Fabrication of asymmetric tubular mixed-conducting dense membranes by a combined spin-spraying and co-sintering process

Mixed-conducting dense ceramic membranes have attracted considerable attention because of their potential application in oxygen separation, oxyfuel combustion and catalytic membrane reaction processes. However, the development of robust mixed-conducting membranes with both high permeability and stability is still a major challenge. In this paper, a crack-free asymmetric tubular membrane made of SrCo _0.4Fe _0.5Zr _0.1O _3-δ perovskite oxide was successfully prepared by a combined spin-spraying and co-sintering method, in which the slurry containing powders was sprayed on a rotating green support tube and followed by sintering process. The issue of the shrinkage mismatch between membrane and support was solved by the optimization of processing parameters, i.e. heating rate, sintering temperature and spraying circles. SEM and nitrogen gas-tight test demonstrated that the surface of membrane was dense, continuous and crack-free, and the thickness of the dense layer was about 20μm. A high oxygen flux of 7.41×10 ^-7molcm ^-2s ^-1 was achieved at 800°C which was 2.35 times that of symmetric membrane. Long-term oxygen permeation measurement (850°C, 200h) showed that the asymmetric membrane was stable under low oxygen partial pressure environment. This work provides a new path for the preparation of asymmetric tubular membrane. This simple and cost-effective fabrication technique can be readily used for mass production.