An Approach To Enhance the CO₂ Tolerance of Fluorite–Perovskite Dual-Phase Oxygen-Transporting Membrane

Most of the alkaline earth-containing perovskite-based oxygen-transporting membranes (OTMs) have insufficient tolerance toward CO 2 that potentially limits their commercial applications, for example, oxy-fuel combustion processes with CO 2 capture. One concern regarding the chemical potential of oxygen that may influence the CO 2 tolerance of perovskites, however, is lacking effective investigations. In the present work, we demonstrate that the approach to increase the chemical potential of oxygen at the feed side contributes to stabilize the oxygen permeation fluxes of the fluorite–perovskite dual-phase OTM under CO 2 -rich atmosphere, and we further verify that oxygen can effectively act as a “buffer” to prevent the carbonate formation. Remarkably, we achieve high and stable oxygen permeation fluxes over 0.84 mL cm –2 min –1 during long-term operation at 900 °C with a 0.5 mm thickness 80 wt % Ce 0.8 Gd 0.15 Cu 0.05 O 2−δ -20 wt % SrFeO 3−δ (CGCO-SFO, nominal composition) dual-phase membrane using oxygen-enriched air as the feed gas and pure CO 2 as the sweep gas.