Epoxidation of olefins is an important chemical reaction throughout the chemical value-chain. Most of the currently studied and operated catalysts use TiIV as the active species, the microporous TS-1 catalyst for propylene to propylene oxide probably being the best studied system. However, until today, the true nature of the active site � and hence the catalytic action � is poorly understood. Moreover, the narrow pores of TS-1 only accommodate small substrate molecules. In order to increase the performance and to extend the substrate-scope, well define catalysts which exclude mass-transfer limitations should be developed.TiCl4 grafted onto isolated silanol-groups on silica provides a convenient approach to obtain well defined surface species. By carefully choosing the synthesis parameters, one can obtain surface sites with different coordination environment and linkages to the surface[1]. Synthesis and characterization of this material is reported elsewhere. In order to shine light onto the active site of those epoxidation catalysts, kinetic experiments under continuous-flow conditions are a good analytical tool to establish structure-activity relationships for these chemical systems.In this contribution, we present kinetic experiments with different catalysts, rationalizing leaching, restructuring and blocking phenomena in TS-1 like materials. Finally a general mechanism will be presented in which changes in the active sites during the reaction are rationalized, together with insight into the chemical mechanism for the epoxidation reaction.

Kinetic studies on the epoxidation of olefins over well-defined Ti<sup>IV</sup>-sites

244th National Meeting (2012)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.

Kinetic studies on the epoxidation of olefins over well-defined TiIV-sites

Kinetic studies on the epoxidation of olefins over well-defined Ti^IV-sites