Highly effective green oxidation of aldehydes catalysed by recyclable tungsten complex immobilized in organosilanes-modified SBA-15

Abstract

Abstract A simple and eco-friendly approach for green oxidation of aldehydes has been proposed, which employed highly efficient heterogeneous catalysts tungsten-doped modified silica SBA-15 (W-SBA-15) as catalysts and H2O2 as a green oxidant. W-SBA-15 were synthesized by immobilizing tungsten species on modified SBA-15 and first used in the aldehydes oxidation reaction. W-SBA-15-APTS (0.002 g, APTS, a kind of modifier) displayed an equivalent catalytic activity comparable to that of homogenous catalyst (H2WO4, 0.5 g) and maintained excellent catalytic activity over 20 cycles. The pore diameter, ca. 7.94–9.14 nm, of W-SBA-15 provides a suitable mesoscopic environment for the substrate, and the product can diffuse freely during the oxidation of glutaraldehyde (GA). Effective but different catalytic performance of W-SBA-15 for the oxidation of other aldehydes suggests the universal applicability of W-SBA-15. The possible mechanism of the oxidation state of tungsten species in W-SBA-15-APTS was proposed; tungsten species are not only attached to APTS but also incorporated into the framework of SBA-15.