Elucidation of the Oxygen Surface Kinetics in a Coated Dual-Phase Membrane for Enhancing Oxygen Permeation Flux

The dual-phase membrane has received much attention as the solution to the instability of the oxygen permeation. Membrane. It has been reported that the oxygen flux of the dual-phase membrane is greatly enhanced by the active coating layer. However, there has been little discussion about the enhancement mechanism by surface coating in the dual-phase membrane: This study investigates the oxygen flux of the Ce0.9Gd0.1O2-delta-La0.7Sr0.3MnO3 +/-delta, (GDC 80 vol %/LSM 20 vol %) composite, membrane depending on the oxygen partial pressure (P-O2) to elucidate the mechanism of enhanced oxygen flux by the surface,modification in. the fluorite-rich phase dual-phase membrane. The oxygen permeation resistances were obtained from the oxygen flux as a function of P-O2 using the oxygen permeation model. The Surface exchange coefficient (k) and the bulk diffusion coefficient (D) were calculated from these, resistances. According to the calculated k and D values, we concluded that the active coating layer (La0.6Sr0.4CoO3-delta) significantly increased. he k value of the membrane. Furthermore, the surface exchange reaction on the permeate side was more sluggish than that at the feed side under Operating conditions (feed: 0.21 atm/permeate side: 4.7 x 10(-4) atm). Therefore, the enhancement of the oxygen surface exchange kinetics at the permeate side is more important in, improving the oxygen permeation flux of the thin film-based fluorite-rich dual-phase membrane. These results provide new insight about the function of the surface coating to enhance the oxygen permeation flux of the dual-phase membrane.