Niobium metallocenes deposited onto mesoporous silica via dry impregnation as catalysts for selective epoxidation of alkenes

作者：Gallo Alessandro; Tiozzo Cristina; Psaro Rinaldo; Carniato Fabio; Guidotti Matteo^*

来源：Journal of Catalysis, 2013, 298: 77-83.

DOI：10.1016/j.jcat.2012.11.015

• Niobium-silica
• Titanium-silica
• Dry impregnation
• Epoxidation
• Limonene
• Hydrogen peroxide
• Heterogeneous catalysis
• Mesoporous silica
• Exocyclic limonene epoxide

A series of niobium catalysts for the selective epoxidation was synthesised by post-synthesis modification of a commercial silica, starting from niobocene dichloride through solventless organometallic precursor dry impregnation (OM-DI) or conventional liquid-phase grafting technique. OM-DI showed to be cheaper, more versatile, less time-consuming and avoided the use of environmentally unfriendly chlorinated solvents. Nb-SiO2 catalysts displayed an excellent performance in the epoxidation of limonene, using aqueous hydrogen peroxide as oxidant. Niobium-silica catalysts were obtained via OM-DI for the first time in this occasion. They showed conversions up to 78% and chemoselectivity to epoxide of 98%. An unexpected regioselectivity to exocyclic epoxide was also observed.

• 出版日期2013-2