Depolymerization of polyesters by a binuclear catalyst for plastic recycling

Abstract

Plastics play an essential role in modern society; however, the relentless growth of their production is threatening both human health and ecosystems. As a result, there are intensive efforts in developing recycling technologies to repurpose waste plastics into the building blocks for valuable materials. Here we show a binuclear complex that can catalyse the degradation of poly(ethylene terephthalate) (PET)—the most widely used polyester globally—and a wide spectrum of other plastics including polylactic acid, polybutylene adipate terephthalate, polycaprolactone, polyurethane and Nylon 66. Inspired by hydrolases, the group of enzymes that catalyse bond cleavages with water, the present catalyst design features biomimetic Zn‒Zn sites that activate the plastic, stabilize the key intermediate and enable intramolecular hydrolysis. This synthetic catalyst delivers an activity of 36 mgPET d−1 gcatal−1 toward PET depolymerization at pH 8 and 40 °C and an activity of 577 gPET d−1 gcatal−1 at pH 13 and 90 °C for scalable PET recycling. We further demonstrate a closed-loop production of bottle-grade PET. This work presents a practical and viable solution for the sustainable management of plastics waste. Plastic pollution forms a major global challenge to the ecosystem. Here the authors show a binuclear catalyst that could degrade various polyesters in an effective and scalable way, providing a promising technological solution to the challenge.