Evaluation of mixed-conducting lanthanum-strontium-cobaltite ceramic membrane for oxygen separation

Authors

  • Lei Ge,

    1. State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology, Nanjing 210009, P.R. China
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  • Zongping Shao,

    Corresponding author
    1. State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology, Nanjing 210009, P.R. China
    • State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology, Nanjing 210009, P.R. China
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  • Kun Zhang,

    1. State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology, Nanjing 210009, P.R. China
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  • Ran Ran,

    1. State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology, Nanjing 210009, P.R. China
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  • J.C. Diniz da Costa,

    1. FimLab-Films and Inorganic Membrane Laboratory, Div. of Chemical Engineering, University of Queensland, Queensland, Australia
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  • Shaomin Liu

    Corresponding author
    1. FimLab-Films and Inorganic Membrane Laboratory, Div. of Chemical Engineering, University of Queensland, Queensland, Australia
    • FimLab-Films and Inorganic Membrane Laboratory, Division of Chemical Engineering, University of Queensland, Queensland, Australia
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Abstract

In this study, La0.4Sr0.6CoO3-δ (LSC) oxide was synthesized via an EDTA-citrate complexing process and its application as a mixed-conducting ceramic membrane for oxygen separation was systematically investigated. The phase structure of the powder and microstructure of the membrane were characterized by XRD and SEM, respectively. The optimum condition for membrane sintering was developed based on SEM and four-probe DC electrical conductivity characterizations. The oxygen permeation fluxes at various temperatures and oxygen partial pressure gradients were measured by gas chromatography method. Fundamental equations of oxygen permeation and transport resistance through mixed conducting membrane were developed. The oxygen bulk diffusion coefficient (Dv) and surface exchange coefficient (Kex) for LSC membrane were derived by model regression. The importance of surface exchange kinetics at each side of the membrane on oxygen permeation flux under different oxygen partial pressure gradients and temperatures were quantitatively distinguished from the oxygen bulk diffusion. The maximum oxygen flux achieved based on 1.6-mm-thick La0.4Sr0.6CoO3-δ membrane was ∼4.0 × 10−7 mol cm−2 s−1at 950°C. However, calculation results show theoretical oxygen fluxes as high as 2.98 × 10−5 mol cm−2 s−1 through a 5-μm-thick LSC membrane with ideal surface modification when operating at 950°C for air separation. © 2009 American Institute of Chemical Engineers AIChE J, 2009

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