Method for degrading thermoplastic plastic polyethylene terephthalate

A polyethylene terephthalate and thermoplastic technology, which is applied in the field of polyester degradation, can solve the problems of unobtainable catalyst, polymetallic residue, long reaction time, etc. Effect

Inactive Publication Date: 2021-08-06
NANJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] In view of the deficiencies in the prior art, that is, catalysts are not easy to obtain, synthesis is difficult, there are many metal residues, and the reaction time is long. The present invention aims to develop an ionic liquid that is easy to synthesize and has easy-to-obtain raw materials as a catalyst for efficiently degrading PET. , and based on the characteristics of ionic liquid catalysts, a set of conventional methods for catalytic degradation of PET was established

Method used

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  • Method for degrading thermoplastic plastic polyethylene terephthalate
  • Method for degrading thermoplastic plastic polyethylene terephthalate
  • Method for degrading thermoplastic plastic polyethylene terephthalate

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0063] Measure 2.48mL (5mmol) of trioctylphosphine, and add it into a 25mL pressure tube (the pressure tube has been dried beforehand); measure 3mL of methanol, mix and stir evenly; add 2.54mL (30mmol) of dimethyl carbonate. React at 140°C for 20 hours. After the reaction, excess dimethyl carbonate and by-product methanol can be removed by low-pressure rotary evaporation. The resulting salt was a colorless oily liquid (2.25 g, 98%), which 1 HNMR spectrum such as figure 1 shown. The deuterium reagent used is DMSO-d 6 , its chemical shift is 2.5, and the ratio of peak area is 3:6:3:6:6:24:9, which is in line with the expectation, and there is no obvious impurity peak. 1 H NMR and 13 C NMR ( figure 2 ) analysis can confirm that the structure of the catalyst (4c) is correct.

Embodiment 2

[0065] Measure 0.921g (2mmol) of the product in Example 1, add it into a 25mL eggplant-shaped bottle, weigh 0.2442g (2mmol) of benzoic acid and add it therein. The reaction was carried out at 50° C. for 2 h. After the reaction was over, the by-product methanol was removed by low-pressure rotary evaporation, and the main product was a colorless oily liquid (1.09 g, 98%). 1 HNMR spectrum such as image 3 shown. The deuterated reagent used is CDCl 3 , its chemical shift is 7.26, the ratio of peak area is 2:1:2:6:3:12:24:9, which is in line with the expectation, and there is no obvious miscellaneous peak. 1 H NMR and 13 C NMR ( Figure 4 ) analysis can confirm that the structure of the catalyst (4b) is correct.

[0066] Two, PET degradation reaction embodiment

Embodiment 3

[0068] Weigh BG80 PET 0.5g (W 0 ,N 0 =2.6mmol), put into a 10mL schlenk tube, measure 2.11mL of ethylene glycol, and 0.05g of catalyst 4c, and add them in sequence. Reaction at 180°C for 4h. After the reaction is over, weigh 0.1 g of the internal standard 1,3,5-trimethoxybenzene, add it directly to the reaction solution, stir for 30 minutes, and then take a sample. 1 According to H NMR analysis, the NMR yield of depolymerized monomer BHET was 87.93%. The reaction solution was filtered while it was hot, and the resulting filter cake was unreacted PET, which was washed 3 times with water at 70°C and dried in a vacuum oven for 12 hours, claiming its mass as 0.024g (W 1 ), the calculated PET degradation rate was 95.2%. The filtrate is BHET, oligomers, catalysts and ethylene glycol. Add 20mL of water to the filtrate and stir at 70°C for 30 minutes, then filter 3 times while it is hot, and place the filtrate directly in a refrigerator at 0°C for 24 hours. Monomer BHET crystalliz...

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Abstract

The invention discloses a method for degrading thermoplastic plastic polyethylene terephthalate, and belongs to the technical field of polyester degradation; a depolymerized monomer ethylene glycol terephthalate (BHET) is obtained by reacting a commercially available Wahaha beverage bottle as a PET raw material, dihydric alcohol as a solvent and a catalyst represented by a formula I provided by the invention. The raw materials of the catalyst used in the method are simple and easy to obtain, the catalyst can be synthesized through a one-step method, no metal residues exist in the whole reaction system, and even if the load of the catalyst is lower than 2%, a good catalytic effect (the degradation rate is larger than or equal to 90%) can be achieved. In addition, the solvent range of PET alcoholysis is expanded, and under the condition of the catalyst, ethylene glycol, propylene glycol, butanediol, hexanediol, butanediamine, hexamethylenediamine, monoethanolamine and diethanolamine serve as solvents, and the PET degradation rate of 90% or above is achieved.

Description

technical field [0001] The invention belongs to the technical field of polyester degradation, and relates to a degradation method of polyethylene terephthalate (PET) catalyzed by an ionic liquid synthesized by taking trioctylphosphine and diester as raw materials. Background technique [0002] Polyethylene terephthalate (PET) is a thermoplastic polymer. Because of its high chemical stability, strong chemical strength, and good biological safety, it is widely used in synthetic fibers, plastic films, and beverage and food packaging (Macromol. Mater. Eng., 2007, 292, 128–146). However, it is precisely because of these excellent physical properties that PET is difficult to be naturally degraded by microorganisms, and the resulting white pollution has caused many adverse effects on the environment (Science, 2016, 351, 1196–1199). Nevertheless, the demand for PET in the world is still very high. In 2017 alone, the global PET production has exceeded 30 million tons, and the averag...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C67/00C07C69/82B01J31/02
CPCC07C67/00B01J31/0288C07C69/82
Inventor 郭凯郑钧波李振江孙琳琳张奔吕湛刘睿奇高罗玉
Owner NANJING UNIV OF TECH
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