Formation of polycyclic aromatic hydrocarbons and soot in fuel-rich oxidation of methane in a laminar flow reactor
Formation of polycyclic aromatic hydrocarbons and soot in fuel-rich oxidation of methane in a laminar flow reactor
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DOI：
10.1016/j.combustflame.2003.09.011
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发表时间：
2004
影响因子：
4.4
通讯作者：
M. Skjøth-Rasmussen;P. Glarborg;M. Østberg;J. Johannessen;H. Livbjerg;A. Jensen;T. Christensen
中科院分区：
文献类型：
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作者：
M. Skjøth-Rasmussen;P. Glarborg;M. Østberg;J. Johannessen;H. Livbjerg;A. Jensen;T. Christensen
在层流反应器中，研究了甲烷在富燃料条件下转化为高级烃、多环芳烃和碳烟的反应。在1073和1823 K之间的温度下研究了化学计量、稀释和水蒸气添加的影响。建立了甲烷氧化反应的化学动力学机理，重点研究了高级烃和多环芳烃的生成。从Frenklach及其同事的工作中采用了烟尘形成的子模型，没有任何变化。模型预测结果与实验结果吻合良好。反应物，稳定的中间体，和PAH化合物通常是很好的预测。计算结果表明，在炭黑生成体系中，自由基对多环芳烃的生成有重要影响，特别是对萘和菲的生成有重要影响。萘和菲似乎是PAH生长的重要中间体，它们对芘的形成有显着的影响，随后导致在所应用的模型中形成烟尘。碳烟模型一般预测碳烟的体积分数是两到三个数量级低于实验获得的，该模型预测的碳烟发生约100 K以下的实验观察。水蒸气的加入对测量的乙炔浓度和在1500 K及以上的烟灰形成有相当大的影响。在此温度范围内，乙炔和碳烟的浓度随着水蒸气添加量的增加而降低。用反应机理定性地描述了这种效应。乙炔的氧化增强归因于水蒸气和氢原子之间反应形成的更高水平的羟基自由基。
Conversion of methane to higher hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), and soot was investigated under fuel-rich conditions in a laminar flow reactor. The effects of stoichiometry, dilution, and water vapor addition were studied at temperatures between 1073 and 1823 K. A chemical kinetic mechanism was established for methane oxidation, with emphasis on formation of higher hydrocarbons and PAH. A submodel for soot formation was adopted from the work of Frenklach and co-workers without changes. Modeling predictions showed good agreement with experimental results. Reactants, stable intermediates, and PAH compounds are generally well predicted. In sooting systems, the calculations indicate that the cyclopentadienyl radical has a significant influence on growth of PAH, particularly in the formation of naphthalene and phenanthrene. Both naphthalene and phenanthrene appear to be important intermediates in PAH growth, and they have a significant influence on the formation of pyrene, which subsequently results in formation of soot in the applied model. The soot model generally predicts soot volume fractions to be two to three orders of magnitude lower than those obtained experimentally, and the model predicts inception of soot to occur approximately 100 K below experimental observations. Addition of water vapor has a considerable effect on the measured acetylene concentration and on soot formation at 1500 K and above. In this temperature regime, concentrations of both acetylene and soot decrease with increasing addition of water vapor. The effect is described qualitatively by the reaction mechanism. The enhanced oxidation of acetylene is attributed to higher levels of hydroxyl radicals, formed from the reaction between the water vapor and hydrogen atoms.