title: Structures and reaction mechanisms of propene oxide isomerization on H-ZSM-5: an ONIOM study.
abstract: The isomerization mechanisms of propene oxide over H-ZSM-5 zeolite have been investigated via the utilization of 5T and 46T cluster models calculated by the B3LYP/6-31G(d,p) and the ONIOM(B3LYP/6-31G(d,p):UFF) methods, respectively. The reactions are considered to proceed through a stepwise mechanism: (1) the epoxide ring protonation, and concurrently the ring-opening, and (2) the 1,2-hydride shift forming the adsorbed carbonyl compound. Because of the asymmetric structure of propene oxide, two different C-O bonds (more or less substituted carbon atom sides) can be broken leading to two different types of products, propanal and propanone. The ring-opening step of these mechanisms is found to be the rate-determining step with an activation barrier of 38.5 kcal/mol for the propanal and of 42.4 kcal/mol for the propanone. Therefore, the propanal is predicted to be the main product for this reaction.
authors.affiliation: Laboratory for Computational and Applied Chemistry, Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.
authors.forename: Supawadee
authors.initials: S
authors.lastname: Namuangruk
authors.forename: Pipat
authors.initials: P
authors.lastname: Khongpracha
authors.forename: Piboon
authors.initials: P
authors.lastname: Pantu
authors.forename: Jumras
authors.initials: J
authors.lastname: Limtrakul