Kinetics of Radical-Radical Reactions in Combustion Chemistry

0853706KnyazevKnyazev本研究旨在确定在碳氢化合物氧化和热解过程中起重要作用的自由基-自由基反应的动力学。这些反应通常起到链终止和分子质量增长的作用。这类反应的某些成员与芳香环和多芳烃的形成有关，这反过来又导致燃烧系统中产生烟尘。尽管自由基-自由基反应对于理解各种燃烧和热解过程的化学很重要，但关于它们的实验信息相当稀少，在许多情况下，还存在争议。这项工作的主要目标是建立一个可靠的数据库，其中包含关于一组基准反应的准确确定的实验数据。该项目涵盖了几种类型的自由基-自由基反应，包括烷基、环烷基、离域和芳香族自由基的自反应和交叉反应。速率常数的温度依赖关系是在直接实验中确定的，条件是在已知浓度下产生自由基，并且所研究的反应不受副作用影响。利用激光光解/光电离质谱技术实时监测自由基浓度的衰减和产物的形成。反应产物的研究通过在线质谱仪和最终产物的GC/MS进行。研究结果将对碳氢燃料的燃烧进行模拟，为进一步发展高水平的反应速率理论和半经验计算工具奠定实验基础。通过提高我们对燃烧发电等商业技术的理解，包括这些过程的安全和环境方面，将提高对社会的好处。拟议工作的其他更广泛的影响将来自教育和研究的结合以及对本科生和研究生的培训和教育的贡献。将通过出版物、在多学科会议和讲习班上的陈述、结果的网络陈述以及对网络基础设施项目的贡献，推动广泛传播成果。

0853706KnyazevThe research is directed at determination of the kinetics of radical-radical reactions important in the oxidation and pyrolysis of hydrocarbons. These reactions usually serve as chain termination and molecular-mass growth pathways. Certain members of this class of reactions have been linked to formation of aromatic rings and polyaromatic hydrocarbons, which leads, in turn, to production of soot in combustion systems. In spite of the importance of radical-radical reactions for understanding the chemistry of a wide variety of combustion and pyrolysis processes, experimental information on them is rather sparse and, in many cases, controversial. The main objective of the work is the establishment of a reliable database of accurately determined experimental data on a benchmark set of reactions. The project covers several types of radical-radical reactions, including self-reactions and cross reactions of alkyl, cycloalkyl, and delocalized and aromatic radicals. Temperature dependences of the rate constants are being determined in direct experiments under conditions where radicals are created in known concentrations and the reactions under study are isolated from side influences. Radical concentration decays and formation of products are monitored in real-time using Laser Photolysis / Photoionization Mass Spectrometry technique. Reaction-product studies are performed by online mass spectrometry as well as GC/MS of final products. Results of the study will be of fundamental importance for modeling the combustion of hydrocarbon fuels, forming an experimental basis for further advancement of high-level theories of reaction rates and semi-empirical computational tools. Benefits to society will be advanced by improving our understanding of commercial technologies such as energy generation through combustion, including the safety and environmental aspects of these processes. Other broader impacts of the proposed work will come from integration of education and research and contributions to training and education of undergraduate and graduate students. Broad dissemination of the results will be advanced via publications, presentations in multi-disciplinary conferences and workshops, web presentation of the findings, and contributing to cyberinfrastructure projects.