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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >PAH Growth Initiated by Propargyl Addition: Mechanism Development and Computational Kinetics
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PAH Growth Initiated by Propargyl Addition: Mechanism Development and Computational Kinetics

机译：炔丙基加成引发的PAH的生长：机理发展和计算动力学

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摘要

Polycyclic aromatic hydrocarbon (PAH) growth is known to be the principal pathway to soot formation during fuel combustion, as such, a physical understanding of the PAH growth mechanism is needed to effectively assess, predict, and control soot formation in flames. Although the hydrogen abstraction C2H2 addition (HACA) mechanism is believed to be the main contributor to PAH growth, it has been shown to under-predict some of the experimental data on PAHs and soot concentrations in flames. This article presents a submechanism of PAH growth that is initiated by propargyl (C3H3) addition onto naphthalene (A2) and the naphthyl radical. C_3H_3 has been chosen since it is known to be a precursor of benzene in combustion and has appreciable concentrations in flames. This mechanism has been developed up to the formation of pyrene (A4), and the temperature-dependent kinetics of each elementary reaction has been determined using density functional theory (DFT) computations at the B3LYP/6-311++G(d,p) level of theory and transition state theory (TST). H-abstraction, H-addition, H-migration, β-scission, and intramolecular addition reactions have been taken into account. The energy barriers of the two main pathways (H-abstraction and H-addition) were found to be relatively small if not negative, whereas the energy barriers of the other pathways were in the range of (6-89 kcal·mol~(-1)). The rates reported in this study may be extrapolated to larger PAH molecules that have a zigzag site similar to that in naphthalene, and the mechanism presented herein may be used as a complement to the HACA mechanism to improve prediction of PAH and soot formation.
机译：众所周知，多环芳烃（PAH）的生长是燃料燃烧过程中烟灰形成的主要途径，因此，需要对PAH的生长机理有一个物理了解，才能有效地评估，预测和控制火焰中烟灰的形成。尽管据信氢提取C2H2的添加（HACA）机制是PAH增长的主要因素，但事实证明，该机制对火焰中PAH和烟灰浓度的一些实验数据预测不足。本文介绍了PAH生长的子机制，该机制是通过将炔丙基（C3H3）加到萘（A2）和萘基上而引发的。选择C_3H_3是因为已知它是燃烧中苯的前体，并且在火焰中具有明显的浓度。一直到形成（（A4）为止，已经开发了这种机理，并且已使用B3LYP / 6-311 ++ G（d，p）上的密度泛函理论（DFT）计算确定了每个基本反应的温度依赖性动力学。 ）理论水平和过渡状态理论（TST）。已经考虑了H吸收，H加成，H迁移，β断裂和分子内加成反应。发现两个主要途径（H吸收和H加成）的能垒相对较小，即使不是负值，而其他途径的能垒则在（6-89 kcal·mol〜（- 1））。这项研究中报道的比率可以外推到具有类似于萘的锯齿形位点的更大的PAH分子，并且本文介绍的机制可以用作HACA机制的补充，以改善对PAH和烟灰形成的预测。

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