Contact angle screening and asymmetric dual-phase CO2 separation membranes
2022
Xing, Wen | Støre, Anne
Dual-phase CO₂ separation membrane consisting of molten carbonates confined in a solid matrix can separate CO₂ at high temperatures. The contact angle of molten carbonates to different oxides that can potentially serve as membrane supports was screened between 450 and 650 °C. These oxides have different electrical transport properties, including oxide ion, mixed, and electronic conducting. The contact angles vary between 80° and 10° for different materials. Asymmetric membranes were fabricated using wettable oxide ion conductors BTM and CGO (Bi₀.₈Tm₀.₂O₁.₅ and Ce₀.₈Gd₀.₂O₂₋δ) infiltrated with molten carbonates supported by the most "non-wetting" oxide BPR (Bi₀.₈Pr₀.₂O₁.₅) selected in the contact angle screening. The membranes show CO₂ flux in the range of 0.035–0.35 ml/min cm² at temperatures from 500 to 650 °C. Compared to a symmetric membrane with similar total membrane thickness, the asymmetric architecture significantly reduces the effective membrane thickness and increases CO₂ flux. After the CO₂ flux measurements, the membrane was examined with SEM and EDS mapping, showing that the molten carbonates were mainly confined within the top membrane and sealing area without penetrating the support layer.
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