Reflected Shock Tube Studies of High-Temperature Rate Constants for OH + NO2→ HO2+ NO and OH + HO2→ H2O + O2
- 1 April 2006
- journal article
- research article
- Published by American Chemical Society (ACS) in The Journal of Physical Chemistry A
- Vol. 110 (21), 6602-6607
- https://doi.org/10.1021/jp057461x
Abstract
The motivation for the present study comes from the preceding paper where it is suggested that accepted rate constants for OH + NO2 → NO + HO2 are high by ∼2. This conclusion was based on a reevaluation of heats of formation for HO2, OH, NO, and NO2 using the Active Thermochemical Table (ATcT) approach. The present experiments were performed in C2H5I/NO2 mixtures, using the reflected shock tube technique and OH-radical electronic absorption detection (at 308 nm) and using a multipass optical system. Time-dependent profile decays were fitted with a 23-step mechanism, but only OH + NO2, OH + HO2, both HO2 and NO2 dissociations, and the atom molecule reactions, O + NO2 and O + C2H4, contributed to the decay profile. Since all of the reactions except the first two are known with good accuracy, the profiles were fitted by varying only OH + NO2 and OH + HO2. The new ATcT approach was used to evaluate equilibrium constants so that back reactions were accurately taken into account. The combined rate constant from the present work and earlier work by Glaenzer and Troe (GT) is kOH+NO2 = 2.25 × 10-11 exp(−3831 K/T) cm3 molecule-1 s-1, which is a factor of 2 lower than the extrapolated direct value from Howard but agrees well with NO + HO2 → OH + NO2 transformed with the updated equilibrium constants. Also, the rate constant for OH + HO2 suitable for combustion modeling applications over the T range (1200−1700 K) is (5 ± 3) × 10-11 cm3 molecule-1 s-1. Finally, simulating previous experimental results of GT using our updated mechanism, we suggest a constant rate for kHO2+NO2 = (2.2 ± 0.7) × 10-11 cm3 molecule-1 s-1 over the T range 1350−1760 K.Keywords
This publication has 58 references indexed in Scilit:
- Ab initio study of the HO2+NO reaction: Prediction of the total rate constant and product branching ratios for the forward and reverse processesThe Journal of Chemical Physics, 2003
- A Temperature-Dependent Kinetics Study of the Important Stratospheric Reaction O(3P) + NO2 → O2 + NOThe Journal of Physical Chemistry A, 2001
- Reply to Comment on “Rate Constants for CH3 + O2 → CH3O + O at High Temperature and Evidence for H2CO + O2 → HCO + HO2”The Journal of Physical Chemistry A, 2000
- The thermal decomposition of C2H5ISymposium (International) on Combustion, 1996
- Ab InitioCalculations and Three Different Applications of Unimolecular Rate Theory for the Dissociations of CCl4, CFCl3, CF2Cl2, and CF3ClThe Journal of Physical Chemistry, 1996
- Kinetics of the reaction between hydroxyl and hydroperoxyl on the singlet potential energy surfaceThe Journal of Physical Chemistry, 1991
- Reactions of HO2 with NO and NO2 studied by mid-infrared laser magnetic resonanceJournal of the Chemical Society, Faraday Transactions, 1990
- Theoretical investigations of reactions of some radicals with hydroperoxo. 1. Hydrogen abstractions by direct mechanismsThe Journal of Physical Chemistry, 1989
- Chemical Kinetic Data Base for Combustion Chemistry. Part I. Methane and Related CompoundsJournal of Physical and Chemical Reference Data, 1986
- HO2 Formation in Shock Heated HNO3 ‐NO2 MixturesBerichte der Bunsengesellschaft für physikalische Chemie, 1975