An Experimental and Computational Study of the Reaction Between 2-Methylallyl Radicals and Oxygen Molecules: Optimizing Master Equation Parameters with Trace Fitting

Timo Pekkanen, Raimo Timonen, Struan Robertson , Gyorgy Lendvay, Satya Prakash Joshi, Timo Tapani Reijonen, Arkke J. Eskola

Tutkimustuotos: ArtikkelijulkaisuArtikkeliTieteellinenvertaisarvioitu

Abstrakti

We have investigated the reaction between 2-methylallyl radicals and oxygen molecules with experimental and computational methods. Kinetic experiments were conducted in a tubular laminar flow reactor using laser photolysis for radical production and photoionization mass spectrometry for detection. The reaction was investigated as a function of temperature (203-730 K) and pressure (0.2-9 torr) in helium and nitrogen bath gases. At low temperatures (T < 410 K), the reaction proceeds by a barrierless reaction to form 2-methylallylperoxyl. Equilibration of the peroxyl adduct and the reactants was observed between 350-410 K. Measurements were extended to even higher temperatures, up to 730 K, but no reaction could be observed. Master equation simulations of the reaction system were performed with the MESMER program. Kinetic parameters in the master equation model were optimized by direct fitting to time-resolved experimental 2-methylallyl traces. Trace fitting is a recently implemented novel feature in MESMER. The trace approach was compared with the more traditional approach where one uses experimental rate coefficients for parameter optimization. The optimized parameters yielded by the two approaches are very similar and do an excellent job at reproducing the experimental data. The optimized master equation model was then used to simulate the reaction under study over a wide temperature and pressure range, from 200 K and 0.01 bar to 1500 K and 100 bar. The simulations predict a small phenomenological rate coefficient under autoignition conditions; about 1 x 10(-18) cm(3) s(-1) at 400 K and 5 x 10(-16) cm(3) s(-1) at 1000 K. We provide modified Arrhenius expressions in PLOG format for the most important product channels to facilitate the use of our results in combustion models.

Alkuperäiskielienglanti
LehtiPhysical Chemistry Chemical Physics
Vuosikerta24
Numero8
Sivut4729-4742
Sivumäärä14
ISSN1463-9076
DOI - pysyväislinkit
TilaJulkaistu - 23 helmik. 2022
OKM-julkaisutyyppiA1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä, vertaisarvioitu

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