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

The oxygen flux of yttria-stabilized-zirconia (YSZ) was measured as a function of membrane thickness and surface coating, under controlled P O 2 gradient (permeate side: ∼3 × 10−12 atm; feed side: 2 × 10−12 to 2 × 10−8 atm) in reducing atmosphere at 1600 °C. The oxygen flux was determined by measuring the change of CO2 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 mm to 0.2 mm. 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 μm by a new experiment setup. Characteristic membrane thickness (LC) 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.