低NOx浓度条件下挥发性有机物的大气氧化机理研究

项目名称： 低NOx浓度条件下挥发性有机物的大气氧化机理研究

项目编号： No.21477038

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 化学工业

项目作者： 王黎明

作者单位： 华南理工大学

项目金额： 88万元

中文摘要： 挥发性有机物(VOCs)的大气氧化是引起区域性大气臭氧超标和PM重度污染的关键因素之一。对VOCs的大气氧化有很多研究，也建立了诸多机理模型，但仍存在很多缺陷，导致如低NOx条件下模型预测和大气实测之间的巨大差异。我们认为机理模型中有机过氧自由基(RO2)异构化反应的缺失是可能的重要原因之一。现有的机理模型中RO2仅与NOx和HO2/R'O2反应；但我们的初步研究表明，一些RO2的H-转移异构化反应可与这些反应相竞争，低NOx时更是如此，且随温度升高变得更重要。但广泛使用的VOCs大气氧化机理模型如SAPRC和MCM完全忽略了RO2的异构化反应，文献中也极少有报导。本项目拟研究几类含氧VOCs和含共轭烯烃的VOCs大气氧化中RO2的异构化及温度的影响，完善其大气氧化机理。逐步修改现有的机理模型，发展新的VOCs大气氧化机理模型，以预测不同NOx浓度和温度条件下VOCs对空气质量的影响。

中文关键词： 大气氧化机理；挥发性有机物；过氧自由基；异构化反应；机理模型

英文摘要： The oxidation of volatile organic compounds (VOCs) is one of the main reasons for the regional high ozone and PM2.5 concentrations in the atmosphere. The atmospheric oxidation mechanism of VOCs is therefore essential in developing reasonable strategy for air quality control. Although there have been plenty of studies on the atmospheric oxidation mechanism of VOCs and a few models on the oxidation mechanism of VOCs have also been developed, deficiency persists in this model, i.e., the big gap between model predictions and field measurements on the ambient hydroxyl radical concentration under low-NOx conditions. We believe, one of the important reasons is that the isomerization reactions of peroxyl raidcals (RO2) were missing in these models. In the existing models, RO2 would react only with NOx and HO2/R'O2. However, our preliminary studies show that the isomerizations through H-shift are fast enough to compete with the bimolecular reactions with NOx and HO2/R'O2 for some RO2 radicals, especially when NOx concentrations are low. The H-shift will be more important with the increased temperature; but the widely used VOCs oxidation models such as SAPRC and MCM completely ignored the isomerization reactions of RO2 radicals and the ensuing reactions, and the literature report on the isomerization of RO2 under the atmospheric conditions was rather limited as well. We propose to study the atmospheric oxidation mechanism of some oxygenated VOCs and some conjugated dialkenes. We plan to examine the isomerization reactions of RO2 radicals formed during the atmospheric oxidation of these VOCs, computing their reaction rates and the temperature effect, and to improve their atmospheric oxidation mechanism. The mechanism for each VOC species will be evaluated and incorporated into the existing models, and a new mechanism model for the atmospheric oxidation of VOCs will be developed. The new model will be suitable for predicting the effect of VOCs on the air quality under different NOx concentrations and temperature conditions.

英文关键词： Atmospheric Oxidation Mechanism;Volatile Organic Compounds;Peroxyl Radical;Isomerization Reaction;Mechanism Model