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Title: Initial Steps of Aromatic Ring Formation in a Laminar Premixed Fuel-Rich Cyclopentene Flame†

Abstract

A fuel-rich, nonsooting, premixed laminar cyclopentene flame (phi = 2.0) at 37.6 Torr (50 mbar) is investigated by flame-sampling photoionization molecular-beam mass spectrometry utilizing vacuum-ultraviolet synchrotron radiation. Mole fractions as a function of distance from the burner are measured for 49 intermediates with ion masses ranging from 2 (H-2) to 106 (C8H10), providing a broad database for flame modeling studies. The isomeric composition is resolved for most species, and the identification of several C4Hx, C7H6, and C7H8 isomers is discussed in detail. The presence of C5H5CCH/C5H4CCH2 and cycloheptatriene is revealed by comparisons between flame-sampled photoionization efficiency data and theoretical simulations, based on calculated ionization energies and Franck-Condon factors. This insight suggests a new potential molecular- weight growth mechanism that is characterized by C-5-C-7 ring enlargement reactions.

Authors:
; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Cornell University
Sponsoring Org.:
USDOE; USDOE IG Office of Audit Services (IG-30); Germantown Operations Office DOE
OSTI Identifier:
1062385
Report Number(s):
DOE-ER-15180-22
Journal ID: ISSN 1089-5639
DOE Contract Number:
FG02-01ER15180
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory; Journal Volume: 111; Journal Issue: 19
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; PHOTOIONIZATION MASS-SPECTROMETRY; PHOTOELECTRON-SPECTRA; IONIZATION-POTENTIALS; HYDROCARBON FORMATION; FORMATION MECHANISMS; PHOTO-IONIZATION; ALIPHATIC FUELS; COMBUSTION; ACETYLENE; ISOMERS

Citation Formats

Hansen, N., Kasper, T., Klippenstein, S. J., Westmoreland, P. R., Law, M. E., Taatjes, C. A., Kohse-Höinghaus, K., Wang, J., and Cool, T. A.. Initial Steps of Aromatic Ring Formation in a Laminar Premixed Fuel-Rich Cyclopentene Flame†. United States: N. p., 2007. Web. doi:10.1021/jp0683317.
Hansen, N., Kasper, T., Klippenstein, S. J., Westmoreland, P. R., Law, M. E., Taatjes, C. A., Kohse-Höinghaus, K., Wang, J., & Cool, T. A.. Initial Steps of Aromatic Ring Formation in a Laminar Premixed Fuel-Rich Cyclopentene Flame†. United States. doi:10.1021/jp0683317.
Hansen, N., Kasper, T., Klippenstein, S. J., Westmoreland, P. R., Law, M. E., Taatjes, C. A., Kohse-Höinghaus, K., Wang, J., and Cool, T. A.. Tue . "Initial Steps of Aromatic Ring Formation in a Laminar Premixed Fuel-Rich Cyclopentene Flame†". United States. doi:10.1021/jp0683317.
@article{osti_1062385,
title = {Initial Steps of Aromatic Ring Formation in a Laminar Premixed Fuel-Rich Cyclopentene Flame†},
author = {Hansen, N. and Kasper, T. and Klippenstein, S. J. and Westmoreland, P. R. and Law, M. E. and Taatjes, C. A. and Kohse-Höinghaus, K. and Wang, J. and Cool, T. A.},
abstractNote = {A fuel-rich, nonsooting, premixed laminar cyclopentene flame (phi = 2.0) at 37.6 Torr (50 mbar) is investigated by flame-sampling photoionization molecular-beam mass spectrometry utilizing vacuum-ultraviolet synchrotron radiation. Mole fractions as a function of distance from the burner are measured for 49 intermediates with ion masses ranging from 2 (H-2) to 106 (C8H10), providing a broad database for flame modeling studies. The isomeric composition is resolved for most species, and the identification of several C4Hx, C7H6, and C7H8 isomers is discussed in detail. The presence of C5H5CCH/C5H4CCH2 and cycloheptatriene is revealed by comparisons between flame-sampled photoionization efficiency data and theoretical simulations, based on calculated ionization energies and Franck-Condon factors. This insight suggests a new potential molecular- weight growth mechanism that is characterized by C-5-C-7 ring enlargement reactions.},
doi = {10.1021/jp0683317},
journal = {Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory},
number = 19,
volume = 111,
place = {United States},
year = {Tue May 01 00:00:00 EDT 2007},
month = {Tue May 01 00:00:00 EDT 2007}
}
  • A fuel-rich, nonsooting, premixed laminar cyclopentene flame ({phi} = 2.0) at 37.6 Torr (50 mbar) is investigated by flame-sampling photoionization molecular-beam mass spectrometry utilizing vacuum-ultraviolet synchrotron radiation. Mole fractions as a function of distance from the burner are measured for 49 intermediates with ion masses ranging from 2 (H{sub 2}) to 106 (C{sub 8}H{sub 10}), providing a broad database for flame modeling studies. The isomeric composition is resolved for most species, and the identification of several C{sub 4}H{sub x}, C{sub 7}H{sub 6}, and C{sub 7}H{sub 8} isomers is discussed in detail. The presence of C{sub 5}H{sub 5}CCH/C{sub 5}H{sub 4}CCH{sub 2}more » and cycloheptatriene is revealed by comparisons between flame-sampled photoionization efficiency data and theoretical simulations, based on calculated ionization energies and Franck-Condon factors. This insight suggests a new potential molecular-weight growth mechanism that is characterized by C{sub 5}-C{sub 7} ring enlargement reactions.« less
  • No abstract prepared.
  • Abstract not provided.
  • Experimental and detailed chemical kinetic modeling work has been performed to investigate aromatic and polycyclic aromatic hydrocarbon (PAH) formation pathways in a premixed, rich, sooting, n-butane-oxygen-argon burner stabilized flame. An atmospheric pressure, laminar flat flame operated at an equivalence ratio of 2.6 was used to acquire experimental data for model validation. Gas composition analysis was conducted by an on-line gas chromatograph/mass spectrometer technique. Measurements were made in the main reaction and post-reaction zones for a number of low molecular weight species, aliphatics, aromatics, and polycyclic aromatic hydrocarbons (PAHs) ranging from two to five-fused aromatic rings. Reaction flux and sensitivity analysismore » were used to help identify the important reaction sequences leading to aromatic and PAH growth and destruction in the n-butane flame. Reaction flux analysis showed the propargyl recombination reaction was the dominant pathway to benzene formation. The consumption of propargyl by H atoms was shown to limit propargyl, benzene, and naphthalene formation in flames as exhibited by the large negative sensitivity coefficients. Naphthalene and phenanthrene production was shown to be plausibly formed through reactions involving resonantly stabilized cyclopentadienyl and indenyl radicals. Many of the low molecular weight aliphatics, combustion by-products, aromatics, branched aromatics, and PAHs were fairly well simulated by the model. Additional work is required to understand the formation mechanisms of phenyl acetylene, pyrene, and fluoranthene in the n-butane flame. 73 refs.« less
  • In line with the studies presented in Parts I (methane flame seeded with allene and propyne) and II (methane flame seeded with 1,3-butadiene) of this paper, the structure of a laminar rich premixed methane flame doped with cyclopentene has been investigated. The gases of this flame contain 15.3% (molar) of methane, 26.7% of oxygen, and 2.4% cyclopentene, corresponding to an overall equivalence ratio of 1.79 and a C{sub 5}H{sub 8}/CH{sub 4} ratio of 15.7%. The flame has been stabilized on a burner at a pressure of 6.7 kPa using argon as dilutant, with a gas velocity at the burner ofmore » 36 cm/s at 333 K. The measured temperature ranged from 627 K close to the burner up to 2027 K. Species quantified by gas chromatography included the usual methane C{sub 0}-C{sub 2} combustion products, but also propyne, allene, propene, propane, 1-butene, 1,3-butadiene, 1,2-butadiene, vinylacetylene, diacetylene, cyclopentadiene, 1,3-pentadiene, benzene, and toluene. A new mechanism for the oxidation of cyclopentene has been developed and added to the former model for the oxidation of small unsaturated hydrocarbons, benzene, and toluene described in Parts I and II. The whole mechanism involved 175 species in 1134 reactions. The main reaction pathways of consumption of cyclopentene and of formation of benzene and toluene are presented and discussed from flow rate analyses. (author)« less