Exploratory Research On Cyclohexanone Ammoximation In Microemulsion

Microemulsion, a thermodynamic stabilized and highly dispersed system with larger interface area between oil and water phases, may have the possibility to influence the reaction occurred intra liquid-liquid phases. The ammoximation of cyclohexanone to cyclohexanone oxime with hydrogen peroxide and ammonia over TS-1 is an environmental friendly process, which was studied in microemulsion. The effect of microemulsion on the reaction of cyclohexanone ammoximation and the mechanism of cyclohexanone ammoximation in microemulsion was investigated simultaneously. Finally, self-assembly of cyclohexanone oxime with function of surfactant was found.The cyclohexanone ammoximation in microemulsion was studied by changing surfactant and cosurfactant concentration, reaction temperature and the input mode of hydrogen peroxide. SEM, IR and XRD were used to study the catalyst TS-1 and cyclohexanone oxime in microemulsion and non-microemulsion respectively. Finally, the structure of cyclohexanone oxime was determined through X-ray single crystal diffraction.A microemulsion system of CTAB/cyclohexanone/t-butanol/ammonia/water can be constructed and the ammoximation of cyclohexanone to cyclohexanone oxime over TS-1 may occur in it. The cyclohexanone ammoximation in microemulsion, the suitable reaction temperature is 60℃; the addition of cosurfactant t-butanol could increase the conversion of cyclohexanone and selectivity to cyclohexanone oxime; with the decrease of surfactant concentration, both the conversion and the selectivity of the oxime increased. H2O2 decomposed during the reaction, therefore, a slow continuous addition of it could enhance the conversion and the selectivity. At optimum reaction condition, more than 88.5% conversion of cyclohexanone and 76.2% selectivity of cyclohexanone oxime could be obtained.The ammoximation of cyclohexanone to cyclohexanone oxime in microemulsion, the surfactant to the certain extent has accelerated the deactivation of TS-1, the addition of t-butanol may make the channels of TS-1 maintain unimpededly and slow down the deactivation of the catalyst. The result showed that the cyclohexanone ammoximation in microemulsion, imine mechanism and hydroxylamine mechanism happen at the same time is more reasonable. The experimental results showed that the...