Waste polyester material recovery method with ion liquid as reaction medium and catalyst

Abstract

The invention relates to a new method for generating terephthalic acid and glycol from chemical degradation of waste polyester (PET), thus realizing the recycling of PET material. The method is characterized in that a hydrolysis reaction is carried out at the temperature of 100-190 DEG C, with ionic liquid of chloride 1-butyl-3-methylimidazole, chloride 1-allyl-3-methylimidazole, chloride 1-phenmethyl-3-methylimidazole, and the like, as reaction media which are easy to be repeatedly utilized, and acid functionalized ionic liquid of 1-methyl-3-(3-sulfo-propyl) imidazole hydrosulfate and 1-methyl-3-(3-sulfo-butyl) imidazole hydrosulfate, and the like, as catalyst. After the reaction, water is added to precipitate precipitation; then the liquid is filtered; glycol and ionic liquid are recycled after the filtrate is distilled and separated; the recycled ionic liquid can be directly reused without any treatment. Filter mass is dissolved with sodium hydroxide solution and then is filtered to remove unmodified PET and other insoluble impurities; the obtained filtrate is acidulated until the precipitation is precipitated, then filtered and dried to get the product terephthalic acid with yield coefficient over 90 percent. Compared with the traditional method, the new method for generating terephthalic acid and glycol from chemical degradation of waste polyester is characterized in that: (1) problems in background technology of consumption of a great deal of high concentration inorganic strong acid / strong alkali and incapacity to be recycled and utilized, and the like, are overcome; and (2) owing to the adoption of ionic liquid which has certain solubility for PET as the reaction medium and catalyst, on one hand, the reaction conditions are alleviated; on the other hand, the ionic liquid can be repeatedly utilized, thus obviously improving problems of equipment eroding and environmental pollution.

Description

technical field [0001] The invention relates to a new method for chemically degrading waste polyester (PET) materials and recovering monomers by using ionic liquid as a reaction medium and a catalyst. technical background [0002] Polyester (PET) is a polymer material polymerized from terephthalic acid (TPA) or dimethyl terephthalate (DMT) with ethylene glycol (EG). Because of its good physical and chemical properties, it is Widely used in food packaging, fiber, film, film base and electrical insulation materials and other fields. With the rapid increase of PET production and sales, more and more waste PET is produced. Although waste PET does not directly pollute the environment, it will occupy a large amount of space. Because of its strong chemical inertia, it is difficult to degrade under natural conditions, so it will not only have a great impact on the environment, but also cause huge Waste of resources. Therefore, the recycling of waste PET has been paid more and mor...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to provide a new method for hydrolyzing waste PET, which overcomes the shortcomings of traditional methods such as the consumption of a large amount of inorganic strong acid or strong alkali, serious equipment corrosion and environmental pollution, non-recyclable catalysts, and harsh reaction conditions.

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