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Catalytic and Spectroscopic Studies of Vanadium Oxide Supported on Group IVb and Vb Metal Oxides for Oxidation of Toluene

In English

Författare

  • Jane Huuhtanen
  • Mehri Sanati
  • Arne Andersson
  • S Lars T Andersson

Summary, in English

Vanadia was deposited on TiO2, ZrO2, HfO2, Nb2O5, and Ta2O5 supports using impregnation with either an oxalic acid solution of NH4VO3 or a solution of vanadyl acetylacetonate in ethanol. Prepared samples, with a nominal vanadia content in the range 0.5–2 monolayers, were characterized with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman and infrared spectroscopy, and were used in toluene oxidation. XRD did not reveal formation of any vanadia phase. XPS spectra showed deposited vanadium to be present mainly as V5+ on all the supports. A plot of the V:( support metal) ratio determined by XPS showed agglomeration of vanadia on TiO2, ZrO2, HfO2, and Nb2O5 to occur at loadings above 0.5 monolayer, while for Ta2O5 the dispersion seemed independent of the loading. Preparations from vanadyl acetylacetonate gave superior dispersion. Raman spectra showed bands from crystalline V2O5 on all the supports except Nb2O5. Raman and infrared bands from dispersed vanadia were present in the spectra of TiO2 (three species), ZrO2 and HfO2 (both one species) supported catalysts. No bands from vanadium-oxygen vibrational modes were seen in the spectra of Nb2O5 supported samples, but a V-OH band was observed, suggesting an amorphous structure. Some evidence was obtained for formation of amorphous VTa9O25 on Ta205. The activity for toluene oxidation increased with vanadia loading for each support, and the activity varied with respect to support at all loadings in the order TiO2 > ZrO2 > Nb2O5 > HfO2 > Ta2O5. The selectivity for formation of benzaldehyde was the highest using TiO2 and Nb2O5 supports, while for benzoic acid TiO2 was the best support.

Publiceringsår

1993

Språk

Engelska

Sidor

197-221

Publikation/Tidskrift/Serie

Applied Catalysis A: General

Volym

97

Issue

2

Dokumenttyp

Artikel i tidskrift

Förlag

Elsevier

Ämne

  • Chemical Engineering
  • Production Engineering, Human Work Science and Ergonomics

Nyckelord

  • XRD)
  • XPS
  • Raman
  • catalyst characterization (IR
  • spectroscopy
  • supports (TiO2
  • ZrO2
  • HfO2
  • NbO2
  • Ta2O5)
  • toluene oxidation
  • vanadia

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 0926-860X