Process and device for recycling dimethyl carbonate through steam permeation method

A technology of dimethyl carbonate and permeation method, which is applied in the field of recovery of dimethyl carbonate by steam permeation method, can solve the problems of high energy consumption, high investment in equipment, complicated separation process, etc., and achieve small processing load, reduced pressure, membrane small area effect

Inactive Publication Date: 2016-09-21
NANJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Due to the limitation of thermodynamics, the azeotrope of methanol and dimethyl carbonate is obtained by general rectification in the production process of dimethyl carbonate, and the common rectification method cannot completely separate dimethyl carbonate at all, and cannot obtain relatively High-purity DMC
It is usually necessary to carry out extractive distillation or pressure swing distillation on the basis of ordinary distillation. The separation process is very complicated, the equipment investment is relatively high, and the energy consumption is relatively large, which seriously does not meet the requirements of "green production".

Method used

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  • Process and device for recycling dimethyl carbonate through steam permeation method

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0047] Add the reaction liquid in the preparation of dimethyl carbonate by transesterification reaction to the initial distillation tower 1, the bottom of the tower is part of by-products, the top of the tower is dimethyl carbonate-methanol azeotrope, and trace impurities, the azeotropic temperature is about 63 °C . After the dimethyl carbonate-methanol azeotrope enters the extractive distillation tower 2 for extraction and separation with water, the bottom of the extractive distillation tower 2 is about 95% of water, 5% of methanol and less than 0.05% of dimethyl carbonate and trace impurities mixture. The control flow rate is 90kg / h. Water-methanol-dimethyl carbonate enters the first evaporator 4, and after being vaporized, enters the first vapor permeation membrane separator 5 composed of 4 MFI molecular sieve membrane modules in series for dealcoholization and separation. The feed temperature in the first steam permeation membrane separator 5 is 120°C, the gauge pressure ...

Embodiment 2

[0049] After the reaction solution in the dimethyl carbonate prepared by transesterification is heated and vaporized, it is added to the extractive distillation tower 2 and water is extracted and separated, and the bottom of the extractive distillation tower 2 is 92% of water, 5% of methanol and less than 3% of Mixture of dimethyl carbonate and trace impurities. The control flow rate is 90kg / h. Water-methanol-dimethyl carbonate enters the first evaporator 4, and after being vaporized, enters the first vapor permeation membrane separator 5 composed of 4 MFI molecular sieve membrane modules in series for dealcoholization and separation. The feed temperature in the first steam permeation membrane separator 5 is 120°C, the gauge pressure on the retentate side of the membrane is 0.23MPa, and the absolute pressure on the permeate side is 10000Pa. Methanol in the feed liquid passes through the steam permeation membrane, is condensed by the first condenser 6 of the permeate, and then ...

Embodiment 3

[0051] Add the reaction solution in the preparation of dimethyl carbonate by methanol carbonylation to the initial distillation tower 1, the bottom of the tower is part of by-products, the top of the tower is dimethyl carbonate-methanol azeotrope, and trace impurities, the azeotropic temperature is 63 ℃ . After the dimethyl carbonate-methanol azeotrope enters the extractive distillation tower 2 and carries out extraction and separation with water, the bottom of the extractive distillation tower 2 is about 94% water, 6% methanol and less than 0.05% dimethyl carbonate ternary sum Mixture of trace impurities. The control flow rate is 180kg / h. Water-methanol-dimethyl carbonate enters the first evaporator 4, and after being vaporized, it enters the first vapor permeation membrane separator 5 composed of 6 MFI molecular sieve membrane modules in series for dealcoholization and separation. The feed temperature in the first steam permeation membrane separator 5 is 120°C, the gauge pr...

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Abstract

The invention relates to a process and device for recycling dimethyl carbonate through a steam permeation method. The process comprises the specific steps that some byproducts are removed after a reaction solution is subjected to primary distillation, and a methanol-dimethyl carbonate azeotrope enters an extractive distillation tower from the middle and makes contact with spraying water on the top of the tower for extractive separation; methyl alcohol is separated out of liquid at the bottom of the extractive tower through a steam permeable membrane, water and trace dimethyl carbonate are retuned to the top of the extractive tower after being subjected to heat exchange, distillate on the top of the extractive tower is separated through a separator, the water layer at the bottom of the separator returns to the extractive tower, the organic matter layer on the upper portion of the separator is further heated to enter the steam permeable membrane, high-concentration dimethyl carbonate is separated out through the separator, the dimethyl carbonate enters a dimethyl carbonate storage pot after being condensed through a condenser, and permeable water returns to the top of the tower after being subjected to heat exchange. The process and device have the advantages that the technological process is simple, the safety coefficient is high, equipment investment is low, the energy utilization rate is high, and the recycling rate is high.

Description

technical field [0001] The invention relates to a process and a device for recovering dimethyl carbonate, in particular to a process and a device for recovering dimethyl carbonate by a steam permeation method, belonging to the application field of steam permeation membranes. Background technique [0002] Dimethyl carbonate is abbreviated as DMC. It is a colorless, transparent, slightly odorous and slightly sweet liquid at room temperature. It can form an azeotrope with water. It is an important intermediate in organic synthesis. DMC can replace highly toxic phosgene as a carbonylating agent, and it is also a new type of fuel additive and green solvent. Due to its special physical and chemical properties, it rarely pollutes the environment during production and application. It is known as "green" organic chemical products and the "new cornerstone" of organic synthesis, and has attracted attention at home and abroad. [0003] The production methods of dimethyl carbonate mai...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C68/08C07C69/96
CPCC07C68/08C07C69/96
Inventor 顾学红曲凡玉仲超宋瑛
Owner NANJING UNIV OF TECH
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