Preparation And Characterization Of Asymmetric Hollow Fiber Ceramic Membranes

In this paper, Yttria Stabilized Zirconia (YSZ) electrolyte membrane, Al2O3 porous membrane and La0.6Sr0.4Co0.2Fe0.8O3-δ(LSCF) oxygen permeation membrane were prepared through the phase inversion and sinter technology. The casting solution composition, internal coagulation bath and spinning technolygical conditions were studied systematically, in order to confirm how these parameters influence the hollow fiber membrane structure and performance. The technological parameters of hollow fiber membrane preparation and the relationship between phase separation procedure and membrane structure were obtained.Gas-tight YSZ hollow fibre membranes having different morphologies were fabricated through a phase inversion/sintering technique. When YSZ powders content in the casting solution increased 50% from 55%, the viscosity increase and formed large finger-like pore structure on cross-section, of the sponge holes. The sponge-like pores structure gradually disappeared near the region of the inner surface. when the non-solvent additives of water content to 5% of the casting solution, the hollow fiber membrane would have more sponge-like pores structure, the suitable dense layer thickness and enough bending strength, which could each 15μmand 212.5MPa, respectively. These benefits were fit for electrolyte support solid oxide fuel cell. When the bore coagulant contains more NMP, a highly asymmetric structure can be obtained with large finger-like pores extending to the inner surface and the formation of porous inner surface. The highly asymmetric hollow fibre membranes are beneficial for increase much higher fluxes than other structures, but are also compromised by the decrease in mechanical strength. The sintering temperature has significant effect on the microstructure, porosity md bending strength for electrolyte membranes.Al2O3 porous ceramic membrane with different micro-structure and performance were fabricated. Meanwhile, the influence of membrane forming factors, such as dry spinning distance, none solvent addition agent and the bore coagulation composition were investigated. Hollow fiber membrane with different structure and performance were prepared by altering the bore coagulant composition. When the content of NMP in the bore coagulation was decreased, the porosity of hollow fiber reduced, meanwhile the bending strength of fiber improved. When NMP was used as bore coagulation, the hollow fiber possessed a remarkable water flux, which was as high as 414.2m3·m-2·h-1, this value is 4.2 times of hollow fiber membrane with pure water as pore coagulation.Gas-tight La0.6Sr0.4Co0.2Fe0.8O3_δ(LSCF6428) perovskite hollow fibre membranes having different morphologies were fabricated through a phase inversion/sintering technique using water-NMP or ethanol-NMP mixture as the bore coagulant. Oxygen permeation fluxes through the obtained hollow fibre membranes were measured under air/He gradient at different temperatures. The results indicate that the bore fluid composition has a dramatic effect on membrane morphology. The LSCF6428 hollow fibre membranes prepared using ethanol-NMP mixture as the bore liquid exhibit higher oxygen permeation flux than those using water-NMP as the bore liquid because of the improved microstructures. When the content of ethanol in the bore liquid is lower than 30wt%, a highly asymmetric structure comprising of one gas tight layer integrated with a porous structure is formed. The highly asymmetric hollow fibre membranes have much higher fluxes than other structures, but are also compromised by the decrease in mechanical strength.