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Enhanced Methanolysis of Waste PET for Sustainable Production of Dimethyl Terephthalate and Cyclic Arylboronic Esters

Research Square (Research Square) 2023
Qingqing Mei, Minghao Zhang, Yunkai Yu, Binghui Yan, Xiuju Song, Yu Liu, Yixiong Feng, Weixiang Wu, Baoliang Chen, Buxing Han

Summary

Researchers developed a method using boric acid to improve the chemical recycling of waste PET plastic via methanolysis, producing high-purity monomers that can be used in new plastic production. More efficient PET recycling reduces the amount of plastic waste that breaks down into microplastics in the environment.

Polymers

Abstract Developing efficient and cost-effective methodologies for high value-added conversion of waste plastic delivers substantial environmental and economic benefits. Herein, we develop a novel approach utilizing boric acid in the methanolysis of waste polyethylene terephthalate (PET) to derive pure dimethyl terephthalate (DMT) and boronic acid esters through in-situ capture of ethylene glycol (EG). It not only upcycles waste PET but also eliminates intricate EG purification processes. Catalyzed by magnalium-aluminum-layered double oxides (Mg 4 Al 1 -LDO), this method achieved 100% conversions of PET with 96% and 100% yields of arylboronic esters and DMT, respectively. Kinetic studies and in-situ Fourier-transform infrared spectroscopy (FT-IR) demonstrated the pivotal role of the monodentate methoxy species, generated through the interaction of medium basic Mg–O ion pairs and methanol. This method demonstrates applicability for the upcycling of assorted discarded PET wastes, polyesters, and polycarbonates with EG units, highlighting its potential as a comprehensive solution for waste plastic management.

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