Preparation and characterization of supported planar Zr0.84Y0.16O1.92-La0.8Sr0.2Cr0.5Fe0.5O3−δ composite membrane

The Zr0.84Y0.16O1.92 (YSZ)−La0.8Sr0.2Cr0.5Fe0.5O3−δ (LSCrF) supported membrane was formed by a new variant of phase inversion tape casting method. A slurry composed of YSZ and LSCrF was co-tape cast with a slurry of graphite, and solidified into a green tape by immersion in the water bath. The as-formed green tape comprised a relatively dense layer at the top derived from the graphite slurry, a finger-like porous layer in the middle and a sponge-like layer at the bottom both derived from the YSZ-LSCrF slurry. After firing at 1420 °C in the air, the graphite layer was eliminated, and the other two layers were converted into ceramics. The resulting membrane consisted of a dense layer of thickness ~150 μm providing the oxygen separation function and a finger-like porous layer of thickness ~850 μm providing mechanical strength. Due to the use of graphite sacrificing layer, the finger-like pores in the support was fully opened up to the outer surface, allowing fast mass transport. The oxygen permeability of the membrane was measured by exposing its dense separation layer to the ambient air and the porous support to flowing CO at elevated temperatures. An oxygen permeation flux as large as 6.82×10−7 mol cm−2 s−1, equivalent to 1.0 ml (STP) cm−2 min−1, was obtained at 850 °C. And no significant changes to the microstructure and phase composition of the membrane were observed after the oxygen permeation test. The reasonably high oxygen permeability together with the satisfactory stability makes the supported planar YSZ-LSCrF composite suitable for practical applications.