C. Ren, Y. Gan, C. Yang, M. Lee, X. Xue
University of South Carolina,
Keywords: asymmetric hollow fiber membrane, dip-coating, thin film, oxygen permeation
Summary:A typical oxygen permeation hollow fiber membrane fabricated by phase-inversion based extrusion process demonstrates heterogeneous porous microstructures, in which the surface layer with relatively low porosity is used as a separation layer after sintering. It is usually not convenient to control the thickness of separation layer. And a high sintering temperature is needed to densify the separation layer, which in turn could destroy the desired porous microstructures in other portion. This paper studies a novel process to fabricate multilayer asymmetric hollow fiber membrane with a rational design using 67 vol. % Gd0.2Ce0.8O2−δ−33 vol. % La0.6Sr0.4Co0.2Fe0.8O3−δ (GDC-LSCF) as a model material system. The phase-inversion based extrusion process in open literature is employed to fabricate a hollow fiber substrate featuring radially well-aligned microchannels open at the inner surface. Built upon hollow fiber substrate, a thin dense separation layer and porous surface catalyst layer at shell side are then fabricated through dip-coating and sintering process alternatively. The oxygen permeation flux of the fabricated hollow fiber membrane reaches 2.68 ml·cm-2·min-1 at 900 oC under Ar/air gradient, the highest performance of the membranes with GDC-LSCF material system in open literature. The innovative fabrication process is able to readily control the thickness of functional layers while decreasing sintering temperatures.