Vapor-Phase Propylene Epoxidation with H2/O2 over Bioreduction Au/TS-1 Catalysts: Synthesis, Characterization, and Optimization

Au/TS-1 catalysts could be prepared by immobilizing the biosynthesized Au sol on TS-1 supports. A variety of techniques, such as N2 physisorption, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectorscopy, UV–visible diffuse reflectance, and thermogravimetric analysis, were employed to characterize both the supports and the bioreduction catalysts. The influence of various parameters (Si/Ti molar ratio, Au loading, immobilization pH, reaction temperature, and space velocity) on the catalytic performance in vapor phase propylene epoxidation with H2/O2 was systematically analyzed. Parameter optimization results manifested that the optimum catalytic activity and stability of bioreduction Au/TS-1 catalysts were obtained under optimum operation conditions of Si/Ti molar ratio of 35, Au loading of 1 wt %, immobilization pH of 2, reaction temperature of 573 K, and space velocity of 4000–8000 mL gcat –1 h–1. Furthermore, efforts were also made to clarify the plausible reaction routes over the bioreduction catalysts.