Characterization and catalytic behavior of highly active tungsten-doped SBA-15 catalyst in the synthesis of glutaraldehyde using an anhydrous approach

Tungsten-doped ordered SBA-15 prepared by the in situ synthesis method was systematically characterized by UV-Raman, UV-vis DRS, Fr-IR, XPS, and H-2-TPR. It was found that the dispersion and nature of the tungsten species depend strongly on the tungsten oxide content. The tungsten species are located mainly in isolated tetrahedral or low-condensed oligomeric environments, and there are strong interaction between tungsten species and the silica-based matrix at tungsten oxide content <20 wt%. Higher tungsten oxide content leads to the formation of bulk tungsten species. It was also found that the ordered hexagonal mesoporous structure of SBA- 15 is retained, and strong Bronsted and Lewis' acid sites are formed on tungsten incorporation. The superior catalytic performance in the selective oxidation of cyclopentene has been attributed to its proper content of tungsten species, high dispersion, and strong surface acidity. (C) 2007 Elsevier Inc. All rights reserved.