CO2-stable and cobalt-free Ce0.8Sm0.2O2-δ-La0.8Ca0.2Al0.3Fe0.7O3-δ dual-phase hollow fiber membranes for oxygen separation

• SDC-LCAF dual phase oxygen permeable hollow fiber membrane are developed. • O 2 flux of dual phase is significantly improved compared to the LCAF membrane. • Dual phase membrane exhibits stable O 2 permeation in CO 2 atmosphere. In this work, 60 wt.% Ce 0.8 Sm 0.2 O 2-δ -40 wt.% La 0.8 Ca 0.2 Al 0.3 Fe 0.7 O 3-δ (SDC-LCAF) dual-phase oxygen permeable hollow fiber membrane precursors were prepared via a combined sol-gel and phase inversion technique. Dual-phase SDC-LCAF hollow fiber membrane with compatible fluorite and perovskite phases was obtained after sintering at 1450 °C. The chemical compatibility, thermal expansion, conductivity, oxygen permeation, CO 2 tolerance, and short-term regenerative durability regarding the phase structure and composition were systematically studied. The oxygen flux of the SDC-LCAF dual-phase membrane was significantly increased compared to that of LCAF single phase membrane. At 950 °C, the oxygen flux of the SDC-LCAF hollow fiber membrane reached 1.84 mL min -1 cm -2 when both the He sweep and the air feed flow rates were 100 mL min -1 , and the dual-phase membrane exhibited stable oxygen permeation fluxes in pure CO 2 atmosphere. When pure CO 2 was used as the sweep gas in a 225-h short-term stability test, the oxygen permeation fluxes decreased slightly because of the inhibiting effect of CO 2 on oxygen surface-exchange reaction. Nevertheless, the ability of the SDC-LCAF membrane to recover the original oxygen permeation performance indicated that the membrane surface did not react irreversibly with CO 2 . The CO 2 stability was not reflected in the LCAF single phase membrane, thus indicating the superior membrane stability following the incorporation of the SDC phase.