High-Temperature Rate Constants for CH₃OH + Kr → Products, OH + CH₃OH → Products, OH + (CH₃)₂CO → CH₂COCH₃ + H₂O, and OH + CH₃ → CH₂ + H₂O

Abstract

The reflected shock tube technique with multipass absorption spectrometric detection of OH radicals at 308 nm (corresponding to a total path length of approximately 4.9 m) has been used to study the dissociation of methanol between 1591 and 2865 K. Rate constants for two product channels [CH3OH + Kr --> CH3 + OH + Kr (1) and CH3OH + Kr --> 1CH2 + H2O + Kr (2)] were determined. During the course of the study, it was necessary to determine several other rate constants that contributed to the profile fits. These include OH + CH3OH --> products, OH + (CH3)2CO --> CH2COCH3 + H2O, and OH + CH3 --> 1,3CH2 + H2O. The derived expressions, in units of cm(3) molecule(-1) s(-1), are k(1) = 9.33 x 10(-9) exp(-30857 K/T) for 1591-2287 K, k(2) = 3.27 x 10(-10) exp(-25946 K/T) for 1734-2287 K, kOH+CH3OH = 2.96 x 10-16T1.4434 exp(-57 K/T) for 210-1710 K, k(OH+(CH3)(2)CO) = (7.3 +/- 0.7) x 10(-12) for 1178-1299 K and k(OH+CH3) = (1.3 +/- 0.2) x 10(-11) for 1000-1200 K. With these values along with other well-established rate constants, a mechanism was used to obtain profile fits that agreed with experiment to within <+/-10%. The values obtained for reactions 1 and 2 are compared with earlier determinations and also with new theoretical calculations that are presented in the preceding article in this issue. These new calculations are in good agreement with the present data for both (1) and (2) and also for OH + CH3 --> products.

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

“…The reaction mechanism reported by Srinivasan et al [7] with the following modifications was used in the modeling. Updated rate coefficients from GRI-Mech 3.0 [18] were used for methyl radical recombination…”

“…1b shows that CH 3 + OH → products is the most sensitive reaction over the entire experimental time frame. Excellent isolation of the target reaction was achieved a For complete mechanism, see [7]. b Rate coefficient units: s because of the low OH concentrations (see Fig.…”

“…The theoretical modeling of Jasper et al [3] indicates that this is a reasonable assumption for the experimental conditions of the present work. The rate coefficient expression recommended by Srinivasan et al [7] was used for reaction (2b). It is pertinent to note that the k 2b value reported in Srinivasan et al is for krypton as the third-body collider, whereas the current measurements were carried out in argon.…”

“…The two most recent measurements of the methanol decomposition reaction were performed by Krasnoperov and Michael [6] and Srinivasan et al [7]. In both studies, OH profiles during methanol decomposition were recorded using multipass absorption spectrometry.…”

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.…”