Abstract
La 0.6Sr 0.4Co 0.8Fe 0.2O 3− α (LSCF) hollow fibre membranes with an asymmetric structure consisting of a central porous layer and two dense surface layers were prepared using a mixture of 50% ethanol + 50% NMP as the internal coagulant. Using the resultant hollow fibre, the influence of CO 2 as the sweep gas on the oxygen permeation behavior of the LSCF membranes has been investigated. The membranes before and after permeation test were characterized by XRD, SEM and EDX. The oxygen permeation fluxes of the LSCF membrane decreased with increasing the CO 2 concentration in sweep gas. The significant poisoning effect of CO 2 on the oxygen permeation through the LSCF perovskite membranes was mainly due to the chemical adsorption of CO 2 to the membrane surface with a result that the oxygen vacancy sites were occupied by the oxygen atoms of CO 2. The reaction between the LSCF membrane material and the adsorbed CO 2 to form carbonates caused Sr segregation and corrosion on the membrane surface during the permeation process. Operated in pure CO 2 as sweep gas for more than 100 h at 900 °C or above, the LSCF hollow fibre still displayed a stable performance. Although some areas of the membrane have been etched with a thickness about 1.4 μm, no sign of membrane collapsing or failure exists.
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