Manipulating Gold Spatial Location on Titanium Silicalite-1 To Enhance the Catalytic Performance for Direct Propene Epoxidation with H2 and O2

Engineering Au spatial locations on support harbors tremendous potential to boost catalytic performance but still remains a scientific and technological challenge. Herein, we devise a strategy to manipulate Au spatial location inside micropores of TS-1 support by tuning Au hydrolysis process. By multitechniques (e.g., quench molecular dynamics simulations, aberration-corrected HAADF-STEM, in situ UV-vis, and quantitative model calculation), the correlation between Au dynamic location and average x in [AuClx(OH)(4-x)](-) complexes is established. It is found that compositions and locations of Au complexes can be effectively manipulated using different preparation temperature. This results in more effective Au clusters in TS-1 microporous channels and smaller -sized Au NPs on external surfaces. Gratifyingly, the optimum Au/TS-1 catalyst shows the reported highest initial PO formation rate without adding promoters and high stable activity for direct propene epoxidation with H-2 and O-2. Moreover, single Au atoms and Au clusters on Au/TS-1 catalyst are directly observed for the first time. However, overmuch Au clusters inside TS-1 only result in diffusion limit and poor performance, indicating that "effectively accommodated Au clusters" play a pivotal role. This strategy together with mechanistic results should allow significant progress in the design of efficient Au catalysts in the near future.