Abstract
The reaction pathways for the oxidation by O 2 of polycyclic aromatic hydrocarbons present in soot particles are investigated using density functional theory at B3LYP/6-311++G(d,p) level of theory. For this, pyrene radical (4-pyrenyl) is chosen as the model molecule, as most soot models present in the literature employ the reactions involving the conversion of 4-pyrenyl to 4-phenanthryl by O 2 and OH to account for soot oxidation. Several routes for the formation of CO and CO 2 are proposed. The addition of O 2 on a radical site to form a peroxyl radical is found to be barrierless and exothermic with reaction energy of 188kJ/mol. For the oxidation reaction to proceed further, three pathways are suggested, each of which involve the activation energies of 104, 167 and 115kJ/mol relative to the peroxyl radical. The effect of the presence of H atom on a carbon atom neighboring the radical site on the energetics of carbon oxidation is assessed. Those intermediate species formed during oxidation with seven-membered rings or with a phenolic group are found to be highly stable. The rate constants evaluated using transition state theory in the temperature range of 300-3000K for the reactions involved in the mechanism are provided. © 2012 The Combustion Institute.
Original language | English (US) |
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Pages (from-to) | 3423-3436 |
Number of pages | 14 |
Journal | Combustion and Flame |
Volume | 159 |
Issue number | 11 |
DOIs | |
State | Published - Nov 2012 |
Bibliographical note
KAUST Repository Item: Exported on 2020-10-01Acknowledgements: This work has been supported by Saudi Aramco, KSA through KAUST CCRC.
ASJC Scopus subject areas
- Energy Engineering and Power Technology
- General Physics and Astronomy
- General Chemical Engineering
- General Chemistry
- Fuel Technology