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Ammoxidation of Toluene over TiO2(B)-Supported Vanadium Oxide Catalysts

Sanati, Mehri LU and Andersson, Arne LU (1990) In Journal of Molecular Catalysis 59(2). p.233-255
Abstract
TiO2(B) was used as a support for vanadium oxide with loadings in the range 1/4 to 10 theoretical layers. The vanadium could be separated into two parts, which were soluble and insoluble in NH3(aq), respectively. Insoluble vanadium, in an amount corresponding to a complete monolayer at high loadings, was present as V4+ in freshly prepared catalysts.

Diffuse reflectance FTIR spectroscopy was used to characterize the catalysts. The bands assigned to stretching vibrations of hydroxyl groups on TiO2(B) were found to decrease in intensity with increasing vanadium loading. Spectra in the V=O and V-O-V vibration region revealed a rather complex growth pattern.

For a catalyst covered with a complete monolayer, vanadium strongly... (More)
TiO2(B) was used as a support for vanadium oxide with loadings in the range 1/4 to 10 theoretical layers. The vanadium could be separated into two parts, which were soluble and insoluble in NH3(aq), respectively. Insoluble vanadium, in an amount corresponding to a complete monolayer at high loadings, was present as V4+ in freshly prepared catalysts.

Diffuse reflectance FTIR spectroscopy was used to characterize the catalysts. The bands assigned to stretching vibrations of hydroxyl groups on TiO2(B) were found to decrease in intensity with increasing vanadium loading. Spectra in the V=O and V-O-V vibration region revealed a rather complex growth pattern.

For a catalyst covered with a complete monolayer, vanadium strongly interacting with the support is present as interconnected tetrahedral V4+ units. When the loading is increased, several additional layers of V5+ in tetrahedral coordination can exist on top of the monolayer. At higher loadings, there is an abrupt change in structure, resulting in the formation of an amorphous phase built up from distorted VO6 octahedra. Also, crystalline V2O5 is formed.

The catalysts were used in the ammoxidation of toluene to benzonitrile. Multilayer catalysts showed better catalytic performance in comparison with crystalline V2O5 and catalysts exposing monolayer species. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Molecular Catalysis
volume
59
issue
2
pages
233 - 255
publisher
Elsevier
external identifiers
  • WOS:A1990DA31900007
  • Scopus:0025405926
DOI
10.1016/0304-5102(90)85055-M
language
English
LU publication?
yes
id
f525cd28-cd1f-402e-a181-f181da4b8d32 (old id 2018021)
date added to LUP
2011-07-05 13:11:22
date last changed
2016-10-30 04:40:38
@misc{f525cd28-cd1f-402e-a181-f181da4b8d32,
  abstract     = {TiO2(B) was used as a support for vanadium oxide with loadings in the range 1/4 to 10 theoretical layers. The vanadium could be separated into two parts, which were soluble and insoluble in NH3(aq), respectively. Insoluble vanadium, in an amount corresponding to a complete monolayer at high loadings, was present as V4+ in freshly prepared catalysts.<br/><br>
Diffuse reflectance FTIR spectroscopy was used to characterize the catalysts. The bands assigned to stretching vibrations of hydroxyl groups on TiO2(B) were found to decrease in intensity with increasing vanadium loading. Spectra in the V=O and V-O-V vibration region revealed a rather complex growth pattern.<br/><br>
For a catalyst covered with a complete monolayer, vanadium strongly interacting with the support is present as interconnected tetrahedral V4+ units. When the loading is increased, several additional layers of V5+ in tetrahedral coordination can exist on top of the monolayer. At higher loadings, there is an abrupt change in structure, resulting in the formation of an amorphous phase built up from distorted VO6 octahedra. Also, crystalline V2O5 is formed.<br/><br>
The catalysts were used in the ammoxidation of toluene to benzonitrile. Multilayer catalysts showed better catalytic performance in comparison with crystalline V2O5 and catalysts exposing monolayer species.},
  author       = {Sanati, Mehri and Andersson, Arne},
  language     = {eng},
  number       = {2},
  pages        = {233--255},
  publisher    = {ARRAY(0xa11f0e8)},
  series       = {Journal of Molecular Catalysis},
  title        = {Ammoxidation of Toluene over TiO2(B)-Supported Vanadium Oxide Catalysts},
  url          = {http://dx.doi.org/10.1016/0304-5102(90)85055-M},
  volume       = {59},
  year         = {1990},
}