Reactive Distillation Process Design And Analysis Of Triethylene Glycol Di-2-ethylehexanoate Synthesis

Triethylene glycol di-2-ethylehexanoate(TGDE)is a new cold-resistant and environmentally friendly plasticizer and widely used in synthetic rubber,adhesives,coatings,sealing materials,and so on.There are many problems,such as poor product yield and selectivity,serious equipment corrosion,complicated post-processing process and environmental pollution,in the traditional production process of TGDE.In this paper,a reactive distillation process is proposed based on the esterification reaction kinetics of triethylene glycol(TEG)and 2-ethylhexanoic acid(2-ETH)under the sulfated zirconia catalyst and thermodynamic parameters determined by experiments.The energy consumption of reactive distillation process is compared with that of traditional process.Firstly,the reaction kinetics of TEG and 2-ETH catalyzed by heterogeneous catalyst sulfated zirconia was carried out in a high-pressure autoclave.The effects of reaction temperature,2-ETH/TEG molar ratio,catalyst loading and stirring speed on the conversion of triethylene glycol and the yield of TGDE were studied.a pseudo-homogeneous model was used to obtain the reaction kinetics.The calculated values of the model were well consistent with the experimental data.The kinetic equation will be used in the simulation of reactive distillation process.Secondly,the liquid-liquid phase equilibrium of two ternary systems of water +TEG + 2-ETH and water + TEG + TGDE at atmospheric pressure was determined.The reliability of the data was tested by three empirical equations。The experimental data was fitted using the NRTL model and the UNIQUAC model to obtain the binary interaction parameters,which provided basic thermodynamic data for the simulation of the reactive distillation process.Finally,based on the experimentally determined reaction kinetics data and thermodynamic data,a reactive distillation model of TGDE was established by using the equilibrium stage model in the process simulation software.The sensitivity analysis method was used to study the influence of parameters,such as the number of rectification stages,the number of the distillation stages,the number of the reaction stages,the residence time,the feeding position,the molar ratio of 2-ETH and TEG and so on,on the yield of TGDE and energy consumption per kilogram product.The optimal structure and operating parameters of the reactive distillation column are obtained.The yield of TGDE was increased to 0.981 and the TGDE with a purity of98.5% can be obtained directly from the bottom of reactive distillation column,which greatly simplify the production process of TGDE.The energy consumption per kilogram TGDE in the reactive distillation process is 1342.4 k J / kg,which reduce59.2% energy consumption compared with of the traditional process.