A chemically consistent rate constant for the reaction of nitrogen dioxide with the oxygen atom

Abstract

In the present study, a chemically consistent rate constant for the reaction between nitrogen dioxide and the oxygen atom has been obtained by combining low-temperature experimental data from the literature and new high-temperature quantum chemical calculations. The expression for our rate constant is k_NO2+O=NO+O2= 2.589 × 10¹⁵T^−1.035 exp(−226/RT) + 4.242 × 10¹⁶T^−0.861exp(−50 917/RT) cm³ mol⁻¹ s⁻¹, where R = 8.314 J mol⁻¹ K⁻¹, and is valid over the temperature range T = 221 to 3000 K. The effect of the inclusion of the new rate constant on the prediction of three detailed reaction models from the literature has been studied using (i) new experimental oxygen atom profiles obtained in a shock tube during nitrogen dioxide pyrolysis, and (ii) published shock tube and jet-stirred reactor data for H₂–NO_x mixtures with and without dioxygen. The impact of the new rate constant on the sensitivity coefficients and reaction pathways has also been analyzed under some conditions. Overall, the predictive capability of the reaction models were improved. The present study suggests that our chemically consistent rate constant should be included in detailed reaction models for combustion applications.