Influences of the molecular fuel structure on combustion reactions towards soot precursors in selected alkane and alkene flames.
Influences of the molecular fuel structure on combustion reactions towards soot precursors in selected alkane and alkene flames.
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DOI：
10.1039/c7cp07743b
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发表时间：
2018-04
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影响因子：
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通讯作者：
L. Ruwe;K. Moshammer;N. Hansen;K. Kohse-Höinghaus
中科院分区：
文献类型：
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作者：
L. Ruwe;K. Moshammer;N. Hansen;K. Kohse-Höinghaus
在本研究中，我们利用火焰取样分子束质谱仪对正戊烷、1-戊烯和2-甲基-2-丁烯(2M2B)在燃烧环境中的高温氧化动力学进行了实验研究。所选的C5燃料是线性和支化的、饱和的和不饱和的燃料组分的原型，具有不同的C-C和C-H键结构。结果表明，通过质量增长反应生成的多环芳烃(PAHs)等物种的形成趋势按正戊烷<；1-戊烯<；2M2B的顺序急剧增加。这项比较研究有助于深入了解气相燃烧机理的燃料依赖反应序列，为观察到的多环芳烃生成趋势的差异提供解释。首先，我们研究了在燃料分解过程中作为中间物种产生的与燃料结构相关的小碳氢化合物物种的形成，因为这些物种是随后质量增长反应路径的起始点。其次，我们回顾了典型的多环芳烃生成反应，考察了依赖于分子燃料结构的重复生长序列。第三，我们讨论了中间物种池中的差异如何影响关键芳环物种的形成反应，这些芳环物种对于碳烟形成下的多环芳烃生长过程是重要的。结果表明，对于具有C[双键，长度为m-短划线]C双键的燃料，其烯丙基燃料自由基及其分解产物的化学组成强烈地影响了与初始形成的芳环物种的结合反应，从而影响了多环芳烃的生成倾向。
In this study, we experimentally investigate the high-temperature oxidation kinetics of n-pentane, 1-pentene and 2-methyl-2-butene (2M2B) in a combustion environment using flame-sampling molecular beam mass spectrometry. The selected C5 fuels are prototypes for linear and branched, saturated and unsaturated fuel components, featuring different C-C and C-H bond structures. It is shown that the formation tendency of species, such as polycyclic aromatic hydrocarbons (PAHs), yielded through mass growth reactions increases drastically in the sequence n-pentane < 1-pentene < 2M2B. This comparative study enables valuable insights into fuel-dependent reaction sequences of the gas-phase combustion mechanism that provide explanations for the observed difference in the PAH formation tendency. First, we investigate the fuel-structure-dependent formation of small hydrocarbon species that are yielded as intermediate species during the fuel decomposition, because these species are at the origin of the subsequent mass growth reaction pathways. Second, we review typical PAH formation reactions inspecting repetitive growth sequences in dependence of the molecular fuel structure. Third, we discuss how differences in the intermediate species pool influence the formation reactions of key aromatic ring species that are important for the PAH growth process underlying soot formation. As a main result it was found that for the fuels featuring a C[double bond, length as m-dash]C double bond, the chemistry of their allylic fuel radicals and their decomposition products strongly influences the combination reactions to the initially formed aromatic ring species and as a consequence, the PAH formation tendency.