Computational thermochemistry of oxygenated polycyclic aromatic hydrocarbons and relevant radicals

Abstract
Oxygenated polycyclic aromatic hydrocarbons (OPAHs) have attracted growing attention due to their toxicological harmfulness and significant role in soot formation. This study comprehensively investigates the thermochemistry of OPAH species and relevant radicals via quantum-chemical calculations. Temperature-dependent enthalpy of formation, entropy, and heat capacity for C5single bondC18 OPAHs (59 molecules and 33 radicals) are consistently determined at the M06–2X/6-311++G(d,p) level of theory. Considerable differences are found to be introduced by different methods when calculating electronic energies, and the G3 method outperforms the composite compound methods G3/G4/CBS-APNO. The calculated thermochemical properties from the G3 method show excellent agreement with literature data. An accurate thermochemistry database for OPAHs is thus developed. In addition, the existing group additivity (GA) method does not apply to OPAHs since the group additivity values (GAVs) derived from small hydrocarbons fail to predict large polycyclic species. Based on our dataset, GAVs are obtained from combinatorial considerations. The updated GAVs can be applied with enhanced confidence to estimate the thermochemical parameters at different temperatures for larger OPAHs where such high-accuracy quantum chemistry calculations are intractable. These thermodynamic properties and GAVs are crucial for the development of accurate kinetic models for OPAH formation chemistry and for achieving emission control.

Citation
Wang, T., Yalamanchi, K. K., Bai, X., Liu, S., Li, Y., Qu, B., Kukkadapu, G., & Sarathy, S. M. (2023). Computational thermochemistry of oxygenated polycyclic aromatic hydrocarbons and relevant radicals. Combustion and Flame, 247, 112484. https://doi.org/10.1016/j.combustflame.2022.112484

Acknowledgements
TW, KKY, YL, and SMS were supported by King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research under the award number OSR-2019-CRG7. We acknowledge support from the KAUST Core Labs’ high performance computing facilities. This work was partly supported by Startup Funds of Aoxiang Overseas Scholar (0602021GH0201182) at Northwestern Polytechnical University. The work (GK) at LLNL was performed under the auspices of the U.S. Department of Energy (DOE), Contract DE-AC52-07NA27344 and was supported by the U.S. Department of Energy, Vehicle Technologies Office, program managers, Mike Weismiller and Gurpreet Singh and was conducted as part of the Partnership to Advance Combustion Engines (PACE). This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. DOE or the U.S. Government

Publisher
Elsevier BV

Journal
Combustion and Flame

DOI
10.1016/j.combustflame.2022.112484

Additional Links
https://linkinghub.elsevier.com/retrieve/pii/S0010218022004837

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