CN-122010717-A - Method for preparing glycolic acid by using chloroacetic acid high-boiling-point substances

CN122010717ACN 122010717 ACN122010717 ACN 122010717ACN-122010717-A

Abstract

The invention belongs to the technical field of acyclic compounds, and particularly relates to a method for preparing glycolic acid by using chloroacetic acid high-boiling residues. Adding water and hydrogen chloride into chloroacetic acid high-boiling residues to perform primary hydrolysis reaction to obtain primary hydrolysis liquid, adding a catalyst into the primary hydrolysis liquid to perform secondary hydrolysis reaction to obtain secondary hydrolysis liquid, cooling the secondary hydrolysis liquid after distillation and dehydration, adding a solvent to extract and separate liquid to obtain reaction liquid, cooling and crystallizing the reaction liquid, centrifuging to obtain a glycolic acid crude product, adding water into the glycolic acid crude product to pulp, cooling and crystallizing, filtering and drying to obtain a glycolic acid finished product. Compared with the production of the glycolic acid by alkali reaction, the method does not produce salt, and does not produce a large amount of wastewater by the application of evaporated water and post-treated water.

Inventors

MA ZHENG
ZHANG MENG
LI PING
JIA HAIPENG
GUO MENGLI
CHEN XIANGYUN
ZHANG JIAYU
SHI LUJUN
TAN PENGHUI

Assignees

湖北民腾新材料科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260410

Claims (10)

1. A method for preparing glycolic acid by using chloroacetic acid high-boiling residues is characterized by comprising the following steps: (1) Adding water and hydrogen chloride into chloroacetic acid high-boiling residues to perform primary hydrolysis reaction to obtain primary hydrolysate; (2) Adding a catalyst into the primary hydrolysate obtained in the step (1) to perform a secondary hydrolysis reaction to obtain a secondary hydrolysate; (3) Distilling and dehydrating the secondary hydrolysate obtained in the step (2), cooling, and adding a solvent to extract and separate liquid to obtain a reaction liquid; (4) Cooling and crystallizing the reaction solution, and centrifuging to obtain a crude product of glycolic acid; (5) And (3) adding water into the crude glycolic acid product for pulping, cooling for crystallization, filtering and drying to obtain a finished product of glycolic acid.
2. The method for preparing glycolic acid by using the chloroacetic acid high-boiling residue according to claim 1, wherein the chloroacetic acid high-boiling residue composition in the step (1) comprises 55-60% of chloroacetic acid, 8-12% of dichloroacetic acid and 10-15% of 2- (2-chloroacetoxy) acetic acid in percentage by mass.
3. The method for preparing glycolic acid by using the chloroacetic acid high-boiling residue according to claim 1, wherein the mass ratio of the chloroacetic acid high-boiling residue to water in the step (1) is 1:0.8-1.3, and the mass ratio of the chloroacetic acid high-boiling residue to hydrogen chloride is 1:0.5-0.8.
4. The method for preparing glycolic acid by using chloroacetic acid high boiling residues according to claim 1, wherein the temperature of the primary hydrolysis reaction in the step (1) is 60-80 ℃, and the time of the primary hydrolysis reaction is 4-6h.
5. The method for preparing glycolic acid by using chloroacetic acid high-boiling residues according to claim 1, wherein the catalyst in the step (2) is aluminum trichloride and zinc chloride, the mass ratio of the aluminum trichloride to the zinc chloride is 6-8:1, and the addition amount of the catalyst is 0.5-1% of the mass of the chloroacetic acid high-boiling residues in the step (1).
6. The method for preparing glycolic acid by using chloroacetic acid high-boiling residues according to claim 1, wherein the temperature of the secondary hydrolysis reaction in the step (2) is 140-160 ℃, and the time of the secondary hydrolysis reaction is 10-16 hours.
7. The method for preparing glycolic acid by using chloroacetic acid high-boiling residues according to claim 1, wherein the amount of water dehydrated in the step (3) is 55-70% of the mass of water in the step (1), and the temperature is reduced to 60-75 ℃.
8. The method for preparing glycolic acid by using the chloroacetic acid high-boiling residue according to claim 1, wherein the solvent in the step (3) is toluene or xylene, and the addition amount of the solvent is 13-20% of the mass of the chloroacetic acid high-boiling residue in the step (1).
9. The method for preparing glycolic acid by using chloroacetic acid high-boiling residues according to claim 1, wherein the temperature of cooling crystallization in the step (4) is 10-20 ℃.
10. The method for preparing glycolic acid by using chloroacetic acid high-boiling residues according to claim 1, wherein in the step (5), the mass ratio of the crude glycolic acid to water is 1:0.2-0.4, the pulping temperature is 40-50 ℃, the pulping time is 0.5-1h, and the temperature of cooling crystallization is 10-20 ℃.

Description

Method for preparing glycolic acid by using chloroacetic acid high-boiling-point substances Technical Field The invention belongs to the technical field of acyclic compounds, and particularly relates to a method for preparing glycolic acid by using chloroacetic acid high-boiling residues. Background The chloroacetic acid production process with acetic anhydride as catalyst uses acetic acid as material and includes chlorination, hydration, hydrogenation and rectification. Because of the mutual reaction of different byproducts in each flow and the tarry of substances at high temperature, some high-boiling substances inevitably exist after rectification, part of the high-boiling substances are chloroacetic acid, and complex compounds such as 2- (2-chloroacetoxy) acetic acid and the like are also included, and although the compounds are relatively complex, substances related to chloroacetic acid structures are relatively large in the rectified high-boiling substances. The existing chloroacetic acid high-boiling-point substance treatment modes generally have two modes, one is biochemical treatment, and the other is incineration by using an incinerator. The main component of the chloroacetic acid high-boiling point is chloroacetic acid, the chloroacetic acid generally accounts for more than 55% of the components of the high-boiling point substances (different high-boiling point substances can be different due to different process conditions), and the chloroacetic acid high-boiling point substances are materials which need to be discharged irregularly in order to control high-boiling point impurities in the chloroacetic acid in the continuous production and rectification process of the chloroacetic acid. The composition of the high-boiling-point substances includes chloroacetic acid, dichloroacetic acid, 2- (2-chloroacetoxy) acetic acid and other substances, and the ester substances mainly comprise ester derivatives of chloroacetic acid. Glycolic acid is the simplest hydroxy acid, can be used as tanning auxiliary agent, water disinfectant, cow-shed disinfectant, boiler scale remover and the like, and has a large number of reports at present because the glycolic acid can react with carboxyl itself. The current industrial production method of glycolic acid uses chloroacetic acid as raw material, and alkaline hydrolysis is carried out to obtain glycolic acid. In view of cost, the use of caustic soda flakes or other types of caustic soda to treat chloroacetic acid high boiling residues is relatively costly, and salts are generated during the production process, which are generally treated as solid wastes in industry, so that if caustic soda is used to treat chloroacetic acid high boiling residues, only one waste is converted into another waste. Chinese patent CN104744239A discloses a preparation method of glycolic acid, which comprises the following steps of sequentially carrying out hydrolysis reaction on an aqueous solution of hydroxyacetonitrile and a sulfuric acid solution with the mass concentration of 70% -90% at 120 ℃ -140 ℃ to obtain a mixed solution of glycolic acid and ammonium sulfate acid salt, adding methanol into the mixed solution to carry out esterification reaction, distilling out a mixture of methanol, water and methyl glycolate, controlling the whole process to be carried out at 110 ℃ -120 ℃, adding water to adjust the mass percentage of the methyl glycolate in the mixture to 10% -25%, hydrolyzing the methyl glycolate into the glycolic acid at the temperature of less than or equal to 100 ℃, and separating out methanol and water, wherein the separated methanol is recycled. The technology of the patent is complex, and the treatment and utilization of chloroacetic acid high-boiling residues are not involved. Disclosure of Invention The invention aims to provide a method for preparing glycolic acid by using chloroacetic acid high-boiling residues, which can effectively utilize the chloroacetic acid high-boiling residues, does not use alkali as a reactant, and is easy to post-treat water generated after production because salt is not generated in the preparation process. The method for preparing the glycolic acid by adopting the chloroacetic acid high-boiling-point substance comprises the following steps: (1) Adding water and hydrogen chloride into chloroacetic acid high-boiling residues to perform primary hydrolysis reaction to obtain primary hydrolysate; (2) Adding a catalyst into the primary hydrolysate obtained in the step (1) to perform a secondary hydrolysis reaction to obtain a secondary hydrolysate; (3) Distilling and dehydrating the secondary hydrolysate obtained in the step (2), cooling, and adding a solvent to extract and separate liquid to obtain a reaction liquid; (4) Cooling and crystallizing the reaction solution, and centrifuging to obtain a crude product of glycolic acid; (5) And (3) adding water into the crude glycolic acid product for pulping, cooling for crystallization, filtering and