Journal of Catalysis, Vol.226, No.1, 25-31, 2004
Influence of the coordination on the catalytic properties of supported W catalysts
Zirconia supported W catalysts were prepared using anionic exchange from a peroxo-tungstate solution and zirconium hydroxides of high surface areas. These solids contain about 20 wt% W and retain a surface area of about 120 m(2)/g after calcinations in air at 873 K, temperature at which their acidity is maximum. Raman spectroscopy shows the presence of tetrahedral W at low temperature, sintered to polytungstates by calcination at 873 K and WO3 at 973 K. These catalysts are active for the oxidation of dibenzothiophene by hydrogen peroxide. The solids containing tetrahedral W cations show higher activity than clusters of WO3. The reaction can be performed with good oxygen selectivity with H2O2 in 2-butanol as solvent, or in decane with tert-butylhydroperoxide as oxidizing agent. The catalysts can be recycled without loss of performances. (C) 2004 Elsevier Inc. All rights reserved.
Keywords:peroxotungsten;anionic exchange;zirconia;coordination of W;acidity;oxidation of dibenzothiophene;sulfone