Mixed ionic and electronic conducting (MIEC) membranes, like perovskite-type membranes, have been drawing considerable attentions due to their promising applications in oxygen separation, solid oxide fuel cells, and partial oxidation of methane to syngas. The oxygen permeation performance of the MIEC membrane can be greatly improved by the reduction of membrane thickness. A supported dense MIEC membrane, which consists of a thin, dense MIEC layer on a porous support, has been considered to be a promising membrane geometry for the practical applications [1, 2]. In most pervious studies, disc-shaped membranes with only a limited membranes area were employed for oxygen permeation as they are easily fabricated using the conventional static-pressing method. However, compared with the planar disc, the tubular design is of obviously advantages, such as higher surface area/volume and ease of high-temperature sealing, in the industrial applications although it is much more difficult to attain this structure.
In this work, SrCo0.4Fe0.5Zr0.1O3-delta (SCFZ) mixed-conducting oxide was selected as the representative membrane material and the support material. The porous supports were prepared by the plastic extrusion, and dense film was spin sprayed on green tube, followed by co-sintering. The sintering behaviors of the membrane layer and the support are well matched by optimizing the sintering procedures. The SCFZ asymmetric tube membrane was successfully prepared by the spin-spraying and co-firing process. SEM and the gas-tight test demonstrated that the surface of the supported membrane was dense. Moreover, the oxygen flux of the supported membrane with a dense layer of 20mm thick and a support layer of 0.5mm thick were 1.792 ml cm-2 min-1 at 900 °C and 0.961 ml cm-2 min-1 at 800 °C, respectively, which were 66% and 133% higher than that of the SCFZ symmetric tubular membrane.
Acknowledgements This work is supported by the National Basic Research Program of China (No. 2009CB623406); National Natural Science Foundation of China (No. 20990222) and China Postdoctoral Science Foundation funded project (No. 20090461105).
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