Highly efficient tungsten trioxide containing mesocellular silica foam catalyst in the O-heterocyclization of cycloocta-1,5-diene with aqueous H2O2

Abstract

Abstract WO 3 -containing mesocellular silica foam (MCF) catalysts have been synthesized via an in situ method by using tetraethyl orthosilicate (TEOS) and sodium tungstate as the precursors and via a traditional impregnation method. All catalysts are highly efficient in the O -heterocyclization of cycloocta-1,5-diene (COD) (see Scheme 1 in Section 3.2) to 2,6-dihydroxy-9-oxabicyclo[3.3.1]nonane ( 1 ) and 2-hydroxy-9-oxabicyclo[3.3.1]nonane-6-one ( 2 ) with a COD conversion up to 100% and ( 1 + 2 ) selectivity up to 98%. The WO x species are well dispersed in the W-containing catalysts via the in situ method with the WO 3 loading up to 20 wt.%, as proved by XRD, TEM, Raman, and UV–vis DRS. TPR and XRD results show that the WO 3 –MCF catalysts derived from the in situ method show much stronger interactions between active tungsten oxide species and the MCF support than the WO 3 /MCF obtained by the traditional impregnation method. The in situ method-derived catalyst also shows far better stability than the impregnation one according to the results from the recycling experiment.