Study On The Synthesis And Separation Technology Of 2,2-Dimethoxypropane

2,2-dimethoxypropane(DMP)is an important organic chemical intermediates,generally sythetised by the condensation reaction of methanol and acetone.This method is of low conversion efficiency and poor process stability.Therefore,it is of great theoretical and practical significance to find suitable condensation reaction catalyst,optimize reaction conditions and develop reasonable separation process.This paper explores the direct process of synthesizing DMP,and uses the batch method as the pre-experiment of continuous method to study the effect of different catalysts.The results show that the D001 acid resin has the best effect of reaching equilibrium in 15 min at-25℃.Besides,it is found that 3A molecular sieve(as the water-absorbing agent)can be selectively adsorbed water from raw materials and DMP.In the continuous process,the raw materials of methanol and acetone flow through the loading of acidic resin and alkaline resin fixed bed at low temperature,basic resin on the reaction of the product to improve the stability of the product.The reaction is shifted in the reverse direction,resulting in a decrease in the content of the product 2,2-dimethoxypropane.The optimum reaction conditions were as follows:reaction temperature-25℃,mass space velocity 0.1h-1,methanol:acetone=4:1(molar ratio),the yield of 2,2-dimethoxypropane was 37.27%,the mass content in the product was 20.85%.Then,a separation scheme was designed for the reaction solution obtained by the reaction.The mixed solution was extracted with an aqueous solution of sodium hydroxide to remove most of the methanol,and the mass content of the residual organic phase was extracted after three extraction(excluding water and Sodium hydroxide)was 4.25%methanol,12.52%acetone,DMP81.21%.And then using hydrochloric acid to reduce the extraction of the basic phase of the organic phase,while adding a small amount of triethylamine,and then the treated mixed solution is distilled to get four different temperature range of the fraction.The temperature of product fractions is 72 ℃-79 ℃,DMP content of 99.12%.The DMP yield obtained by two steps of extraction and distillation was about 68%.Then the reaction separation process of DMP was simulated using Aspen Plus.The module of reactor simulating is chosed to use the RYield and simulates at setting DMP yield in 37.27%.The reactor design uses tube-type heat exchanger,the design parameters for the diameter φ25mm × 2.5mm,tube length 4500mm,tube 144.The distillation columns T-1 and T-2 determine and optimize their design and operating parameters via the simple calculation module DSTWU and the rigorous calculation module Rad Frac.The relevant parameters of T-1 distillation column are theoretical plate number 16,feed plate position 5,reflux ratio 1.6,operating pressure 0.1MPa,plate tower,plate spacing 0.35m,tower inner diameter 0.8m,tower height 14.2m.The relevant parameters of T-2 distillation column are theoretical plate number 20,feed plate position 8,reflux ratio 1.1,operating pressure 0.1 MPa,plate tower,plate spacing 0.35m,tower inner diameter 0.8m,tower height 17.0m.The other modules such as extraction separation,heat transfer and other modules of the parameters,according to the reaction and separation experimental data obtained in the previous chapters,and finally the entire process parameters are confirmed,which product DMP production of 294.3kg/h at 99.0%purity.Set the annual operating time as 8000 hours,the annual output will be 2354.4 tons/year.In this paper,through the DMP synthesis and separation in the laboratory of small test,and the Aspen Plus process simulating,we can provide reference data for the DMP production pilot and industrial production.