Kinetic Modeling of CO Production from the Reaction of CH₃with O₂in Shock Waves

Abstract

CO concentration‐time profiles have been measured by using CO laser resonance absorption in shock tube experiments on the reaction of CH3 with O2 in the temperature range from 1150 to 1560 K. Computer kinetic modeling of our profile data yielded k2 = 1.0 x 1014 e−(15,500 ± 1,100)/T cm3mol sec for the CH3 + O2 → CH3O + O reaction. An RRKM calculation, which took into consideration branching of the CH3 + O2 reaction into different product channels, revealed that by assuming a loose transition state (allowing two free internal rotations) leading to the CH3O + O product channel, we could account very satisfactorily for our results as well as those reported previously for the reaction. A three‐parameter leastsquares fit of a smooth curve covering data from three independent studies gave rise to the expression: k2 = 2.20 x 1034 (T/K)−5.94 exp (–21,300 K/T) cm3mol sec for the temperature range 1150‐2300 K.

Theoretical Study of the Adsorption/Dissociation Reactions of Formic Acid on the α-Al2O3(0001) Surface

“…Other experimental and theoretical energetic barriers for the dehydrogenation and dehydration reactions of formic acid are shown in Table . The energetic barrier of the dehydrogenation reaction of formic acid in the gas phase with our model is 65.3 kcal/mol in this work, and it is the same as the experiment of 65–68 kcal/mol; however, it is different from the experimental value of of 48.5 kcal/mol which is tested at the low voltage of 0.03–0.3 atm, and it is consistent with the calculated value of 65.2 kcal/mol at the level of PMP4/­6-311++G(d,p)//­UMP2/6-311G(d,p) and of 67.8 kcal/mol at the level of B3LYP/­6-311+G(2d,p)//­HF/3-21G(d,p) . The values at the level of MP2/6-311G//HF/6-311G and B3LYP/6-311G(2d,p)//­MP2/6-311G(2d,p) are 77.6 and 73.3 kcal/mol, respectively.…”

Catalytic Effect of CO2 and H2O Molecules on •CH3 + 3O2 Reaction

“…In the Earth's atmosphere, • CH 3 radical is formed by the oxidation of methane by several tropospheric oxidizing agents such as OH, NO 3 radicals and the Cl atom. The kinetics of a • CH 3 + O 2 reaction have been a key topic in combustion chemistry for the last five decades [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. The reaction mechanism behind • CH 3 oxidation is certainly an important part of the kinetic modeling of volatile organic compounds (VOCs).…”

“…The reaction mechanism behind • CH 3 oxidation is certainly an important part of the kinetic modeling of volatile organic compounds (VOCs). Several research groups have been proposed for the oxidation mechanism for the • CH 3 + O 2 reaction, as given below [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17];…”

“…• CH 3 can also be oxidized to form an oxygen-centered methoxy radical ( • CH 3 O) and an O atom via O-O breaking (R3) [11]. Many experimental and theoretical studies on the • CH 3 ••• 3 O 2 reaction system have been performed under atmospheric and combustion conditions [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Several research groups have used various experimental techniques, such as flash photolysis, gas chromatography, and molecular modulation spectrometry, to monitor the decay of reactants or products.…”

“…Several research groups have used various experimental techniques, such as flash photolysis, gas chromatography, and molecular modulation spectrometry, to monitor the decay of reactants or products. By using a shock tube, the rate constants of reactions for R1 and R2 have been measured between 1000 and 3000 K [3][4][5][6][7][8][9][10][11][12]. The proposed rate constants show large discrepancies between the groups.…”