Evaluation of Collaboration between Intrinsic Activity and Diffusion: a Descriptor for Alkene Epoxidation Catalyzed by TS-1

The systemic evaluation of the collaboration between intrinsic activity of active sites and substrate/product diffusion rate is a key challenge for rational optimization in reaction performance in alkene epoxidation. Herein, we constructed a series of TS-1 catalysts with adjustable local microenvironment around active sites to explore their performance of alkene epoxidation. This was achieved by controlling the contributions of classical and non-classical routines during crystallization process. Based on the characterization of active sites, product diffusion and their alkene epoxidation activity, we proposed a descriptor, R_a/d, for quantitative evaluation of the collaboration between intrinsic activity and products diffusion in TS-1 catalysts. This descriptor successfully explains the catalytic performance of various TS-1 including commercial TS-1 and guide further improvement of TS-1 in different alkene epoxidations. The optimal R_a/d is found in various epoxidation, corresponding to peak epoxidation performance across different substrates due to the well-balanced intrinsic activity and diffusion rate.