A method for recovering polyesters by rare earth catalyzed aminolysis

By using rare earth catalysts to react with imidazole salts, the problems of high energy consumption and solvent use in polyester recycling have been solved, achieving efficient depolymerization of polyester and regeneration of organic diacids, resulting in easily separable value-added chemicals.

CN117736147BActive Publication Date: 2026-07-03东方电气股份有限公司 +2
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
东方电气股份有限公司
Filing Date
2023-12-18
Publication Date
2026-07-03

AI Technical Summary

Technical Problem

Existing technologies for recycling polyester suffer from high energy consumption, reduced product performance, and the need for additional solvents. In particular, physical recycling leads to molecular chain breakage, while chemical depolymerization requires additional solvents.

Method used

Amine hydrolysis is carried out under mild conditions using rare earth catalysts and imidazole salts. The rare earth catalyst catalyzes the substitution reaction between the adjacent groups of waste polyester and imidazole salts, converting carbon-oxygen bonds into carbon-nitrogen bonds, thereby achieving the depolymerization of polyester and the regeneration of organic diacids.

Benefits of technology

Achieving complete depolymerization of polyester under mild conditions reduces energy consumption, yields easily separable value-added chemicals, reduces solvent use, and increases product value.

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Abstract

The application discloses a method for recycling polyester by amine decomposition under rare earth catalyst, comprising: under the catalysis of a rare earth catalyst, waste polyester and imidazole salt substances are subjected to amine decomposition reaction to obtain a crude product; the waste polyester comprises at least one of polyethylene terephthalate, polytrimethylene terephthalate, polyethylene isophthalate, polytrimethylene isophthalate, polyethylene succinate, polyethylene adipate, polyethylene suberate and polyethylene sebacate; the crude product is hydrolyzed in an alkali solution, extracted, and the organic phase is taken to obtain hydroxyethyl imidazole salt substances and / or hydroxypropyl imidazole salt substances; the water phase is acidified and precipitated, and solid-liquid separation is performed to obtain organic diacid. The application can utilize a large amount of recycled polyester materials, one-pot method is used to recycle dibasic carboxylic acid and imidazole salt value-added chemicals, and the recycled dibasic carboxylic acid and imidazole salt value-added chemicals can be applied to the polyester industry again.
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