Fixed-bed process of liquid-phase ammoximation of cyclohexanone over titanosilicates

Liquid-phase ammoximation of cyclohexanone to the corresponding oxime was conducted in a fixed-bed reactor over titanium silicalite (TS-1), which was proved to be a feasible and universal process. The primary rules of ammoximation were explored in the fixed-bed reactor system. The initial results indicated that the utilization of H₂O₂ was enhanced obviously through this mode, which is attributed to successful hydroxylamine generation and smooth contact with ketones. Further investigations of H₂O₂ reaction behavior showed that the proper weight hourly space velocity of H₂O₂ and the concentrations of ammonia and ketone both play a key role in highly efficient utilization of H₂O₂. The cyclohexanone and H₂O₂ conversion, cyclohexanone-oxime selectivity, and H₂O₂ efficiency reached 18.7%, 94.7%, 99.5%, and 98.7%, respectively, under the optimum reaction conditions of temperature of 333 K, ammonia concentration higher than 2%, cyclohexanone/H₂O₂ molar ratio of 5, and WHSV (H₂O₂) of 0.083 h^-1 with 85% t-BuOH as solvent.