摘要
氢提取反应不仅在燃料的裂解和氧化过程中很重要,而且对于多环芳烃(PAH)长大及碳烟表面生长也至关重要,因为其中最主要的途径——氢提取乙炔加成(HACA)反应的第一步就是氢提取反应。但是文献中报道的该反应的速率常数相差几个量级。为了更准确的确定多环芳烃长大及碳烟表面生长中氢提取反应的速率常数,本文利用量子化学高精度从头算方法和一些密度泛函方法研究了苯和萘氢提取反应势能面,并计算了反应速率常数。通过比较高精度从头算方法与各种密度泛函方法的计算结果,确定了一种适用于研究多环芳烃氢提取反应的密度泛函方法,并用它计算了几个PAH的氢提取反应。该计算结果既适用于多环芳烃,也可用于表征碳烟表面的氢提取反应速率常数。
Hydrogen abstraction reactions by hydrogen atoms not only play an important role in fuel cracking and oxidation processes, but also are essential for polycyclic aromatic hydrocarbons(PAH) formation and soot surface growth, as the hydrogen abstraction reaction by H is the first step in the Hydrogen-Abstraction-Carbon-Addition(HACA) mechanism. However, literature data on H abstraction rate constants differ by several orders of magnitude. To obtain an accurate rate constant, we applied both ab initio methods at very high level of theory and density functional theory(DFT) methods to investigate the potential energy surfaces and compute the rate constants of hydrogen abstraction reactions for benzene and naphthalene. Relatively accurate DFT methods were then selected to study the reaction kinetics of hydrogen abstraction reactions of several large PAHs. The rate constant computed in this study may be used in both PAH chemistry and soot surface growth models.
引文