a b s t r a c tA novel series of cobalt-free dense oxygen-permeable dual-phase membranes with a composition of 60 wt% Ce 0.8 Sm 0.2 O 2 À δ and 40 wt% Ba 0.95 La 0.05 Fe 1 À x Zr x O 3 À δ (SDC-BLFZ, x ¼0-0.20) are successfully developed and systematically evaluated as potential oxygen transport membranes for oxy-fuel combustion. The effects of substituting zirconium for iron on the structural characteristics, oxygen permeability, and CO 2 resistance of these membranes are studied. Experimental results show that appropriate doping of zirconium slightly decreases the oxygen permeability of the SDC-BLFZ membranes under helium but significantly enhances the structural stability and CO 2 tolerance. For the sample with x ¼0.15, a stable oxygen permeation flux of 0.24 ml min À 1 cm À 2 was achieved at 925 1C for a 1.0 mm thick membrane with CO 2 as the sweep gas for more than 80 h. This flux value is only 19% lower than that under an air/He gradient, which is much better than that obtained with most alkaline-metalcontaining composite dual-phase membranes. The enhanced CO 2 tolerance of the Zr-doped SDC-BLFZ membranes is attributed to the declining basicity of BLFZ induced by the substitution of Fe by Zr, as revealed by X-ray photoelectron spectroscopy (XPS). The stable oxygen permeability of the SDC-BLFZ membranes under CO 2 demonstrates the potential application of SDC-BLFZ in oxy-fuel combustion technology.
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