Au/TS-1 catalyst prepared by deposition–precipitation method for propene epoxidation with H2/O2: Insights into the effects of slurry aging time and Si/Ti molar ratio

• First direct evidence showing that aging time changes the location of Au on TS-1.
• At longer aging time, Au clusters tend to locate inside the micropores of TS-1.
• More tiny Au clusters inside micropores of TS-1 result in higher initial activity.
• Higher Si/Ti ratio favors the deposition of Au NPs inside the micropores of TS-1.
• Au/TS-1(100) catalyst shows higher activity but lower stability than Au/TS-1(35).

Au/TS-1 catalyst prepared by deposition–precipitation method is efficient for propene epoxidation with H2/O2, and its performance is significantly affected by the preparation parameters and the properties of support. In this work, effects of the slurry aging time and Si/Ti ratio of support on the location of Au nanoparticles inside or outside the micropores of TS-1 supports are examined by multi-techniques such as in situ characterization and molecular dynamics simulation, and the as-obtained catalysts are tested for propene epoxidation. It is found that longer slurry aging time facilitates the evolution of Au complex into smaller sized species which is easier to locate inside the micropores. Accordingly, the as-reduced catalyst has more tiny Au nanoparticles that are extremely active inside micropores and shows higher initial PO formation rate (gPO h−1 gAu−1). In addition, high Si/Ti ratio of TS-1 also favors the deposition of Au nanoparticles inside micropores, resulting in higher initial activity but lower stable activity.

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