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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 32, Number 6
BKCSDE 32(6)
June 20, 2011 

 
Title
Zeolite-catalyzed Isomerization of 1-hexene to trans-2-hexene: An ONIOM Study
Author
Yan-Feng Li, Ji-Qin Zhu, Hui Liu*, Peng He, Peng Wang, Hui-Ping Tian
Keywords
Hexene, ZSM-5, Double-bond isomerization, Active site, Density functional theory
Abstract
Details of the double-bond isomerization of 1-hexene over H-ZSM-5 were clarified using density functional theory. It is found that the reaction proceeds by a mechanism which involves the Brønsted acid part of the zeolite solely. According to this mechanism, 1-hexene is first physically adsorbed on the acidic site, and then, the acidic proton transfers to one carbon atom of the double bond, while the other carbon atom of the double bond bonds with the Brønsted host oxygen, yielding a stable alkoxy intermediate. Thereafter, the Brønsted host oxygen abstracts a hydrogen atom from the C6H13 fragment and the C–O bond is broken, restoring the acidic site and yielding trans-2-hexene. The calculated activation barrier is 12.65 kcal/mol, which is in good agreement with the experimental value. These results well explain the energetic aspects during the course of double-bond isomerization and extend the understanding of the nature of the zeolite active sites.
Page
1851 - 1858
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