Shock-tube study of propane pyrolysis. Rate of initial dissociation from 1400 to 2300 K

Journal Article · Thu Feb 03 04:00:00 EST 1983 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100226a025· OSTI ID:5902731

Al-Alami, M Z; Klefer, J H

The pyrolysis of propane in mixtures of 2% and 4% C/sub 3/H/sub 8/ in Kr has been studied in incident shock waves with the laser-schlieren technique. Forty-seven separate experiments covering 1400 to 2300 K were analyzed for the rate of the initial dissociation, C/sub 3/H/sub 8/ ..-->.. CH/sub 3/ + C/sub 2/H/sub 5/, using a simulation-assisted extrapolation to the time origin for reaction. The simulation employs a mechanism of 30 reactions, the rates for all but the initial dissociation selected from the literature, and is able to fit all features of the density gradient profiles. The derived unimolecular rates show definite indications of falloff, the best fit at low temperatures (< 1800 K) being first order with k = 7.74 x 10/sup 11/ exp(-28030/T) +- 20% (s/sup -1/), for 1400 < T < 1800 K, 1.5 < rho < 6 ..mu..mol/cm/sup 3/. For higher T the best fit in second order, k = 2.68 x 10/sup 17/ exp(-28300/T) +- 20% (cm/sup 3//(mol s)), 1800 < T 2300 K, 0.8 < rho < 1.8 ..mu..mol/cm/sup 3/. The data were also fitted with an RRKM calculation using a modified Gorin model transition state. This fit suggests parameters which seem reasonable on comparison with previous similar calculations, and extrapolates to an infinite-pressure rate constant k/sub infinity/ = 1.48 x 10/sup 17/ exp(-43500/T) )s/sup -1/) which is within a factor of 2 of the prior estimate of Tsang, effectively supporting this estimate.

• Research Organization: Univ. of Illinois, Chicago
• OSTI ID: 5902731
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 87:3; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400800* -- Combustion
Pyrolysis
&amp; High-Temperature Chemistry
ALKANES
ALKYL RADICALS
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
DECOMPOSITION
ELEMENTS
ETHYL RADICALS
FLUIDS
GASES
HYDROCARBONS
KINETICS
KRYPTON
METHYL RADICALS
NONMETALS
ORGANIC COMPOUNDS
PROPANE
PYROLYSIS
RADICALS
RARE GASES
REACTION KINETICS
SHOCK TUBES
THERMOCHEMICAL PROCESSES
VERY HIGH TEMPERATURE
YIELDS