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For the oxy-fuel combustion,air separation unit is required for the production of pure oxygen.Cryogenic air separation is suitable for the large-scale air separation but requires high energy consumption.Nitrogen-selective adsorptive air separation is not appropriate for large-scale oxygen production and has poor selectivity.If an oxygen-selective adsorbent is used for air separation,the adsorptive separation may replace the conventional cryogenic process even for large-scale production.In this study,oxygen-selective BaO sorbent with uniformly mixed MgO which can stabilize BaO/BaO2 particles at high temperature was prepared by crystallization of double carbonate and reduction to oxide.From thermogravimetric analysis,sorption isotherm strongly depended on the temperature and oxygen pressure.When the oxygen pressure was below 45 mmHg,sorption of O2 did not increased with pressure at 650oC.However,sorption isotherm curve sharply increased when the pressure increased to 45 mmHg.As the temperature increased to 700oC and 750oC,the transition O2 pressure increased to 124 mmHg and 280 mmHg respectively.Sorption capacity at about 600 mmHg O2 was 2.24,2.02,and 1.87 mmol/g at 650oC,700oC,and 750oC respectively.The Mg/BaO sorbent exhibited a good stability during 10 times cyclic operations of sorption and desorption at 700oC.The time for 80% of sorption and desorption at 700oC was around 1 to 2 min,meaning the uniformly mixed Mg/BaO sorbent has fast reaction kinetics enough to apply for continuous process operation.