High performance yttrium-doped BSCF hollow fibre membranes

Publication: Research - peer-reviewJournal article – Annual report year: 2012

  • Author: Haworth, P., Australia

    Films and Inorganic Membrane Laboratory, School of Chemical Engineering, University of Queensland, Australia

  • Author: Smart, S., Australia

    Films and Inorganic Membrane Laboratory, School of Chemical Engineering, University of Queensland, Australia

  • Author: Glasscock, Julie

    Mixed Conductors, Department of Energy Conversion and Storage, Technical University of Denmark

  • Author: Diniz da Costa, J.C., Australia

    Films and Inorganic Membrane Laboratory, School of Chemical Engineering, University of Queensland, Australia

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Oxygen production from BSCF (Ba0.5Sr0.5Co0.8Fe0.2O3−δ) and yttrium-doped BSCF (Ba0.5Sr0.5Co0.8Fe0.175Y0.025O3−δ) hollow fibres was investigated, and the role of yttrium in the crystal structure was further explored using high-temperature X-ray diffraction. Yttrium substitution acted to increase the oxygen flux significantly, from 4.9 to 7.0mlcm−2min−1 at 900°C for the BSCF and the BSCFY membranes, respectively. Permeation was particularly enhanced at lower temperatures, between 66% and 92% over the range 650–800°C. The lattice expansion determined from high temperature X-ray diffraction measurements in air was similar for both compositions, suggesting that the higher oxygen fluxes obtained for BSCFY hollow fibres could be attributed to the higher non-stoichiometry due to yttrium addition to the BSCF crystal structure. In addition, the improvement of oxygen fluxes for small wall thickness (∼0.3mm) hollow fibres operating below the critical length (i.e. limited surface kinetics regime) indicates that yttrium has enhanced the surface exchange rates. XRD patterns showed split peaks around 2θ 31° and 56° above 200°C, likely corresponding to a coexisting hexagonal perovskite phase. This peak-splitting was more pronounced for BSCFY, suggesting that the kinetics of the hexagonal phase formation may be faster for the yttrium-doped perovskite. The lattice volume of BSCFY expanded more than BSCF when exposed to nitrogen at 900°C, confirming a higher release of oxygen and enhanced oxygen non-stoichiometry.
Original languageEnglish
JournalSeparation and Purification Technology
Publication date2012
Volume94
Pages16-22
ISSN1383-5866
DOIs
StatePublished
CitationsWeb of Science® Times Cited: 6

Keywords

  • BSCF, Hollow fibres, BSCFY, Yttrium, Oxygen separation, Perovskite
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