Abstract: The catalytic activity of the TS-1 catalyst for cyclohexanone ammoximation to cyclohexanone oxime was investigated under the conditions of WHSV=6 h-1 and 70 ℃ in a continuous slurry reactor, and the catalyst samples run for different time were characterized by thermogravimetric and differential thermal analysis, temperature-programmed desorption, N2 physisorption, temperature-programmed oxidation, and Fourier transform infrared spectroscopy. The results show that the activity of TS-1 keeps stable within 60 h and then decreases rapidly. Coking is the main reason for the deactivation. Two types of carbon species are formed on the internal surface of TS-1 micropores. Soft coke is located near Ti sites and can be easily oxidized at 350 ℃, while refractory coke that deposits on the strong acid centers, Si[KG-45x]-[KG-20x]OHs, can be removed at 700 ℃. The framework structure of TS-1 is unchanged before and after deactivation, and the catalytic activity can be recovered completely after calcining the deactivated catalyst at 700 ℃.

Key words: titanium silicalite, zeolite catalyst, coking, deactivation, cyclohexanone, ammoximation, cyclohexanone oxime, hydrogen peroxide