## Abstract

Reaction experiments on mixtures of N_{2}O/H_{2}O/N_{2} were performed in a variable pressure flow reactor over temperature, pressure, and residence time ranges of 1103–1173 K, 1.5–10.5 atm, and 0.2–0.8 s, respectively. Mixtures of approximately 1% N_{2}O in N_{2} were studied with the addition of varying amounts of water vapor, from background to 3580 ppm. Experimentally measured profiles of N_{2}O, O_{2}, NO, NO_{2}, H_{2}O, and temperature were compared with predictions from detailed kinetic modeling calculations to assess the validity of a reaction mechanism developed from currently available literature thermochemical and rate constant parameters. Sensitivity and reaction flux analyses were performed to determine key elementary reaction path processes and rates. Reaction rate constants for the uni‐molecular reaction, N_{2}O → N_{2} + O, were determined at various pressures in order to match overall experimental and numerical decomposition rates of N_{2}O. The numerical model included a newly determined rate constant for N_{2}O + OH → HO_{2} + N_{2} with an upper limit of 5.66 × 10^{8} cm^{3} mol^{−1} sec^{−1} at 1123 K. This is considerably smaller than presently reported in the literature. The experimentally observed rate of N_{2}O decomposition was found to be slightly dependent on added water concentration. The rate constant determined for the elementary decomposition is strongly dependent on the choice of rate constants for the N_{2}O + O ⇔ N_{2} + O_{2} and N_{2}O + O ⇔ NO + NO reactions. In the absence of accurate data at the temperatures of this work, and based on these and other experiments in this laboratory, we presently recommend rate constants from the review of Baulch et al. The basis for this recommendation is discussed, including the impact on the rate constants derived for elementary nitrous oxide decomposition. The uncertainties in the rate constants as reported here are ±30%. The present mechanism was applied to previously reported high‐pressure shock tube data and yields a high‐pressure limit rate constant a factor of three larger than previously reported at these temperatures. The following expressions for the elementary decomposition reaction are recommended: k 0, N 2 = 9.13 × 10^{14} exp (−57, 690/RT) cm^{3} mol^{−1} s^{−1} and k_{∞} = 7.91 × 10^{10} exp(−56020/RT) s^{−1}. Simple Lindemann fits utilizing these parameters reproduce the pressure dependent rate constants measured here within ±25%. © 1995 John Wiley & Sons, Inc.

Original language | English (US) |
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Pages (from-to) | 883-909 |

Number of pages | 27 |

Journal | International Journal of Chemical Kinetics |

Volume | 27 |

Issue number | 9 |

DOIs | |

State | Published - Sep 1995 |

## All Science Journal Classification (ASJC) codes

- Biochemistry
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry