Oxygen permeability and structural stability of BaCe 0.15Fe 0.85O 3− δ membranes

Abstract

Cobalt-free BaCe x Fe 1− x O 3− δ ( x = 0.15–0.85) membranes have both high oxygen permeation flux and high structure stability even in reducing atmosphere at high temperature. The oxygen flux of BaCe 0.15Fe 0.85O 3− δ (BCF1585) membrane reached at 0.5 ml/min cm 2 at 900 °C with a thickness of 1.4 mm. Oxygen permeation results showed that oxygen permeation controlling step mainly was oxygen ion diffusion in the membrane bulk if the membrane thicker than 1.0 mm, and mainly was surface oxygen exchange if the membrane thinner than 0.78 mm. Ba 0.5Sr 0.5Co 0.8Fe 0.2O 3− δ (BSCF) porous layer coated on the membrane surfaces could effectively accelerate the surface oxygen exchange rate, thus greatly improve the oxygen permeability of the membrane. In some cases, the oxygen permeation flux of the membrane coated with BSCF was even two times higher than that of the membrane without coating. Perovskite structure of BCF1585 was still maintained at 950 °C even after it was exposed to 5% H 2 + Ar mixture gas for 1 h.