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Method for degrading polyethylene terephthalate

A technology of polyethylene terephthalate and ethylene phthalate, applied in the field of ester degradation, can solve the problems of strong acid and alkali, equipment corrosion, consumption and the like, and achieve the effect of easing reaction conditions

Inactive Publication Date: 2011-08-17
HEFEI UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The technical problem that needs to be solved is to overcome the problems existing in the traditional method that consume a large amount of strong acid and strong alkali, seriously corrode the equipment, and the catalyst solvent cannot be reused.

Method used

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  • Method for degrading polyethylene terephthalate

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] Put 1.0g of polyethylene terephthalate into the reaction kettle, and add 3.0g of 1-butyl-3-ethylimidazolium bromide ionic liquid, 5.0g of methanol, 0.015g of zinc acetate, and mix well React at 140°C for 6 hours, cool to room temperature after the reaction, add 5mL of methanol to dilute, then filter to remove undegraded polyethylene terephthalate to obtain filtrate a, add water to filtrate a to precipitate precipitate, filter and separate Obtain filtrate b and precipitate, filtrate b is separated and recovered by vacuum distillation to obtain ethylene glycol and 1-butyl-3-ethylimidazolium bromide ionic liquid, dry the precipitate at 30°C for 24 hours, add chloroform to dissolve, filter to remove impurities The filtrate c was obtained, and the chloroform was distilled off from the filtrate c to obtain dimethyl terephthalate (DMT). The yield of DMT was 82.6%.

Embodiment 2

[0019] Put 1.0g of polyethylene terephthalate into the reaction kettle, and add 2.0g of 1-butyl-3-ethylimidazolium bromide ionic liquid, 4.0g of methanol, 0.015g of zinc acetate, and mix well React at 150°C for 5 hours, cool to room temperature after the reaction, add 10mL of methanol to dilute, then filter to remove undegraded polyethylene terephthalate to obtain filtrate a, add water to filtrate a to precipitate precipitate, filter and separate Obtain filtrate b and precipitate, filtrate b is separated and recovered by vacuum distillation to obtain ethylene glycol and 1-butyl-3-ethylimidazolium bromide ionic liquid, dry the precipitate at 30°C for 24 hours, add chloroform to dissolve, filter to remove impurities The filtrate c was obtained, and the chloroform was distilled off from the filtrate c to obtain dimethyl terephthalate (DMT). The yield of DMT was 81.7%.

Embodiment 3

[0021] Put 1.0g of polyethylene terephthalate into the reaction kettle, and add 1.0g of 1-butyl-3-ethylimidazolium bromide ionic liquid, 3.0g of methanol, and 0.015g of lead acetate in sequence, mix well React at 160°C for 4 hours, cool to room temperature after the reaction, add 8 mL of methanol to dilute, and then filter to remove undegraded polyethylene terephthalate to obtain filtrate a, add water to filtrate a to precipitate precipitate, filter and separate to obtain filtrate b and precipitation, the filtrate b was separated and recovered by distillation under reduced pressure to obtain ethylene glycol and 1-butyl-3-ethylimidazolium bromide ionic liquid, dried the precipitate at 30°C for 24 hours, added chloroform to dissolve, and filtered to remove impurities to obtain the filtrate c. Dimethyl terephthalate (DMT) was obtained after distilling off the chloroform from the filtrate c, and the yield of DMT was 83.8%.

[0022] Table 1 Repeated reuse results of ionic liquids ...

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Abstract

The invention discloses a method for degrading polyethylene terephthalate. The method comprises the following steps: carrying out alcoholysis reaction on the polyethylene terephthalate in the presence of a catalyst by utilizing a brominated 1-butyl-3-ehtyl imidazole ionic liquid and methanol as solvents; and filtering and separating so as to obtain glycol and dimethyl terephthalate, and simultaneously recovering the brominated 1-butyl-3-ehtyl imidazole ionic liquid. By using the method, the characteristic that used high-concentration inorganic strong acid or strong alkaline can not be recycled is overcome, reaction conditions are mild, and the high requirement on equipment is improved.

Description

1. Technical field [0001] The invention relates to a method for degrading esters, in particular to a method for degrading polyethylene terephthalate. 2. Background technology [0002] Polyethylene terephthalate (PET) material is a thermoplastic polymer material with excellent performance. It has the advantages of good barrier property, low cost, light weight, high strength, acid and alkali resistance, convenient drinking and high safety in use. , and has better environmental protection and energy saving, the production energy consumption is only 41-64% of glass bottles, so it is very suitable for packaging of bottled water, carbonated drinks, juice drinks, tea drinks and other beverages. With the rapid increase in the production and sales of polyethylene terephthalate, more and more waste polyethylene terephthalate is produced. These materials themselves are not very toxic, but due to their bulky and extremely strong It is chemically inert and difficult to degrade under nat...

Claims

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Application Information

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IPC IPC(8): C07C27/00C07C31/20C07C29/128C07C69/82C07C67/03
CPCY02P20/54
Inventor 史铁钧谢磊
Owner HEFEI UNIV OF TECH
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