The Formation of OH*(<Superscript>2</Superscript>Σ<Superscript>+</Superscript>) Radical in the Reaction of Hydrogen with Oxygen behind a Shock Wave in Nonequilibrium Conditions

The mechanism of formation of the electronically excited radical OH*(A²Σ⁺) has been studied by analyzing calculations quantitatively describing the results of shock wave experiments carried out in order to determine the moment of maximum OH* radiation at temperatures T < 1500 K and pressures P ≤ 2 atm in the H₂ + O₂ mixtures diluted by argon when the vibrational nonequilibrium is a factor determining the mechanism and rate of the overall process. In kinetic calculations, the vibrational nonequilibrium of the initial H₂ and O₂ components, the HO₂, OH(X²Π), O₂*(¹Δ) intermediates, and the reaction product H₂O were taken into account. The analysis showed that under these conditions the main contribution to the overall process of OH* formation is caused by the reactions OH + Ar → OH* + Ar, H₂ + HO₂ → OH* + H₂O, H₂ + O*(¹D) → OH* + H, HO² + O → OH* + O² and H + H²O → OH* + H², which occur in the vibrational nonequilibrium mode (their activation barrier is overcome due to the vibrational excitation of reactants), and by H + O₃ → OH* + O₂ and H + H₂O₂ → OH* + H₂O, which are reverse to the reactions of chemical quenching.     

IR laser absorption diagnostic for C2H4 in shock tube kinetics studies

An IR laser absorption diagnostic has been further developed for accurate and sensitive time‐resolved measurements of ethylene in shock tube kinetic experiments. The diagnostic utilizes the P14 line of a tunable CO₂ gas laser at 10.532 μm (the (0 0 1) → (1 0 0) vibrational band) and achieves improved signal‐to‐noise ratio by using IR photovoltaic detectors and accurate identification of the P14 line via an MIR wavemeter. Ethylene absorption cross sections were measured over 643–1959 K and 0.3–18.6 atm behind both incident and reflected shock waves, showing evident exponential decay with temperature. Very weak pressure dependence was observed over the pressure range of 1.2–18.6 atm. By measuring ethylene decomposition time histories at high‐temperature conditions (1519–1895 K, 2.0–2.8 atm) behind reflected shocks, the rate coefficient of the dominant elementary reaction C₂H₄ + M → C₂H₂ + H₂ + M was determined to be k₁ = (2.6 ± 0.5) × 10¹⁶exp(?34,130/T, K) cm³ mol^?1 s^?1 with low data scatter. Ethylene concentration time histories were also measured during the oxidation of 0.5% C₂H₄/O₂/Ar mixtures varying in equivalence ratio from 0.25 to 2. Initial reflected shock conditions ranged from 1267 to 1440 K and 2.95 to 3.45 atm. The measured time histories were compared to the modeled predictions of four ethylene oxidation mechanisms, showing excellent agreement with the Ranzi et al. mechanism (updated in 2011). This diagnostic scheme provides a promising tool for the study and validation of detailed hydrocarbon pyrolysis and oxidation mechanisms of fuel surrogates and realistic fuels. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 423–432, 2012     

Kinetics of ethane oxidation

Ethane oxidation in jet-stirred reactor has recently been investigated at high temperature (800–1200 K) in the pressure range 1–10 atm and molecular species (H₂, CO, CO₂, CH₄, C₂H₂, C₂H₄, C₂H₆) concentration profiles were obtained by probe sampling and GC analysis. Ethane oxidation was modeled using a comprehensive kinetic reaction mechanism including the most recent findings concerning the kinetics of the reactions involved in the oxidation of C₁? C₄ hydrocarbons. The proposed mechanism is able to reproduce experimental data obtained in our high-pressure jet stirred reactor and ignition delay times measured in shock tube in the pressure range 1–13 atm, for temperatures extending from 800 to 2000 K and equivalence ratios of 0.1 to 2. It is also able to reproduce atoms concentrations (H,O) measured in shock tube at ≈2 atm. The same detailed kinetic mechanism can also be used to model the oxidation of methane, ethylene, propyne, and allene in similar conditions.     

Shock‐tube and modeling study of acetaldehyde pyrolysis and oxidation

Pyrolysis and oxidation of acetaldehyde were studied behind reflected shock waves in the temperature range 1000–1700 K at total pressures between 1.2 and 2.8 atm. The study was carried out using the following methods, (1) time‐resolved IR‐laser absorption at 3.39 μm for acetaldehyde decay and CH‐compound formation rates, (2) time‐resolved UV absorption at 200 nm for CH₂CO and C₂H₄ product formation rates, (3) time‐resolved UV absorption at 216 nm for CH₃ formation rates, (4) time‐resolved UV absorption at 306.7 nm for OH radical formation rate, (5) time‐resolved IR emission at 4.24 μm for the CO₂ formation rate, (6) time‐resolved IR emission at 4.68 μm for the CO and CH₂CO formation rate, and (7) a single‐pulse technique for product yields. From a computer‐simulation study, a 178‐reaction mechanism that could satisfactorily model all of our data was constructed using new reactions, CH₃CHO (+M) → CH₄ + CO (+M), CH₃CHO (+M) → CH₂CO + H₂(+M), H + CH₃CHO → CH₂CHO + H₂, CH₃ + CH₃CHO → CH₂CHO + CH₄, O₂ + CH₃CHO → CH₂CHO + HO₂, O + CH₃CHO → CH₂CHO + OH, OH + CH₃CHO → CH₂CHO + H₂O, HO₂ + CH₃CHO → CH₂CHO + H₂O₂, having assumed or evaluated rate constants. The submechanisms of methane, ethylene, ethane, formaldehyde, and ketene were found to play an important role in acetaldehyde oxidation. © 2007 Wiley Periodicals, Inc. 40: 73–102, 2008     

An experimental and modeling study of ethanol oxidation kinetics in an atmospheric pressure flow reactor

Experimental profiles of stable species concentrations and temperature are reported for the flow reactor oxidation of ethanol at atmospheric pressure, initial temperatures near 1100 K and equivalence ratios of 0.61–1.24. Acetaldehyde, ethene, and methane appear in roughly equal concentrations as major intermediate species under these conditions. A detailed chemical mechanism is validated by comparison with the experimental species profiles. The importance of including all three isomeric forms of the C₂H₅O radical in such a mechanism is demonstrated. The primary source of ethene in ethanol oxidation is verified to be the decomposition of the C₂H₄OH radical. The agreement between the model and experiment at 1100 K is optimized when the branching ratio of the reactions of C₂H₅OH with OH and H is defined by (30% C₂H₄OH + 50% CH₃CHOH + 20% CH₃CH₂O) + XH. As in methanol oxidation, HO₂ chemistry is very important, while the H + O₂ chain branching reaction plays only a minor role until late in fuel decay, even at temperatures above 1100 K.     

Kinetic modeling of propane oxidation and pyrolysis

Propane oxidation in jet-stirred reactor was modeled using a comprehensive kinetic reaction mechanism including the most recent findings concerning the kinetics of the reactions involved in the oxidation of C₁? C₄ hydrocarbons. The present detailed mechanism is able to reproduce experimental species concentration profiles obtained in our high-pressure jet-stirred reactor (900 ? T/K ? 1200; 1 ? P/atm ? 10; 0.15 ? ? ? 4) and in a turbulent flow reactor at 1 atm; ignition delay times measured in shock tube (1200 ? T/K ? 1700; 2 ? P/atm ? 15; 0.125 ? ? ? 2); H-atoms concentrations measured in shock tube during the pyrolysis of propane and burning velocities of freely propagating premixed propane-air laminar flames. The computed results are discussed in terms of pressure and equivalence ratio (?) effects on propane oxidation. The same detailed kinetic reaction mechanism can also be used to model the oxidation of methane, ethylene, ethane, and propene in similar conditions. © John Wiley & Sons, Inc.     

Experimental and kinetic modeling study of the effect of sulfur dioxide on the mutual sensitization of the oxidation of nitric oxide and methane

New experimental results were obtained for the mutual sensitization of the oxidation of NO and methane in a fused silica jet‐stirred reactor operating at 10⁵ Pa, over the temperature range 800–1150 K. The effect of the addition of sulfur dioxide was studied. Probe sampling followed by online FTIR analyses and off‐line GC‐TCD/FID analyses allowed the measurement of concentration profiles for the reactants, stable intermediates, and final products. A detailed chemical kinetic modeling of the present experiments was performed. An overall reasonable agreement between the present data and modeling was obtained. According to the present modeling, the mutual sensitization of the oxidation of methane and NO proceeds via the NO to NO₂ conversion by HO₂ and CH₃O₂. The conversion of NO to NO₂ by CH₃O₂ is more important at low temperatures (800 K) than at higher temperatures (850–900 K) where the production of NO₂ is mostly due to the reaction of NO with HO₂. The NO to NO₂ conversion is favored by the production of the HO₂ and CH₃O₂ radicals yielded from the oxidation of the fuel. The production of OH resulting from the oxidation of NO accelerates the oxidation of the fuel: NO + HO₂ → OH+ NO₂ followed by OH + CH₄→ CH₃. In the lower temperature range of this study, the reaction further proceeds via CH₃ + O₂→ CH₃O₂; CH₃O₂+ NO → CH₃O + NO₂. At higher temperatures, the production of CH₃O involves NO₂: CH₃+ NO₂→ CH₃O. This sequence of reactions is followed by CH₃O → CH₂O + H; CH₂O +OH → HCO; HCO + O₂ → HO₂ and H + O₂ → HO₂ → CH₂O + H; CH₂O +OH → HCO; HCO + O₂ → HO₂ and H + O₂ → HO₂. The data and the modeling show that unexpectedly, SO₂ has no measurable effect on the kinetics of the mutual sensitization of the oxidation of NO and methane in the present conditions, whereas it frequently acts as an inhibitor in combustion. This result was rationalized via a detailed kinetic analysis indicating that the inhibiting effect of SO₂ via the sequence of reactions SO₂+H → HOSO, HOSO+O₂ → SO₂+HO₂, equivalent to H+O₂?HO₂, is balanced by the reaction promoting step NO+HO₂ → NO₂+OH. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 406–413, 2005     

Experimental and kinetic modeling of the reduction of NO by isobutane in a Jsr at 1 atm

A kinetic study of the reduction of nitric oxide (NO) by isobutane in simulated conditions of the reburning zone was carried out in a fused silica jet‐stirred reactor operating at 1 atm, at temperatures ranging from 1100 to 1450 K. In this new series of experiments, the initial mole fraction of NO was 1000 ppm, that of isobutane was 2200 ppm, and the equivalence ratio was varied from 0.75 to 2. It was demonstrated that for a given temperature, the reduction of NO is favored when the temperature is increased and a maximum NO reduction occurs slightly above stoichiometric conditions. The present results generally follow those reported in previous studies of the reduction of NO by C₁ to C₃ hydrocarbons or natural gas as reburn fuel. A detailed chemical kinetic modeling of the present experiments was performed using an updated and improved kinetic scheme (979 reversible reactions and 130 species). An overall reasonable agreement between the present data and the modeling was obtained. Furthermore, the proposed kinetic mechanism can be successfully used to model the reduction of NO by ethylene, ethane, acetylene, a natural gas blend (methane‐ethane 10:1), propene, and HCN. According to this study, the main route to NO reduction by isobutane involves ketenyl radical. The model indicates that the reduction of NO proceeds through the reaction path: iC₄H₁₀ → C₃H₆ → C₂H₄ → C₂H₃ → C₂H₂ → HCCO; HCCO + NO → HCNO + CO and HCN + CO₂; HCNO + H → HCN → NCO → NH; NH + NO → N₂ and NH + H → followed by N + NO → N₂; NH + NO → N₂O followed by N₂O + H → N₂. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 365–377, 2000     

Experimental measurements and kinetic modeling of CO/H2/O2/NOx conversion at high pressure

This paper presents results from lean CO/H₂/O₂/NO_x oxidation experiments conducted at 20–100 bar and 600–900 K. The experiments were carried out in a new high‐pressure laminar flow reactor designed to conduct well‐defined experimental investigations of homogeneous gas phase chemistry at pressures and temperatures up to 100 bar and 925 K. The results have been interpreted in terms of an updated detailed chemical kinetic model, designed to operate also at high pressures. The model, describing H₂/O₂, CO/CO₂, and NO_x chemistry, is developed from a critical review of data for individual elementary reactions, with supplementary rate constants determined from ab initio CBS‐QB3 calculations. New or updated rate constants are proposed for important reactions, including OH + HO₂ ? H₂O + O₂, CO + OH ? [HOCO] ? CO₂ + H, HOCO + OH ? CO + H₂O₂, NO₂ + H₂ ? HNO₂ + H, NO₂ + HO₂ ? HONO/HNO₂ + O₂, and HNO₂(+M) ? HONO(+M). Further validation of the model performance is obtained through comparisons with flow reactor experiments from the literature on the chemical systems H₂/O₂, H₂/O₂/NO₂, and CO/H₂O/O₂ at 780–1100 K and 1–10 bar. Moreover, introduction of the reaction CO + H₂O₂ → HOCO + OH into the model yields an improved prediction, but no final resolution, to the recently debated syngas ignition delay problem compared to previous kinetic models. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 454–480, 2008     

High temperature pyrolysis of methane in shock waves. Rates for dissociative recombination reactions of methyl radicals and for propyne formation reaction

The pyrolysis of 2% CH₄ and 5% CH₄ diluted with Ar was studied using both a single–pulse and time–resolved spectroscopic methods over the temperature range 1400–2200 K and pressure range 2.3–3.7 atm. The rate constant expressions for dissociative recombination reactions of methyl radicals, CH₃ + CH₃ → C₂H₅ + H and CH₃ + CH₃ → C₂H₄ + H₂, and for C₃H₄ formation reaction were investigated. The simulation results required considerably lower value than that reported for CH₃ + CH₃ → C₂H₄ + H₂. Propyne formation was interpreted well by reaction C₂H₂ + CH₃ → P-C₃H₄ + H with ?? = 6.2 × ¹⁰12 exp(?17 kcal/RT) ^cm3 mol^?1 s^?1.     

The high temperature pyrolysis of 1,3-butadiene: heat of formation and rate of dissociation of vinyl radical

The high temperature pyrolysi of 1,3-butadiene has been investigated in the shock tube with two time-resolved diagnostic techniques: laser schlieren measurements of density gradient with 1, 2, 4, and 5% C₄H₆ in Ar or Kr, 0.26 < P₂ < 0.66 atm, over 1550–2200 K, and time-of-flight mass spectra for 3% C₄H₆–Ne, P₅ ～ 0.4 atm, 1400–2000 K. When combined with a recent single-pulse shock tube product analysis covering 1050–2050 K, these measurements permit a complete modeling of major species in C₄H₆ pyrolysis. Extrapolated density gradients and product analyses show initiation is dominated by C₄H₆ → 2C₂H₃., significant falloff and Arrhenius curvature being seen in the derived rates. A restricted rotor, Gorin model RRKM fit to these rates with reasonable parameters generates The derived barrier, ΔH${}_{\text{0}}^{\text{º}}$ = 99 ± 4 kcal/mol, translates to ΔH${}_{\text{f}}^{\text{º}}$ _,298 = 63.4 ± 2 kcal/mol for the heat of formation of vinyl radical. A mechanism for the formation of all products detected in the above experiments is given, together with a successful but semiquantitative kinetic model for major products. The measurements require the rate of vinyl radical dissociation, C₂H₃ + M → C₂H₂ + H + M, to be extremely low, k < 10⁹ cm³/mol s for 1600 K, so that the dominant chain carrier in C₄H₆ pyrolysis is vinyl radical.     

The kinetics and the mechanism of the oxidation of carbon monoxide in the presence of hydrogen

The kinetics of the slow oxidation of CO in the presence of H₂ have been studied above the second explosion limit for the mixture 2CO + O₂ + X% H₂ at the temperature range of 530–570°C, pressures from 300 to 530 torr, and hydrogen contents of 1.1, 2.8, and 5.7%. The second explosion limit has been experimentally determined for the mixture of 2CO + O₂ containing 1.0, 3.0, and 5.7% H₂. On the basis of the oxidation scheme of CO in the presence of H₂, which includes the accepted mechanism of oxidation of hydrogen supplemented by the reactions in which CO takes part, the second explosion limit and the profiles of the slow reaction are calculated by computer methods. The agreement found between experimental and calculated values allows one to conclude that the scheme under consideration rather completely described the slow reaction above the second limit and the occurrence of the second explosion limit in the mixture CO–O₂–H₂. The rate constant for the reaction HO₂ + CO → OH + CO₂ was calculated from the experimental data and was found to agree with previous determinations.     

Thermal decomposition of ethane in shock waves

The thermal decomposition of ethane was studied behind reflected shock waves over the temperature range 1200–1700 K and over the pressure range 1.7?2.5 atm, by both tracing the time variation of absorption at 3.39 μm and analyzing the concentration of the reacted gas mixtures. The mechanism to interpret well not only the earlier stage of C₂H₆ decomposition, but also the later stage was determined. The rate constant of reactions, C₂H₆ → CH₃ + CH₃, C₂H₆ + C₂H₃ → C₂H₅ + C₂H₄, C₂H₅ → C₂H₄ + H were calculated. The rate constants of the other reactions were also discussed.     

Study of the pyrolysis of H2O2 in the presence of H2and CO by use of UV absorption of HO2

In dissociation experiments of H₂O₂ under shock wave conditions, the spectra of H₂O₂ and HO₂ have been observed in the UV at 2200 ≤ 2800 Å. By the use of these spectra the H₂O₂ decomposition in the presence of H₂ and CO at 870 ≤ T ≤ 1000°K has been analyzed. It was found that in this temperature range, in contrast to low temperature behavior, reactions of H atoms with H₂O₂ and with HO₂ are equally important. The rate of the reaction H + H₂O₂ ← HO₂ + H₂ was estimated in comparison with the rate of the reaction between H and HO₂. Good agreement between calculated and measured concentration profiles of HO₂ and H₂O₂ was obtained.     

Additive effect of hydrocarbons on OH radical production in H2 oxidation

Mixtures of hydrocarbons (methane, allene, propyne, propene, and propane)–H₂–O₂ highly diluted with argon were heated to a temperature ranging from 1200 to 1900 K behind reflected shock waves, and the additive effects of methane, allene, propyne, propene, and propane on OH radical production in H₂ oxidation were studied by observing time‐resolved UV‐absorption (306.7 nm). It was found that, in H₂ oxidation below 1500 K, the addition of these hydrocarbons prolonged the delay time of the onset of the rapid OH radical production. An analysis using reported kinetic modeling of C₁–C₄ oxidation gave valuable information for reactions between hydrocarbons and H, O atoms and OH radicals. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 37: 50–55, 2005     

Experimental and Kinetic Modeling Study of C2H2 Oxidation at High Pressure

A detailed chemical kinetic model for oxidation of acetylene at intermediate temperatures and high pressure has been developed and evaluated experimentally. The rate coefficients for the reactions of C₂H₂ with HO₂ and O₂ were investigated, based on the recent analysis of the potential energy diagram for C₂H₃ + O₂ by Goldsmith et al. and on new ab initio calculations, respectively. The C₂H₂ + HO₂ reaction involves nine pressure‐ and temperature‐dependent product channels, with formation of triplet CHCHO being dominant under most conditions. The barrier to reaction for C₂H₂ + O₂ was found to be more than 50 kcal mol^?1 and predictions of the initiation temperature were not sensitive to this reaction. Experiments were conducted with C₂H₂/O₂ mixtures highly diluted in N₂ in a high‐pressure flow reactor at 600–900 K and 60 bar, varying the reaction stoichiometry from very lean to fuel‐rich conditions. Model predictions were generally in satisfactory agreement with the experimental data. Under the investigated conditions, the oxidation pathways for C₂H₂ are more complex than those prevailing at higher temperatures and lower pressures. Acetylene is mostly consumed by recombination with H to form vinyl (reducing conditions) or with OH to form a CHCHOH adduct (stoichiometric to lean conditions). Both C₂H₃ and CHCHOH then react primarily with O₂. The CHCHOH + O₂ reaction leads to formation of significant amounts of glyoxal (OCHCHO) and formic acid (HOCHO), and the oxidation chemistry of these intermediates is important for the overall reaction.     

A comprehensive mechanism for methanol oxidation

A comprehensive detailed chemical kinetic mechanism for methanol oxidation has been developed and validated against multiple experimental data sets. The data are from static-reactor, flow-reactor, shock-tube, and laminar-flame experiments, and cover conditions of temperature from 633–2050 K, pressure from 0.26–20 atm, and equivalence ratio from 0.05–2.6. Methanol oxidation is found to be highly sensitive to the kinetics of the hydroperoxyl radical through a chain-branching reaction sequence involving hydrogen peroxide at low temperatures, and a chain-terminating path at high temperatures. The sensitivity persists at unusually high temperatures due to the fast reaction of CH₂OH+O₂=CH₂O+HO₂ compared to CH₂OH+M=CH₂O+H+M. The branching ratio of CH₃OH+OH=CH₂OH/CH₃O+H₂O was found to be a more important parameter under the higher temperature conditions, due to the rate-controlling nature of the branching reaction of the H-atom formed through CH₃O thermal decomposition. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 805–830, 1998     

Vibrational nonequilibrium and electronic excitation in the reaction of hydrogen with oxygen behind a shock wave

A theoretical analysis of ignition and combustion processes in a hydrogen-oxygen mixture behind a shock wave is presented (1000 K ≤ T ≤ 2500 K; 2.0 atm ≥ P ≥ 0.3 atm). The experiments performed using stoichiometric mixtures with the detection of OH (²Σ⁺) and rich mixtures with the detection of OH (²Π) were interpreted in terms of a general kinetic approach. In this case, the apparent rate constant of the chain branching reaction H + O₂ → O + OH was the only adjustable parameter. It was found that this rate constant increased with decreasing hydrogen content and exceeded equilibrium values. In this context, the mechanism of chain branching, which occurs through the formation of the vibrationally excited radical HO₂(v), and the role of secondary vibrationally nonequilibrium O₂ and O₂(¹Δ) molecules and the reaction H + O₂(¹Δ) → O + OH are discussed. New mechanisms of the formation and quenching of electronically excited OH(²Σ⁺) radicals, O(¹ D) atoms, and O₂(¹Δ) molecules are considered. The results of a nonempirical (ab initio) analysis of molecular systems and the corresponding estimations of reaction rate constants were widely used.     

Measurement of the rate coefficient of the reaction CH+O2 → products in the temperature range 2200 to 2600 K

The rate coefficient of the reaction CH+O₂ → products was determined by measuring CH-radical concentration profiles in shock-heated 100–150 ppm ethane/1000 ppm O₂ mixtures in Ar using cw, narrow-linewidth laser absorption at 431.131 nm. Comparing the measured CH concentration profiles to ones calculated using a detailed kinetics model, yielded the following average value for the rate coefficient independent of temperature over the range 2200–2600 K: The experimental conditions were chosen such that the calculated profiles were sensitive mainly to the reactions CH+O₂ → products and CH₃+M → CH+H₂+M. For the methyl decomposition reaction channel, the following rate-coefficient expression provided the best fit of the measured CH profiles: Additionally, the rate coefficient of the reaction CH₂+H→CH+ H₂ was determined indirectly in the same system: © 1997 John Wiley & Sons, Inc.     

Flow reactor studies and kinetic modeling of the H2/O2/NOX and CO/H2O/O2/NOX reactions

Flow reactor experiments were performed over wide ranges of pressure (0.5–14.0 atm) and temperature (750–1100 K) to study H₂/O₂ and CO/H₂O/O₂ kinetics in the presence of trace quantities of NO and NO₂. The promoting and inhibiting effects of NO reported previously at near atmospheric pressures extend throughout the range of pressures explored in the present study. At conditions where the recombination reaction H + O₂ (+M) = HO₂ (+M) is favored over the competing branching reaction, low concentrations of NO promote H₂ and CO oxidation by converting HO₂ to OH. In high concentrations, NO can also inhibit oxidative processes by catalyzing the recombination of radicals. The experimental data show that the overall effects of NO addition on fuel consumption and conversion of NO to NO₂ depend strongly on pressure and stoichiometry. The addition of NO₂ was also found to promote H₂ and CO oxidation but only at conditions where the reacting mixture first promoted the conversion of NO₂ to NO. Experimentally measured profiles of H₂, CO, CO₂, NO, NO₂, O₂, H₂O, and temperature were used to constrain the development of a detailed kinetic mechanism consistent with the previously studied H₂/O₂, CO/H₂O/O₂, H₂/NO₂, and CO/H₂O/N₂O systems. Model predictions generated using the reaction mechanism presented here are in good agreement with the experimental data over the entire range of conditions explored. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 705–724, 1999