By cobalt-doping of the mixed conducting phase PSFC, a good combination of high CO 2 stability and high oxygen permeability is obtained for the 60 wt% Ce 0.9 Pr 0.1 O 2Àd -40 wt% Pr 0.6 Sr 0.4 Fe 0.5 Co 0.5 O 3Àd(CP-PSFC) dual phase membrane, which suggests that CP-PSFC is a promising membrane for industrial applications in the oxyfuel process for CO 2 capture.CO 2 capture and storage technologies in power plants have gained attention worldwide 1 since the combustion of fossil fuel is considered to be the main contribution to CO 2 emissions. Oxygen transporting membranes (OTMs) 2 based on mixed electronic and ionic conductors, can supply oxygen of 100% purity to power stations for CO 2 capture according to the oxyfuel for CO 2 capture and storage. 3 The oxyfuel concept involves the combustion of fossil fuels with an oxygen/exhaust gas mixture. The pure oxygen used in the oxyfuel process can be produced using the Linde cryogenic technique. However, by using OTMs, oxygen can be separated from air by using a part of the exhaust gas CO 2 as a sweep gas. Oxygen production by using OTMs can reduce the costs by 35% and save 60% energy compared to the conventional cryogenic process. 4 A part of the exhaust gas CO 2 is sequestrated, and another part is recycled and used as sweep gas for the oxygen separation through the OTMs. Thus, the OTMs for CO 2 capture in the oxyfuel process should have not only good stability in a CO 2 atmosphere but also high oxygen permeation performance at elevated temperatures. Moreover, OTMs can be used in many promising potential applications, such as in high-purity oxygen production, 5 in catalytic membrane reactors, 6 and as cathodes in solid oxide fuel cells (SOFCs). 7 Among OTMs, many cobalt-based single phase perovskite-type membranes such as Ba 1Àx Sr x Co 1Ày Fe y O 3Àd exhibit high oxygen permeability 8 since cobalt can provide a high concentration of mobile oxygen vacancies in the perovskite lattice over a wide temperature range. 9 However, under a CO 2 atmosphere these membranes immediately lose their oxygen permeation flux, since the alkaline-earth metals on the A site of the perovskite framework form carbonates with CO 2 . 10 Recently, dual phase membranes with good structural stability and CO 2 resistance, made of a micro-scale mixture of well separated grains of the two phases of an oxygen ionic conductor and an electronic conductor, have attracted much attention for the application of the O 2 production in the oxyfuel concept. However, the low oxygen permeability of dual phase membranes needs to be improved to meet the industrial application requirements. (CP-PSF). 16 The CP-PSF membrane shows a good chemical stability under the harsh conditions of the POM reaction and in a CO 2 atmosphere at high temperatures. 16 Thus, cobalt-doping of the PSF phase in the dual phase CP-PSF membrane can enhance the oxygen vacancy concentration in the membrane lattice, which should result in a combination of good CO 2 stability and high oxygen permeability. In this paper, we present the novel ...

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High oxygen permeability and good thermochemical stability of oxygen-transporting membranes (OTMs) are two main requirements concerning the applicability of these devices in chemical processes, such as CO2 capture using the oxyfuel concept or catalytic membrane reactors. In this work, a single-phase perovskite-type membrane Pr0.6Sr0.4Co0.5Fe0.5O3-δ (PSCF) with 0.6-mm thickness was subjected to periodic thermal cycling in the temperature range between 850 and 1000 °C in a 1000-h long-term permeation test with pure CO2 as the sweep gas. The results of this long-term permeation operation revealed a stepwise increase in oxygen permeation values at 1000 °C after each thermal cycle, reaching from 1.38 cm(3) (STP) min(-1) cm(-2) in the first cycle to 1.75 cm(3) (STP) min(-1) cm(-2) in the fourth cycle. Furthermore, the membrane showed very good CO2 stability at 900 °C and above. Despite a partial decrease in oxygen permeation fluxes at 850 °C, a steady state of 0.25 cm(3) (STP) min(-1) cm(-2) was reached and maintained for more than 100 h. The newly developed PSCF membrane also exhibited a higher oxygen permeation flux with He and CO2 sweeping at all measured temperatures compared to a similar La0.6Sr0.4Co0.8Fe0.2O3-δ (LSCF) membrane.

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