期刊
JOURNAL OF CATALYSIS
卷 246, 期 1, 页码 223-231出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.jcat.2006.12.008
关键词
4-tert-butylphenol; p-cresol; hydrogenation; Zr-zeolite beta; rhodium; cis-stereoselectivity; cascade reaction; bifunctional catalyst
The hydrogenation of 4-tert-butylphenol and p-cresol was investigated over Zr-beta-supported rhodium catalysts. By designing a suitable bifunctional catalyst, the intermediate, 4-alkylcyclohexanone, formed by metal-catalyzed hydrogenation of 4-alkylphenol, could be reduced via the highly stereoselective Meerwein-Ponndorf-Verley reduction over zirconium Lewis acid sites. Thus, in the presence of 2-propanol as solvent and MPV reductant, a high stereoselectivity to cis-4-alkylcyclohexanol was observed. Over 0.5% Rh/Zr-beta, 4-tert-butylphenol, and in-cresol were hydrogenated to the cis-alcohols with 95 and 89% stereoselectivity, respectively. A higher metal loading or the use of solvents such as hexane or tert-butanol led to a lower stereoselectivity, as metal-catalyzed hydrogenation predominated. Similarly, the cis:trans alcohol ratio was lower for rhodium supported on zirconia or Al-beta. Compared with rhodium, palladium was less active in the hydrogenation of the 4-alkylphenols, requiring a higher hydrogen pressure and temperature. A two-step cascade reaction mechanism is proposed for the conversion of 4-alkylphenols to cis-4-alkylcyclohexanols. (c) 2006 Elsevier Inc. All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据