Improved olefin epoxidation performance of a discrete bis(8-quinolinol)oxovanadium(IV) complex covalently attached on SBA-15 by a metal-template/metal-exchange method

A metal-template/metal-exchange method was used for the covalent attachment of a discrete bis(8-quinolinol) oxovanadium(IV) complex onto mesoporous silica SBA-15 to obtain a heterogeneous catalyst (VOT)-T-IV. For comparison, its homogeneous counterpart (VON)-N-IV and the randomly ligand-grafted heterogeneous analogue VO(IV)G were also prepared. UV-vis spectra of the VOIV catalysts show (VOT)-T-IV adopts a more solution-like bis(8-quinolinol) coordination environment than VO(IV)G. Correspondingly, olefin epoxidation with tert-butyl hydroperoxide shows (VOT)-T-IV has improved reactivity, epoxide selectivity and recyclability than (VON)-N-IV or VO(IV)G. The homogeneity of the discrete bis(8-quinolinol)oxovanadium(IV) complex immobilized on SBA-15 should be responsible for the superior performances of the templated catalyst. (C) 2010 Elsevier B.V. All rights reserved.