[VO(acac)(2)] hybrid catalyst: from complex immobilization onto silica nanoparticles to catalytic application in the epoxidation of geraniol

作者：Pereira Clara^*; Silva Jose F; Pereira Andre M; Araujo Joao P; Blanco Ginesa; Pintado Jose M; Freire Cristina

来源：Catalysis Science & Technology, 2011, 1(5): 784-793.

DOI：10.1039/c1cy00090j

This work reports the preparation of a novel hybrid nanocatalyst through the immobilization of oxidovanadium(IV) acetylacetonate ([VO(acac)(2)]) onto silica nanoparticles functionalized with 3-aminopropyltriethoxysilane (APTES) and its catalytic application in the allylic epoxidation of geraniol. All the nanomaterials were characterized by chemical analysis, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The parent and amine-functionalized silica nanoparticles were also analyzed by Si-29 and C-13 solid-state nuclear magnetic resonance and the supported [VO(acac)(2)] nanomaterial was characterized by magnetic susceptibility measurement. The APTES organosilane was grafted onto the silica nanoparticles with an efficiency of 90%, through mono-and bidentate covalent grafting. The [VO(acac)(2)] complex was covalently anchored on the surface of the APTES-functionalized silica nanoparticles with 25% of efficiency. Magnetic susceptibility measurements in combination with XPS indicated that the oxidation state of the metal center (VO2+) was preserved upon the immobilization reaction. The catalytic performance of the novel hybrid [VO(acac)(2)] nanocatalyst was evaluated in the epoxidation of geraniol, at room temperature, using tert-butyl hydroperoxide as an oxygen source. The nanocatalyst presented 100% of substrate conversion, 99% of selectivity towards the 2,3-epoxygeraniol product and was stable upon reuse in further four cycles.

• 出版日期2011