期刊
GREEN CHEMISTRY
卷 16, 期 4, 页码 2281-2291出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/c3gc42534g
关键词
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资金
- National Natural Science Foundation of China [21373119]
- Ministry of Education of China [NCET-11-0251, IRT13022]
- 111 Project [B12015]
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin)
- Deutsche Forschungsgemeinschaft
Ti-Beta zeolite has been successfully prepared via a reproducible and scalable two-step post-synthesis strategy, which consists of creating vacant T sites with associated silanol groups by dealumination of H-Beta and subsequent dry impregnation of the resulting Si-Beta with titanocene dichloride. The mechanism of Ti incorporation into the framework of Beta is investigated by diffuse reflectance infrared Fourier transform (DRIFT) and multinuclear solid-state nuclear magnetic resonance (SSNMR) spectroscopy. Characterization results obtained from diffuse reflectance ultraviolet-visible (UV-vis) and X-ray photoelectron spectroscopy (XPS) reveal that the majority of incorporated Ti species exist in the form of isolated tetrahedrally coordinated Ti(IV) in the zeolite framework while a minority exists in the form of isolated octahedrally coordinated Ti(VI) at framework or extra-framework positions. The obtained Ti-Beta zeolites are highly active and selective catalysts for the epoxidation of unsaturated ketones, e. g. 2-cyclohexen-1-one, with hydrogen peroxide as an oxidant. A quasilinear correlation between the epoxidation rate and the number of framework Ti(IV) species could be drawn evidencing that these Ti(IV) species are responsible for the epoxidation activity of the Ti-Beta zeolites under study. The impact of preparation parameters and reaction conditions on the catalytic performances of the Ti-Beta zeolites in the epoxidation of unsaturated organic compounds with hydrogen peroxide is discussed in detail.
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