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@ARTICLE{vanGestel:10140,
      author       = {van Gestel, T. and Sebold, D. and Hauler, F. and
                      Meulenberg, W. A. and Buchkremer, H. P.},
      title        = {{P}otentialities of microporous membranes for
                      {H}(2)/{CO}(2) separation in future fossil fuel power
                      plants: {E}valuation of {S}i{O}(2), {Z}r{O}(2),
                      {Y}(2){O}(3)-{Z}r{O}(2) and {T}i{O}(2)-{Z}r{O}(2) sol-gel
                      membranes},
      journal      = {Journal of membrane science},
      volume       = {359},
      issn         = {0376-7388},
      address      = {New York, NY [u.a.]},
      publisher    = {Elsevier},
      reportid     = {PreJuSER-10140},
      pages        = {64 - 79},
      year         = {2010},
      note         = {Financial support from the Helmholtz Association of German
                      Research Centres (Initiative and Networking Fund) through
                      the MEM-BRAIN Helmholtz Alliance is gratefully acknowledged.
                      Stephan Roitsch (Ernst Ruska-Centre, FZ-Julich) and
                      Christoph Somsen (Institut fur Werkstoffe,
                      Werkstoffwissenschaft, Ruhr-Universitat Bochum) are thanked
                      for providing the TEM results.},
      abstract     = {In this work, an experimental study is made on the
                      preparation, the morphological characterization and the gas
                      permeation of graded ceramic multilayer membranes with
                      silica and non-silica toplayers. The membranes were prepared
                      on porous alpha-Al2O3 or 8Y(2)O(3)-ZrO2 supports by
                      dip-coating methods, where sols with different particle
                      sizes were used as coating liquids. In a first step,
                      mesoporous alumina or graded zirconia sublayers with a pore
                      size of 7-3 nm were deposited, starting from sols with a
                      particle size in the range 60-30 nm. The active toplayer of
                      the membrane is a SiO2, ZrO2, 8Y(2)O(3)-ZrO2 or
                      50TiO(2)-50ZrO(2) thin film with a thickness in the range
                      50-200 nrn. Nano-particles of these materials were prepared
                      by a precipitate-free hydrolysis-condensation synthesis
                      method, starting from metal-organic precursors. An important
                      consideration is that the properties of the novel zirconia
                      based sublayers and toplayers, which are developed for
                      typical higher steam pressure areas, are comparable to the
                      commonly used -y-Al2O3 and silica layers. Gas permeation
                      tests showed a decrease of permeation in the order He > H-2
                      > CO2 > N-2 and suggested that the membranes with silica
                      toplayers are microporous. Moreover, optimising all
                      conditions in the membrane manufacturing procedure in our
                      lab, such as the properties of the support and the sols and
                      the use of cleanroom coating, resulted in a $100\%$ H-2/CO2
                      selectivity for a few samples. The formation of crack-free
                      non-silica toplayers was initially experienced as very
                      difficult, but after optimization of the sol synthesis and
                      coating methodology and by restricting the layer thickness
                      below 100 nm, comparable ultra-thin toplayers are obtained.
                      Further, extensive gas permeation testing confirmed that
                      each of these toplayers posses a very low number of defects
                      and a comparable low or zero CO2 permeation is obtained. On
                      the other hand, extremely low He and H-2 permeation -
                      especially for the samples fired at 400 and 500 degrees C -
                      suggested the formation of thin dense toplayers. This
                      behaviour is found for the crystalline ZrO2 and
                      8Y(2)O(3)-ZrO2 layers as well as the amorphous
                      50TiO(2)-50ZrO(2) layers and indicates the presence of a
                      totally different structure in the non-silica material. The
                      amorphous silica toplayer is probably formed of 5-, 6-, 7-,
                      8- and also larger Si-O bonded rings which enable H-2
                      permeation, while our results suggest that the non-silica
                      toplayers are characterized by a more dense atomic packing
                      hindering H-2 permeation. For future H-2/CO2 separation in a
                      power plant, membranes will however need to out-perform the
                      discussed materials. Amorphous silica toplayers hold the
                      potential to combine an excellent selectivity with a
                      relatively high gas permeation, but lack the required
                      stability to operate over a wide range of conditions, and
                      the discussed non-silica toplayers which are considered as
                      the best until now in the literature - based on their zero
                      CO2 permeation - are to dense to allow the passage of H-2.
                      (C) 2010 Elsevier B.V. All rights reserved.},
      keywords     = {J (WoSType)},
      cin          = {IEF-1},
      ddc          = {570},
      cid          = {I:(DE-Juel1)VDB809},
      pnm          = {Rationelle Energieumwandlung},
      pid          = {G:(DE-Juel1)FUEK402},
      shelfmark    = {Engineering, Chemical / Polymer Science},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000279953300008},
      doi          = {10.1016/j.memsci.2010.04.002},
      url          = {https://juser.fz-juelich.de/record/10140},
}