PAH growth initiated by propargyl addition: Mechanism development and computational kinetics

Handle URI:
http://hdl.handle.net/10754/563508
Title:
PAH growth initiated by propargyl addition: Mechanism development and computational kinetics
Authors:
Raj, Abhijeet Dhayal; Rachidi, Mariam El ( 0000-0001-7392-6777 ) ; Chung, Suk-Ho ( 0000-0001-8782-312X ) ; Sarathy, Mani ( 0000-0002-3975-6206 )
Abstract:
Polycyclic aromatic hydrocarbon (PAH) growth is known to be the principal pathway to soot formation during fuel combustion, as such, a physical understanding of the PAH growth mechanism is needed to effectively assess, predict, and control soot formation in flames. Although the hydrogen abstraction C2H2 addition (HACA) mechanism is believed to be the main contributor to PAH growth, it has been shown to under-predict some of the experimental data on PAHs and soot concentrations in flames. This article presents a submechanism of PAH growth that is initiated by propargyl (C 3H3) addition onto naphthalene (A2) and the naphthyl radical. C3H3 has been chosen since it is known to be a precursor of benzene in combustion and has appreciable concentrations in flames. This mechanism has been developed up to the formation of pyrene (A4), and the temperature-dependent kinetics of each elementary reaction has been determined using density functional theory (DFT) computations at the B3LYP/6-311++G(d,p) level of theory and transition state theory (TST). H-abstraction, H-addition, H-migration, β-scission, and intramolecular addition reactions have been taken into account. The energy barriers of the two main pathways (H-abstraction and H-addition) were found to be relatively small if not negative, whereas the energy barriers of the other pathways were in the range of (6-89 kcal·mol-1). The rates reported in this study may be extrapolated to larger PAH molecules that have a zigzag site similar to that in naphthalene, and the mechanism presented herein may be used as a complement to the HACA mechanism to improve prediction of PAH and soot formation. © 2014 American Chemical Society.
KAUST Department:
Clean Combustion Research Center; Physical Sciences and Engineering (PSE) Division; Mechanical Engineering Program; Chemical and Biological Engineering Program; Combustion and Laser Diagnostics Laboratory
Publisher:
American Chemical Society (ACS)
Journal:
The Journal of Physical Chemistry A
Issue Date:
24-Apr-2014
DOI:
10.1021/jp410704b
Type:
Article
ISSN:
10895639
Sponsors:
KAUST CCRC is grateful to Saudi Aramco for sponsoring this research.
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division; Chemical and Biological Engineering Program; Mechanical Engineering Program; Clean Combustion Research Center

Full metadata record

DC FieldValue Language
dc.contributor.authorRaj, Abhijeet Dhayalen
dc.contributor.authorRachidi, Mariam Elen
dc.contributor.authorChung, Suk-Hoen
dc.contributor.authorSarathy, Manien
dc.date.accessioned2015-08-03T11:53:11Zen
dc.date.available2015-08-03T11:53:11Zen
dc.date.issued2014-04-24en
dc.identifier.issn10895639en
dc.identifier.doi10.1021/jp410704ben
dc.identifier.urihttp://hdl.handle.net/10754/563508en
dc.description.abstractPolycyclic aromatic hydrocarbon (PAH) growth is known to be the principal pathway to soot formation during fuel combustion, as such, a physical understanding of the PAH growth mechanism is needed to effectively assess, predict, and control soot formation in flames. Although the hydrogen abstraction C2H2 addition (HACA) mechanism is believed to be the main contributor to PAH growth, it has been shown to under-predict some of the experimental data on PAHs and soot concentrations in flames. This article presents a submechanism of PAH growth that is initiated by propargyl (C 3H3) addition onto naphthalene (A2) and the naphthyl radical. C3H3 has been chosen since it is known to be a precursor of benzene in combustion and has appreciable concentrations in flames. This mechanism has been developed up to the formation of pyrene (A4), and the temperature-dependent kinetics of each elementary reaction has been determined using density functional theory (DFT) computations at the B3LYP/6-311++G(d,p) level of theory and transition state theory (TST). H-abstraction, H-addition, H-migration, β-scission, and intramolecular addition reactions have been taken into account. The energy barriers of the two main pathways (H-abstraction and H-addition) were found to be relatively small if not negative, whereas the energy barriers of the other pathways were in the range of (6-89 kcal·mol-1). The rates reported in this study may be extrapolated to larger PAH molecules that have a zigzag site similar to that in naphthalene, and the mechanism presented herein may be used as a complement to the HACA mechanism to improve prediction of PAH and soot formation. © 2014 American Chemical Society.en
dc.description.sponsorshipKAUST CCRC is grateful to Saudi Aramco for sponsoring this research.en
dc.publisherAmerican Chemical Society (ACS)en
dc.titlePAH growth initiated by propargyl addition: Mechanism development and computational kineticsen
dc.typeArticleen
dc.contributor.departmentClean Combustion Research Centeren
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.contributor.departmentMechanical Engineering Programen
dc.contributor.departmentChemical and Biological Engineering Programen
dc.contributor.departmentCombustion and Laser Diagnostics Laboratoryen
dc.identifier.journalThe Journal of Physical Chemistry Aen
dc.contributor.institutionDepartment of Chemical Engineering, Petroleum Institute, Abu Dhabi, United Arab Emiratesen
kaust.authorChung, Suk-Hoen
kaust.authorSarathy, Manien
kaust.authorRachidi, Mariam Elen
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