Non-Hydrolytic Synthesis of Titanosilicate Xerogels by Acetamide Elimination and their Use as Epoxidation Catalysts
| Autoři | |
|---|---|
| Rok publikování | 2012 |
| Druh | Článek v odborném periodiku |
| Časopis / Zdroj | Journal of Sol-Gel Science and Technology |
| Fakulta / Pracoviště MU | |
| Citace | |
| www | http://link.springer.com/article/10.1007%2Fs10971-012-2808-5 |
| Doi | http://dx.doi.org/10.1007/s10971-012-2808-5 |
| Obor | Anorganická chemie |
| Klíčová slova | Non-hydrolytic; amide elimination; titanosilicate; epoxidation; catalysis |
| Přiložené soubory | |
| Popis | Novel non-hydrolytic syntheses of titanosilicate xerogels by polycondensation of silicon acetate, Si(OAc)4, with titanium (IV) dimethylamide or diethylamide, Ti(NR2)4 (R = Me, Et), are presented. The reactions are based on acetamide elimination and yield gels with a high content of Si-O-Ti bonds in comparison with the ester elimination route. Although a ligand exchange was observed, it was interestingly not followed by homo-condensation and during the synthesis the phase separation to SiO2 and TiO2 was avoided. The degree of condensation reached up to 68 %. The xerogels prepared for a comparison by ester elimination from Si(OAc)4 and titanium (IV) isopropoxide featured a significantly lower content of the Si-O-Ti bonds. The initial tests in the epoxidation of cyclohexene by cumyl hydroperoxide (CHP) indicated a high selectivity and moderate activity of the xerogels. The catalytic properties were significantly improved by combining non-hydrolytic and hydrolytic methods yielding mesoporous and homogeneous Si/Ti mixed oxides. The catalysts prepared by these methods provided a complete epoxidation of cyclohexene in 2 h at 65 oC. |
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