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

Abstract

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 H2 and O2. 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.