Chem. J. Chinese Universities ›› 2022, Vol. 43 ›› Issue (2): 20210563.doi: 10.7503/cjcu20210563

• Physical Chemistry • Previous Articles     Next Articles

Rate Rules for Hydrogen Abstraction Reactions of Polycyclic Aromatic Hydrocarbons and Unsaturated Radicals

DENG Hongri1,2, CAO Xiaomei3, WANG Jingbo1,2(), LI Xiangyuan1,2   

  1. 1.College of Chemical Engineering,Sichuan University,Chengdu 610065,China
    2.Engineering Research Center of Combustion and Cooling for Aerospace Power,Ministry of Education,Sichuan University,Chengdu 610065,China
    3.Hypervelocity Aerodynamic Institute,China Aerodynamics Research and Development Center,Mianyang 621000,China
  • Received:2021-08-10 Online:2022-02-10 Published:2021-11-23
  • Contact: WANG Jingbo E-mail:wangjingbo@scu.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(91741201)

Abstract:

The reaction kinetics for a series of polycyclic aromatic hydrocarbons(PAHs) containing up to six aroma-tic rings by propynyl radical(C3H3), allyl radical(C3H5), butadienyl radical(nC4H5, iC4H5), pentadienyl radical (C5H5) and phenyl radical(C6H5) were systematically investigated via the M06-2X/cc-pVTZ method. Based on the electronic structure calculations, the rate constants of title reactions were calculated by using transition state theory coupled with Eckart tunneling correction at the temperature range of 500—2500 K. The effects of PAH sizes and structures on the rate constants were examined. The results show that the PAH sizes have little effect on the rate constants, while the structures of PAHs influence the rate constant significantly. Hence, the hydrogen abstraction reactions are simplified into C5 and C6 reaction classes depending on the abstraction site on the five-membered or six-membered ring. The simple two classes are conducive to construct the combustion model of PAHs. The results indicate that C6 class possesses a higher activity than the C5 class. Hydrogen extraction reactions classes from PAHs by nC4H5, iC4H5 and C6H5 radicals are studied in a systematic way, and the reactivity of different H-abstraction reactions from PAHs by different radicals shows the following trends: C6H5>nC4H5>iC4H5. The rate rules are summarized by taking the average values of rate constants of a representative set of reactions in each class, which are applicable for the chemical model construction of PAHs.

Key words: Polycyclic aromatic hydrocarbons, Unsaturated radical, Hydrogen abstraction, Rate rule

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