New approaches to anchoring or inserting highly dispersed tungsten oxo(peroxo) species in mesoporous silicates

The preparation of supported and/or grafted complexes involving [n-(C4H9)(4)N](2) [(HPO4){W2O2 (mu -O-2)(2)(O-2)(2)}], denoted "PW2", and silica beads or mesoporous silica has been described and the materials characterised by P-31 NMR spectroscopy and catalysis tests. The major part of ''PW2" is mobile on the silica surface, but different immobilised species are formed with siliceous MCM-41. Tungsten mesoporous molecular sieves can be synthesised in acidic media by the hydrolysis of tetraethyl orthosilicate in aqueous acid. in the presence of neutral or anionic low-condensed W(VI) oxoperoxo species and a cationic surfactant. The materials have a nearly homogeneous distribution of the dopants and promising catalytic activities. (C) 2001 Elsevier Science B.V. All rights reserved.