TY - JOUR
T1 - Hydrogen shift isomerizations in the kinetics of the second oxidation mechanism of alkane combustion. Reactions of the hydroperoxypentylperoxy OOQOOH radical
AU - Xing, Lili
AU - Bao, Junwei Lucas
AU - Wang, Zhandong
AU - Wang, Xuetao
AU - Truhlar, Donald G
N1 - Publisher Copyright:
© 2018 The Combustion Institute
PY - 2018/11
Y1 - 2018/11
N2 - Hydroperoxyalkylperoxy species are important intermediates that are generated during the autoignition of transport fuels. In combustion, the fate of hydroperoxyalkylperoxy is important for the performance of advanced combustion engines, especially for autoignition. A key fate of the hydroperoxyalkylperoxy is a 1,5 H-shift, for which kinetics data are experimentally unavailable. In the present work, we study 1-hydroperoxypentan-3-yl)dioxidanyl (CH3CH2CH(OO)CH2CH2OOH) as a model compound to clarify the kinetics of 1,5 H-shift of hydroperoxyalkylperoxy species, in particular α-H isomerization and alternative competitive pathways. With a combination of electronic structure calculations, we determine previously missing thermochemical data, and with multipath variational transition state theory (MP-VTST), a multidimensional tunneling (MT) approximation, multiple-structure anharmonicity, and torsional potential anharmonicity, we obtained much more accurate rate constants than the ones that can computed by conventional single-structure harmonic transition state theory (TST) and than the empirically estimated rate constants that are currently used in combustion modeling. The roles of various factors in determining the rates are elucidated. The pressure-dependent rate constants for these competitive reactions are computed using system-specific quantum RRK theory. The calculated temperature range is 298–1500 K, and the pressure range is 0.01–100 atm. The accurate thermodynamic and kinetics data determined in this work are indispensable in the detailed understanding and prediction of ignition properties of hydrocarbons and alternative fuels.
AB - Hydroperoxyalkylperoxy species are important intermediates that are generated during the autoignition of transport fuels. In combustion, the fate of hydroperoxyalkylperoxy is important for the performance of advanced combustion engines, especially for autoignition. A key fate of the hydroperoxyalkylperoxy is a 1,5 H-shift, for which kinetics data are experimentally unavailable. In the present work, we study 1-hydroperoxypentan-3-yl)dioxidanyl (CH3CH2CH(OO)CH2CH2OOH) as a model compound to clarify the kinetics of 1,5 H-shift of hydroperoxyalkylperoxy species, in particular α-H isomerization and alternative competitive pathways. With a combination of electronic structure calculations, we determine previously missing thermochemical data, and with multipath variational transition state theory (MP-VTST), a multidimensional tunneling (MT) approximation, multiple-structure anharmonicity, and torsional potential anharmonicity, we obtained much more accurate rate constants than the ones that can computed by conventional single-structure harmonic transition state theory (TST) and than the empirically estimated rate constants that are currently used in combustion modeling. The roles of various factors in determining the rates are elucidated. The pressure-dependent rate constants for these competitive reactions are computed using system-specific quantum RRK theory. The calculated temperature range is 298–1500 K, and the pressure range is 0.01–100 atm. The accurate thermodynamic and kinetics data determined in this work are indispensable in the detailed understanding and prediction of ignition properties of hydrocarbons and alternative fuels.
KW - Autoignition
KW - Hydroperoxyalkylperoxy
KW - Kinetics
KW - Quantum chemical calculation
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U2 - 10.1016/j.combustflame.2018.07.013
DO - 10.1016/j.combustflame.2018.07.013
M3 - Article
AN - SCOPUS:85051124856
SN - 0010-2180
VL - 197
SP - 88
EP - 101
JO - Combustion and Flame
JF - Combustion and Flame
ER -