Hydrogen shift isomerizations in the kinetics of the second oxidation mechanism of alkane combustion. Reactions of the hydroperoxypentylperoxy OOQOOH radical

Lili Xing, Junwei Lucas Bao, Zhandong Wang, Xuetao Wang, Donald G Truhlar

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)88-101
Number of pages14
JournalCombustion and Flame
Volume197
DOIs
StatePublished - Nov 2018

Bibliographical note

Funding Information:
This work was supported in part by Key Science Foundation of Higher Education of Henan ( 19A480002 ), by the U.S. Department of Energy , Office of Basic Energy Sciences, under Award Number DE-SC0015997 , by King Abdullah University of Science and Technology (KAUST) , Office of Sponsored Research (OSR) under Award No. OSR-2016-CRG5-3022 and Saudi Aramco under the FUELCOM program, by the Henan Science and Technology Innovation Talent Program (Outstanding Youth) ( 114100510010 ), and by the National Natural Science Foundation of Henan Province ( 182300410256 ). The authors are grateful to Feng Zhang for helpful discussions.

Keywords

  • Autoignition
  • Hydroperoxyalkylperoxy
  • Kinetics
  • Quantum chemical calculation

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