Combustion and Flame, Vol.147, No.3, 195-208, 2006
Investigation of the reaction of toluene with molecular oxygen in shock-heated gases
The reaction of toluene with molecular oxygen to yield benzyl and hydroperoxyl radicals has been studied using ultraviolet laser absorption of benzyl radicals at 266 nm in shock-heated gases. Test gas mixtures of toluene with excess oxygen diluted in helium and argon were heated in reflected shock waves to temperatures ranging from 1117 to 1366 K at total pressures around 1.7 bar. The growth in benzyl absorbance was monitored at 266 nm, allowing determination of the rate coefficient for the C6H5CH3 + O-2 -> C6H5CH2 + HO2, reaction (1). The high signal-to-noise ratio provided by laser absorption provides rate coefficient determinations with an estimated uncertainty of +/- 20%. Fitting both these high-temperature shock tube results and the rate recommendation of Ingham et al. [Proc. Combust. Inst. 25 (1994) 767-774] at 773 K, the rate coefficient for reaction (1) can be described with a three-parameter Arrhenius expression by k(1) (T) = 2.18 x 10(7) T-2.5 exp(-46,045 [cal/mol]/RT) [cm(3) mol(-1) s(-1)]. In addition, the measured benzyl time-histories can be used as experimental targets for the development and validation of detailed mechanisms for toluene oxidation. (c) 2006 The Combustion Institute. Published by Elsevier Inc. All rights reserved.