Study On The Process Of Bromoethane Synthesis Via Reactive Distillation

As an important raw material of organic intermediates,bromoethane is widely used in all kinds of fields.With the rapid development of science and technology,especially the application of phase transfer catalytic reaction technique,the demand of bromoethane which is served as phase transfer catalyst core has an increasingly rapid growth.Thanks to the high cost and serious pollution to the environment of the traditional preparation of bromoethane,the preparation process with green economy will have more development space and market application prospect.In this paper,ethanol and hydrobromic acid were used as raw materials to prepare bromoethane,and the process of reactive distillation of bromoethane through both experiments and computer simulations aspects were researched comprehensively and deeply.At the beginning of the reactive distillation experiment,the minimum theory stage number was measured by separation of ethanol-isopropanol system and the result is 11,calculated by Fenske Equation.The effects of mole ratio of hydrobromic acid to ethanol,reflux ratio,reaction temperature and reaction time on the yield of bromoethane were investigated in the experiments of the reactive distillation of bromoethane.The orthogonal experiments were carried out to study the degree of influence of each factor,whose results showed that the reaction temperature had the greatest effect on the yield of bromoethane,followed by the ratio of reflux ratio.Finally,the reaction time and the molar ratio of acid to alcohol were optimized.The optimum reaction conditions were as follows:reaction temperature was 100?,reflux ratio was 3,molar ratio of acid to alcohol was 4:1,and the reaction time was 3h.The yield of bromoethane can reach above 90%under this condition.In order to provide the relevant parameters for computer simulation,the study of reaction kinetics was carried out.Through the determination of the reaction rate constant at different temperatures,and then according to the Arrhenius formula,the reaction activation energy was obtained.In addition,on the basis of the experiment,bromoethane via reative distillation processes were simulated by computer.Aspen Batch Distillation was selected as the unit operation module of simulation which is suitable for the batch distillation and the NRTL activity coefficient model was used in this simulation which can be adapted to the highly non-ideal system.Based on which resuilt,the vapor-liquid equilibrium phase diagram was drawn.Impacts of conditions such as mole ratio of hydrobromic acid to ethanol,reflux ratio and heating temperature of tower kettle on results of the process were studied and compared with results of experiments as whose verification and direction.The results showed that the simulation data is consistent with the experimental data,but the yield of ethane is higher than that of the experimental results.What's more,the preliminary design process with an annual output of 10 thousand tons of bromoethane was conducted on the basis of experiment and simulation from the aspects of design index,process flow,layout of pipeline and instrument,environmental pollution analysis and economic analysis,which will lay the foundation for the industrialization of bromoethane.