Immobilization of Vanadyl Acetylacetonate on Amino Functionalized Hollow Silica Nanospheres and Its Catalytic Performance for Selective Oxidation of Thioanisole

Vanadyl acetylacetonate [VO(acac)(2)] was immobilized on amino functionalized mesoporous silica hollow nanospheres, as well as on amino functionalized SBA-15 (2D hexagonal mesostnicture) and SBA-16 (cage-like mesostructure). All the heterogeneous catalysts exhibited high selectivity for sulfoxide (over 99.0%) in the selective oxidation of thioanisole under mild reaction conditions. The vanadium nanospheres exhibited higher turnover frequency than the counterparts of SBA-15 and SBA-16, which is attributed to the fact that the small nanoparticles would facilitate the diffusion of the products and reactants, as well as the exposure of catalytic active sites. The catalysts could be reused several times with little loss of their activity and selectivity.