Polar curved polycyclic aromatic hydrocarbons in soot formation

Authors
Bowal, K 
Menon, A 
Slavchov, RI 
Akroyd, J 

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Article
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Abstract

© 2018 The Combustion Institute. In this paper, we consider the impact of polar curved polycyclic aromatic hydrocarbons (cPAH) on the process of soot formation by employing electronic structure calculations to determine the earliest onset of curvature integration and the binding energy of curved homodimers. The earliest (smallest size) onset of curvature integration was found to be a six ring PAH with at least one pentagonal ring. The σ bonding in the presence of pentagons led to curvature, however, the π bonding strongly favored a planar geometry delaying the onset of curvature and therefore the induction of a flexoelectric dipole moment. The binding energies of cPAH dimers were found to be of similar magnitude to flat PAH containing one or two pentagons, with an alignment of the dipole moments vectors. For the more curved structures, steric effects reduced the dispersion interactions to significantly reduce the interaction energy compared with flat PAH. Homogeneous nucleation of cPAH at flame temperatures then appears unlikely, however, significant interactions are expected between chemi-ions and polar cPAH molecules suggesting heterogeneous nucleation should be explored.

Publication Date
2019
Online Publication Date
2018-06-19
Acceptance Date
2018-05-21
Keywords
Curved polycyclic aromatic hydrocarbons, Flexoelectric dipole, Soot formation, Combustion, Dimers
Journal Title
Proceedings of the Combustion Institute
Journal ISSN
1540-7489
1873-2704
Volume Title
37
Publisher
Elsevier BV
Sponsorship
National Research Foundation Singapore (via Cambridge Centre for Advanced Research and Education in Singapore (CARES)) (unknown)
This project is supported by the National Research Foundation (NRF), Prime Minister’s Office, Singapore under its Campus for Research Excellence and Technological Enterprise (CREATE) programme.