8. Phase Development in the Catalytic System V2O5/Tio2 Under Oxidizing Conditions

  1. William M. Mullins,
  2. Andrew Wereszczak and
  3. Egar Lara-Curzio
  1. D. Habel1,
  2. E. Feike1,
  3. C. Schroder1,
  4. H. Schubert1,
  5. A. Hösch2,
  6. J. B. Stelzer3,
  7. J. Caro3,
  8. C. Hess4 and
  9. A. Knop-Gericke4

Published Online: 26 MAR 2008

DOI: 10.1002/9780470291375.ch8

Synthesis and Processing of Nanostructured Materials: Ceramic Engineering and Science Proceedings, Volume 27, Issue 8

Synthesis and Processing of Nanostructured Materials: Ceramic Engineering and Science Proceedings, Volume 27, Issue 8

How to Cite

Habel, D., Feike, E., Schroder, C., Schubert, H., Hösch, A., Stelzer, J. B., Caro, J., Hess, C. and Knop-Gericke, A. (2007) Phase Development in the Catalytic System V2O5/Tio2 Under Oxidizing Conditions, in Synthesis and Processing of Nanostructured Materials: Ceramic Engineering and Science Proceedings, Volume 27, Issue 8 (eds W. M. Mullins, A. Wereszczak and E. Lara-Curzio), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470291375.ch8

Author Information

  1. 1

    Institute for Material Science and -technologies, TU Berlin Englische Straße 20 D-105 87 Berlin, Germany

  2. 2

    Institute for Applied Geosciences, TU Berlin Strafledes 17. Juni 135 D- 10669 Berlin, Germany

  3. 3

    Institute for Physical Chemistry & Electrochemistry, University of Hanover Callinstraße 3 - 3a D- 30167 Hanover, Germany

  4. 4

    Fritz-Haber-Institute of the Max Planck Society, Department of Inorganic Chemistry, Farddayweg 4-6 D-14195 Berlin, Germany

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 2007

ISBN Information

Print ISBN: 9780470080511

Online ISBN: 9780470291375

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Keywords:

  • temperatures;
  • oxidation;
  • catalyst;
  • phenomena;
  • transition

Summary

The target of this work was to investigate phase development in the catalyst system consisting of TiO2 (Anatase) and V2O5 (Shcherbinaite). Thus a set of V2O5/TiO2 specimens was prepared by ball milling and exposed to subsequent annealing in air in the temperature range from 400 to 700 °C. The XRD-results showed the presence of Anatase and Shcherbinaite as the only phases up to 525 °C. For temperatures above 525 °C Rutile as a new TiO2-phase occured. Peak intensities and positions were shifted. No loss of oxygen or vanadium was detected. The reaction involves the formation of a Rutile solid solution containing VOx species. XPS studies showed an oxidation state of 4.75 for V in the Rutile solid solution as compared to 4.65 in the Shcherbinaite. The Rutile solid solution was first found at 525 °C < T < 550 °C for compositions of 3 mole % < V2O5 < 5 mole %. The phase field for Rutile solid solutions extends to 10 mole% < V2O5 < 12.5 mole % at 675 °C. For very high V2O5 concentrations an eutectic reaction was found at 631 °C (95 mole% V2O5). A Shcherbinaite structure remained with shifted peak intensities and positions due to the alloying of Ti-ions.

SEM inspections showed that the Rutile formation and the eutectic reaction both cause a substantial grain growth and a loss of surface area. The catalytic activity is entirely lost. The knowledge of phase relations helps to find the appropriate processing conditions and to understand the aging phenomena of catalysts.