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Method for depolymerizing waste polyester bottle

A polyester bottle and waste technology, which is applied in the field of depolymerization of waste polyester bottles, can solve the problems of long reaction time, side reactions, and corrosion reaction equipment, so as to reduce recycling links, reduce possibilities, and increase yield Effect

Active Publication Date: 2012-07-04
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In US4605762, the reaction time of polyester waste is long, and it needs to be carried out under high temperature and high pressure conditions, and the implementation cost is high; in US3952053, strong acid and strong alkali are used many times, which not only corrodes the reaction equipment, but also pollutes the environment with waste liquid; in CN101906218A, The reaction time and cooling crystallization time are as long as 5 to 10 hours, which is not conducive to large-scale production and is accompanied by side reactions
In CN1571810A, the equipment investment is large, and the whole process takes a long time
In CN1390826A, the depolymerization product is a colored viscous substance with complex components, and it is not easy to separate solid and liquid. Only pure ethylene glycol is used to wash the depolymerization product, which cannot guarantee the purity of the target product. A large amount of ethylene glycol and complex components in the washing liquid are used. Sexuality will increase the difficulty of recycling ethylene glycol

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] (1) Add 3g of waste polyester bottle crushed material about 3mm×3mm in size, 3.3g of sodium bicarbonate, 40ml of distilled water, 10ml of ethylene glycol into the reaction kettle, seal the lid of the kettle, and heat to 180 at a stirring speed of 40r / min. ℃, and reacted at this temperature for 30 minutes to obtain a light yellow liquid product and insoluble impurities. The reaction product was filtered with suction, and the mass of insoluble impurities was weighed to be 0.008g. The depolymerization rate of PET was 99.73%.

[0028] (2) Add 0.15 g of activated carbon and put it into the filtrate for decolorization, take a water bath at 50° C. for half an hour, filter with suction, add 0.15 g of activated carbon again and put it into the filtrate, take a water bath at 50° C. for half an hour, and filter with suction to obtain a colorless transparent liquid.

[0029] (3) Heat the beaker containing the liquid product to 30°C on the battery furnace, gradually add hydrochloric ...

Embodiment 2

[0033] (1) Add 3g of waste polyester bottle pulverized material about 3mm×3mm in size, 3.3g of sodium bicarbonate, 50ml of distilled water, 15ml of ethylene glycol into the reaction kettle, seal the lid of the kettle, and heat to 170 at a stirring speed of 40r / min. °C, reacted at this temperature for 30 minutes to obtain a light yellow liquid product and insoluble impurities, the reaction product was filtered with suction, and the weight of the insoluble impurities was weighed to be 0.010g, and the depolymerization rate of PET was 99.67%.

[0034] (2) Add 0.195g of activated carbon and put it into the filtrate for decolorization, take a water bath at 50°C for half an hour, filter with suction, add 0.195g of activated carbon again and put it into the filtrate, take a water bath at 50°C for half an hour, and filter with suction to obtain a colorless transparent liquid.

[0035] (3) Heat the beaker containing the liquid product to 45°C on the battery furnace, gradually add hydroch...

Embodiment 3

[0039](1) Add 3g of waste polyester bottle crushed material about 3mm×3mm in size, 3g of sodium bicarbonate, 50ml of distilled water, 10ml of ethylene glycol into the reaction kettle, seal the lid of the kettle, heat to 180°C without stirring, The reaction was carried out for 30 minutes to obtain a light yellow liquid product and insoluble impurities. The reaction product was filtered with suction, and the mass of insoluble impurities was weighed to be 0.030 g. The depolymerization rate of PET was 99.00%.

[0040] (2) Add 0.18g of activated carbon and put it into the filtrate for decolorization, take a water bath at 50°C for half an hour, filter with suction, add 0.18g of activated carbon again and put it into the filtrate, take a water bath at 50°C for half an hour, and filter with suction to obtain a colorless transparent liquid.

[0041] (3) Heat the beaker containing the liquid product to 60°C on the battery furnace, gradually add hydrochloric acid (the mass concentration o...

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Abstract

The invention provides a method for depolymerizing a waste polyester bottle, comprising the following steps of: adding the waste polyester bottle, ethylene glycol, sodium bicarbonate and distilled water into a high-temperature and high-pressure reaction kettle according to a certain proportion and reacting at a temperature of 170-200 DEG C for 15-40 minutes to depolymerize the waste polyester bottle into sodium terephthalate, ethylene glycol and other byproducts; then, adsorbing by active carbon and de-coloring; acidifying by hydrochloric acid, and cooling and crystallizing by ice water; filtering, washing and drying to obtain terephthalic acid; and carrying out rotary evaporation on a filtering solution to obtain the ethylene glycol to be repeatedly utilized. According to the method for depolymerizing the waste polyester bottle, by utilizing a mixed reaction system, the depolymerization temperature is reduced, the reaction time is shortened, the energy source consumption is reduced, the equipment investment is reduced, the depolymerization rate of PET (Polyethylene Terephthalate) reaches to be more than 99% and the yield of the target product, namely terephthalic acid, is more than 94%.

Description

Technical field: [0001] The invention relates to a method for depolymerizing waste polyester bottles, more specifically a method for depolymerizing waste polyester bottles in a closed high-temperature and high-pressure reaction kettle using ethylene glycol and water under weakly alkaline conditions. Background technique: [0002] Polyester bottles have been widely used in beverage, food, medicine and other fields due to their characteristics of odorlessness, non-toxicity, light weight, high strength, good air tightness and good transparency. At present, the recycling amount of waste polyester bottles in the world is more than 600kt / a, the recycling rate is about 18%, and more than 60% of the recycled polyester is used for fiber production. However, the recovery rate of waste polyester bottles in China is only 6% to 10%, of which 40% to 60% are used for fiber production. [0003] There are two main types of recycling methods for polyester bottles, one is physical utilization...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08J11/24C08G63/78C07C63/26C07C51/00C07C31/20C07C29/00
CPCY02W30/62
Inventor 周涛卓强蒋崇文吕克新桂颖
Owner CENT SOUTH UNIV
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