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Method for continuously producing glycolic acid

A technology of glycolic acid and oxalic acid, applied in chemical instruments and methods, preparation of organic compounds, separation/purification of carboxylic acid compounds, etc., can solve the problems of product separation, complicated refining, low cost of raw materials, high equipment requirements, etc. The effect of low requirements, less by-products, and high product purity

Active Publication Date: 2021-03-19
LINHAI LIANSHENG CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The yield of glycolic acid is close to 90% at 90MPa. This method has low cost of raw materials, but requires high equipment, and the separation and purification of products are complicated.

Method used

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  • Method for continuously producing glycolic acid
  • Method for continuously producing glycolic acid

Examples

Experimental program
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Effect test

Embodiment 1

[0064] (1) Dimethyl oxalate and water were mixed at a molar ratio of 60:1, preheated and passed into a hydrolysis reactor for self-catalyzed semi-hydrolysis reaction at a temperature of 50°C and a hydrolysis reaction time of 40 minutes. The hydrolyzate containing monomethyl oxalate obtained through hydrolysis reaction is purified through rectification to obtain monomethyl oxalate, wherein the selectivity of monomethyl oxalate is ≥ 95%. In addition, the water and dimethyl oxalate separated by atmospheric distillation and vacuum distillation can be returned to the hydrolysis reactor to continue to participate in the hydrolysis reaction.

[0065] (2) the monomethyl oxalate that step (1) obtains is passed in the fixed-bed reactor. At the same time, a certain amount of hydrogen gas was introduced so that the molar ratio of monomethyl oxalate to hydrogen gas was 1:50. At 150°C, the pressure is 1MPa, and the mass space velocity of monomethyl oxalate is 5h -1 Under the following con...

Embodiment 2

[0067] (1) Mix dimethyl oxalate and water at a molar ratio of 30:1, preheat and pass it into a hydrolysis reactor for self-catalyzed semi-hydrolysis reaction at a temperature of 50°C and a hydrolysis reaction time of 40 minutes. The hydrolyzed solution containing monomethyl oxalate obtained through hydrolysis is purified through rectification to obtain monomethyl oxalate, wherein the selectivity of monomethyl oxalate is ≥ 90%. In addition, the water and dimethyl oxalate separated by atmospheric distillation and vacuum distillation can be returned to the hydrolysis reactor to continue to participate in the hydrolysis reaction.

[0068] (2) the monomethyl oxalate that step (1) obtains is passed in the fixed-bed reactor. At the same time, a certain amount of hydrogen gas was introduced so that the molar ratio of monomethyl oxalate to hydrogen gas was 1:50. At 120°C, the pressure is 2MPa, and the mass space velocity of monomethyl oxalate is 0.1h -1 Under the conditions, the ZSM-...

Embodiment 3

[0070] (1) Dimethyl oxalate and water were mixed at a molar ratio of 10:1, preheated and passed into a hydrolysis reactor for self-catalyzed semi-hydrolysis reaction at a temperature of 50°C and a hydrolysis reaction time of 40 minutes. The hydrolyzed solution containing monomethyl oxalate obtained through hydrolysis is purified through rectification to obtain monomethyl oxalate, wherein the selectivity of monomethyl oxalate is ≥ 90%. In addition, the water and dimethyl oxalate separated by atmospheric distillation and vacuum distillation can be returned to the hydrolysis reactor to continue to participate in the hydrolysis reaction.

[0071] (2) the monomethyl oxalate that step (1) obtains is passed in the fixed-bed reactor. At the same time, a certain amount of hydrogen gas was introduced so that the molar ratio of monomethyl oxalate to hydrogen gas was 1:50. At 120°C, the pressure is 1MPa, and the mass space velocity of monomethyl oxalate is 3h -1 Under the present invent...

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Abstract

The invention provides a method for continuously producing glycolic acid, and the method comprises the following steps of: A) mixing dimethyl oxalate and water, performing preheating, carrying out autocatalytic semi-hydrolysis reaction, and rectifying and purifying the obtained hydrolysate to obtain monomethyl oxalate; and B) carrying out catalytic hydrogenation reaction on the monomethyl oxalateobtained in the step A) and hydrogen in the presence of a catalyst, and rectifying and purifying the reaction product to obtain glycollic acid. According to the method, a process of hydrolyzing and then hydrogenating is adopted, and a hydrolysis process is an autocatalytic semi-hydrolysis reaction, so that compared with an industrially adopted hydrolysis reaction, the method is easier to control,the amount of byproducts generated by the reaction is small, and the product yield is greatly improved; the hydrogenation reaction conditions of monomethyl oxalate are milder; no side reaction occursin the hydrogenation reaction, products in materials obtained through the reaction are easy to separate, and the product purity is high; the byproduct oxalic acid can be directly sold as a product, thereby reducing the generation of waste materials and following the green production principle.

Description

technical field [0001] The invention belongs to the technical field of organic synthesis, in particular to a method for continuous production of glycolic acid. Background technique [0002] Glycolic acid was mainly used in the manufacture of boiler descaling agents and cleaning agents in the past. In recent years, it has been widely used in cosmetics and pharmaceuticals, and it has also attracted attention as a raw material for polyglycolic acid. Glycolic acid can be used to prepare high molecular weight polyglycolic acid. Although traditional polymer materials such as PET, PE, PP, PS, etc. have brought a lot of convenience to the lives of ordinary people and played an important role in social and economic development, due to imperfect recycling and their own inability in the earth environment Degradable or difficult to degrade, causing serious "white pollution". With the increasing emphasis on environmental protection in society, various countries and regions have success...

Claims

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Application Information

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IPC IPC(8): C07C51/09C07C51/44C07C59/06C07C67/313C07C69/36
CPCC07C51/09C07C51/44C07C67/313C07C69/36C07C59/06
Inventor 黄斌黄卫国童斌陈多安姚素李燕虎陆盼婷严瑾
Owner LINHAI LIANSHENG CHEM
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