Spectroscopic, calorimetric, and catalytic evidences of hydrophobicity on Ti-MCM-41 silylated materials for olefin epoxidations
tHydrophobic Ti-MCM-41 samples prepared by post-synthesis silylation treatment demonstrate to behighly active and selective catalysts in olefins epoxidation by using organic hydroperoxides as oxidizingagents in liquid phase reaction systems. Epoxide yields show important enhancements with increaseds...
| Autores: | , , , , , , |
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| Formato: | artículo |
| Fecha de publicación: | 2015 |
| País: | España |
| Recursos: | Universitat Politècnica de València (UPV) |
| Repositorio: | RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia |
| Idioma: | inglés |
| OAI Identifier: | oai:riunet.upv.es:10251/71399 |
| Acesso em linha: | https://riunet.upv.es/handle/10251/71399 |
| Access Level: | acceso abierto |
| Palavra-chave: | Hydrophobic materials Ti-MCM-41 catalyst Silylation treatment Immersion calorimetry Catalytic epoxidation QUIMICA ORGANICA |
| Resumo: | tHydrophobic Ti-MCM-41 samples prepared by post-synthesis silylation treatment demonstrate to behighly active and selective catalysts in olefins epoxidation by using organic hydroperoxides as oxidizingagents in liquid phase reaction systems. Epoxide yields show important enhancements with increasedsilylation degrees of the Ti-mesoporous samples. Catalytic studies are combined and correlated withspectroscopic techniques (e.g. XRD, XANES, UV-Visible,29Si MAS-NMR) and calorimetric measurementsto better understand the changes in the surface chemistry of Ti-MCM-41 samples due to the post-synthesis silylation treatment and to ascertain the role of these trimethylsilyl groups incorporated inolefin epoxidation. In such manner, the effect of the organic moieties on solids, and both water and gly-col molecules contents on the catalytic activity and selectivity are analyzed in detail. Results show thatthe hydrophobicity level of the samples is responsible for the decrease in water adsorption and, conse-quently, the negligible formation of the non-desired glycol during the catalytic process. Thus, catalystdeactivation by glycol poisoning of Ti active sites is greatly diminished, this increasing catalyst stabilityand leading to practically quantitative production of the corresponding epoxide. The extended use ofthese hydrophobic Ti-MCM-41 catalysts together with organic hydroperoxides for the highly efficientand selective epoxidation of natural terpenes is also exemplified. |
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