Mechanistic studies on the oxidation reaction of n-pentane

[Display omitted] •The oxidation reaction mechanism of n-pentane was investigated.•The n-pentane oxidation reaction process was controlled by ring-closing and H-atom transfer reactions.•Thirteen reaction pathways initiated by the addition of oxygen to the active site of the n-pentyl radical were elu...

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Bibliographic Details
Published in:Journal of molecular liquids 2024-11, Vol.414, p.126004, Article 126004
Main Authors: Xi, Zhilin, Chu, Yujie, Chen, Tao, She, Wenxuan, Ren, Jialu
Format: Article
Language:English
Subjects:
Activation energy
Flammable liquids
N-pentane
Oxidation mechanism
Radical reaction
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Summary:[Display omitted] •The oxidation reaction mechanism of n-pentane was investigated.•The n-pentane oxidation reaction process was controlled by ring-closing and H-atom transfer reactions.•Thirteen reaction pathways initiated by the addition of oxygen to the active site of the n-pentyl radical were elucidated. The oxidation reaction mechanism of n-pentane is investigated using density functional theory and transition state theory as a case study to elucidate the combustion characteristics of liquids with low boiling points. This study divides the oxidation reaction of n-pentane into four steps. First, n-pentane decomposes to form n-pentyl radicals C5H11 and H, CH3 and C4H9, and C2H5 and C3H7 radicals. Second, n-pentane primarily undergoes H-abstraction reactions with H, CH3, C2H5, and C3H7 radicals to form the C5H11 radicals. Subsequently, C5H11 radicals react with O2 in an addition reaction to form n-pentyl peroxy radicals ROO. Finally, ROO radical undergoes internal H-atom transfer to form hydroperoxy pentyl radicals QOOH, which then undergoes cyclization and bond scission to produce cyclic ethers, alkenes, aldehydes, OH radicals, and HO2 radicals. Results indicate that n-pentane readily decomposes into C2H5 and C3H7 radicals, with a bond dissociation energy of 367.1 KJ/mol. The H-abstraction reactions involving H and CH3 radicals have the fastest rates, which require the lowest energy barriers of 21.6 and 41.9 KJ/mol, respectively. The reaction between C5H11 and O2 is a barrierless addition reaction. The oxidation of n-pentane, which leads to the formation of 2-methyloxirane and OH radicals, exhibits the fastest reaction rate.
ISSN:0167-7322
DOI:10.1016/j.molliq.2024.126004