Study On The Preparation Of Epichlorohydrin From Glycerol

In the present work, market status at home and abroad of epichlorohydrin and production technology routes were introduced. The production capacity of epichlorohydrin in China has been saturated, and it is not suitable for adding new equipment. In addition, allyl chloride process was maturity, but the process was not environmental friendly. Allylic Selenides process was low unit consumption, but the cost was high. Glycerin chlorinated process will be the trend of technology development in the future with the enough glycerin from biodiesel by-product. Therefore, we used glycerol as raw materials to synthesize epichlorohydrin, and the discussions of chemical engineering problems in the process were given. It was pointed out that the research focus would be put on the two main reactions (chlorination and cyclization). The work and conclusions in this paper are as follows:1. The direct preparation of 1,3-dichloro-2-propanol from glycerol was carried out in a batch reactor using acetic acid catalyst at 363-393 K. The analytical technique, gas chromatography, was employed in order to follow the time evolution of the reagents. The kinetic model of the process was developed. Furthermore, the model parameters of the process were also determined by data fitting. The results show that the direct preparation follows the S_N2 mechanism. Kinetic model corresponding to the mechanism was proposed in this work. The experimental results show that the kinetic model agrees well with the experiments. Also, the direct preparation of epichlorohydrin from 1,3- dichloro-2-propanol was carried out in a batch reactor at 298-323K. The kinetic model of the reaction was established, cyclization of dichloropropanol is a simple second order reaction, then the activation energies and pre exponential factor were obtained. The orthogonal experiment shows that the optimum condition for chlorination of glycerol is as follows: mole ratio (n_HCl/n_GLY) is 4 and reaction time is 180 min at 383K. And the optimum condition for cyclization of dichloropropanol is as follows: mole ratio (n_NaOH/n_DCP) is 1.2 and reaction time is 3min at 323K. The main kinetic equations are as follows, the nomenclature and parameter values in the equations will be found in the text: 2. In accordance with the study on reaction kinetics and technological condition, laboratory-scale semi-continuous device was designed and investigated. In order to analyze the reason of the low efficiency, reactive distillation column was used as a solution. From such improvement, high yield and selectivity were obtained. And the determined laboratory-scale semi-continuous devices are as follows: 3. The simulation enlargement of core unit (reactive distillation unit) in the laboratory-scale semi-continuous was studied. Kinetic study provided basic data for the simulation and calculation of the process of reactive distillation. The process of reactive distillation was analyzed using Aspen plus simulation software. A simulation model based on RadFrac block using NRTL property method was established. The operation parameters of the distillation column, such as reflux ratio, feed stage and material ratio were optimized on the basis of sensitivity analysis, which would be useful for the farther work, and the optimum condition is obtained.