New Insights into Thermal Decomposition of Polycyclic Aromatic Hydrocarbon Oxyradicals
journal contributionposted on 04.12.2014, 00:00 by Peng Liu, He Lin, Yang Yang, Can Shao, Chen Gu, Zhen Huang
Thermal decompositions of polycyclic aromatic hydrocarbon (PAH) oxyradicals on various surface sites including five-membered ring, free-edge, zigzag, and armchair have been systematically investigated by using ab initio density functional theory B3LYP/6-311+G(d,p) basis set. The calculation based on Hückel theory indicates that PAHs (3H-cydopenta[a]anthracene oxyradical) with oxyradicals on a five-membered ring site have high chemical reactivity. The rate coefficients of PAH oxyradical decomposition were evaluated by using Rice–Ramsperger–Kassel–Marcus theory and solving the master equations in the temperature range of 1500–2500 K and the pressure range of 0.1–10 atm. The kinetic calculations revealed that the rate coefficients of PAH oxyradical decomposition are temperature-, pressure-, and surface site-dependent, and the oxyradical on a five-membered ring is easier to decompose than that on a six-membered ring. Four-membered rings were found in decomposition of the five-membered ring, and a new reaction channel of PAH evolution involving four-membered rings is recommended.