A Critical Review of the Gas-Phase Reaction Kinetics of the Hydroxyl Radical

Abstract

The literature pertinent to reactions of the hydroxyl radical has been reviewed. An extensive discussion is given for reactions of the hydroxyl radical with itself and with CO, H2, and CH4. These four reactions are: (1) OH+OH→H2O+O; (2) CO+OH→CO2+H; (3) H2+OH→H2O+H; (4) CH4+OH→CH3+H2O. Values are recommended for k1 and k2 and for the ratio k3/k2 and k4/k2. These rate ratios are used with the previously established value of k2 to obtain recommended values for k3 and k4. The recommended values in cm3 mol-1·s-1, the temperature range, and the uncertainty are: k1=1.55×1012, 300 K, log k±0.1, 05k2=3.1×1011 exp(−300/T), 300−2000 K, log k±.3k3/k2=73 exp(2300/T), 300−2000 K, log k3/k2±.3k3=3.8×1013 exp(−2600/T), 300−2000 K, log k±.3k4/k2=92 exp(2200/T), 300−2000 K, log k3/k2±.3k4=2.85×1013 exp(−2500/T), 300−2000 K, log k±.7. Rate expressions are also recommended for a number of other hydroxyl reactions whose rates are less well established.

The reaction of OH with CO

“…In the present paper a kinetic study of reaction (1) in competition with reaction (2) (1) O H + CO + CO + H (2) O H + Hz -+ Hz0 + H is reported with particular emphasis upon the effect of total pressure. The O H radicals are generated by the photolysis of NzO at 2139 A in the presence of excess Hz:…”

“…I n the presence of CO the OH radicals can react in accordance with reactions (1) and (2). By following the production of CO2 as a function of reaction conditions the values of kz/kl could be determined.…”

A computational study of physical and chemical inhibition in a perfectly stirred reactor

“…The rate data associated with the three H2/02 mechanisms are shown in Table 1. Mechanism I consists of reactions (1)-(7), mechanism I1 contains reactions (1)- (9), and I11 is the full set of hydrogen/ oxygen reactions (1)- (13). Much of the kinetic data associated with the HO2 reactions is estimated and is taken from the review of Lloyd.12 The reactant HO2 is difficult to generate without other radicals being present so that single elementary reactions of HO2 cannot be isolated for study.…”

Development of Predictive Models of the Kinetics of a Hydrogen Abstraction Reaction Combining Quantum-Mechanical Calculations and Experimental Data

“…In addition to their technological and scientific importance, hydrogen abstraction reactions have a simple mechanism that allows for detailed studies, and hence this class of reactions is very well-documented. 3,4 Reliable sources of data may be found in databases reviewing experimental studies for the gas-phase rate constants for the reactions of hydroxyl radical with alkanes and cycloalkanes spanning temperature ranges from approximately 180 to 2000 K. [5][6][7][8][9][10][11] It is common practice to fit the experimental values to an empirical model, usually the Arrhenius equation, 12 to obtain kinetic parameters. The Arrhenius model contains two parameters: the pre-exponential factor and the activation energy, which are strictly applicable within the temperature interval used in the fitting.…”