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.