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@PHDTHESIS{Ellett:5437,
      author       = {Ellett, Anna Judith},
      title        = {{O}xygen {P}ermeation and {T}hermochemical {S}tability of
                      {MIEC} {M}embrane materials for the {O}xyfuel {P}rocess},
      volume       = {43},
      issn         = {1866-1793},
      school       = {RWTH Aachen},
      type         = {Dr. (Univ.)},
      address      = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {PreJuSER-5437},
      isbn         = {978-3-89336-581-4},
      series       = {Schriften des Forschungszentrums Jülich : Energie $\&$
                      Umwelt / Energy $\&$ Environment},
      year         = {2009},
      note         = {Record converted from VDB: 12.11.2012; RWTH Aachen, Diss.,
                      2009},
      abstract     = {The reduction of CO$^{2}$ emissions, generally held to be
                      one of the most significant contributors to global warming,
                      is a major technological issue. CO$^{2}$ Capture and Storage
                      (CCS) techniques applied to large stationary sources such as
                      coal-fired power plants could efficiently contribute to the
                      global carbon mitigation effort. The oxyfuel process, which
                      consists in the burning of coal in an oxygen-rich atmosphere
                      to produce a flue gas highly concentrated in CO$^{2}$, is a
                      technology considered for zero CO$^{2}$ emission coal-fired
                      power plants. The production of this O$_{2}$-rich combustion
                      gas from air can be carried out using high purity oxygen
                      separation membranes. Some of the most promising materials
                      for this application are mixed ionic-electronic conducting
                      (MIEC) materials with perovskite and K$_{2}$NiF$_{4}$
                      perovskite-related structures. The present work examines the
                      selection of
                      La$_{0.58}$Sr$_{0.4}$Co$_{0.2}$Fe$_{0.8}$O$_{3-\delta}$
                      (LSCF58), La$_{2}$NiO$_{4+\delta}$,
                      Pr$_{0.58}$Sr$_{0.4}$Co$_{0.2}$Fe$_{0.8}$O$_{3-\delta}$
                      (PSCF58) and
                      Ba$_{0.5}$Sr$_{0.5}$Co$_{0.8}$Fe$_{0.2}$O$_{3-\delta}$
                      (BSCF50) as membrane materials for the separation of O$_{2}$
                      and N$_{2}$ in the framework of the oxyfuel process with
                      flue gas recycling. Annealing experiments were carried out
                      on pellets exposed to CO$_{2}$, water vapour, O$_{2}$ and
                      Cr$_{2}$O$_{3}$ in order to determine the thermo-chemical
                      resistance to the atmospheres and the high temperature
                      conditions present during membrane operation in a coal-fired
                      power plant. The degradation of their microstructure was
                      investigated using Scanning Electron Microscopy (SEM) in
                      combination with electron dispersive spectroscopy (EDS) as
                      well as X-Ray Diffraction (XRD). Also, the oxygen permeation
                      fluxes of selected membranes were investigated as a function
                      of temperature. The membrane materials selected were
                      characterised using thermo-analytical techniques such as
                      precision thermogravimetric analysis (TGA) and thermo
                      mechanical analysis (TMA). An increase in thermal expansion
                      and oxygen permeation associated with an increase in oxygen
                      vacancy concentration, observed also in the TGA curves,
                      occurs during heating. BSCF50 exhibits permeation fluxes
                      well above those of LSCF58, PSCF58 and
                      La$_{2}$NiO$_{4+\delta}$, which are quite similar to each
                      other. After exposure, no degradation of LSCF58,
                      La$_{2}$NiO$_{4+\delta}$ and PSCF58 occurs. On the other
                      hand BSCF50 is found to be unstable in CO$_{2}$- and/or
                      H$_{2}$O-containing atmospheres and also to exhibit a
                      chemical demixing. The thermo-chemical stability and the
                      oxygen permeation performances are both crucial factors in
                      the selection of high purity oxygen separation membranes for
                      the oxyfuel process, thus making LSCF58, PSCF58 and
                      La$_{2}$NiO$_{4+\delta}$ in this study the most suitable
                      materials for this application. Serious issues arise,
                      however, from the fact that secondary non-ion conducting
                      oxide phases are formed in the bulk of every material,
                      forming obstacles for oxygen ion migration, and also that a
                      reaction with chromia occurs, preventing their use without
                      protection.},
      cin          = {IEF-2},
      cid          = {I:(DE-Juel1)VDB810},
      pnm          = {Rationelle Energieumwandlung},
      pid          = {G:(DE-Juel1)FUEK402},
      typ          = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
      url          = {https://juser.fz-juelich.de/record/5437},
}