Gold supported on nitrogen-incorporated TS-1 for gas-phase epoxidation of propylene

Nitrogen-incorporated titanium silicalite-1 (NTS-1) was used to prepare a supported gold catalyst for direct gas-phase epoxidation of propylene using H2 and O2. The NTS-1 was synthesized by direct calcination of the TS-1 powder in a flow of NH3 at high temperature. Gold catalyst supported on NTS-1 was synthesized by the deposition-precipitation method. The samples were characterized by X-ray diffraction, N2 adsorption-desorption, diffuse reflectance ultraviolet-visible spectroscopy, inductively coupled plasma optical emission spectrometry, elemental analysis, X-ray photoelectron spectroscopy, and transmission electron microscopy. The results indicated that nitrogen was incorporated into the TS-1 framework, and that the NTS-1 preserved the multidimensional fatigue inventory (MFI) structure well. It was found that NH3-treatment resulted in decreased acidity of the TS-1 zeolite support and improved both the Au capture efficiency and dispersion, which remarkably improved the catalytic performance. The enhanced activity was ascribed to the decrease in acidic surface sites and the ligand effect of the terminal NH2 groups on the support surface.