Continuous extractive distillation separation method of dimethyl carbonate-methanol azeotropic mixture

Abstract

The invention discloses a continuous extractive distillation separation method of a dimethyl carbonate-methanol azeotropic mixture, and relates to a continuous extractive distillation method. The technical process of the method is as follows: ethylene glycol is used as an extraction agent at normal pressure; the solvent ratio is 1-3; the separated dimethyl carbonate-methanol azeotropic mixture is fed from the middle part of a tower, the extraction agent is fed from the top of the tower, and the reflux ratio is 2; high-purity methanol is extracted from the tower top of an extractive distillation tower, and the dimethyl carbonate and the extraction agent are extracted from the tower bottom; the fraction at the tower bottom enters an extraction agent recovery tower, and the reflux ratio is 3; and dimethyl carbonate is extracted from the tower top, and the extraction agent extracted from the tower bottom can be recycled. The method disclosed by the invention adopts ethylene glycol as an extraction agent, and improves the separation effect of the dimethyl carbonate-methanol azeotropic mixture; and since ethylene glycol is a co-production product in synthesizing dimethyl carbonate by a transesterification method, the source is conveniently available, and the cost caused by introducing other substances is avoided.

Description

technical field [0001] The invention relates to a continuous extraction and rectification method, in particular to a continuous extraction and rectification separation method of dimethyl carbonate-methanol azeotropic mixture. Background technique [0002] Dimethyl carbonate is a basic organic chemical raw material, mainly used in the methylation, carbonylation and synthesis of pharmaceutical and chemical products. It was registered as a non-toxic substance in Europe in 1992 and is known as a green organic chemical for the 21st century. In addition, because dimethyl carbonate has excellent physical properties such as good compatibility, high octane number and dielectric constant, it is also widely used in fields such as solvents, gasoline additives, lithium-ion battery electrolytes, and can also be directly Synthetic products such as food additives, antioxidants, plant protection agents, advanced resins, fuels, pharmaceutical intermediates and surfactants. At present, the m...

AI Technical Summary

Problems solved by technology

At present, the main methods of synthesizing dimethyl carbonate are transesterification and methanol oxidative carbonylation. These two methods initially obtain a mixture of dimethyl carbonate and methanol (dimethyl carbonate mass fraction 30%), azeotropic The temperature is 64°C, so it is difficult to obtain high-purity dimethyl carbonate by conventional separation methods, and special separation techniques are required to achieve separation

Images