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Insights into the mechanism of the solvolysis of propylene oxide over titanium silicalite-1: a theoretical study.
- Source :
- Physical Chemistry Chemical Physics (PCCP); 8/28/2023, Vol. 25 Issue 32, p21358-21375, 18p
- Publication Year :
- 2023
-
Abstract
- In order to probe into the mechanism of solvolysis (alcoholysis/hydrolysis) of propylene oxide (PO), the formation of propylene glycol (PG), 1-methoxy-2-propanol (PPM) and 2-methoxy-1-propanol (SPM) over the TS-1 catalyst with tetrahedral Ti and Ti/defect sites was systematically discussed using an embedded quantum mechanical/molecular mechanics (QM/MM) approach. The results showed that the activity of PO solvolysis is closely related to the ring-opening ability of active substances, and the ring-opening ability is in the following order: Si–O(H)–Ti > Ti–OH > 5MR Ti–OOH > Ti–OCH<subscript>3</subscript> (tetrahedral Ti site); 3MR Ti–OOH > Ti–OH > 5MR Ti–OOH > Ti–OCH<subscript>3</subscript> (Ti/defect site). At the tetrahedral site, the concerted mechanism is the dominant pathway for PO ring opening to form PPM, while a competitive relationship exists between stepwise and concerted mechanisms to form PG and SPM. Si–O(H)–Ti exhibits excellent PO ring-opening activity because of its strong Brønsted acidity, but it is difficult to form. At the Ti/defect site, the stepwise mechanism via PO ring opening with 3MR Ti–OOH and then successive hydrolysis/alcoholysis to form product is the dominant pathway. The overall energy barrier of the optimal route is relatively lower as compared to the tetrahedral Ti site. This work opens up a new path for providing more information on the detailed mechanism in the solvolysis of PO over the TS-1 catalyst from a theoretical point of view. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 14639076
- Volume :
- 25
- Issue :
- 32
- Database :
- Complementary Index
- Journal :
- Physical Chemistry Chemical Physics (PCCP)
- Publication Type :
- Academic Journal
- Accession number :
- 169970527
- Full Text :
- https://doi.org/10.1039/d3cp01696j