Kinetic analysis of the pathways to naphthalene formation from phenyl + 1,3-Butadiyne reaction

Peng Liu*, William L. Roberts

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Having a better understanding of polycyclic aromatic hydrocarbon (PAH) formation under flame conditions contributes to optimizing the fuel reforming process, where soot poisons the downstream catalyst. In this work, the phenyl + 1,3-Butadiyne reaction is systematically investigated to examine its contribution to naphthalene formation. The reaction potential energy surfaces were calculated using DFT/M06–2X/cc-pvtz and G4 methods. The temperature- and pressure-dependent reaction rate constants were calculated using RRKM theory with solving master equation. The results revealed that 2-naphthyl could be directly formed by phenyl + 1,3-Butadiyne reaction. With H assistance, naphthalene could be formed by the pathway of phenyl + 1,3-Butadiyne → C6H5CHCCCH (+H) → C6H5CHCHCCH (+H) →naphthalene +H. The proposed pathway is kinetically favorable, and featured by relatively low energy barrier. The importance of the proposed pathway reaction was confirmed in a premixed and a diffusion C2H4/O2/Ar flame simulations, where the enhancement of naphthalene by the investigated reactions is notable. The mole fraction of A2 is promoted by a factor of 10% in premix C2H4/O2/Ar flame and 30% in C2H4/O2/Ar counterflow flame, bringing the prediction results closer to the experimental results. The relative contribution of different reaction route to A2 formation is evaluated for HACA, cyclopentadienyl radical-cyclopentadienyl radical, phenyl-vinylacetylene[1], benzyl radical-propargyl radical, indene-CH2 and phenyl-1,3-Butadiyne routes in premixed and diffusion C2H4/O2/Ar flames. This work suggests that the PAH growth by 1,3-Butadiyne addition reaction is an effective pathway for A2 formation, which should be considered in future PAH mechanism.

Original languageEnglish (US)
Pages (from-to)63-71
Number of pages9
JournalProceedings of the Combustion Institute
Issue number1
StatePublished - Jan 2023


  • DFT
  • Naphthalene
  • PAH
  • Reaction mechanism
  • Soot

ASJC Scopus subject areas

  • General Chemical Engineering
  • Mechanical Engineering
  • Physical and Theoretical Chemistry


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