Abstract Elucidating the formation of combustion intermediates is crucial to validate reaction pathways, develop reaction mechanisms and examine kinetic modeling predictions. While high-temperature pyrolysis and oxidation intermediates of alkanes have been thoroughly studied, comprehensive analysis of cool flame intermediates from alkane autoxidation is lacking and challenging due to the complexity of intermediate species produced. In this work, jet-stirred reactor autoxidation of four C10 alkanes: n-decane, 2-methylnonane, 2,7-dimethyloctane, and n-butylcyclohexane, as model compounds of diesel fuel, was investigated from 500 to 630 K using synchrotron vacuum ultraviolet photoionization molecular beam mass spectrometry (SVUV-PIMS). Around 100 intermediates were detected for each fuel. The classes of molecular structures present during the autoxidation of the representative paraffinic functional groups in transport fuels, i.e., n-alkanes, branched alkanes, and cycloalkanes were established and were found to be similar from the oxidation of various alkanes. A theoretical approach was applied to estimate the photoionization cross sections of the intermediates with the same carbon skeleton as the reactants, e.g., alkene, alkenyl keto, cyclic ether, dione, keto-hydroperoxide, diketo-hydroperoxide, and keto-dihydroperoxide. These species are indicators of the first, second, and third O2 addition reactions for the four C10 hydrocarbons, as well as bimolecular reactions involving keto-hydroperoxides. Chemical kinetic models for the oxidation of these four fuels were examined by comparison against mole fraction of the reactants and final products obtained in additional experiments using gas chromatography analysis, as well as the detailed species pool and mole fractions of aforementioned seven types of intermediates measured by SVUV-PIMS. This works reveals that the models in the literature need to be improved, not only the prediction of the fuel reactivity and final products, but also the reaction network to predict the formation of many previous undetected intermediates.

中文翻译：

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柴油替代化合物的冷焰化学：正癸烷、2-甲基壬烷、2,7-二甲基辛烷和正丁基环己烷

摘要 阐明燃烧中间体的形成对于验证反应途径、发展反应机制和检查动力学建模预测至关重要。虽然已经对烷烃的高温热解和氧化中间体进行了深入研究，但由于产生的中间体物种的复杂性，缺乏对烷烃自氧化的冷焰中间体的综合分析。在这项工作中，使用同步加速器真空从 500 到 630 K 研究了四种 C10 烷烃的喷射搅拌反应器自氧化：正癸烷、2-甲基壬烷、2,7-二甲基辛烷和正丁基环己烷作为柴油燃料的模型化合物紫外光电离分子束质谱（SVUV-PIMS）。每种燃料检测到大约 100 种中间体。在运输燃料中代表性链烷烃官能团（即，正构烷烃、支链烷烃和环烷烃）的自动氧化过程中存在的分子结构类别已确定，并且发现与各种烷烃的氧化相似。应用理论方法来估计与反应物具有相同碳骨架的中间体的光电离截面，例如烯烃、烯基酮、环醚、二酮、酮-氢过氧化物、二酮-氢过氧化物和酮-二氢过氧化物。这些物质是四种 C10 烃的第一次、第二次和第三次 O2 加成反应以及涉及酮氢过氧化物的双分子反应的指标。通过与使用气相色谱分析的额外实验中获得的反应物和最终产物的摩尔分数进行比较，以及上述七种类型中间体的详细物质库和摩尔分数，通过比较来检查这四种燃料氧化的化学动力学模型。 SVUV-PIMS。这项工作表明，文献中的模型需要改进，不仅是对燃料反应性和最终产物的预测，还包括反应网络来预测许多以前未检测到的中间体的形成。