Method for continuous extraction distillation separation of dimethyl carbonate-methanol azeotropic mixture

Abstract

The invention discloses a method for continuous extraction distillation separation of a dimethyl carbonate-methanol azeotropic mixture, and belongs to separation technologies of the dimethyl carbonate-methanol azeotropic mixture. According to the method, N,N-dimethylformamide, N-formylmorpholine or a mixture consisting of N,N-dimethylformamide and N-formylmorpholine in any proportion is used as an extracting agent. The operation condition of an extraction distillation tower and a solvent recovery tower are that the pressure is a normal pressure or reduced pressure, the ratio of a distillate at the top of the extraction distillation tower to the extracting agent is (0.5:1)-(10:1), and the feed (mass) ratio of the extracting agent to a mixture is (1:10)-(5:1). Two distillation towers are used in the method to achieve cycle utilization of the extracting agent. Methanol meeting requirements is obtained at the top of the extraction distillation tower, and the distillate at the bottom of the tower enters the solvent recovery tower; high-purity methyl carbonate is obtained at the top of the solvent recovery tower, and a high-purity extracting agent is obtained at the bottom of the tower; and a pump is used for pumping the extracting agent into the extraction distillation tower for cycle utilization. The method has the advantages that the extracting agent is adopted to destroy a dimethyl carbonate-methanol azeotropic system, and the aims of separating high-purity dimethyl carbonate and methanol and ensuring cycle utilization of the extracting agent are achieved. The continuous distillation has the advantages of high tower efficiency, high yield and the like.

Description

technical field [0001] The invention relates to a continuous extraction and rectification separation method of dimethyl carbonate-methanol azeotrope, which belongs to the separation technology of dimethyl carbonate-methanol azeotrope. Background technique [0002] Dimethylcarbonate (Dimethylcarbonate, referred to as DMC) is a new type of green chemical product that has been widely concerned by the chemical industry at home and abroad in the past ten years. Because its molecule contains methyl, methoxy, carbonyl and carbonylmethoxy, it has good properties. Its chemical reactivity can replace highly toxic or carcinogenic substances such as phosgene, dimethyl sulfate, methyl chloride and methyl chloroformate in many fields for carbonylation, methylation and transesterification reactions to generate a variety of fine chemicals. Therefore, it is known as the "new cornerstone" of organic synthesis in the 21st century. Its demand is also increasing at an annual rate of 20% interna...

AI Technical Summary

Problems solved by technology

However, patent 200710121912.4 requires harsh operating conditions, especially high operating pressure (0.1-0.6Mpa), which will increase the investment cost of the membrane separation device

And its direct saturated steam feeding method will also increase the stringent requirements on the insulation performance between the pipelines

At the same time, both the invention patent 200710121912.4 and the utility model patent CN201020549621.2 adopt the method of vacuum side condensation to collect the permeate, which will also increase the cooling power consumption of the condensing equipment and consume a lot of energy

Patents such as the United States and Japan have also done research on this azeotropic system, but no major breakthroughs have been found

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