Kinetics of the Methyl-Vinyl Radical + O-2 Reactions Associated with Propene Oxidation

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Joshi , S P , Pekkanen , T T , Timonen , R S , Lendvay , G & Eskola , A J 2019 , ' Kinetics of the Methyl-Vinyl Radical + O-2 Reactions Associated with Propene Oxidation ' , Journal of Physical Chemistry A , vol. 123 , no. 5 , pp. 999-1006 . https://doi.org/10.1021/acs.jpca.8b11017

Title: Kinetics of the Methyl-Vinyl Radical + O-2 Reactions Associated with Propene Oxidation
Author: Joshi, Satya P.; Pekkanen, Timo T.; Timonen, Raimo S.; Lendvay, Gyorgy; Eskola, Arkke J.
Contributor: University of Helsinki, Department of Chemistry
University of Helsinki, Department of Chemistry
University of Helsinki, Department of Chemistry
University of Helsinki, Department of Chemistry
Date: 2019-02-07
Language: eng
Number of pages: 8
Belongs to series: Journal of Physical Chemistry A
ISSN: 1089-5639
URI: http://hdl.handle.net/10138/301150
Abstract: The bimolecular rate coefficients of reactions CH3CCH2 + O-2 (1) and cis/trans-CH3CHCH + O-2 (2a/3a) have been measured using a tubular laminar flow reactor coupled with a photoionization mass spectrometer (PIMS). These reactions are relevant in the combustion of propene. Pulsed excimer laser photolysis of a ketone or a bromide precursor molecule at 193 or 248 nm wavelength was used to produce radicals of interest homogeneously along the reactor. Time-resolved experiments were performed under pseudo-first-order conditions at low pressure (0.3-1.5 Torr) over the temperature range 220-660 K. The measured bimolecular rate coefficients were found to be independent of bath gas concentration. The bimolecular rate coefficients possess negative temperature dependence at low temperatures (T <420 K) and appear to be independent of temperature at high temperatures (T > 420 K). Observed products of the reaction CH3CCH2 + O-2 were CH3 and H2CO, while for the reaction cis/trans-CH3CHCH + O-2, observed products were CH3CHO and HCO. Current results indicate that the reaction mechanism of both reactions is analogous to that of C2H3 + O-2. Methyl substitution of the vinyl radical changes its reactivity toward O-2 upward by ca. 50% if it involves the alpha-position and downward by ca. 30% if the methyl group takes either of the beta-positions, respectively.
Subject: ACTIVE THERMOCHEMICAL TABLES
TEMPERATURES
OXIDATION
CHLORINE
IGNITION
OCTANE
OXYGEN
TIME
116 Chemical sciences
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