观察到乙炔与萘基自由基加成形成 C14H10 多环芳烃,Physical Chemistry Chemical Physics

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观察到乙炔与萘基自由基加成形成 C14H10 多环芳烃
Physical Chemistry Chemical Physics ( IF 2.9 ) Pub Date : 2021-06-15 , DOI: 10.1039/d1cp01565f
Jeehyun Yang ₁ , Mica C Smith ₂ , Matthew B Prendergast ₂ , Te-Chun Chu ₂ , William H Green ₂

Affiliation

燃烧过程中多环芳烃（PAHs）的形成对环境污染和公众健康产生重大影响。氢提取-乙炔加成 (HACA) 机制有望成为含有两个以上环的较大多环芳烃的重要来源。在本研究中，1-萘基和2-萘基自由基与乙炔（C ₂ H ₂) 使用 VUV 光电离飞行时间质谱在 500 至 800 K、15 至 50 托和反应时间长达 10 ms 下进行研究。我们的实验条件使我们能够探索 Bittner-Howard 和修改后的 Frenklach HACA 路线，而不是需要多个自由基来驱动化学反应的路线。将动力学测量与使用量子化学计算构建的温度相关动力学模型进行比较，并考虑化学活化和衰减效应。我们从 2-萘基自由基与 C ₂ H ₂的反应中测量了大量的 C ₁₄ H ₁₀（可能是菲和蒽）以及 2-乙炔基萘（C ₁₂ H ₈）; 这些结果与动力学模型和 HACA 机制的预测一致，但与之前的实验研究相矛盾，该研究表明在 2-萘基 + C ₂ H ₂反应中没有 C ₁₄ H ₁₀形成。在1-萘基+C ₂ H ₂反应体系中，测量的主要产物是C ₁₂ H ₈，与通过HACA形成苊的预测一致。目前的工作提供了直接的实验证据，表明单自由基 HACA 可能是形成大于萘的 PAH 的重要机制，验证了燃烧模型中的常见假设。

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C14H10 polycyclic aromatic hydrocarbon formation by acetylene addition to naphthalenyl radicals observed

The formation of polycyclic aromatic hydrocarbons (PAHs) during combustion has a substantial impact on environmental pollution and public health. The hydrogen-abstraction-acetylene-addition (HACA) mechanism is expected to be a significant source of larger PAHs containing more than two rings. In this study, the reactions of 1-naphthalenyl and 2-naphthalenyl radicals with acetylene (C₂H₂) are investigated using VUV photoionization time-of-flight mass spectrometry at 500 to 800 K, 15 to 50 torr, and reaction times up to 10 ms. Our experimental conditions allow us to probe the Bittner–Howard and modified Frenklach HACA routes, but not routes that require multiple radicals to drive the chemistry. The kinetic measurements are compared to a temperature-dependent kinetic model constructed using quantum chemistry calculations and accounting for chemical-activation and fall-off effects. We measure significant quantities of C₁₄H₁₀ (likely phenanthrene and anthracene), as well as 2-ethynylnaphthalene (C₁₂H₈), from the reaction of the 2-naphthalenyl radical with C₂H₂; these results are consistent with the predictions of the kinetic model and the HACA mechanism, but contradict a previous experimental study that indicated no C₁₄H₁₀ formation in the 2-naphthalenyl + C₂H₂ reaction. In the 1-naphthalenyl radical + C₂H₂ reaction system, the primary product measured is C₁₂H₈, consistent with the predicted formation of acenaphthylene via HACA. The present work provides direct experimental evidence that single-radical HACA can be an important mechanism for the formation of PAHs larger than naphthalene, validating a common assumption in combustion models.

更新日期：2021-06-24

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