Enhanced Catalytic Performance for Propene Epoxidation with H2 and O2 over Bimetallic Au–Ag/Uncalcined Titanium Silicate-1 Catalysts

Abstract

Gradually emerging environmental concerns have triggered the development of highly efficient catalysts for propene epoxidation with H2 and O2. Unfortunately, intensifying the activity and stability is still a challenging task. Herein, Au–Ag bimetallic catalysts were deposited on titanium silicate-1 with blocked pores (TS-1-B). Via density functional theory calculations together with multiple types of characterization (e.g., high-angle annular dark-field scanning transmission electron microscopy, ultraviolet–visible, and X-ray photoelectron spectrometry), we found that the synergy between Au and Ag significantly improved the catalytic performance via not only the decrease in the Au nanoparticle size but also the enhanced oxygen adsorption and electron transfer ability from Au to O2. Furthermore, a volcano-shaped relationship between the Au/Ag ratio and catalytic performance was also established, and the Au10–Ag1/TS-1-B catalyst showed an excellent stable PO formation rate (174–233 gPO h–1 gAu–1) and a H2 efficiency of 44%, higher than those of the reported stable catalysts. The insights and methodology reported here may pave the way for maximizing Au utilization efficiency and unraveling the intrinsic structure–performance relationship of bimetallic catalysts for propene epoxidation.