Kinetics of 1-butyl and 2-butyl radical reactions with molecular oxygen : Experiment and theory

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Eskola , A J , Pekkanen , T T , Joshi , S P , Timonen , R S & Klippenstein , S J 2019 , ' Kinetics of 1-butyl and 2-butyl radical reactions with molecular oxygen : Experiment and theory ' , Proceedings of the Combustion Institute , vol. 37 , no. 1 , pp. 291-298 . https://doi.org/10.1016/j.proci.2018.05.069

Title: Kinetics of 1-butyl and 2-butyl radical reactions with molecular oxygen : Experiment and theory
Author: Eskola, Arkke J.; Pekkanen, Timo T.; Joshi, Satya P.; Timonen, Raimo S.; Klippenstein, Stephen J.
Contributor organization: Molecular Science
Department of Chemistry
Date: 2019
Language: eng
Number of pages: 8
Belongs to series: Proceedings of the Combustion Institute
ISSN: 1540-7489
DOI: https://doi.org/10.1016/j.proci.2018.05.069
URI: http://hdl.handle.net/10138/310372
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 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.
Subject: Radical reaction kinetics
Photoionization mass spectrometer
1-butyl and 2-butyl radicals
Ab initio calculations
Transition state theory
VRC-TST
AUTOIGNITION CHEMISTRY
PRODUCT FORMATION
BUTYL RADICALS
PLUS O-2
TEMPERATURE
PROPYL
114 Physical sciences
116 Chemical sciences
Peer reviewed: Yes
Rights: cc_by_nc_nd
Usage restriction: openAccess
Self-archived version: acceptedVersion


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