化学学报 ›› 2021, Vol. 79 ›› Issue (10): 1214-1231.DOI: 10.6023/A21050224 上一篇    下一篇

综述

典型芳香烃大气氧化机理研究进展

宋梦迪, 刘莹, 李歆*(), 陆思华   

  1. 北京大学环境科学与工程学院 环境模拟与污染控制国家重点联合实验室 教育部区域污染控制国际合作联合实验室 北京 100871
  • 投稿日期:2021-05-20 发布日期:2021-08-02
  • 通讯作者: 李歆
  • 作者简介:

    宋梦迪, 博士研究生, 2019年进入北京大学环境科学与工程学院. 主要研究方向为芳香烃氧化机理及环境效应, 大气挥发性有机物的特征、来源与二次转化, 臭氧污染成因.

    刘莹, 博士, 北京大学环境科学与工程学院副研究员. 2007年获北京大学博士学位. 主要研究方向为城市和区域大气有机碳的活性和来源、化学行为及环境影响等, 包括健全和完善有机物在线质谱技术, 开展我国高污染和强氧化性条件下含氧有机物的二次转化机制和化学演变特征、活性有机物的来源及其对二次污染贡献、二次有机气溶胶形成机制等关键科学问题的研究. 承担和参加多项国家自然科学基金、国家重点研发计划、环保部公益项目等.

    李歆, 博士, 北京大学环境科学与工程学院青年千人计划研究员, 博士生导师. 2010 年获得北京大学博士学位, 2014年9月~2016年6月就职于德国Juelich研究中心对流层研究所. 2016 年获得北京大学职位. 主要研究方向为大气活性物种的在线监测技术与来源转化机制, 致力于大气氧化性构成和演变特征、一次污染物大气氧化产生二次污染的化学反应机制、识别影响大气氧化进程的关键化学和物理要素等研究. 承担和参与多项国家自然科学基金委项目和国家重点研发计划项目.

    陆思华, 北京大学环境科学与工程学院, 教授级高工. 主要研究方向为区域大气有机污染物的来源、转化、环境影响等. 研究工作主要包括: 城市和区域大气VOCs的组成特征及环境影响、VOCs重点行业污染源排放特征及污染来源解析、大气中VOCs和SVOCs分析测试技术及质控等. 近年来, 作为课题负责人或课题骨干, 负责和参加了大气重污染成因与治理公关项目、科技部大气重点研发计划、国家环保公益性行业科研专项及横向协作等多项科研工作.

  • 基金资助:
    国家自然科学基金(91844301); 国家自然科学基金(91644108)

Advances on Atmospheric Oxidation Mechanism of Typical Aromatic Hydrocarbons

Mengdi Song, Ying Liu, Xin Li(), Sihua Lu   

  1. State Key Joint Laboratory of Environmental Simulation and Pollution Control, International Joint Laboratory for Regional Pollution Control, Ministry of Education (IJRC), College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
  • Received:2021-05-20 Published:2021-08-02
  • Contact: Xin Li
  • Supported by:
    National Natural Science Foundation of China(91844301); National Natural Science Foundation of China(91644108)

芳香烃作为城市大气臭氧(O3)和二次有机气溶胶(SOA)的重要前体物, 由于其对大气二次污染、气候变化及人体健康具有重要影响, 因此芳香烃氧化机理研究成为当前大气环境化学领域最具挑战的热点研究之一. 本文综述了芳香烃氧化机理的研究成果, 详细讨论了它们与OH自由基在高低氮氧化物条件下的各反应通道和影响因素, 重点关注近年来芳香烃氧化反应研究中的新发现和新理论. 芳香烃的大气氧化反应起始由OH自由基主导, 根据其反应产物主要分为醛通道、酚通道、双环RO2通道和环氧化物通道. 随着形成多羟基化合物、烷氧自由基环氧化、双环过氧自由基分子内氢转移、醛类化合物氢转移、CO-loss生成低碳产物等新理论的提出, 对芳香烃氧化的理解虽然有所提高, 但反应过程仍存在碳质量不守恒和自由基不闭合的问题, 导致对后续O3和SOA形成机制的认识还十分有限. 理论计算和实验室模拟是目前芳香烃氧化机理研究的主要手段. 质谱法和光谱法是芳香烃氧化产物最常用的测量技术, 在线质谱技术尝试从分子水平上捕捉示踪性中间产物的转化, 对揭示芳烃氧化机理具有重要作用. 随着示踪物测量技术的发展, 特别是色谱-质谱联用技术为中间产物的精准测量和芳香烃氧化机制的完善开拓了新方向. 在此基础上, 厘清芳烃氧化中的碳平衡和自由基收支等关键科学问题、探究实际大气中芳香烃的环境效应有望成为未来该领域的重点研究方向.

关键词: 芳香烃, 醛途径, 酚途径, 双环RO2途径, 氢转移反应

Aromatic hydrocarbons are important precursors of ozone and secondary organic aerosols in the urban atmosphere, which have important impact on air pollution, climate change and human health. Thus the research on the oxidation mechanism of aromatic hydrocarbons has become one of the most challenging hotspots topics in atmospheric environmental chemistry. This paper reviews the recent studies of aromatic hydrocarbons oxidation mechanism, discusses the reaction channels and influencing factors during the oxidation process under high/low NOx conditions, and focuses on new discoveries and new theories in the studies of aromatic hydrocarbon oxidation reactions. In the atmosphere, the initiation of aromatic hydrocarbons is dominated by the reaction with the OH radicals. According to the different reaction products, the oxidation reaction of aromatic hydrocarbon is mainly divided into aldehyde pathway, phenolic pathway, bicyclic RO2 pathway and epoxide pathway. With the development of new theories such as the formation of polyhydroxy compounds by aldehyde pathway, alkoxy radical epoxidation reaction, intramolecular H-migration reaction of bicyclic peroxy radicals, 1,5-aldehydic H-shift reaction, and the generation of low-carbon products by CO-loss reaction, the understanding of aromatic hydrocarbons oxidation mechanisms has improved. However, due to the carbon missing and radical budgets imbalance problems in the existing oxidation mechanism, our understanding about the subsequent O3 and secondary organic aerosols formation mechanisms are very limited. Theoretical calculation and experiment are the main methods to study the oxidation mechanism of aromatic hydrocarbons. Mass spectrometry and spectroscopy are the dominant measurement techniques for the oxidation intermediates of aromatic hydrocarbons. Online mass spectrometry can capture the tracer intermediates at the molecular level, which plays an important role in revealing the oxidation mechanism of aromatic hydrocarbons. In recent years, tracer measurement technology, especially chromatography-mass spectrometry technology has developed rapidly. This open up a new direction for the accurate measurement of intermediates and the improvement of aromatic hydrocarbon oxidation mechanism. On this basis, improving aromatic hydrocarbons oxidation mechanism, paying attention to the carbon missing and radical budgets imbalance in the oxidation reaction, and exploring the environmental implication of aromatic hydrocarbons oxidation in the real atmospheric conditions are expected to become the important directions of aromatic hydrocarbon oxidation study in the future.

Key words: aromatic hydrocarbon, aldehyde pathway, phenolic pathway, bicyclic RO2 pathway, H-migration