摘要
随着塑料产量和消费量持续增加,废塑料的处理和循环利用问题愈发严重.化学回收被认为是解决这一难题的有效途径之一,离子液体作为新型溶剂和催化剂,在废塑料的化学回收中展现出巨大潜力,取得了系列进展.本文综述了离子液体介导的废塑料化学回收研究进展,重点介绍了离子液体在聚酰胺(PA)、聚对苯二甲酸乙二醇酯(PET)、聚碳酸酯(PC)、聚乳酸(PLA)、聚乙烯(PE)、聚氯乙烯(PVC)等塑料化学回收中的应用,探讨了离子液体介导的塑料化学降解过程机理,分析了存在的难题及发展趋势.
The ever-growing production and consumption of plastics have led to significant challenges in waste management and recycling.Plastics,primarily synthesized from small monomers through polymerization or condensation reactions,are integral to modern society due to their durability,design flexibility,and cost-effectiveness.However,the recycling rate of plastics remains low,around 10%,due to complex recycling processes and poor degradability,leading to substantial resource wastage and environmental pollution.The growing global focus on CO_(2) emission reduction and the promotion of a circular economy has elevated plastic recycling to a pivotal area of research.This shift offers significant economic advantages,mitigates environmental pollution,and preserves petroleum resources.Chemical recycling processes break down polymer chains into monomers or other valuable chemicals,complementing physical recycling methods that struggle with low-value waste plastics such as cross-linked polymers and thermoplastic elastomers.Chemical recycling presents a viable solution for transforming waste plastics into valuable products,both economically and environmentally.By employing methods such as pyrolysis,reforming,gasification,and chemolysis,it is possible to extract monomers,high-energy liquid oils,various carbon materials,hydrogen,syngas,and other valuable chemicals from various plastic waste.These processes typically necessitate high temperatures due to the inherent chemical stability of plastics.Among various chemical recycling methodologies,solvolysis–which encompasses hydrolysis,alcoholysis,and ammonolysis–demonstrates superior selectivity by effectively targeting specific bonds within polymer structures,including ether,ester,amide,and even the more robust C–C bonds.This process is particularly suitable for condensation polymers such as PET,PC,and PLA,and it represents a form of closed-loop recycling.In addition,solvolysis requires significantly lower temperatures compared to plastic depolymerization methods like pyrolysis,which generally demand temperatures exceeding 400°C.ILs,composed of cations and anions with designable structure,exhibit unique properties such as high hydrogen bond disrupting ability,good solubility for natural and synthetic polymers,low vapor pressure,non-flammability,and high chemical stability,making them ideal for plastic solvolysis.The structural tunability of ionic liquids(ILs)allows for precise modulation of their physical and chemical properties,thereby enhancing their capacity to dissolve and depolymerize polymers effectively.Additionally,the incorporation of Lewis or Brönsted acidic sites within ILs can facilitate the depolymerization of plastics under milder reaction conditions.Furthermore,immobilizing ionic liquids on heterogeneous supports presents a promising strategy to improve their practical applicability and broaden their use in large-scale processes.This review consolidates recent advancements in the chemical recycling of plastics mediated by ILs,emphasizing their role in the depolymerization of common plastics such as polyamide(PA),polyethylene terephthalate(PET),polycarbonate(PC),polylactic acid(PLA),polyethylene(PE),and polyvinyl chloride(PVC).ILs have shown considerable promise due to their ability to swell plastics effectively,allowing coordinated activation through cation-anion interactions that provide catalytic sites with Lewis or Brönsted acidity.The mechanisms underlying these processes often involve hydrogen bonding between IL cations and carbonyl oxygen in polymers,which enhances the electrophilicity of the carbonyl carbon.Concurrently,hydrogen bonding between nucleophilic agents(e.g.,alcohols,water,amines)and IL anions boosts nucleophilicity,facilitating C-X(X=O or N)bond cleavage through nucleophilic substitution.While summarizing the advances achieved through the use of various ionic liquids for the solvolysis of plastics containing C–O,C–N,and C–C bonds,this review underscores the primary research gaps that require further investigation.It aims to provide valuable insights to guide the development of enhanced plastic upcycling techniques employing ionic liquids.
作者
张振磊
艾佳臻
史国靖
张香平
Zhenlei Zhang;Jiazhen Ai;Guojing Shi;Xiangping Zhang(State Key Laboratory of Heavy Oil Processing,College of Chemical Engineering and Environment,China University of Petroleum(Beijing),Beijing 102249,China;Beijing Key Laboratory of Ionic Liquids Clean Process,Institute of Process Engineering,Chinese Academy of Sciences,Beijing 100190,China)
出处
《科学通报》
北大核心
2025年第26期4473-4487,共15页
Chinese Science Bulletin
基金
国家自然科学基金(22408397)
中央高校基本科研业务费专项资金(2462024BJRC001,2462022YJRC012)资助。
关键词
废塑料
离子液体
化学回收
溶剂解
waste plastic
ionic liquids
chemical upcycling
solvolysis
