(573g) Simulation On the Process of Direct Hydration of Cyclohexene by Catalytic Distillation

Cyclohexanol is an important organic chemical product, and mainly used for adipic acid and caprolactam production. It is the indispensably intermediate of polyacidamide products. Currently there are three commercial routes to produce cyclohexanol: the hydrogenation of phenol, the oxidation of cyclohexane, and the direct hydration of cyclohexene. Of these, phenol hydrogenation route mainly suffers from high phenol prices and heavy hydrogen consumption. The cyclohexane oxidation route has the disadvantages of poor safety, low selectivity, low convertion and great energy consumption. The cyclohexene hydration route has gained more and more attentions, after a safer and cheaper route to produce cyclohexanol was successfully developed by Asahi Chemical Industry Co., Ltd. In this route, benzene partially hydrogenates to prepare cyclohexene firstly, and then cyclohexene hydrates to produce cyclohexanol. In recent years, the direct hydration of cyclohexene has become a research hotspot. Although this route overcomes the above-mentioned problems, still suffers from very slow reaction rate and fairly low equilibrium conversion. Therefore, a novel route for the synthesis of cyclohexanol from cyclohexene was proposed by us. In this route, a co-solvent was added into the system to improve the solubility of cyclohexene in water, and the cyclohexene hydration reaction was set off in a catalytic distillation column. It seemed to offer a solution for the problems of the former technologies.

 Firstly, the reaction conditions and kinetics of the direct hydration of cyclohexene were studied in a high-pressure reactor. A-36wet was selected as a catalyst and 1, 4-dioxane was selected as a co-solvent. Then, the effects of agitation speed, reaction temperature, reaction initial pressure, reaction time, co-solvent dosage on cyclohexene hydration reaction were investigated. Meanwhile, cyclohexene hydration reaction kinetics was explored primarily and a homogeneous kinetics model was established. The activation energy of positive reaction and reverse reaction were determined to be 46.634kJ/mol and 63.946kJ/mol respectively. And the relation between reaction equilibrium constant and the temperature was obtained. The comparision of the model values and the experimental values indicated that the model can characterize the reaction process well.

Secondly, on the basis of equilibrium stage model, aspen plus software was used to simulate the process of synthesis of cyclohexanol by catalytic distillation. During the research process, the effects of feed location, feed rate, ratio of distillation rate to feed rate, stage number of reactive zone, stage number of stripping section and column pressure on conversion of cyclohexene were investigated and the suitable operating conditions were got. The simulation results were satisfactory.