Microtube Reaction-distillation Separation Integrated Synthesis Of DMAE And DMAEE

Preparation of ethanolamines using ethylene oxide(EO)and dimethylamine(DMA)is the most important method for producing dimethylaminoethoxyethanol(DMAE)and 2-[2-[2-(dimethylamino)ethoxy]ethoxy]ethanol(DMAEE).The rate of ring-opening addition of EO and DMA is very fast,and EO can also undergo further ring-opening addition reaction with products(DMAE and DMAEE).Therefore,how to effectively control the degree of reaction of EO and increase the selectivity of the target product is crucial.The development and design of suitable reactors and reaction processes has always been a research hotspot in this field.The introduction of the microtubule reactor system into the chain reaction of EO and DMA can accurately control the reaction temperature,residence time,speed up the reaction rate,and enable the materials to be instantaneously mixed in an exact ratio,so that the products of EO and DMA reaction can be controlled at the DMAEE stage effectively,and the yield,selectivity and safety of the reaction have been improved.This led to the development of a DMAE and DMAEE synthesis process based on the idea of product integration.A suitable microtubule reactor system is constructed in this paper.The homogeneous liquid-phase reaction of EO and DMA with water as the catalyst is carried out in a microtube reactor with an inner diameter of 500 μm and a length of 100 cm.Based on the idea of product integration,the experimental results show that the reaction temperature is 90℃,the reaction time is 24s,the liquid flow rate is 0.042m/s,and the mass feed ratio of water to DMA is 2:1.The molar feed ratio of EO to DMA can control the content of DMAE in the product between 13.8 mol%and 95.9 mol%,the content of DMAEE between 4.1 mol%and 80.1 mol%,and the conversion rate of EO is over 94%,the conversion rate of DMA is above 98%,and the selectivity of DMAEEE in the product is below 6.1%.Based on the above studies,according to the reaction mechanism,it is determined that EO reacts with DMA to generate DMAE,DMAEE,and DMAEEE is irreversible concatenation reaction,and the rate expressions of the reaction is established,and simulation calculations are performed based on experimental data and obtained the kinetic parameters.The expression of the corresponding kinetic equation is:-dcDMA/dt=k1cDMAcEO-dcEO/dt=k1cDMAcEO+k2cDMAEcEO+k3cDMAEEcEO dcDMAE/dt=k1cDMAcEO-k2cDMAEcEO dcDMAEE/dt=k2cDMAEcEO-k3cDMAEEcEO dcDMAEEE/dt=k3cDMAEEcEOAccording to the Arrhenius equation,the relationship between the reaction rate constants and the reaction temperature is obtained:lnk1=ln2.09-1674.4/(RT)lnk2=lnl.392-1555.5/(RT)lnk3=ln11.6-1364.3/(RT)In addition,because a large amount of water is used as a reaction catalyst in the reaction process,a set of micro-tube reaction-retriematic separation coupled circulation device is designed to recycle water in order to reduce iste water discharge.Based on a series of experiments on the reaction of EO and DMA in microtubule reactors,the optimal reaction product is used as a distillation substrate,and a three-column continuous distillation model is established to separate the water in the product.DMAE and DMAEE are separated and purified,and Aspen software is used to simulate the distillation process.NRTL-RK is selected as the physical property method of the vacuum distillation tower,and the effects of the reflux ratio,feed position,and the number of plates on the rectification efficiency of each vacuum distillation column are studied,and the optimum process parameters are determined:the theoretical plate of the vacuum rectification column 1 is 24,and the molar reflux ratio is 0.36 and the feed position is the 15th plate;the theoretical plate of the vacuum distillation column 2 is 15,the molar reflux ratio is 0.46,the feed position is the 8th plate;the theoretical plate of the vacuum distillation column 3 is 17.The molar reflux ratio is 0.019 and the feeding position is the 9th plate.The purity of the water obtained by the continuous distillation of the three towers is 99.99%,and the recycling efficiency is 99.8%.The purity of DMAE is 96.5%,the recovery rate is greater than 99.99%,the purity of DMAEE is 99.98%,and the recovery rate is greater than 99.99%.