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Chemical recycling of post-consumer polyester wastes using a tertiary amine organocatalyst

Cell Reports Physical Science 2024 6 citations ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count.
Shaoqu Xie, Caiqi Wang, Wenda Hu, Jian Zhi Hu, Yong Wang, Zhun Dong, Nadia N. Intan, Jim Pfaendtner, Hongfei Lin

Summary

Researchers developed a metal-free chemical recycling method using a common amine catalyst to break down PET and other polyesters from post-consumer plastic waste — including textiles and multilayer packaging — into reusable monomers with 100% yield. This technique offers a simpler, more efficient path to closing the plastic recycling loop.

Recycling diverse waste plastics poses challenges due to complex sorting and processing, resulting in high costs and inefficiency. To tackle this, we present a metal-free catalytic sorting method for targeted deconstruction of polyester from post-consumer plastic waste, encompassing textiles, plastic mixtures, and multilayer packaging materials. This method employs N-methylpiperidine, a tertiary amine catalyst in methanol, to depolymerize polyethylene terephthalate (PET). Operating under these conditions (160°C, 1 h), we achieve 100% yields of dimethyl terephthalate and ethylene glycol. This technique also effectively breaks down other polyesters, including polylactic acid, polycarbonate, and polybutylene terephthalate, yielding high-yield monomers at relatively low temperatures. Through comprehensive nuclear magnetic resonance (NMR) analysis, we propose that N-methylpiperidine’s role is in enhancing methanol nucleophilicity and activating PET’s ester bond. Our insights advance the chemical recycling of post-consumer plastic waste, offering a potentially simple and efficient path to closing the polyester production loop.

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