Method for catalyzing alcoholysis of waste PET ethylene glycol by heteroatom-doped zinc oxide

A zinc oxide and heteroatom technology, applied in the fields of polymer degradation, green catalysis technology and plastics, can solve the problems of poor product selectivity and low yield, and achieve the effects of high selectivity, low cost, and easy separation and purification

Active Publication Date: 2022-06-07
NANJING UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] Purpose of the invention: The technical problem to be solved by the present invention is to provide a method for efficiently catalyzing the alcoholysis of waste PET ethylene

Method used

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  • Method for catalyzing alcoholysis of waste PET ethylene glycol by heteroatom-doped zinc oxide
  • Method for catalyzing alcoholysis of waste PET ethylene glycol by heteroatom-doped zinc oxide
  • Method for catalyzing alcoholysis of waste PET ethylene glycol by heteroatom-doped zinc oxide

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1-4

[0031] The waste PET, its mass 1% Co / ZnO, Mo / ZnO, ZnO and its mass ratio of 4:1 ethylene glycol were put into a single-necked flask, heated to 180 °C, reacted for 1 h, and magnetically stirred. After the reaction, 400 mL of ultrapure water was added and stirred vigorously to prevent the precipitation of monomer crystals. Then collect the insoluble PET and oligomers and filtrate filtered by suction, and after the filtrate is adjusted to 1L, take an appropriate amount of solution for later use. After the reaction, the product BHET was analyzed by HPLC, and the yield of BHET and the conversion rate of PET were calculated. For the BHET yield and PET conversion data of different metal-doped ZnO catalysts for the glycolysis of waste PET, please refer to the serial numbers 1-4 in Table 1 for details.

[0032] Table 1 Effects of different metal-doped ZnO on the alcoholysis of waste PET catalyzed by glycol

[0033] Example catalyst PET conversion rate / % BHET yield / % ...

Embodiment 5-8

[0036] The waste PET and its catalyst Mo / ZnO (the mass ratio of Mo = 0.8-27.9 wt %) and its mass ratio of 4:1 were sequentially added to a 25 mL single-neck flask. After the temperature was raised to 180°C, the reaction was carried out for 1 h, and the mixture was magnetically stirred. After the reaction, 400 mL of ultrapure water was added and stirred vigorously to prevent the precipitation of monomer crystals. Then collect the insoluble PET and oligomers and filtrate filtered by suction, and after the filtrate is adjusted to 1L, take an appropriate amount of solution for later use. After the reaction, the product BHET was analyzed by HPLC, and the yield of BHET and the conversion rate of PET were calculated. The effect of Mo addition on the catalyzed alcoholysis of PET glycol by Mo / ZnO catalyst is shown in the serial numbers 5-8 in Table 2.

[0037] Table 2 Examples 5-8 Influence of Mo addition on Mo / ZnO catalyzed glycolysis of waste PET

[0038] Example Mo ma...

Embodiment 9-13

[0041] The waste PET, Mo / ZnO with a mass ratio of 0.1 to 5% and ethylene glycol with a mass ratio of 4:1 were put into a single-necked flask, and the temperature was raised to 180° C. and reacted for 60 min. After the reaction, the product BHET was analyzed by HPLC, and the yield of BHET and the conversion rate of PET were obtained by calculation, as shown in the serial numbers 9-13 in Table 3 for details.

[0042] Table 3 Influence of the amount of Mo / ZnO on the alcoholysis of waste PET with glycol

[0043] Example catalyst(%) PET conversion rate / % BHET yield / % 9 0.1 82.7 76.9 10 0.2 91.2 86.1 11 1 100 94.5 12 2 100 92.7 13 5 100 93.2

[0044] 4. Effects of different reaction temperatures on 0.8% Mo / ZnO catalyzed glycolysis of waste PET

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Abstract

The invention discloses a method for catalyzing alcoholysis of waste PET (polyethylene terephthalate) ethylene glycol by using heteroatom-doped zinc oxide, which is characterized in that metal heteroatom-doped two-dimensional defect-rich zinc oxide is used as a catalyst, ethylene glycol is used as a solvent, and the alcoholysis of the waste PET is catalyzed. Under the conditions that the dosage of the catalyst is 0.1%-10% of the mass of PET, the reaction temperature is 140-190 DEG C, the reaction time is 15-180 minutes, and the mass ratio of ethylene glycol to PET is 1: 4, the yield of BHET is 54.5%-94.5%. The method has the characteristics that the catalyst is easy to recover and can be recycled, the reaction process is pollution-free, the reaction condition is mild and the like, the degradation product does not need to be decolored and has low requirements on raw materials, and the alcoholysis product is easy to separate and purify.

Description

technical field [0001] The invention belongs to the fields of polymer degradation, green catalysis technology and plastics, and relates to a method for recycling waste PET by alcoholysis of ethylene glycol by using heteroatom-doped zinc oxide as a catalyst. Background technique [0002] At present, the chemical recycling of waste plastics has become a research hotspot. Polyethylene terephthalate (PET) has good mechanical properties and processing properties, and is widely used in textiles, beverage bottles and other fields. The chemical depolymerization of PET (alcoholysis catalytic method) to prepare bishydroxyethyl terephthalate (BHET) monomer is a very important recycling method, especially the obtained BHET monomer can be directly polymerized to prepare fresh PET. Catalysts play an important role in the depolymerization process, and the development of high-efficiency catalysts to catalyze the alcoholysis of waste PET is a research hotspot. [0003] So far, there are ma...

Claims

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Application Information

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IPC IPC(8): C07C67/03C07C69/82
CPCC07C67/03C07C69/82Y02W30/62
Inventor 江伟曹静静林宇恒周天鹏孙平张全兴
Owner NANJING UNIV
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