CN112441917B - Process for recovering terephthalate from waste PET - Google Patents
Process for recovering terephthalate from waste PET Download PDFInfo
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- CN112441917B CN112441917B CN201910835007.8A CN201910835007A CN112441917B CN 112441917 B CN112441917 B CN 112441917B CN 201910835007 A CN201910835007 A CN 201910835007A CN 112441917 B CN112441917 B CN 112441917B
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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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- 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
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Abstract
The invention relates to a method for recovering terephthalate from waste PET, which mainly solves the problems of low reaction speed and low product yield in the prior art. The present invention adopts a method for recovering terephthalate from waste PET, comprising: (1) Adding waste PET, terephthalic acid, alkyl alcohol and an ester exchange catalyst into a reactor to obtain an initial reaction mixture; (2) The technical scheme of reacting the PET with the alkyl alcohol under the condition of ester exchange reaction to obtain the terephthalate better solves the technical problem and can be used for recycling the waste polyester PET.
Description
Technical Field
The present invention relates to a process for recovering terephthalate from waste PET.
Background
Purified terephthalic acid, commonly known as PTA, is a basic raw material for synthesizing polyethylene terephthalate (PET), the demand of which is continuously increased, and the demand of global PTA is estimated to reach 6000 million tons in 2018. Meanwhile, a large amount of waste PET is generated every year, and although the waste PET does not harm the environment greatly, the waste PET is degraded slowly in nature and also has great harm to the environment due to accumulation. At present, the recovery method of the waste PET mainly comprises a physical method and a chemical method, wherein the physical method mainly adopts a mechanical recovery method and a hot melting method, and the recovered product can only be used for producing low-end products; the chemical method comprises a chemical improvement method and a chemical alcoholysis method, the chemical method technology is not mature enough, the purity of the recovered product is low, and the application is also limited greatly.
Chinese patent CN201710017715 (a method for recycling waste polyester PET at low temperature and high efficiency) discloses a method for recycling waste PET, which uses NaOH and quaternary ammonium salt as catalysts, and produces dimethyl terephthalate (DMT) through low temperature methanolysis, and then reacts with SO2 to obtain a main product terephthalic acid with purity of about 92%, but the whole reaction time is too long, and meanwhile, the product post-treatment method is too long, and a large amount of waste water is also caused due to the use of NaOH.
Chinese patent CN201110456201 (a method for preparing plasticizer terephthalate by waste polyester PET alcoholysis) discloses a recovery method, wherein a bi-acid ionic liquid catalyst is adopted, isooctyl alcohol is taken as an alcoholysis agent, and the reaction is carried out for 9 hours at 190 ℃ to obtain 94.9% diisooctyl terephthalate. Long reaction time and large catalyst consumption.
Disclosure of Invention
The invention aims to solve the technical problems of low reaction speed and low product yield in the prior art, and provides a method for recovering terephthalate from waste PET.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
a method of recovering terephthalate from waste PET comprising:
(1) Adding waste PET, terephthalic acid, alkyl alcohol and an ester exchange catalyst into a reactor to obtain an initial reaction mixture;
(2) Reacting PET and alkyl alcohol under the condition of ester exchange reaction to obtain the terephthalate.
Because terephthalic acid is added into the initial reaction mixture, the transesterification reaction of alkyl alcohol and PET is promoted, and the method has the characteristics of high reaction speed or high yield of target products.
In the above-mentioned aspect, the alkyl alcohol is preferably a C1 to C8 alcohol, and is, for example, at least one selected from the group consisting of a C1 alkyl alcohol, a C2 alkyl alcohol, a C3 alkyl alcohol, a C4 alkyl alcohol, a C5 alkyl alcohol, a C6 alkyl alcohol, a C7 alkyl alcohol and a C8 alkyl alcohol.
In the above technical solution, the alkyl alcohol is preferably a monohydric alcohol.
In the above technical solution, preferably, the transesterification catalyst includes a substance having a halogenated imidazole structure in a molecule.
In the above technical solution, it is preferable that the substance having a halogenated imidazole structure in a molecule corresponds to the following formula I:
wherein, R1 and R2 are independently selected from C1-C4 alkyl, such as but not limited to, R1 and R2 are independently selected from C1 alkyl, C2 alkyl, C3 alkyl or C4 alkyl; and X is Cl or Br.
In the above technical scheme, the mass ratio of terephthalic acid to waste PET in the initial reaction mixture is preferably 0.05-1; for example, but not limited to, the mass ratio of terephthalic acid to waste PET in the initial reaction mixture is 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, and the like.
In the technical scheme, the mass ratio of the alkyl alcohol to the waste PET in the initial reaction mixture is preferably 3-10; for example, but not limited to, the mass ratio of alkyl alcohol to waste PET in the initial reaction mixture is 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, and so forth.
In the technical scheme, the mass ratio of the catalyst to the waste PET in the initial reaction mixture is preferably 0.01-0.1; for example, but not limited to, the mass ratio of catalyst to spent PET in the initial reaction mixture is 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, and the like.
In the technical scheme, the reaction temperature in the step (2) is preferably 250-300 ℃; for example, but not limited to, the reaction temperature in step (2) is 255 ℃, 260 ℃, 265 ℃, 270 ℃, 275 ℃, 280 ℃, 285 ℃, 290 ℃, 295 ℃ and the like.
In the technical scheme, the pressure of the reaction in the step (2) is 8-15 MPa; for example, but not limited to, the pressure of the reaction of step (2) is 8.5MPa, 9MPa, 9.5MPa, 10MPa, 10.5MPa, 11MPa, 11.5MPa, 12MPa, 12.5MPa, 13MPa, 13.5MPa, 14MPa, 14.5MPa, etc.
In the technical scheme, the reaction time of the step (2) is preferably 30-240 min; such as, but not limited to, the reaction time of step (2) is 40min, 50min, 60min, 70min, 80min, 90min, 100min, 110min, 120min, 130min, 140min, 150min, 160min, 170min, 180min, 190min, 200min, 210min, 220min, 230min, and the like.
When step (2) is completed, there is no particular limitation on the method for separation and purification from the product mixture, and those skilled in the art can make a reasonable choice without inventive effort.
In the products of the examples and the comparative examples of the invention, the liquid phase adopts gas chromatography, and the chromatographic conditions are as follows: GDX-103 packed column (2 m × 4 mm), FID detector, and internal standard method for product quantification; after the solid phase is dried, the solid phase is dissolved in methanol and analyzed by High Performance Liquid Chromatography (HPLC), and the chromatographic conditions are as follows: the column temperature is 30 ℃, the wavelength of the detector is 254nm, the mobile phase comprises methanol, acetonitrile and phosphate buffer solution, and the sample injection amount is 5ul; the mobile phase composition (V/V) is as follows: 25% of methanol, 20% of acetonitrile, 55% of phosphate buffer (1 thousandth V/V) and 3-4% of PH; the flow rate was 1mL/min. Quantification was performed by internal standard method.
Actual DMT mass = DMT mass in product-terephthalic acid mass x 194 ÷ 166;
theoretical DMT mass = mass of DMT produced by complete alcoholysis of PET.
The method for recycling the waste polyester PET has the advantages of low catalyst consumption, short reaction time, high DMT yield and better effect.
The invention is further illustrated by the following examples.
Detailed Description
[ example 1 ]
The reaction was carried out in a 500ml autoclave made of titanium material with a magnetic stirrer, a gas feed pipe, a reflux condenser, a thermocouple, and a rupture disk, with a stirring speed of 400rpm, and electrically heated. The reaction steps are as follows:
1) 10g of waste polyester PET, 3g of terephthalic acid, 80g of methanol and 0.15g of 1, 3-dimethyl imidazolium bromide salt are weighed, uniformly mixed, added into an autoclave and sealed.
2) Adding 10.0MPa nitrogen gas to carry out airtight test for 30min, and determining that the pressure drop is not more than 0.1MPa within 30min.
3) And (3) decompressing to normal pressure, then purging for 3 times by using nitrogen, closing an air inlet switch, starting a stirrer, raising the temperature to 280 ℃ at the stirring speed of 400rpm, and reacting for 60min at 280 ℃ while keeping the pressure of 10.0 MPa.
4) And after the reaction, switching to nitrogen again, cooling to room temperature, relieving pressure, adding 100g of pure water at 5 ℃ into the reaction kettle, discharging, performing vacuum filtration to obtain a solid sample and a liquid sample, washing the solid sample with pure water for 5 times, wherein the using amount of the pure water is 500ml each time, performing suction filtration on the washed product, drying at 110 ℃ for 8 hours, and cooling and analyzing.
Specific reaction conditions and product data analysis are shown in table 1.
[ example 2 ]
The reaction was carried out in a 500ml autoclave made of titanium material with a magnetic stirrer, a gas feed pipe, a reflux condenser, a thermocouple, and a rupture disk, with a stirring speed of 400rpm, and electrically heated. The reaction steps are as follows:
1) 10g of waste polyester PET, 1g of terephthalic acid, 80g of methanol and 0.15g of 1, 3-dimethyl imidazolium bromide salt are weighed, uniformly mixed, added into an autoclave and sealed.
2) Adding 10.0MPa nitrogen gas to carry out airtight test for 30min, and determining that the pressure drop is not more than 0.1MPa within 30min.
3) And (3) releasing the pressure to normal pressure, then purging for 3 times by using nitrogen, closing an air inlet switch, starting a stirrer, raising the temperature to 280 ℃ at a stirring speed of 400rpm, and reacting for 60min at 280 ℃ while keeping the pressure of 10.0 MPa.
4) And after the reaction, switching to nitrogen again, cooling to room temperature, relieving pressure, adding 100g of pure water at 5 ℃ into the reaction kettle, discharging, performing vacuum filtration to obtain a solid sample and a liquid sample, washing the solid sample with pure water for 5 times, wherein the using amount of the pure water is 500ml each time, performing suction filtration on the washed product, drying at 110 ℃ for 8 hours, and cooling and analyzing.
Specific reaction conditions and product data analysis are shown in table 1.
[ example 3 ]
The reaction was carried out in a 500ml autoclave made of titanium material with a magnetic stirrer, a gas feed pipe, a reflux condenser, a thermocouple, and a rupture disk, with a stirring speed of 400rpm, and electrically heated. The reaction steps are as follows:
1) 10g of waste polyester PET, 6g of terephthalic acid, 80g of methanol and 0.15g of 1, 3-dimethyl imidazolium bromide salt are weighed, uniformly mixed, added into an autoclave and sealed.
2) Adding 10.0MPa nitrogen gas to carry out airtight test for 30min, and determining that the pressure drop is not more than 0.1MPa within 30min.
3) And (3) decompressing to normal pressure, then purging for 3 times by using nitrogen, closing an air inlet switch, starting a stirrer, raising the temperature to 280 ℃ at the stirring speed of 400rpm, and reacting for 60min at 280 ℃ while keeping the pressure of 10.0 MPa.
4) And after the reaction, switching to nitrogen again, cooling to room temperature, relieving pressure, adding 100g of pure water at 5 ℃ into the reaction kettle, unloading, performing vacuum filtration to obtain a solid sample and a liquid sample, washing the solid sample with pure water for 5 times, wherein the using amount of the pure water is 500ml each time, performing suction filtration on the washed product, drying at 110 ℃ for 8h, and cooling for analysis.
Specific reaction conditions and product data analysis are shown in table 1.
[ example 4 ]
The reaction was carried out in a 500ml autoclave made of titanium material with a magnetic stirrer, a gas feed pipe, a reflux condenser, a thermocouple, and a rupture disk, with a stirring speed of 400rpm, and electrically heated. The reaction steps are as follows:
1) 10g of waste polyester PET, 3g of terephthalic acid, 30g of methanol and 0.15g of 1, 3-dimethyl imidazolium bromide salt are weighed, uniformly mixed, added into an autoclave and sealed.
2) Adding 10.0MPa nitrogen gas to carry out airtight test for 30min, and determining that the pressure drop is not more than 0.1MPa within 30min.
3) And (3) releasing the pressure to normal pressure, then purging for 3 times by using nitrogen, closing an air inlet switch, starting a stirrer, raising the temperature to 280 ℃ at a stirring speed of 400rpm, and reacting for 60min at 280 ℃ while keeping the pressure of 10.0 MPa.
4) And after the reaction, switching to nitrogen again, cooling to room temperature, relieving pressure, adding 100g of pure water at 5 ℃ into the reaction kettle, discharging, performing vacuum filtration to obtain a solid sample and a liquid sample, washing the solid sample with pure water for 5 times, wherein the using amount of the pure water is 500ml each time, performing suction filtration on the washed product, drying at 110 ℃ for 8 hours, and cooling and analyzing.
Specific reaction conditions and product data analysis are shown in table 1.
[ example 5 ]
The reaction was carried out in a 500ml autoclave made of titanium material with a magnetic stirrer, a gas feed pipe, a reflux condenser, a thermocouple, and a rupture disk, with a stirring speed of 400rpm, and electrically heated. The reaction steps are as follows:
1) 10g of waste polyester PET, 3g of terephthalic acid, 100g of methanol and 0.15g of 1, 3-dimethyl imidazolium bromide salt are weighed, uniformly mixed, added into an autoclave and sealed.
2) Adding 10.0MPa nitrogen gas to carry out airtight test for 30min, and determining that the pressure drop is not more than 0.1MPa within 30min.
3) And (3) decompressing to normal pressure, then purging for 3 times by using nitrogen, closing an air inlet switch, starting a stirrer, raising the temperature to 280 ℃ at the stirring speed of 400rpm, and reacting for 60min at 280 ℃ while keeping the pressure of 10.0 MPa.
4) And after the reaction, switching to nitrogen again, cooling to room temperature, relieving pressure, adding 100g of pure water at 5 ℃ into the reaction kettle, unloading, performing vacuum filtration to obtain a solid sample and a liquid sample, washing the solid sample with pure water for 5 times, wherein the using amount of the pure water is 500ml each time, performing suction filtration on the washed product, drying at 110 ℃ for 8h, and cooling for analysis.
Specific reaction conditions and product data analysis are shown in table 1.
[ example 6 ]
The reaction was carried out in a 500ml autoclave made of titanium material with a magnetic stirrer, a gas feed pipe, a reflux condenser, a thermocouple, and a rupture disk, with a stirring speed of 400rpm, and electrically heated. The reaction steps are as follows:
1) Weighing 10g of waste polyester PET, 3g of terephthalic acid, 80g of methanol and 0.15g of 1, 3-dimethyl imidazolium bromide, uniformly mixing, adding into an autoclave, and sealing.
2) Adding 10.0MPa nitrogen gas to carry out airtight test for 30min, and determining that the pressure drop is not more than 0.1MPa within 30min.
3) And (3) decompressing to normal pressure, then purging for 3 times by using nitrogen, closing an air inlet switch, starting a stirrer, raising the temperature to 280 ℃ at the stirring speed of 400rpm, and reacting for 30min at 280 ℃ while keeping the pressure of 10.0 MPa.
4) And after the reaction, switching to nitrogen again, cooling to room temperature, relieving pressure, adding 100g of pure water at 5 ℃ into the reaction kettle, discharging, performing vacuum filtration to obtain a solid sample and a liquid sample, washing the solid sample with pure water for 5 times, wherein the using amount of the pure water is 500ml each time, performing suction filtration on the washed product, drying at 110 ℃ for 8 hours, and cooling and analyzing.
Specific reaction conditions and product data analysis are shown in table 1.
[ example 7 ]
The reaction was carried out in a 500ml autoclave made of titanium material equipped with a magnetic stirrer, a gas feed pipe, a reflux condenser, a thermocouple, and a rupture disk, with a stirring speed of 400rpm, and electrically heated. The reaction steps are as follows:
1) 10g of waste polyester PET, 3g of terephthalic acid, 80g of methanol and 0.15g of 1, 3-dimethyl imidazolium bromide salt are weighed, uniformly mixed, added into an autoclave and sealed.
2) Adding 10.0MPa nitrogen gas to carry out airtight test for 30min, and determining that the pressure drop is not more than 0.1MPa within 30min.
3) And (3) decompressing to normal pressure, then purging for 3 times by using nitrogen, closing an air inlet switch, starting a stirrer, raising the temperature to 280 ℃ at the stirring speed of 400rpm, and reacting for 90min at 280 ℃ while keeping the pressure of 10.0 MPa.
4) And after the reaction, switching to nitrogen again, cooling to room temperature, relieving pressure, adding 100g of pure water at 5 ℃ into the reaction kettle, discharging, performing vacuum filtration to obtain a solid sample and a liquid sample, washing the solid sample with pure water for 5 times, wherein the using amount of the pure water is 500ml each time, performing suction filtration on the washed product, drying at 110 ℃ for 8 hours, and cooling and analyzing.
Specific reaction conditions and product data analysis are shown in table 1.
Comparative example 1
The reaction was carried out in a 500ml autoclave made of titanium material with a magnetic stirrer, a gas feed pipe, a reflux condenser, a thermocouple, and a rupture disk, with a stirring speed of 400rpm, and electrically heated. The reaction steps are as follows:
1) 10g of waste polyester PET, 80g of methanol and 0.15g of 1, 3-dimethyl imidazolium bromide are weighed, uniformly mixed, added into an autoclave and sealed.
2) Adding 10.0MPa nitrogen gas to carry out airtight test for 30min, and determining that the pressure drop is not more than 0.1MPa within 30min.
3) And (3) releasing the pressure to normal pressure, then purging for 3 times by using nitrogen, closing an air inlet switch, starting a stirrer, raising the temperature to 280 ℃ at a stirring speed of 400rpm, and reacting for 30min at 280 ℃ while keeping the pressure of 10.0 MPa.
4) And after the reaction, switching to nitrogen again, cooling to room temperature, relieving pressure, adding 100g of pure water at 5 ℃ into the reaction kettle, discharging, performing vacuum filtration to obtain a solid sample and a liquid sample, washing the solid sample with pure water for 5 times, wherein the using amount of the pure water is 500ml each time, performing suction filtration on the washed product, drying at 110 ℃ for 8 hours, and cooling and analyzing.
Specific reaction conditions and product data analysis are shown in table 1.
Comparative example 2
The reaction was carried out in a 500ml autoclave made of titanium material equipped with a magnetic stirrer, a gas feed pipe, a reflux condenser, a thermocouple, and a rupture disk, with a stirring speed of 400rpm, and electrically heated. The reaction steps are as follows:
1) 10g of waste polyester PET, 3g of terephthalic acid and 80g of methanol are weighed, uniformly mixed, added into an autoclave and sealed.
2) Adding 10.0MPa nitrogen gas to carry out airtight test for 30min, and determining that the pressure drop is not more than 0.1MPa within 30min.
3) And (3) decompressing to normal pressure, then purging for 3 times by using nitrogen, closing an air inlet switch, starting a stirrer, raising the temperature to 280 ℃ at the stirring speed of 400rpm, and reacting for 30min at 280 ℃ while keeping the pressure of 10.0 MPa.
4) And after the reaction, switching to nitrogen again, cooling to room temperature, relieving pressure, adding 100g of pure water at 5 ℃ into the reaction kettle, discharging, performing vacuum filtration to obtain a solid sample and a liquid sample, washing the solid sample with pure water for 5 times, wherein the using amount of the pure water is 500ml each time, performing suction filtration on the washed product, drying at 110 ℃ for 8 hours, and cooling and analyzing.
Specific reaction conditions and product data analysis are shown in table 1.
Comparative example 3
The reaction was carried out in a 500ml autoclave made of titanium material with a magnetic stirrer, a gas feed pipe, a reflux condenser, a thermocouple, and a rupture disk, with a stirring speed of 400rpm, and electrically heated. The reaction steps are as follows:
1) 10g of waste polyester PET and 80g of methanol are weighed, uniformly mixed, added into an autoclave and sealed.
2) Adding 10.0MPa nitrogen gas to carry out airtight test for 30min, and determining that the pressure drop is not more than 0.1MPa within 30min.
3) And (3) releasing the pressure to normal pressure, then purging for 3 times by using nitrogen, closing an air inlet switch, starting a stirrer, raising the temperature to 280 ℃ at a stirring speed of 400rpm, and reacting for 30min at 280 ℃ while keeping the pressure of 10.0 MPa.
4) And after the reaction, switching to nitrogen again, cooling to room temperature, relieving pressure, adding 100g of pure water at 5 ℃ into the reaction kettle, discharging, performing vacuum filtration to obtain a solid sample and a liquid sample, washing the solid sample with pure water for 5 times, wherein the using amount of the pure water is 500ml each time, performing suction filtration on the washed product, drying at 110 ℃ for 8 hours, and cooling and analyzing.
Specific reaction conditions and product data analysis are shown in table 1.
TABLE 1
Claims (9)
1. A process for recovering terephthalate from waste PET comprising:
(1) Adding waste PET, terephthalic acid, alkyl alcohol and an ester exchange catalyst into a reactor to obtain an initial reaction mixture;
(2) Reacting PET and alkyl alcohol under the condition of ester exchange reaction to obtain terephthalate;
the transesterification catalyst includes a substance having a halogenated imidazole structure in a molecule.
2. The method as set forth in claim 1, wherein the alkyl alcohol is a C1-C8 alcohol.
3. The method as set forth in claim 1, wherein the alkyl alcohol is a monohydric alcohol.
4. A process according to any one of claims 1 to 3, characterized in that the substance containing a halogenated imidazole structure in the molecule corresponds to formula I below:
wherein R1 and R2 are independently selected from C1-C4 alkyl, and X is Cl or Br.
5. A process according to any one of claims 1 to 3, characterized in that the mass ratio of terephthalic acid to waste PET in the initial reaction mixture is between 0.05 and 1.
6. A process according to any one of claims 1 to 3, characterized in that the mass ratio of alkyl alcohol to waste PET in the initial reaction mixture is between 3 and 10.
7. A process according to any one of claims 1 to 3, characterized in that the mass ratio of catalyst to spent PET in the initial reaction mixture is between 0.01 and 0.1.
8. The method as set forth in any one of claims 1 to 3, characterized in that the temperature of the reaction in the step (2) is 250 to 300 ℃.
9. The method as set forth in any one of claims 1 to 3, characterized in that the pressure of the reaction in the step (2) is 8 to 15MPa; and/or the reaction time is 30-240 min.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5319128A (en) * | 1989-03-15 | 1994-06-07 | Synergistics Industries, Ltd. | Production of terephthalate esters by degradative transesterification of scrap or virgin terephthalate polyesters |
| CN102603532A (en) * | 2011-12-19 | 2012-07-25 | 青岛科技大学 | Method for preparing plasticizer terephthalate by alcoholysis of waste polyester PET |
| CN109503378A (en) * | 2018-12-06 | 2019-03-22 | 沈阳化工大学 | A method of passing through ester transesterification path synthesizing propionate |
-
2019
- 2019-09-04 CN CN201910835007.8A patent/CN112441917B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5319128A (en) * | 1989-03-15 | 1994-06-07 | Synergistics Industries, Ltd. | Production of terephthalate esters by degradative transesterification of scrap or virgin terephthalate polyesters |
| CN102603532A (en) * | 2011-12-19 | 2012-07-25 | 青岛科技大学 | Method for preparing plasticizer terephthalate by alcoholysis of waste polyester PET |
| CN109503378A (en) * | 2018-12-06 | 2019-03-22 | 沈阳化工大学 | A method of passing through ester transesterification path synthesizing propionate |
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