Preparation and characterization of mixed-conducting thin tubular membrane

A mixed-conducting thin tubular membrane (o.d. = 2.6 mm, i.d. = 1.7 mm), Al₂O₃-doped SrCo_0.8Fe_0.2O_3-δ (SCFA), has been successfully prepared by the plastic extrusion. By controlling the weight ratio of the SCFA ceramic powder to the polymer binder and sintering temperatures, the SCFA thin tubular membrane with gas-tight properties can be obtained. The characterization of the morphology, sintering ability, mechanical strength and oxygen permeability of the SCFA thin tubular membranes were investigated in detail. The prepared thin tubular membrane showed a symmetric structure and the mechanical strength of the tube was up to 122 MPa after sintering at 1200 °C for 5 h. A high oxygen flux of 1.1 mL (STP)/cm² min was achieved at 900 °C which was much higher than that obtained from the conventional SCFA disk-shaped membrane. The oxygen partial pressure dependence of the oxygen permeation indicated that both surface reaction and bulk diffusion were the rate-determining steps for the oxygen permeation through the thin walled tubular membrane.