Oxygen permeable ceramics based on mixed conductors attracting much attention for use in partial oxidation of hydrocarbons as a novel technique for syngas and pure hydrogen production. This paper describes the preparation and oxygen permeation properties including the methane reforming property of a novel member of oxygen permeable ceramics. The materials used are solid solutions of (La0.5Ba0.3 Sr0.2)(FexIn1-x)O3-δ. The single phase of perovskite-type (La0.5Ba0.3 Sr0.2)(FexIn1-x)O3-δ is obtained in the range of x=0.4 to 0.9. The highest oxygen flux densities of 2.2 and 11 μmol/cm2 s (membrane thickness, L=0.2 mm) are attained for (La0.5Ba0.3 Sr0.2)(FexIn1-x)O3-δ (x=0.6) at 1000°C under He/air and CH4/air gradients, respectively. The electrical conductivity of (La0.5 Ba0.3Sr0.2)(Fe0.6In0.4) O3-δ is dominated by p-type conduction having a slope of 1/4 under the high P(O2) region. The oxide-ion conductivity of the same sample is estimated to be 0.05 S/cm at 800°C. Even though the oxygen flux density slightly decreases with increasing time, high CO selectivity of 90% is kept for 100 h. The oxygen flux density of the solid solution is also discussed in the context of surface exchange kinetics.
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