摘要
在我国政府加大环保力度、积极倡导实施“双碳”目标的背景下,塑料废弃物的资源化利用已成为社会关注的焦点议题.一方面,塑料具有较强的稳定性,在自然条件下难以降解,并会释放微塑料不断地毒害生物;另一方面塑料来自化石资源的合成,塑料的使用加剧能源的消耗.聚对苯二甲酸乙二醇酯(PET)作为产量最高的聚酯塑料之一,被广泛用于生产各种日常用品和一次性包装材料.尽管PET的回收从其生产之初已经得到开展,然而现在PET的回收率仍处于较低水平.近年来关于PET回收技术的研究与日俱增,尤其在化学回收方面,以期实现废弃PET的闭环回收.本文回顾了PET塑料的生产和回收技术,对目前PET化学解聚的传统技术研究现状和解聚单体高值化的新策略进行了系统梳理,并对未来PET废塑料制备高价值单体的研究重点、难点和发展前景进行了展望,为推动社会和经济的可持续发展提供了新的视角和思考.
Plastics are ubiquitous in daily life due to their outstanding performance and cost-effectiveness.However,plastics are not without their drawbacks.Plastics are synthesized from fossil resources,and their widespread use accelerates the depletion of non-renewable resources.Additionally,their inherent stability makes them resistant to degradation under natural conditions,and they continuously release microplastics that pose significant harm to living organisms.As a result,plastic consumption and pollution are considered to be a critical environmental crisis that threatens sustainable human development.Against the backdrop of China’s heightened environmental protection efforts and its active promotion of“dual carbon”goals,the resource utilization of plastic waste has become a central societal issue.Polyethylene terephthalate(PET),one of the most widely produced polyester plastics,is extensively used in the manufacture of various everyday products and single-use packaging materials.PET synthesis began in the 1940s and has been used on a large scale for disposable packaging since the 1970s.PET is synthesized through the polycondensation of bis(2-hydroxyethyl)terephthalate(BHET),which can be produced by esterification of terephthalic acid(TPA)with ethylene glycol or from dimethyl terephthalate(DMT)and ethylene glycol.Despite existing initiatives aimed at recycling PET,the current recycling rate remains low.PET recycling is generally classified into primary,secondary,tertiary,and quaternary recycling.Primary and secondary recycling involve physical methods that recover PET waste without altering its chemical structure,for instance,PET waste plastic bottles are melt-spun to make recycled polyester fibers.Tertiary recycling restores the molecular value(chemical recycling),while quaternary recycling creates energy from the waste.With the rise of the circular economy,there has been a marked increase in research on PET recycling technologies,particularly in chemical recycling,which aims to establish a closed-loop system in which discarded PET is reintegrated into production.Chemical depolymerization pathways have been developed,allowing PET waste to be broken down into aromatic monomers and ethylene glycol.Through further purification and polycondensation,recycled PET can be produced from these monomers,thereby enabling closed-loop recycling.The depolymerization processes are typically hydrolysis,methanolysis,and glycolysis.Among them,hydrolysis usually requires the participation of water and the reaction with acidic or alkaline substances.Methanolysis requires an excess of methanol to react with PET.Glycolysis likewise requires the addition of large amounts of additional glycol for the reaction.These chemical depolymerization routes have a common by-product,ethylene glycol.However,due to the high boiling point of ethylene glycol,the chemical depolymerization of PET presents significant challenges in terms of separation and purification.In recent years,new recycling strategies have emerged that combine organic synthesis,electrochemical,and photochemical techniques to enhance the utilization of ethylene glycol including selective oxidation reactions to make carboxylic compounds.These innovative strategies not only preserve the valuable aromatic monomers of PET but also facilitate the recovery of new high-value chemicals.This paper reviews the production and recycling technologies for PET plastics,with a particular focus on the chemical depolymerization pathways involved in PET chemical recycling.It systematically examines the current status of traditional PET chemical depolymerization techniques and new strategies for their further development.Additionally,the paper explores the key challenges,research priorities,and prospects for producing high-value monomers from waste PET.This review offers new perspectives and insights for advancing sustainable development and the circular economy while promoting the importance of the waste plastic recycling industry.
作者
刘佳铭
欧阳雪儿
张译天
罗刚
梅清清
张士成
Jiaming Liu;Xueer Ouyang;Yitian Zhang;Gang Luo;Qingqing Mei;Shicheng Zhang(Department of Environmental Science and Engineering,Fudan University,Shanghai 200438,China;Shanghai Technical Service Platform for Pollution Control and Resource Utilization of Organic Waste,Shanghai 200438,China;Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention(LAP3),Shanghai 200438,China;Shanghai Institute of Pollution Control and Ecological Security,Shanghai 200438,China;College of Environmental and Resource Sciences,Zhejiang University,Hangzhou 310012,China)
出处
《科学通报》
北大核心
2025年第18期2878-2891,共14页
Chinese Science Bulletin
