Abstract
The kinetics of the unimolecular dissociation of propyne and allene, C 3H4 + M → C3H3 + H + M, was investigated behind reflected shock waves at temperatures between 1400 and 2150 K and at pressures near 0.3, 1.3, 2.6 (propyne only), and 4.0 bar with argon as bath gas. Rate coefficients were obtained from the initial slope of the hydrogen-atom concentration-time profiles monitored with atomic resonance absorption spectroscopy at the Lyman α wavelength (121.6 nm). Within the experimental uncertainty (±30%), identical rate coefficients for propyne and allene decomposition were obtained, indicating a fast mutual isomerization. The dissociation reactions are shown to be in the low-pressure limit with a bimolecular rate coefficient kbim(T)=(3.4±1.0)×1012exp[-(36, 300±400)K/T]bar-1s-1. From a combination of our experimental results with kinetic data from the literature, we infer the following temperature and pressure dependence of the rate coefficient, which reproduces most of the experimental data at temperatures between 1200 and 2400 K and pressures between 0.1 and 5 bar better than within a factor of two: k(T,P)=2.58×1041(T/K)-7. 81exp(-50,590K/T)(P/bar)s-1. This corresponds to a bimolecular rate coefficient in concentration units of kbim(T)=3.56×1019(T/K)-6.81exp(-50,590K/T) cm3s-1.
Original language | English (US) |
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Pages (from-to) | 267-272 |
Number of pages | 6 |
Journal | Proceedings of the Combustion Institute |
Volume | 33 |
Issue number | 1 |
DOIs | |
State | Published - 2011 |
Externally published | Yes |
Bibliographical note
Funding Information:Financial Support by the Deutsche Forschungsgemeinschaft (SFB 551 “Carbon from the Gas Phase: Elementary Reactions, Structures, Materials” and Ol 85/2-1) is gratefully acknowledged.
Keywords
- Allene
- Elementary reactions
- Propyne
- Reaction kinetics
- Shock tube
ASJC Scopus subject areas
- General Chemical Engineering
- Mechanical Engineering
- Physical and Theoretical Chemistry