Thermal reduction of NO by NH3: Kinetic modeling of the NH2+NO product branching ratio

M. J. Halbgewachs*, Wei-Guang Diau, A. M. Mebel, Ming-Chang Lin, C. F. Melius

*Corresponding author for this work

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15 Scopus citations

Abstract

The product-branching ratio for the reaction NH2+NO→HN2+OH (1) and N2+H2O (2) has been determined in the temperature range of 950-1200 K by pyrolysis of Ar-diluted NH3+NO mixtures and at 1173 and 1200 K by pyrolysis of Ar-diluted NH3-NO-CO mixtures. Analysis of the pyrolyzed and unpyrolyzed mixtures was carried out by the FTIR spectrometric method. Kinetic modeling of the decay rates of NH3 and NO and the production rate of CO2 by varying the branching ratio, α1=k1/(k1+k2), and keeping the known total rate constant (kt=k1+k2=9.6×1014T-0.85 cm3 mol-1 s-1) unchanged at each temperature allows determination of the value of α1 with good reproducibility. Kinetic modeling of α1, using previously measured H2O formation data [28] from the NH3+NO reaction in the temperature range of 1123-1273 K was also carried out. The branching ratio was found to increase rapidly from 0.27 at 950 K to 0.58 at 1273 K, which is fully consistent with the sharply rising trend recently reported from NH3-NO flame studies, in which α1∼0.5 at 1500 K and rose to 0.9 at 2000 K. These new findings cast doubt on the much lower values, α1≤0.17 at T≤1173 K, obtained by laser kinetic measurements.

Original languageEnglish
Pages (from-to)2109-2115
Number of pages7
JournalSymposium (International) on Combustion
Volume26
Issue number2
DOIs
StatePublished - 1 Jan 1996

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