Oxygen-permeating zirconia membrane: The effect of thickness and surface coating

Abstract

The oxygen flux of yttria-stabilized-zirconia (YSZ) was measured as a function of membrane thickness and surface coating, under controlled P-O2, gradient (permeate side: similar to 3 x atm; feed side: 2 x 10(-12) to 2 x 10(-8) atm) in reducing atmosphere at 1600 degrees C. The oxygen flux was determined by measuring the change of CO, content in CO gas stream of permeate side with gas chromatograph. In order to study the effect of surface-exchange kinetics. YSZ membranes with or without LaCrO3 coating were used. The oxygen flux increased with decreasing YSZ thickness from 0.7 rum to 0.2 rum. The oxygen flux was controlled by both the bulk diffusion and surface exchange kinetics. Permeation experiment was possible for the membrane as thin as 200 mu m by a new experiment setup. Characteristic membrane thickness (L-C) which divides the bulk diffusion and surface-exchange limits was calculated as 0.365 mm. Based on this study, the increased permeation flux is expected for YSZ with different coating layer. (c) 2007 Elsevier Ltd. All rights reserved.