The PAHs-C₂H₂ pathway (PAHs + C₂H₂ → intermediate → product + H₂) has been shown, in theory, to be the important contributor to the growth of polycyclic aromatic hydrocarbons (PAHs) and soot in the post-flame region where H atoms are rare. Calculations of the potential energy surface (PES) using the DFT B3LYP 6-311 + G(d,p) method, and the reaction rate coefficients using the RRKM theory, reveal that armchair and bridge surface sites share similar kinetic characteristics, and are more likely to be the targets of C₂H₂ molecules in flames compared to zig-zag and 5-membered ring surface sites. Results show that the energy barrier of a 2-H elimination reaction (14–23.8 kcal/mol) is much lower than that of a 1-H elimination (typically 30–40 kcal/mol) for some molecules. The formation of pyrene from phenanthrene via HACA (PAHs + H → PAHs radical (+ C₂H₂) → intermediate → product + H) and PAHs-C₂H₂ pathways is investigated using a closed homogeneous zero-dimensional reactor with combustion parameters abstracted from the premixed stagnation C₂H₄/O₂/Ar sooting flame. Results show that the HACA pathway is the dominant pathway for the formation of PAHs and soot surface growth in the main-flame region where H atoms are abundant, but that the PAHs-C₂H₂ pathway is the preferred pathway in the post-flame region. Our study also suggests that the soot nucleation involving a chemical coalescence of moderate-sized PAHs into a crosslinked three-dimensional structure via the addition reactions of PAHs and PAH radicals in the main-flame region should be considered for inclusion in any soot modeling.

从理论上讲，PAHs-C ₂ H ₂途径（PAHs + C ₂ H ₂  →中间体→产物+ H ₂）已被证明是后期多环芳烃（PAHs）和烟灰生长的重要因素。 -H原子稀有的火焰区域。使用DFT B3LYP 6-311 + G（d，p）方法计算势能表面（PES），并使用RRKM理论计算反应速率系数，发现扶手椅和桥表面的位置具有相似的动力学特性，并且更多可能是C ₂ H ₂的目标与之字形和5元环表面位点相比，火焰中的分子含量更高。结果表明，对于某些分子，2-H消除反应的能垒（14–23.8 kcal / mol）比1-H消除反应的能垒（通常为30–40 kcal / mol）低得多。使用具有燃烧参数的封闭均质零维反应器，研究了通过HACA（菲+ H→PAHs自由基（+ C ₂ H ₂）→中间体→产物+ H）和PAHs-C ₂ H ₂途径由菲形成of的过程。从预混停滞中提取C ₂ H ₄ / O ₂/ Ar吹灰。结果表明，HACA途径是在H原子丰富的主火焰区域中PAHs形成和烟灰表面生长的主要途径，而PAHs-C ₂ H ₂途径是火焰后的首选途径地区。我们的研究还表明，在任何烟灰模型中都应考虑通过中等火焰中PAH和PAH自由基在主火焰区域的加成反应将中等大小的PAHs化学聚结成交联的三维结构的烟灰成核。