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 N-2 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 H-2/O-2 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 g(cat)(-1) h(-1). Furthermore, efforts were also made to clarify the plausible reaction routes over the bioreduction catalysts.