Kinetics of 1-butyl and 2-butyl radical reactions with molecular oxygen: Experiment and theory
| Autor: | Satya P. Joshi, Arkke J. Eskola, Stephen J. Klippenstein, Raimo S. Timonen, Timo T. Pekkanen |
|---|---|
| Přispěvatelé: | Molecular Science, Department of Chemistry |
| Rok vydání: | 2019 |
| Předmět: |
Transition state theory
General Chemical Engineering Radical Radical reaction kinetics 1-butyl and 2-butyl radicals 116 Chemical sciences Kinetics Ab initio Thermodynamics 010402 general chemistry Combustion 114 Physical sciences 01 natural sciences 7. Clean energy Reaction coordinate Chemical kinetics 0103 physical sciences VRC-TST Physical and Theoretical Chemistry TEMPERATURE AUTOIGNITION CHEMISTRY Alkane chemistry.chemical_classification PLUS O-2 BUTYL RADICALS 010304 chemical physics Chemistry Mechanical Engineering 0104 chemical sciences PRODUCT FORMATION 13. Climate action Photoionization mass spectrometer Ab initio calculations PROPYL |
| Zdroj: | Proceedings of the Combustion Institute. 37:291-298 |
| ISSN: | 1540-7489 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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