expensive elements of La and Co. Here, we compared the oxygen sorption behavior of the BaFeO3−δ and SrFeO3−δ samples which are composed of much inexpensive elements. These oxide samples were synthesized and then evaluated for oxygen sorption and desorption characteristics by the variation of oxygen partial pressure, with the simultaneous observation of change in crystal structure. As a result, it was found that the prepared BaFeO3−δ and SrFeO3−δ samples gave a relatively high amount of sorbed oxygen at lower (ca. 300°C) and higher (ca. 700°C) temperature, respectively. In addition, the reversible change in crystal structure associated with oxygen sorption/desorption was observed for both oxides at each best operating temperature.
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