Screening method for regenerating PET (polyethylene terephthalate) and PTA (pure terephthalic acid) by chemical or enzymatic method

By measuring specific indicators of PET and PTA using high-performance liquid chromatography and isotope ratio mass spectrometry, and combining this with index calculation, the problem of distinguishing between PET and PTA materials in existing technologies has been solved, achieving efficient and economical screening results.

CN121476462APending Publication Date: 2026-02-06NANJING SUXIN TECHNOLOGY CO LTD
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Patent Information

Application Number
CN202511722296.2
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2025-11-21
Publication Date
2026-02-06

AI Technical Summary

Technical Problem

Existing technologies lack fast, accurate, and reliable methods to distinguish and screen chemically or enzymatically recycled PET and PTA materials, especially since it is difficult to differentiate them from virgin materials, leading to frequent instances of false or mislabeled products in the market.

Method used

The contents of p-methylbenzoic acid, p-carboxybenzaldehyde, and m-terephthalic acid were determined by high performance liquid chromatography. The isotopic ratios of oxygen-18 and oxygen-16 were determined by high-temperature pyrolysis and isotope ratio mass spectrometry. The products were classified by calculating the cleanliness index, oxygen-18 index, and bottle/flake index.

Benefits of technology

It enables precise and objective screening of PET and PTA materials, improves screening efficiency, reduces economic costs, and ensures the reliability of classification results.

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Abstract

The invention provides a chemical or enzymic method regenerated PET and PTA screening method, which comprises the following steps: pretreating a PET or PTA sample 1, and measuring the content of p-toluic acid, the content of p-carboxybenzaldehyde and the content of m-terephthalic acid by using high performance liquid chromatography; the method comprises the following steps: pretreating a PET or PTA sample 2, pretreating by using a high-temperature pyrolysis method, and measuring an isotope ratio of oxygen-18 to oxygen-16 by using an isotope ratio mass spectrometer; the method comprises the following steps: calculating a cleanliness index, an oxy-18 index and a bottle flake index by using a formula based on a test result, and classifying PET and PTA samples through a decision tree according to the indexes; combining and mixing the PET and PTA products based on the classification result and the requirements of downstream customers on the regeneration method and the regenerated material content; the method is convenient, accurate and reliable, the classification result is objective, the screening efficiency of PET and PTA regenerated by a chemical or enzyme method can be improved, and the economic cost is saved.
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