In:
Physical Chemistry Chemical Physics, Royal Society of Chemistry (RSC), Vol. 24, No. 15 ( 2022), p. 8672-8682
Abstract:
OH-initiated oxidation reactions of o -xylene are widely concerned both in combustion and atmospheric chemistry. In this work, the kinetics of the o -xylene reaction with OH radicals has been studied systematically in a wide temperature range of 220–3000 K for the high-pressure limit and several selected pressures from 1 torr to 500 atm using multi-structural variational transition state theory with the small-curvature tunneling approximation (MS-CVT/SCT) and the system-specific quantum Rice–Ramsperger–Kassel (SS-QRRK) method. The calculations fully considered various factors which could affect the accuracy of the calculated rate constants including anharmonicity of both low- and high-frequency modes and multiple low-energy conformers, variational effect, and tunneling. The results are in good agreement with the available experimental data. The obtained overall rate constants exhibit a nonmonotonic temperature dependence due to the competition between the hydrogen abstraction and addition reactions. At low temperatures, the addition channels are dominant reactions, but the abstraction reactions are also non-ignorable with a ∼12% contribution to the overall rate constants at 298 K and 1 atm. Above 800 K, the abstraction reactions become dominant under all the pressure conditions. In addition, we observed a more significant pressure dependence of o -xylene plus OH reaction as compared to the similar toluene plus OH reaction, which is the effect of the additional methyl group. At T = 500–1000 K, the pressure can influence the total rate constants of the o -xylene reaction by a factor of up to 2.5. These kinetics data provide us with a comprehensive understanding of the mechanism and pressure-dependence of kinetics for the o -xylene + OH reaction, which is also beneficial for the study of other similar aromatic hydrocarbon reactions.
Type of Medium:
Online Resource
ISSN:
1463-9076
,
1463-9084
Language:
English
Publisher:
Royal Society of Chemistry (RSC)
Publication Date:
2022
detail.hit.zdb_id:
1476283-3
detail.hit.zdb_id:
1476244-4
detail.hit.zdb_id:
1460656-2
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