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摘要
Highly dispersed Au catalysts supported on amorphous titanosilicate supports with three-dimensional wormhole-like mesoporosity were prepared by deposition precipitation method, which show excellent performance in propylene epoxidation with H-2 and O-2. The best catalytic performance, propylene conversion of 12.8%, propylene oxide selectivity of 76.2% and PO space-time yield of 160.9 g(po)/Kg(cat)/h, was obtained at the reaction temperature of 300 degrees C. The Ti/Si molar ratio of the supports and some experimental parameters, such as the urea amount, loading temperature and Au loading on the as-produced catalyst are optimized. In addition, with the assistance of in-situ Fourier transform infrared spectroscopy (In-situ FT-IR), adsorption and desorption of PO, propylene and the reaction mixture on the catalyst are conducted to further explore the deactivation mechanism. It suggests that propylene and PO can be irreversibly and strongly adsorbed on the catalyst surface and finally transform to carbonate adsorbed on the active sites Ti-OH, resulting in catalyst deactivation.
