TS-1 with Abundant Micropore Channel-Supported Au Catalysts toward Improved Performance in Gas-Phase Epoxidation of Propylene

The gas-phase propylene epoxidation reaction catalyzed by Au/TS-1 has attracted great attention due to its clean and efficient merits. However, high conversion of propylene (>10%) and high selectivity of propylene oxide (PO) (>90%) often cannot be obtained at the same time. Although a variety of TS-1 supports with different microstructures have been developed to improve the catalytic performance, few have met the above criteria. In this work, we have reported a silane-assisted strategy to prepare TS-1-CTES zeolites containing abundant micropore channels, which showed both high propylene conversion (13.3%) and high PO selectivity (92.7%). The silane, (3-chloropropyl) triethoxysilane (CTES), not only participates in constructing the MFI framework but also serves as a spatial filling agent to build secondary micropore channels. Ar physisorption characterization exhibited the increased micropore volume and surface area of the as-synthesized TS-1-CTES, which benefit molecule diffusion. XPS results showed an enriched Ti concentration on the surface of TS-1-CTES and a decreased electron density of Ti atoms. A few more Au nanoparticles were proved to be distributed inside the TS-1-CTES crystal compared with those inside TS-1. The optimized distribution of Au and Ti active sites in Au/TS-1-CTES enhanced their synergistic catalytic effects. The PO formation rate remained relatively stable for 24 h, superior to traditional Au/TS-1. The construction of a micropore-rich TS-1 structure opens a way for the reasonable design and manufacture of the Au/TS-1 catalyst, for the gas-phase epoxidation of propylene.