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Incubation in cyclohexene decomposition at high temperatures
Author(s) -
Shi Jichun,
Barker John R.
Publication year - 1990
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550220207
Subject(s) - chemistry , thermal decomposition , shock tube , decomposition , thermodynamics , range (aeronautics) , atmospheric temperature range , reaction rate constant , constant (computer programming) , master equation , kinetic energy , incubation , atomic physics , shock wave , kinetics , quantum mechanics , physics , organic chemistry , materials science , composite material , computer science , quantum , programming language , biochemistry
A detailed master equation simulation has been carried out for the thermal unimolecular decomposition of C 6 H 10 in a shock tube. At the highest temperatures studied experimentally [J. H. Kiefer and J. N. Shah, J. Phys. Chem., 91, 3024 (1987)], the average thermal vibrational energy is greater than the reaction threshold and therefore 〈Δ E 〉 (up and down steps) is positive for molecules at that energy, rather than negative; the converse is true at lower temperatures. The calculated incubation time, in which the decomposition rate constant rises to 1/e of its steady state value, is found to be only weakly dependent on temperature (at constant pressure) between 1500 K and 2000 K and to depend almost exclusively on 〈Δ E 〉 d (down steps, only), and not on collision probability model. Simulations of the experimental data show the magnitude of 〈Δ E 〉 d depends weakly on assumed collision probability model, but is nearly independent of temperature. The second moment 〈Δ E 〉 ½ is found to be independent of both temperature and transition probability model. The experimental data are not very sensitive to the possible energy‐dependence of 〈Δ E 〉 d for a wide range of assumptions. It is concluded that the observed experimental “delay times” probably can be identified with the incubation time; further experiments are desirable to test this possibility and obtain more direct measures of the incubation time.