Guo Zhenbo, Li Yuchen, Wang Meng, Ma Ding
Beijing National Laboratory for Molecular Sciences, New Cornerstone Science Laboratory, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
Acc Chem Res. 2025 Sep 15. doi: 10.1021/acs.accounts.5c00493.
ConspectusThe global plastic waste crisis, driven by exponential growth in plastic production, has necessitated the development of innovative approaches for recycling and upcycling. Poly(ethylene terephthalate) (PET), one of the most widely used polyesters, poses significant environmental challenges due to its chemical stability and non-degradable nature. While existing methodologies have made significant contributions to the recycling of PET waste through mechanical or chemical processes, an emerging strategy of upcycling PET into high-value products may offer greater potential to present significant advantages in economic feasibility and long-term sustainability. Over the past ten years, hundreds of publications have explored the upcycling of PET in the laboratory through catalytic reactions with various co-reactants, primarily water, hydroxides, alcohols, and amines. In this Account, we summarize our contributions on the design of novel catalytic strategies for the upcycling of PET along with other problematic wastes and H. For instance, we explored the co-upcycling of PET with other plastics such as poly(vinyl chloride) (PVC) and polyoxymethylene (POM), demonstrating how the chlorine from PVC could be utilized to depolymerize PET into terephthalic acid (TPA) and 1,2-dichloroethane (EDC) and how the formaldehyde derived from POM could be converted into 1,3-dioxolane through the condensation reaction with ethylene glycol (EG) derived from PET. We also developed a one-pot catalytic system that simultaneously hydrogenated PET and CO into high-value chemicals, leveraging a dual-promotion effect on both CO hydrogenation and PET methanolysis and achieving high yields of EG, dimethyl cyclohexanedicarboxylate (DMCD) and -xylene (PX). A H-free, one-pot, two-step catalytic process was further presented to upcycle PET with CO, yielding formic acid (FA) and TPA. Moreover, we demonstrated a direct hydrogenation strategy to convert PET into a degradable polyester, poly(ethylene terephthalate)-poly(ethylene-1,4-cyclohexanedicarboxylate) (PET-PECHD), through controlled hydrogenation of its aromatic rings, which preserved the polymer's mechanical and thermal properties while introducing degradability, offering a sustainable alternative for packaging materials.Our research highlights the importance of catalyst design, reaction engineering, and process optimization in achieving efficient and scalable PET upcycling processes. By integrating multiple catalytic steps and leveraging waste-derived resources, we outline a roadmap for the near future of PET upcycling, aiming to enable breakthroughs in real-life plastic upcycling.
综述
全球塑料垃圾危机由塑料产量的指数级增长所驱动，这使得开发创新的回收和升级再造方法成为必要。聚对苯二甲酸乙二酯（PET）是使用最广泛的聚酯之一，因其化学稳定性和不可降解性而带来了重大的环境挑战。虽然现有方法通过机械或化学过程对PET废料的回收做出了重大贡献，但将PET升级再造为高价值产品的新兴策略可能在经济可行性和长期可持续性方面具有更大潜力并展现出显著优势。在过去十年中，数百篇出版物探讨了在实验室中通过与各种共反应物（主要是水、氢氧化物、醇和胺）的催化反应对PET进行升级再造。在本综述中，我们总结了我们在设计用于PET以及其他有问题的废料和H的升级再造的新型催化策略方面所做的贡献。例如，我们探索了PET与其他塑料如聚氯乙烯（PVC）和聚甲醛（POM）的共升级再造，展示了PVC中的氯如何用于将PET解聚为对苯二甲酸（TPA）和1,2 - 二氯乙烷（EDC），以及POM衍生的甲醛如何通过与PET衍生的乙二醇（EG）的缩合反应转化为1,3 - 二氧戊环。我们还开发了一种一锅催化体系，该体系同时将PET和CO氢化为高价值化学品，利用对CO氢化和PET甲醇解的双重促进作用，实现了EG、二甲基环己烷二甲酸酯（DMCD）和对二甲苯（PX）的高产率。进一步提出了一种无H的一锅两步催化过程，用于将PET与CO进行升级再造，生成甲酸（FA）和TPA。此外，我们展示了一种直接氢化策略，通过对PET的芳香环进行可控氢化，将其转化为可降解聚酯聚对苯二甲酸乙二酯 - 聚（乙烯 - 1,4 - 环己烷二甲酸酯）（PET - PECHD），该策略在保持聚合物机械和热性能的同时引入了可降解性，为包装材料提供了一种可持续的替代方案。我们的研究强调了催化剂设计、反应工程和工艺优化在实现高效且可扩展的PET升级再造过程中的重要性。通过整合多个催化步骤并利用废料衍生资源，我们勾勒了PET升级再造近期的路线图，旨在实现实际塑料升级再造的突破。
