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Thermochemically stable ceramic composite membranes based on Bi₂O₃ for oxygen separation with high permeability

Xing, Wen, Carvalho, Patricia A., Polfus, Jonathan M., Li, Zuoan
Chemical communications 2019 v.55 no.24 pp. 3493-3496
asymmetric membranes, carbon dioxide, ceramics, combustion, fossil fuels, greenhouse gas emissions, oxygen, permeability, power generation, temperature
Ceramic oxygen separation membranes can be utilized to reduce CO₂ emissions in fossil fuel power generation cycles based on oxy-fuel combustion. State-of-the-art oxygen permeable membranes based on Ba₀.₅Sr₀.₅Co₀.₈Fe₀.₂O₃₋δ (BSCF) offer high oxygen permeability but suffer from long-term instability, especially in the presence of CO₂. In this work, we present a novel ceramic composite membrane consisting of 60 vol% (Bi₀.₈Tm₀.₂)₂O₃₋δ (BTM) and 40 vol% (La₀.₈Sr₀.₂)₀.₉₉MnO₃₋δ (LSM), which shows not only comparable oxygen permeability to that of BSCF but also outstanding long-term stability. At 900 °C, oxygen fluxes of 1.01 mL min⁻¹ cm⁻² and 1.33 mL min⁻¹ cm⁻² were obtained for membranes with thicknesses of 1.35 mm and 0.75 mm, respectively. Moreover, significant oxygen fluxes were obtained at temperatures down to 600 °C. A stable operation of the membrane was demonstrated with insignificant changes in the oxygen flux at 750 °C for approx. one month and at 700 °C with 50% CO₂ as the sweep gas for more than two weeks.