High Oxygen Permeation in Ba0.95La0.05FeO3-δ Membranes with Surface Modification

Selective oxygen separation from air was carried out using ceramic membranes composed of Ba0.95La0.05FeO3-delta. We demonstrated that surface abrasion of Ba0.95La0.05FeO3-delta membranes led to a significant increase in oxygen permeation fluxes at 700-930 degrees C because of an increase in surface reaction sites. Abrasion of the oxygen desorption side of the membrane resulted in a higher oxygen permeability than with abrasion on the oxygen sorption side. Moreover, an increase in the area of the oxygen desorption side also increased the oxygen permeability. The results suggest that oxygen permeation through Ba0.95La0.05FeO3-delta membranes is limited by the desorption of oxygen (surface reaction) and bulk diffusion. Attachment of a porous layer made of Ba0.95La0.05FeO3-delta to the membrane surface was also effective in increasing oxygen permeability. For example, a high permeation flux of 3.2 cm(3) min(-1) cm(-2) was achieved at 930 degrees C under a He/air gradient for a membrane (0.5 mm thickness) coated with a porous layer (14.4 mu m).