A new asymmetric SrCo0.8Fe0.1Ga0.1O3−δ perovskite hollow fiber membrane for stable oxygen permeability under reducing condition

A new SrCo0.8Fe0.1Ga0.1O3−δ (SCFG) perovskite material has been successfully synthesized using an EDTA–CA complexing method. The resultant SCFG powder calcined at 900 °C shows perovskite-type crystal structure upon calcination at 900 °C for 5 h. The oxygen-permeating SCFG hollow fiber membrane prepared from the SCFG powder by the phase inversion–sintering method shows a unique asymmetric structure with porous internal–external surfaces and a dense middle layer. This SCFG hollow fiber membrane is able to achieve a good oxygen permeability of 3.5 mL min−1 cm−2 at 950 °C and 0.55 mL min−1 cm−2 at 600 °C when supplied with air using He as a sweep gas. The presence of Ga was found to significantly lower the activation energy of SCFG hollow fiber membrane. The unique asymmetric structure played a critical role in elevating the critical temperature to 900 °C for transition from surface-reaction to bulk-diffusion controlled regime. Furthermore the SCFG hollow fiber membrane is very stable under reducing environment of 20 mL min−1 methane for at least 100 h with an enhanced permeation of 3.4 mL min−1 cm−2 at 900 °C.