High‐temperature shock tube study of the reactions CH₃ + OH → products and CH₃OH + Ar → products

Abstract

The reaction between methyl and hydroxyl radicals has been studied in reflected shock wave experiments using narrow-linewidth OH laser absorption. OH radicals were generated by the rapid thermal decomposition of tert-butyl hydroperoxide. Two different species were used as CH 3 radical precursors, azomethane and methyl iodide. The overall rate coefficient of the CH 3 + OH reaction was determined in the temperature range 1081-1426 K under conditions of chemical isolation. The experimental data are in good agreement with a recent theoretical study of the reaction. The decomposition of methanol to methyl and OH radicals was also investigated behind reflected shock waves. The current measurements are in good agreement with a recent experimental study and a master equation simulation. C 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 488-495, 2008

Comment on “high temperature shock tube study of the reactions CH3 + OH → products and CH3OH + Ar → products”

“…The rate constant for reaction (3) was estimated to be k 3 = 1.4 × 10 13 cm 3 mole −1 s −1 based on the shape of the methane profile in the propane-air flame in [2] at 1700 K with an estimated error of ∼30%. Perhaps fortuitously, this rate constant does agree well with the rate constant of k 3 = 1.5 × 10 13 cm 3 mole −1 s −1 measured in [1] at 1426 K, although it is my understanding that products were not identified. It also agrees with the theoretical fit to the data in Fig.…”

“…Methane and acetylene emissions increase rapidly as the fuel mixture is enriched beyond the stoichiometric fuel-air ratio in spark-ignited engines because of the persistence of acetylene and methane in the postflame gases of rich flames [5,6]. The authors of [1] are to be commended for their important study of the rate constant of the CH 3 + OH reaction. An experimental determination of the products of this reaction would also be very important.…”

“…In [1], experiments are performed on the title reactions to determine the rate coefficients for these reactions as a function of temperature. The authors' result for the reaction CH 3 + OH → products is very important to understanding the acetylene-methane chemistry in the postflame region of moderately rich ( = 1.5), atmospheric pressure, nonsooting, hydrocarbonair flames [2].…”

Autoignition of methanol: Experiments and computations

“…Alexiou and Williams [29] have investigated the soot formation during the pyrolysis of a toluene-methanol mixture behind a reflected shock. Kinetics of the thermal disassociation of methanol has been studied by Krasnoperov and Michael [30] and Vasudevan et al [31], using the reflected shock technique. Earlier studies on the autoignition of methanol include the work of Cooke et al [32], Bowman [33], Tsuboi and Hashimoto [34], and Natarajan and Bhaskaran [35].…”

Implementation of a variational code for the calculation of rate constants and application to barrierless dissociation and radical recombination reactions: CH3OH = CH3 + OH

“…The use of alcohols as fuels for internal combustion engines has been considered a promising renewable energy resource and considerable attention has been given to methanol reactions as it is an important alternative fuel. Theoretical calculations and experimental works aiming for the thermal decomposition of CH 3 OH are available in the literature [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] although new investigations of the elementary reactions have been encouraged, specially the unimolecular dissociation (Reaction I), which appears as the main important step in the thermal decomposition kinetic model. [26] The main goal of this article is to evaluate the implementation of the canonical variational TST in the kcvt program, as well as to investigate the calculation of rate constants within different models for treating low vibrational frequencies and their contribution for the reaction dynamics.…”