Ammoxidation Of Cyclohexanone To Oxime Catalyzed By Titanium Silicalite-1Formed In Inorganic System

Cyclohexanone omixe is one of the most important intermediate in the production of Caprolactam. Conventionally it is synthesized in the cyclohexanone-hydroxylamine way. In the middle of 1980's Montedipe S.P.A of Italy successfully developed a new technology in which the ammoxidation of cyclohexanone was catalyzed by titanium silicalite-1. In this way the shortcomings of the conventional techniques can be overcomed and the Caprolactam benefit can be increased. Especially it basically realizes "Zero Emission" and meets to the request of "Green Chemical Engineering". It will bring new brighter prospect to the Caprolactam production and have great significance. But in the conventional way of the synthesis of TS-1, the high cost and harsh synthesis conditions and bad reappearance have greatly limited its large-scale industrial application. How to reduce the production cost and guarantee the quality of TS-1zeolite is becoming the most urgently to resolve problem in the development of TS-1and the ammoxidation of cyclohexanone to oxime. TS-1catalyst is synthesized successfully using mineral materials in inorganic system. The analysis of XRD and IR and SEM shows that titanium atoms have come into the zeolite's framework. By the studying of the effects of the synthetic conditions on the physicochemical properties of TS-1samples, the rule of the synthetic condition effects on the catalytic performance is obtained. The results show that adding seeds,promoter,agitation and the pretreatment of TS-1 samples can affect the catalytic performance greatly by the effects on its physicochemical properties. Through the comparison of the catalytic performance of a series of TS-1samples with different crystal sizes, the relationship of TS-1crystal size and the ammoxidation reaction rate is obtained. The result indicates that TS-1catalyst has great crystal size effect on the ammoxidation reaction. The ammoxidation process is controlled by the surface reaction when the TS-1sample's size is less than 0.6μm else is controlled by the inside crystal diffusion. The larger crystal size is the main reason that causes the catalytic capability of TS-1 synthesized in inorganic system to reduce. The TS-1 sample's crystal size is smaller synthesized with adding seeds in dynamic state, and after pretreating the cyclohexanone conversion and oxime yield can reach to more than 95% respectively.Through a series of beforehand experiments, based on the proposed imine mechanism and Hydroxylamine mechanism and reasonable simplifications, two kinetic models are built respectively. By determining the model parameters and employing the optimization technique, the one that proposes the reaction bases on the imine mechanism and hydrogen peroxide is absorbed and surface reaction control the ammoxidation process is optimal. The calculation values agree better with the experimental data.By studying of the kinetic of the ammoxidation, the reaction disciplinarians in the ammoxidation process are researched and the ammoxidation reaction conditions are optimized.