Research In Vapor-Liquid Equilibrium Of Cyclohexanone Oxime-water-tert-butanol System

Caprolactam, as an important chemical material, is produced in the liquid cyclohexanone ammoximation method which is China’s own technology based on TS-1 as the catalyst and hydrogen peroxide as an oxygen source. To obtain high purity cyclohexanone oxime from the mixture of tert-butanol, water, cyclohexanone oxime, ammonia and cyclohexanone efficiently and with low power consumption, mechanism models, which can be used in designing separation processes and optimizing operating conditions, are needed to be established. Equilibrium relationship is the basis of establishing the mechanism models. To optimize the distillation separation process of liquid cyclohexanone ammoximation method, research on the vapor-liquid equilibrium (VLE) of cyclohexanone oxime-water-tert-butanol ternary systems was executed. Our purpose is to establish mathematical models which can describe the VLE behavior of the ternary system and provide basic data for the purification process of cyclohexanone oxime. The main work is as follows:According to physicochemical properties of the ternary system, the vapor-liquid two-phase condensation cycle was built to prepare samples and VLE data were measured by gas chromatography. First VLE data of water-tert-butanol was measured to ensure the reliability of the experimental devices and the accuracy of the model parameters. Then the vapor-liquid equilibrium (VLE) data of cyclohexanone oxime-water-tert-butanol ternary systems were measured to provide basic data for designing and optimizing the separation process of cyclohexanone oxime and also for regressing of different model parameters.NRTL model and UNIQUAC model were used to regress the binary interaction parameters with the Maximum Likelihood principle. Good consistency of calculated data with the experimental data certificated the reliability of the model parameters, which showed the established NRTL model and UNIQUAC model can be employed to correlate and predict VLE behavior of the ternary system.With the process simulation software Aspen Plus, a model of distillation separation process of the ternary system was established and simulated using obtained NRTL model in this work. Sensitivity analysis and optimization of operating parameters such like reflux ratio, the amount of overhead and quantity of siding were executed to obtain ideal separation results with low power consumption. Cyclohexanone oxime bottom is 90% mass fraction and recovery rate is 95%, which can be a good guide for the actual production process.