ISSN:
0538-8066
Keywords:
Chemistry
;
Physical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Ignition delay times of acetonitrile (CH3CN) in mixtures containing acetonitrile and oxygen diluted in argon were studied behind reflected shock waves. The temperature range covered was 1420-1750 K at overall concentrations behind the reflected shock wave ranging from 2 to 4×10-5 mol/cm3. Over this temperature and concentration range the ignition delay times varied by approximately one order of magnitude, ranging from ca. 100 μs to slightly above 1 ms. From a total of some 70 tests the following correlation for the ignition delay times was derived: tign=9.77×10-12 exp(41.7×103/RT)×{[CH3CN]0.12[O2]-0.76[Ar]0.34} s, where concentrations are expressed in units of mol/cm3 and R is expressed in units of cal/(K mol). The ignition delay times were modeled by a reaction scheme containing 36 species and 111 elementary reactions. Good agreement between measured and calculated ignition delay times was obtained. A least-squares analysis of 60 computed ignition delay times from six different groups of initial conditions gave the following temperature and concentration dependence: E=46.2×103 cal/mol, βCH3CN=0.43, βO2=-1.18, and βAr=0.18. The ignition process is initiated by H-atom ejection from acetonitrile. The addition of oxygen atoms to the system from the dissociation of molecular oxygen and from the reaction CH3CN+O2 → HO2·+CH2CN·is negligible. In view of the relatively high concentration of methyl radicals obtained in the reaction CH3CN+H → CH3+HCN, the branching step CH3+O2 → CH3O+O plays a more important role than the parallel step H+O2→ OH+O. A discussion of the mechanism in view of the sensitivity analysis is presented. © 1997 John Wiley & Sons, Inc. Int J Chem Kinet 29: 839-849, 1997
Additional Material:
11 Ill.
Type of Medium:
Electronic Resource
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