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Title: Kinetics of 1-Butyl and 2-Butyl Radical Reactions with Molecular Oxygen: Experiment and Theory

Abstract

The reaction of O-2 with butyl radicals is a key early step in the oxidation of n-butane, which is a prototypical alkane fuel with combustion properties that mimic those of many larger alkanes. Current combustion mechanisms employ kinetic descriptions for such radical oxidations that are based on fairly limited information. The present work employs a combination of experiment and theory to probe the kinetics of O-2 reacting with both 1- and 2-butyl radicals. The experiments employ laser photolysis to generate butyl radicals and thereby initiate the reaction kinetics. Photoionization mass spectrometric observations of the time-dependent butyl radical concentration yield rate coefficients for the overall reaction. The experiments cover temperatures ranging from 200 to 500 K and He bath gas pressures ranging from 0.3 to 6 Torr. Ab initio transition state theory (TST) based master equation calculations are used to predict the kinetics over a broad range of conditions. The calculations consider both the barrierless R + O-2 entrance channel, treated with direct CASPT2 variable reaction coordinate TST, and the decomposition of the RO2 complex to HO2 + alkenes, treated with CCSD(T)/CBS based TST. Theory and experiment are in good agreement, with maximum discrepancies of about 30%, suggesting the appropriateness ofmore » the theory based predictions for conditions of greater relevance to combustion. The kinetic description arising from this work should be of considerable utility to combustion modeling of n-butane, as well as of other related saturated hydrocarbons. (C) 2018 The Combustion Institute. Published by Elsevier Inc. All rights reserved.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
Academy of Finland; USDOE Office of Science - Office of Basic Energy Sciences - Chemical Sciences, Geosciences, and Biosciences Division
OSTI Identifier:
1510028
DOE Contract Number:  
AC02-06CH11357
Resource Type:
Conference
Resource Relation:
Conference: 37th International Symposium on Combustion, 07/29/18 - 08/03/18, Dublin, IE
Country of Publication:
United States
Language:
English

Citation Formats

Eskola, Arkke J., Pekkanen, Timo T., Joshi, Satya P., Timonen, Raimo S., and Klippenstein, Stephen J. Kinetics of 1-Butyl and 2-Butyl Radical Reactions with Molecular Oxygen: Experiment and Theory. United States: N. p., 2019. Web. doi:10.1016/j.proci.2018.05.069.
Eskola, Arkke J., Pekkanen, Timo T., Joshi, Satya P., Timonen, Raimo S., & Klippenstein, Stephen J. Kinetics of 1-Butyl and 2-Butyl Radical Reactions with Molecular Oxygen: Experiment and Theory. United States. doi:10.1016/j.proci.2018.05.069.
Eskola, Arkke J., Pekkanen, Timo T., Joshi, Satya P., Timonen, Raimo S., and Klippenstein, Stephen J. Tue . "Kinetics of 1-Butyl and 2-Butyl Radical Reactions with Molecular Oxygen: Experiment and Theory". United States. doi:10.1016/j.proci.2018.05.069.
@article{osti_1510028,
title = {Kinetics of 1-Butyl and 2-Butyl Radical Reactions with Molecular Oxygen: Experiment and Theory},
author = {Eskola, Arkke J. and Pekkanen, Timo T. and Joshi, Satya P. and Timonen, Raimo S. and Klippenstein, Stephen J.},
abstractNote = {The reaction of O-2 with butyl radicals is a key early step in the oxidation of n-butane, which is a prototypical alkane fuel with combustion properties that mimic those of many larger alkanes. Current combustion mechanisms employ kinetic descriptions for such radical oxidations that are based on fairly limited information. The present work employs a combination of experiment and theory to probe the kinetics of O-2 reacting with both 1- and 2-butyl radicals. The experiments employ laser photolysis to generate butyl radicals and thereby initiate the reaction kinetics. Photoionization mass spectrometric observations of the time-dependent butyl radical concentration yield rate coefficients for the overall reaction. The experiments cover temperatures ranging from 200 to 500 K and He bath gas pressures ranging from 0.3 to 6 Torr. Ab initio transition state theory (TST) based master equation calculations are used to predict the kinetics over a broad range of conditions. The calculations consider both the barrierless R + O-2 entrance channel, treated with direct CASPT2 variable reaction coordinate TST, and the decomposition of the RO2 complex to HO2 + alkenes, treated with CCSD(T)/CBS based TST. Theory and experiment are in good agreement, with maximum discrepancies of about 30%, suggesting the appropriateness of the theory based predictions for conditions of greater relevance to combustion. The kinetic description arising from this work should be of considerable utility to combustion modeling of n-butane, as well as of other related saturated hydrocarbons. (C) 2018 The Combustion Institute. Published by Elsevier Inc. All rights reserved.},
doi = {10.1016/j.proci.2018.05.069},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2019},
month = {1}
}

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