Wei Mingrui, Zhang Tingting, Chen Xianfeng, Yan Fuwu, Guo Guanlun, Zhang Dongju
Hubei Key Laboratory of Advanced Technology for Automotive Components, Hubei Collaborative Innovation Center for Automotive Components Technology, Wuhan University of Technology Wuhan 430070 PR China
School of Resources and Environmental Engineering, Wuhan University of Technology Wuhan 430070 China.
RSC Adv. 2018 Apr 10;8(24):13226-13236. doi: 10.1039/c8ra01449c. eCollection 2018 Apr 9.
The formation of polycyclic aromatic hydrocarbons (PAHs) on the CH potential energy surface involved in the reactions of a phenyl radical (CH) with -3-penten-1-yne (-CH[triple bond, length as m-dash]C-CH[double bond, length as m-dash]CH-CH, referred to as CH) and its three radicals (CH[triple bond, length as m-dash]C-Ċ[double bond, length as m-dash]CH-CH, CH[triple bond, length as m-dash]C-CH[double bond, length as m-dash]Ċ-CH, and -CH[triple bond, length as m-dash]C-CH[double bond, length as m-dash]CH-ĊH, referred to as the C-, C-, and C-radicals with the same chemical components, CH) assisted by H atoms is investigated by performing combined density functional theory (DFT) and calculations. Five potential pathways for the formation of PAHs have been explored in detail: Pathways I-II correspond to the reaction of CH with CH at the C and C position, and Pathways III-V involve the reaction of CH with the C-, C-, and C-radicals with the assistance of H atoms. The initial association of CH with CH or CH is found to be highly exothermic with only minor barriers (1.4-7.1 kcal mol), which provides a large driving force for the formation of PAHs. The hydrogen atom is beneficial for the ring enlargement and ring formation processes. The present calculations predict 9 potential PAHs, six (CS6, CS10, CS13, CS26, CS28 and CS29) of which are indicated to be energetically more favorable along Pathways I, III, IV and V at low temperature. The calculated barriers for the formation of these PAHs are around 19.2-38.0 kcal mol. All PAHs products could be formed at flame temperature, for the medium barriers are easily overcome in various flame conditions. The theoretical results supplement the PAH formation pathway and provide help to understand PAH growth mechanism.
通过结合密度泛函理论（DFT）计算，研究了苯基自由基（CH）与-3-戊烯-1-炔（-CH≡C-CH═CH-CH，简称CH）及其三个自由基（CH≡C-Ċ═CH-CH、CH≡C-CH═Ċ-CH和-CH≡C-CH═CH-ĊH，分别简称为具有相同化学成分CH的C-、C-和C-自由基）反应中，CH势能面上多环芳烃（PAHs）的形成。详细探索了PAHs形成的五条潜在途径：途径I-II对应于CH与CH在C和C位置的反应，途径III-V涉及CH在H原子辅助下与C-、C-和C-自由基的反应。发现CH与CH或CH的初始缔合是高度放热的，只有很小的势垒（1.4 - 7.1 kcal/mol），这为PAHs的形成提供了很大的驱动力。氢原子有利于扩环和环形成过程。目前的计算预测了9种潜在的PAHs，其中六种（CS6、CS10、CS13、CS26、CS28和CS29）在低温下沿途径I、III、IV和V在能量上更有利。这些PAHs形成的计算势垒约为19.2 - 38.0 kcal/mol。所有PAHs产物在火焰温度下都可以形成，因为在各种火焰条件下中等势垒很容易被克服。理论结果补充了PAH形成途径，有助于理解PAH生长机制。
