CN114989011A - Method for preparing diethyl terephthalate - Google Patents
Method for preparing diethyl terephthalate Download PDFInfo
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- CN114989011A CN114989011A CN202210509938.0A CN202210509938A CN114989011A CN 114989011 A CN114989011 A CN 114989011A CN 202210509938 A CN202210509938 A CN 202210509938A CN 114989011 A CN114989011 A CN 114989011A
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- terephthalate
- catalyst
- polyester
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- diethyl terephthalate
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/03—Preparation of carboxylic acid esters by reacting an ester group with a hydroxy group
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/48—Separation; Purification; Stabilisation; Use of additives
- C07C67/52—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/48—Separation; Purification; Stabilisation; Use of additives
- C07C67/52—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation
- C07C67/54—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation by distillation
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/584—Recycling of catalysts
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/62—Plastics recycling; Rubber recycling
Abstract
A process for producing diethyl terephthalate, the process comprising: (1) metal salt, oxide, chelate and complex are used as catalysts; (2) the reaction equipment is a high-pressure reaction kettle; (3) replacing a reaction kettle with nitrogen to be used as protective gas, weighing polyester, adding the polyester into the reaction kettle, adding ethanol and a catalyst to carry out depolymerization, closing a feed inlet to carry out reaction, cooling to the ambient temperature after the reaction is finished, and discharging the material; feeding the obtained material into a distillation kettle, and distilling off ethanol at normal pressure; distilling the ethylene glycol under reduced pressure, and then carrying out solvent extraction, washing and purification on the residue to obtain recrystallized diethyl terephthalate; and (4) after washing, taking the precipitate as a catalyst for recycling.
Description
Technical Field
The invention relates to a solid waste recycling technology in the field of resource recycling science, in particular to a method for preparing diethyl terephthalate by depolymerizing polyethylene glycol terephthalate. .
Background
Technique of
The polyester waste recycling refers to a technical method for recovering materials and energy from polyester waste by adopting management and process measures, accelerating the circulation of the materials and the energy and creating wide economic value. Reprocessing of the recovered polyester has disadvantages such as a small molecular weight and insufficient strength, and therefore, it is necessary to depolymerize the polyester into monomers for reuse.
The recycled plastic is the optimal solution for carbon neutralization of the plastic, the energy consumption is only 12.3 percent of that of the primary plastic, the carbon emission is only 62.2 percent of that of the primary plastic, and compared with the degradable plastic, the energy resources such as petroleum and the like can be greatly saved. The current european food grade recycled plastic demand of nearly 100 million tons per year has been rapidly opened, and the price of the recycled material is about $ 500/ton higher than that of the original raw material. The development space of domestic recycled plastics is quickly opened, and the English recycling (southeast Asia + domestic double layout, channel + obvious technical pre-development advantages) and the triple rainbow common (advanced technical process, complete layout in the fields of rPET, polyester, chemical fiber and the like) of the recycled plastic head enterprises are suggested to be concerned.
With the existing technology: the plastic bottle is recycled to be used for producing polyester fiber clothes, and the synthetic polyester method is used for producing a common garment from raw materials to ready-made clothes and then to be finally abandoned, and carbon dioxide is discharged; and the polyester has high molecular weight and insufficient strength during reprocessing.
Disclosure of Invention
The purpose of the invention is as follows: the invention provides a novel polyester depolymerization recovery method, namely a method for preparing diethyl terephthalate, aiming at the technical defects of large molecular weight, insufficient strength and the like in polyester reprocessing existing in the prior art for recovering polyethylene glycol terephthalate by a polyester synthesis method.
The technical scheme is as follows:
a process for producing diethyl terephthalate, the process comprising the steps of:
(1) screening the catalyst, namely taking metal salts, oxides, chelates and complexes of zinc, titanium, aluminum and magnesium as the catalyst, preferably taking a terephthalic acid series multivalent salt as the catalyst;
(2) the reaction equipment is a high-pressure reaction kettle with the pressure of 3-10 MPa;
(3) replacing a reaction kettle with nitrogen to be used as protective gas, weighing polyester, adding the polyester into the reaction kettle, adding ethanol with the mass of 0.5-4 times that of the polyester and a catalyst with the mass of 0.001-0.005 time that of the polyester for depolymerization, and closing a feed inlet; controlling the temperature of the reaction kettle to be 140-; cooling to ambient temperature and discharging the material; feeding the obtained material into a distillation kettle, and distilling off ethanol at normal pressure; distilling the ethylene glycol under reduced pressure at-0.05 MPa and 120 ℃, and then carrying out solvent extraction, washing and purification on the residue to obtain diethyl terephthalate; and (4) after washing, taking the precipitate as a catalyst for recycling.
Further, the polyester is a polyethylene glycol terephthalate material, the polyethylene glycol terephthalate, ethanol and a catalyst are placed in a reactor, and under the protection of nitrogen, the mixture reacts at the temperature of 140-240 ℃ for 0.5-2 hours, and then is filtered, so that solid and liquid crude products are obtained and sent to a distillation still.
Further, distilling out ethanol in the distillation kettle at normal pressure; raising the temperature of the system to 140-160 ℃, keeping the temperature, connecting a vacuum pump, and carrying out reduced pressure distillation, wherein the liquid obtained by reduced pressure distillation is ethylene glycol; washing residues with water, recrystallizing and recovering to obtain diethyl terephthalate, and recycling precipitates as a catalyst.
Further, when polyethylene terephthalate is depolymerized, the mass ratio of the polyethylene terephthalate to the catalyst is 1: 0.001-0.005; the mass of the ethanol is 0.5-4 times that of the polyester.
An application for preparing diethyl terephthalate.
As a starting material for fine chemicals/pharmaceutical intermediates; the catalyst is used for synthesizing high-quality polyethylene terephthalate and medicines, and can be recycled.
Compared with the prior art, the invention has the following advantages:
at present, no relevant research on preparation of diethylene glycol terephthalate by a polyester depolymerization method exists, and diethyl terephthalate is prepared aiming at the technical defects of large molecular weight, insufficient strength and the like in the process of synthesizing polyester, so that the diethyl terephthalate has small molecular weight and high strength; the waste can be changed into valuable, and the national laws and related planning requirements are met; the emission of 2.5 kilograms of carbon dioxide can be reduced by reducing one piece of clothes manufactured by the prior process. The depolymerization process of polyethylene terephthalate can recover the waste clothes.
The invention takes the terephthalic acid series high-valence salt as the catalyst, and realizes the regeneration and resource utilization of the polyester according to the principle of introducing no or little impurities; the polyester depolymerization method for preparing diethyl terephthalate has short reaction time and high speed, the catalyst can be recycled, and the obtained product has high purity and can be used as a raw material of fine chemicals/medical intermediates; the catalyst is used for synthesizing high-quality polyethylene glycol terephthalate and medicines, and can be recycled.
Description of the drawings:
FIG. 1 is a chart of an infrared spectrum of polyethylene terephthalate according to the present invention;
FIG. 2 is an infrared spectrum of a diethyl terephthalate sample of example 1 in accordance with the present invention;
FIG. 3 is an infrared spectrum of a sample of diethyl terephthalate of example 2 of the present invention;
FIG. 4 is a chart of an infrared spectrum of a sample of diethyl terephthalate of example 3 of the present invention;
FIG. 5 is an infrared spectrum of a diethyl terephthalate standard sample of the present invention.
The specific implementation mode is as follows:
a method for preparing diethyl terephthalate comprises the following steps:
(1) screening the catalyst, namely taking metal salts, oxides, chelates and complexes of zinc, titanium, aluminum and magnesium as the catalyst, preferably taking a terephthalic acid series multivalent salt as the catalyst;
(2) the reaction equipment is a high-pressure reaction kettle with the pressure of 3-10 MPa;
(3) replacing a reaction kettle with nitrogen to be used as protective gas, weighing polyester, adding the polyester into the reaction kettle, adding ethanol with the mass of 0.5-4 times that of the polyester and a catalyst with the mass of 0.001-0.005 time that of the polyester for depolymerization, and closing a feed inlet; controlling the temperature of the reaction kettle to be 140-; cooling to ambient temperature and discharging the material; feeding the obtained material into a distillation kettle, and distilling off ethanol at normal pressure; distilling the ethylene glycol under reduced pressure at-0.05 MPa and 120 ℃, and then carrying out solvent extraction, washing and purification on the residue to obtain diethyl terephthalate; and (4) after washing, taking the precipitate as a catalyst for recycling.
The polyester is a polyethylene glycol terephthalate material, the polyethylene glycol terephthalate, ethanol and a catalyst are put into a reactor, and under the protection of nitrogen, the reaction is finished for 0.5 to 2 hours at the temperature of 140 to 240 ℃ and then the reaction is filtered, so as to obtain solid and liquid crude product materials which are sent into a distillation still.
Distilling off ethanol in a distillation still at normal pressure; raising the temperature of the system to 140-160 ℃, keeping the temperature, connecting a vacuum pump, and carrying out reduced pressure distillation, wherein the liquid obtained by reduced pressure distillation is ethylene glycol; washing residues with water, recrystallizing and recovering to obtain diethyl terephthalate, and recycling precipitates as a catalyst.
When polyethylene terephthalate depolymerization is carried out, the mass ratio of the polyethylene terephthalate to the catalyst is 1: 0.001-0.005; the mass of the ethanol solvent is 0.5-4 times of that of the polyester.
An application for preparing diethyl terephthalate.
As a raw material for fine chemicals/pharmaceutical intermediates; the catalyst is used for synthesizing high-quality polyethylene terephthalate and medicines, and can be recycled.
The present invention will be described in detail with reference to the following specific examples:
example 1:
10g of polyethylene terephthalate material, polyester, ethanol and a catalyst (magnesium terephthalate) are weighed according to the proportion of 1:4:0.001 and added into a reaction kettle to react for 2.0 hours at 140 ℃ and 5MPa under the protection of nitrogen. After the reaction, the product was distilled under reduced pressure to obtain 34.2g of ethanol and 4.3g of ethylene glycol. The residue was washed with water and recrystallized to recover 11.5g of diethyl terephthalate (see FIG. 1 for details). The precipitate is reused as catalyst.
Example 2:
weighing 10g of polyethylene terephthalate material, polyester, ethanol and a catalyst (titanium terephthalate) according to the ratio of 1:3:0.004, adding into a reaction kettle, and reacting at 180 ℃ and 7MPa for 1.5 hours under the protection of nitrogen. After the reaction, the product was distilled under reduced pressure to obtain 23.8g of ethanol and 4.2g of ethylene glycol. The residue is washed by water and recrystallized to obtain 12g of diethyl terephthalate (see the attached figure 2 for details). The precipitate is reused as catalyst.
Example 3:
10g of polyethylene terephthalate material, polyester, ethanol and a catalyst (zinc terephthalate) are weighed and added into a reaction kettle according to the proportion of 1:3:0.004, and reacted for 1.5 hours at 200 ℃ and 8MPa under the protection of nitrogen. After the reaction is finished, the product is distilled under reduced pressure frequently to obtain 23.8g of ethanol and 4.4g of ethylene glycol. The residue was washed with water and recrystallized to obtain 11.8g of diethyl terephthalate (see FIG. 3 for details). The precipitate is reused as catalyst.
Example 4:
10g of polyethylene terephthalate material, polyester, ethanol and catalyst (aluminum terephthalate) are weighed according to the proportion of 1:0.5:0.005 and added into a reaction kettle to react for 0.5 hour at the temperature of 240 ℃ and under the pressure of 9MPa under the protection of nitrogen. After the reaction, the product was distilled under reduced pressure to obtain 5.3g of ethanol and 3.1g of ethylene glycol. The residue was washed with water and recrystallized to obtain 8.6g of diethyl terephthalate. The precipitate is reused as catalyst. The product characteristics are very similar to those of the attached figures 2, 3 and 4.
FIG. 1 is an infrared spectrum of polyethylene terephthalate (1700 cm) -1 And 700cm -1 The characteristic peaks are shown in the specification, and the characteristic peaks are carbonyl and phenyl respectively. FIG. 2, FIG. 3 and FIG. 4 are the infrared spectra of the sample of example 1, the sample of example 2 and the sample of example 3, wherein 3080cm -1 And 700cm -1 Is phenyl at 2850-3000 cm -1 Three peaks in between are methyl and methylene, 1700cm -1 The position is carbonyl, and the attached figure 5 is an infrared spectrogram of a diethyl terephthalate standard substance. The infrared spectrum of 3 samples of the examples is basically consistent with the infrared spectrum of the standard, and the product is proved to be diethyl terephthalate.
The invention takes the terephthalic acid series high-valence salt as the catalyst, and realizes the regeneration and resource utilization of the polyester according to the principle of introducing no or little impurities; the polyester depolymerization method for preparing diethyl terephthalate has short reaction time and high speed, the catalyst can be recycled, and the obtained product has high purity and can be used as a raw material of fine chemicals/medical intermediates; the catalyst is used for synthesizing high-quality polyethylene glycol terephthalate and medicines, and can be recycled.
In addition to the above examples, the present invention has other embodiments (such as selection of washing solvent, etc.), and all technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope claimed by the present invention.
Claims (10)
1. A method for preparing diethyl terephthalate is characterized in that: the method comprises the following steps:
(1) metal salt, oxide, chelate and complex are used as catalysts;
(2) the reaction equipment is a high-pressure reaction kettle;
(3) replacing a reaction kettle with nitrogen to be used as protective gas, weighing polyester, adding the polyester into the reaction kettle, adding ethanol and a catalyst to carry out depolymerization, closing a feed inlet to carry out pressure heating reaction, cooling to the ambient temperature after the reaction is finished, and discharging the material; feeding the obtained material into a distillation kettle, and distilling off ethanol at normal pressure; then carrying out reduced pressure distillation to obtain ethylene glycol, and then carrying out solvent extraction, water washing and purification on the remainder to obtain recrystallized diethyl terephthalate; and (4) recycling the precipitate after washing as a catalyst.
2. The process for producing diethyl terephthalate as claimed in claim 1, wherein: the step (1) takes metal salts, oxides, chelates and complexes of zinc, titanium, aluminum and magnesium as catalysts.
3. The process for producing diethyl terephthalate as claimed in claim 2, wherein: the catalyst is terephthalic acid series multivalent salt.
4. The process for producing diethyl terephthalate as claimed in claim 3, wherein: the catalyst is selected from titanium terephthalate and aluminum terephthalate.
5. The process for producing diethyl terephthalate as claimed in claim 1, wherein: the pressure-bearing pressure of the high-pressure reaction kettle in the step (2) is 3-10 MPa.
6. The process for producing diethyl terephthalate as claimed in claim 1, wherein: in the step (3), the polyester is polyethylene glycol terephthalate and modified polyester thereof, and the adding amount of the ethanol is 0.5-4 times of the mass of the polyester; the addition amount of the catalyst is 0.001-0.005 times of the mass of the polyester.
7. The process for producing diethyl terephthalate as claimed in claim 1, wherein: the reaction temperature in the step (3) is controlled to be 140-240 ℃; the reaction pressure is 5-9MPa, and the reaction time is 0.5-2.0 hours, so as to obtain solid and liquid crude products.
8. The process for producing diethyl terephthalate as claimed in claim 1, wherein: the reduced pressure distillation in the step (3) is carried out under the conditions of-0.05 MPa and 120 ℃, the system temperature is increased to 140 ℃ and 160 ℃ after the ethanol distillation is finished, the temperature is kept, a vacuum pump is connected for reduced pressure distillation, and the liquid obtained by reduced pressure distillation is ethylene glycol.
9. An application for preparing diethyl terephthalate.
10. The use according to claim 9 for the preparation of diethyl terephthalate, wherein: as a raw material for fine chemicals/pharmaceutical intermediates; the catalyst can be repeatedly used when being used for synthesizing polyethylene terephthalate and medicines.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210509938.0A CN114989011A (en) | 2022-05-11 | 2022-05-11 | Method for preparing diethyl terephthalate |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210509938.0A CN114989011A (en) | 2022-05-11 | 2022-05-11 | Method for preparing diethyl terephthalate |
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| CN202210509938.0A Pending CN114989011A (en) | 2022-05-11 | 2022-05-11 | Method for preparing diethyl terephthalate |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1413178A (en) * | 1999-10-22 | 2003-04-23 | 帝人株式会社 | Method for separating and recovering dimethyl terephthalate and ethylene glycol from polyester waste |
| CN101565374A (en) * | 2009-04-03 | 2009-10-28 | 北京化工大学 | Method for depolymerizing waste polyester |
| CN107417492A (en) * | 2017-06-28 | 2017-12-01 | 中国科学院山西煤炭化学研究所 | A kind of method of controlled degradation recovery pet material |
-
2022
- 2022-05-11 CN CN202210509938.0A patent/CN114989011A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1413178A (en) * | 1999-10-22 | 2003-04-23 | 帝人株式会社 | Method for separating and recovering dimethyl terephthalate and ethylene glycol from polyester waste |
| CN101565374A (en) * | 2009-04-03 | 2009-10-28 | 北京化工大学 | Method for depolymerizing waste polyester |
| CN107417492A (en) * | 2017-06-28 | 2017-12-01 | 中国科学院山西煤炭化学研究所 | A kind of method of controlled degradation recovery pet material |
Non-Patent Citations (1)
| Title |
|---|
| 上海医药工业研究院药物制剂研究中心编著: "《药用辅料应用技术》", 中国医药科技出版社, pages: 179 * |
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