The influence of CO2 on the O permeation performance of perovskite-type (Ba0.5Sr0.5)(Co0.8Fe0.2)O3−δ (BSCF) membranes under different experimental conditions was presented. First, pure CO2 was applied as the sweep gas at 875C yielding an immediate cessation of the O permeation. In order to probe the reversibility of this stagnancy, several cycles of changing the sweep gas between helium and CO2 were conducted. The analysis of the microstructure after permeation experiments were carried out by transmission electron microscopy, X-ray diffraction as well as by scanning electron microscopy. It was found that both microstructure as well as O permeation were recovered in a helium atmosphere. Additionally, long-time treatment with pure CO2 for 72h on the permeate side and the concentration effect of CO2 in the sweep gas were accomplished showing that the perovskite structure was impaired only up to a depth of 50μm. Further on, the impact of CO2 on the feed side was examined by adding certain amounts of CO2 to the feed air. It was found that the impact of CO2 on the O permeation applied in the sweep gas was superior to that applied on the feed gas.

Influence of CO2 on the Oxygen Permeation Performance and the Microstructure of Perovskite-Type (Ba0.5Sr0.5)(Co0.8Fe0.2)O3−δ Membranes. M.Arnold, H.Wang, A.Feldhoff: Journal of Membrane Science, 2007, 293[1-2], 44-52