Preparation of Tunable (BaSrMg)O for Oxygen Chemisorption: Formation Mechanism and Characterization

Composition-tunable single-phase three-component alkaline earth oxide of (BaSrMg)O was prepared based on the consecutive precipitation and thermal decomposition of (BaSrMg)­CO₃. First, the single-phase (BaSrMg)­CO₃ was coprecipitated via ion self-assembly, phase-transformation, and agglomeration. The element composition of (BaSrMg)­CO₃ could be simply tuned by the composition of the reactants. Then, (BaSrMg)­CO₃ was converted to (BaSrMg)O under an H₂ atmosphere at 750 °C. This (BaSrMg)O showed fast chemisorption–desorption responses with oxygen chemisorption rate: <i>t</i>₈₀ = 3.9 min and desorption rate: <i>t</i>₈₀ = 14 min and a high thermal stability for the redox reaction of BaO–BaO₂. In addition, the chemisorption capacity of (BaSrMg)O (4.39% Sr composition) is ∼1.92 mmol/g, which is much higher than the chemisorption capacity of BaO/MgO at 1.75 mmol/g (Jin et al., <i>Ind. Eng. Chem. Res.</i>, <b>2005</b>, 44, 2942), while the transient oxygen pressure for the redox reaction of (BaSrMg)­O (4.39% Sr composition) was significantly enhanced from 76 to 135 mmHg due to the inclusion of Sr in (BaSrMg)­O. The transient oxygen pressure could be further improved via adjusting the Sr composition in (BaSrMg)­O. Consequently, the tunable (BaSrMg)O has a high potential as a chemisorbent for the industrial application of oxygen separation