Epoxidation of cyclic allylic alcohols on titania-silica aerogels studied by attenuated total reflection infrared and modulation spectroscopy

被引：15

作者：

Gisler, A ^{[1
]}

Bürgi, T ^{[1
]}

Baiker, A ^{[1
]}

机构：

[1] ETH Honggerberg, Swiss Fed Inst Technol, Inst Chem & Bioengn, CH-8093 Zurich, Switzerland

来源：

JOURNAL OF CATALYSIS | 2004年 / 222卷 / 02期

关键词：

titania-silica aerogels; epoxidation; allylic alcohols; attenuated total reflection infrared spectroscopy; in situ spectroscopy; hydroxy assisted; silanol assisted;

D O I：

10.1016/j.jcat.2003.12.009

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

Epoxidation of cyclohex-2-en-1-ol and cyclooct-2-en-1-ol on titania-silica aerogel catalysts using t-butylhydroperoxide (TBHP) as oxidant was studied by in situ attenuated total reflection (ATR) Fourier transform infrared spectroscopy. Probing of the catalytic liquid-solid interface revealed different adsorption behaviors for the two allylic alcohols on the aerogel. Cyclohexenol was found to adsorb stronger and less reversible on the catalyst surface and Ti sites than cyclooctenol. The spectroscopic measurements under working conditions support the previously proposed hydroxy-assisted mechanism for the formation of cyclohexenot oxide and the silanol-assisted mechanism for cyclooctenol epoxidation. The evidence of the former is traced to the occurrence of a framework vibration upon adsorption of cyclohexenol, whereas the latter is supported by large negative bands of the silanol groups at 3700 and 980 cm(-1) in the case of cyclooctenol epoxidation. (C) 2004 Elsevier Inc. All rights reserved.

引用

页码：461 / 469

页数：9

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