Impacts of Criegee intermediate decomposition and reaction with water determined by direct measurements in ozonolysis reactions

通过直接测量臭氧分解反应确定 Criegee 中间体分解和与水反应的影响

• 批准号: NE/P012876/1
• 负责人: Daniel Stone
• 金额: $ 54.62万
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FP012876%2F1
• 关键词: Impacts; Criegee; intermediate; decomposition; reaction

According to DEFRA poor air quality costs the UK ~£15billion per year, and is governed by the chemical composition of the atmosphere. Knowledge of the gas phase oxidation of hydrocarbons (HCs) and volatile organic compounds (VOCs) emitted into the atmosphere as a result of biogenic or anthropogenic processes is central to the impacts of emissions on NOx (NOx = NO + NO2), ozone, methane lifetimes, and formation of secondary organic aerosol (SOA), and thus on air quality and climate change.An important class of oxidation reactions are initiated by ozone, and involve the oxidation of unsaturated VOCs (including both anthropogenic and biogenic sources) in ozonolysis reactions. These reactions have long been postulated to produce reactive Criegee intermediates (CIs), and have been shown to dominate atmospheric radical production at night and in low light conditions. In 2012, the first direct kinetic measurements of CI reactions were made, using photolytic sources of CIs in the laboratory, with results indicating much higher reactivity than previously expected on the basis of indirect measurements. Experiments using the newly identified photolytic sources have cast doubt on our understanding of the role of CI species in the atmosphere, with initial results indicating an enhanced role in the oxidation of SO2 and NO2. However, the competing reaction with water vapour is critical to the atmospheric impacts of CIs.The simplest CI species, CH2OO, has been shown to react rapidly with the water dimer, but the reactions of larger CIs with water (both monomers and dimers) have received relatively little attention, and no temperature dependent kinetics are available for the larger species for use in atmospheric models. Products of the reactions with water will determine the ultimate atmospheric impacts of these reactions, and are highly uncertain. Unimolecular decomposition reactions have also been highlighted as potentially significant loss mechanisms for large CI species, with little information available regarding the kinetics or products of these reactions. This work will address the uncertainties in the kinetics and products of CI decomposition and reactions with water.Moreover, we will also develop capabilities for monitoring of CI species directly in ozonolysis reactions using UV/vis absorption spectroscopy, enabling the direct determination of CI yields from ozonolysis reactions and the investigation of CI chemistry under more realistic atmospheric conditions. This study will therefore address concerns regarding the applicability of kinetic results obtained in experiments in which CI are produced photolytically.This work will reduce the significant uncertainties in the atmospheric fate and impact of Criegee intermediates, leading to improvements in capabilities for numerical modelling of atmospheric composition, air quality and climate.

根据Defra的说法，空气质量较差，英国每年耗资约150亿英镑，受大气化学成分的约束。由于生物或人为过程而导致的气相（HCS）（HCS）和挥发性有机化合物（VOC）的气相氧化知识，这对于发射或人为过程的结果是排放对NOX的影响至关重氧化反应是由臭氧引发的，涉及臭氧反应中不饱和VOC（包括人为和生物源）的氧化。这些反应长期以来一直在假设产生反应性的Criegee中间体（CIS），并已证明在夜间和低光条件下主导了大气自由基的生产。在2012年，使用实验室中CI的光解源进行了对CI反应的第一个直接动力学测量，结果表明，根据间接测量值，其反应性比以前预期的要高得多。使用新鉴定的光解源的实验使我们对我们对CI物种在大气中的作用的理解产生了怀疑，最初的结果表明在SO2和NO2的氧化中起着增强的作用。然而，与水蒸气的竞争反应对顺式的大气影响至关重要。最简单的CI物种CH2OO已显示出与水二聚体的迅速反应，但是较大的CIS与水（单体和二聚体都相对较少的关注，且没有依赖温度的动力学可用于大气模型中的较大的温度动力学。与水反应的产物将决定这些反应的最终大气影响，并且高度不确定。单分子分解反应也被强调为大型CI物种的潜在重要损失机制，几乎没有有关这些反应的动力学或产物的信息。这项工作将解决CI分解和与水反应的动力学和产物中的不确定性。更重要的是，我们还将使用UV/Vis Absratration Spartroscopicy在臭氧溶解反应中直接监测CI物种的能力，从而使CI收益率直接确定CI的收益率从ozonolsosis Reactions Reactions Reactions和CI Isvestptions Provistions Pressptions Pressptions ci Chemistical Chemistict Chemistictiond Chemistict yrististions杂乱无变。因此，这项研究将解决有关在CI通过光解的实验中获得的动力学结果的适用性的担忧。这项工作将减少在大气命运和Criegee中间体的影响中的重大不确定性，从而改善了大气组成，空气质量和气候的数值建模功能。

项目成果

Kinetics of the gas phase reaction of the Criegee intermediate CH2OO with SO2 as a function of temperature.

Criegee 中间体 CH2OO 与 SO2 的气相反应动力学随温度的变化。

• DOI: 10.1039/d1cp02932k
• 发表时间: 2021
• 期刊: PCCP
• 作者: Onel L