Morphology control of the perovskite hollow fibre membranes for oxygen separation using different bore fluids

La(0.6)Sr(0.4)Co(0.2)Fe(0.8)O(3-alpha) (LSCF6428) perovskite hollow fibre membranes were fabricated through a phase inversion/sintering technique. The effects of the internal coagulant (bore fluid) compositions on the morphology of the resultant hollow fibres were systematically investigated. The bore fluids were specially designed to vary the solvent-nonsolvent exchange rates in the phase inversion stage by mixing different polymer solvent (1-methyl-2-pyrrolidinone-NMP) content inside the water or ethanol internal coagulant. The prepared hollow fibre membranes were characterized with scanning electron microscopy (SEM), porosity and bending strength measurements, gas-tightness examination and oxygen permeation tests at high temperatures. The results indicate that the bore fluid composition has dramatic effects on the microstructure of the resultant hollow fibre membranes. With the gradual increase of NMP concentration in the bore fluids, the membrane morphology evolution from multi-dense layers to one single dense layer has been clearly demonstrated. LSCF6482 hollow fibre membranes with one dense layer near the outside surface integrated with the highly porous structure showed the highest oxygen fluxes with a maximum value of 34.4 mmol m(-2) s(-1) under air/He gradient at 1000 degrees C. The relationships between bore fluid composition and membrane morphology change and their significant effects on oxygen permeation have been discussed extensively. This work shows the feasibility of achieving ceramic hollow fibre membranes with different architectures for various purposes in one single step simply by adjusting the bore fluid composition. (C) 2011 Elsevier B.V. All rights reserved.