Establishment of a Structure-Activity Relationship in Heterogeneous Titanosilicate Catalysts for Olefin Epoxidation via a Building Block Method

The non-aqueous building block (NABB) method is a synthetic method that has the goal of producing atomically dispersed, well-defined, single-site heterogeneous catalysts. The active sites of these catalysts are able to be structured on the nanometer scale using the process of sequential additions. The method is designed in such a manner that it should be able to produce a series of catalysts each with a unique, well-defined, single active site. This series of catalysts can then be used to elucidate the structure-activity relationship for the active site in a particular chemical reaction.

In this dissertation a new building block, butyltin cube, is developed for the NABB method. The preparation of the butyltin cube uses reagents that are less toxic and costly than the reagents used to prepare the previous methyltin cube starting material. A series of titanium NABB materials containing different active sites was prepared. The local structure around the active site of these materials was then probed using quantitative NMR, FT-IR, Raman, XANES, and EXAFS. The activity and selectivity of these materials in the epoxidation of cyclohexene with tert-butylhydroperoxide was then measured. The information was then used to propose a structure-activity relationship for olefin epoxidation and comparisons were made with structure-activity relationships noted in the literature.