A novel heterogeneous La_0.8Sr_0.2CoO_3−δ/(La_0.5Sr_0.5)₂CoO_4+δ dual‐phase membrane for oxygen separation

Abstract

Abstract Dual‐phase membrane is an attractive concept that combines the advantages of two different phases into single membrane matrix. The recently reported significant enhancement of oxygen surface kinetics on the La 0.8 Sr 0.2 CoO 3−δ (LSC)/(La 0.5 Sr 0.5 ) 2 CoO 4+δ (LSC 214 ) hetero‐interface due to the formation of fast oxygen transport paths along hetero‐interface is adopted into dual‐phase membrane to achieve enhanced oxygen permeability. The 1300°C sintered LSC/LSC 214 (4:1 weight ratio) hollow fiber displayed a maximum oxygen flux of 3.35 ml·min −1 ·cm −2 at 900°C and 200 ml min −1 helium sweep gas flow rate, which represents up to 80% enhancement relative to that of the 1300°C sintered LSC hollow fiber at the same experimental condition. Such enhancement is enabled by the enlargement of triple phase boundaries to larger areas across the membrane surface for dual‐phase case as confirmed by the significantly lower area specific resistance for LSC/LSC 214 |Ce 0.8 Sm 0.2 O 1.9 (SDC)|LSC/LSC 214 relative to LSC|SDC|LSC symmetrical cell between 600°C and 800°C. This nominal dual‐phase LSC/LSC 214 hollow fiber also showed very stable fluxes of 3.3 and 2.3 ml·min −1 ·cm −2 during 300‐hr permeation test at 900°C and 850°C, respectively.