Investigation of the photo-oxidation of benzaldehyde and hydroxylated aromatic compounds: application of laser ionization mass spectrometry

苯甲醛和羟基芳香族化合物的光氧化研究：激光电离质谱的应用

• 批准号: 40199714
• 负责人: Professor Dr. Thorsten Benter
• 金额: --
• 依托单位: Fachgruppe Chemie und Biologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2007
• 资助国家: 德国
• 起止时间: 2006-12-31 至 2010-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/40199714?language=en
• 关键词: Investigation; photo; oxidation; benzaldehyde; hydroxylated

It is well established that the gas phase photo-oxidation of aromatic hydrocarbons (AH), benzene, toluene and the xylene isomers (BTX), leads to formation of secondary organic aerosol (SOA). While the primary reaction steps have been intensively studied, secondary and subsequent reaction steps, which lead to compounds eventually producing SOA, remain obscure. There is evidence that further oxidation of primary ring-retaining products, e.g., aromatic aldehydes, phenols (mono- and dihydroxy substituted), and nitrophenols, could play an important role in the initiation of SOA formation. To date studies on the further oxidation of the primary products using the available analytical techniques have only been marginally successful in identifying i) the chemical nature of the main products and ii) the main aerosol precursors as well as the chemical composition of the aerosol. The main aim of this project is, therefore, a detailed investigation of the reaction products from the OH and NO3radical initiated photo-oxidation of selected primary ring-retaining compounds observed in the oxidation of AH. The investigations will be performed in large volume photoreactors. In addition to available in situ FTIR und GC-MS analytical methods the chemical evolution of selected systems will be monitored using new novel mass spectrometric techniques, which are based on the Atmospheric Pressure Laser Ionization (APLI) method, recently introduced by our group. The application of the laser based ionization methods will serve to identify products which are not easily amendable or not detectable with conventional analytical techniques. Such studies are of fundamental importance for obtaining a better Benter/Barnes POXSA general understanding of the overall photo-oxidation mechanism of aromatic hydrocarbons and assessing their ability to form secondary organic aerosol. The broader impact of the proposed work is expected to be high in several regards. First, the results from the smog-chamber studies will contribute significantly i) to our understanding of the secondary processes involved in the oxidation of aromatic hydrocarbons (BTX), ii) it will help to remove many of the uncertainties currently inherent in chemical models of atmospheric chemistry and iii) it will improve our general understanding of the potential of these processes to form aerosol in the atmosphere. Second, the work will provide and an important platform for demonstrating the laser based mass spectrometric techniques which will be applied. Third, the scientific training of the involved Ph.D. students as well as Diploma/Masters students will encompass a broad variety of interdisciplinary research work. After completion of their Ph.D. thesis they will be well prepared for either entering the work market, or continuing their research work at the university level.

芳香烃(AH)、苯、甲苯和二甲苯异构体(BTX)的气相光氧化可导致二次有机气溶胶(SOA)的形成。虽然主要的反应步骤已经得到了深入的研究，但导致化合物最终产生SOA的第二和后续反应步骤仍然不清楚。有证据表明，初级保环产物的进一步氧化，如芳香醛、苯酚(单羟基和二羟基取代)和硝基苯酚，可能在启动SOA的形成中发挥重要作用。迄今为止，利用现有的分析技术对初级产品的进一步氧化进行的研究在确定一)主要产品的化学性质和二)主要气溶胶前体以及气溶胶的化学成分方面仅略微取得成功。因此，本项目的主要目的是详细研究在AH的氧化过程中观察到的部分初级保环化合物由OH和NO_3自由基引发的光氧化反应产物。研究将在大容量光反应堆中进行。除了现有的原位FTIR和GC-MS分析方法外，还将使用基于我们小组最近介绍的大气压激光电离(APLI)方法的新的质谱学技术来监测选定体系的化学演化。基于激光的电离方法的应用将有助于识别用传统分析技术不易修改或无法检测的产品。这些研究对于更好地了解芳香烃的整体光氧化机理和评估它们形成二次有机气溶胶的能力具有基本的重要性。预计拟议工作的更广泛影响将在几个方面产生很大影响。首先，烟雾室研究的结果将大大有助于：1)有助于我们了解芳香烃(BTX)氧化所涉及的次级过程；2)它将有助于消除目前大气化学化学模型中固有的许多不确定因素；3)它将提高我们对这些过程在大气中形成气溶胶的可能性的总体理解。第二，这项工作将为展示将要应用的激光质谱学技术提供一个重要的平台。第三，对博士生和文凭/硕士学生的科学培训将包括广泛的跨学科研究工作。完成博士论文后，他们将为进入就业市场或继续在大学层面的研究工作做好准备。