15N tracers have been applied in a pulse reactor to investigate the mechanism of the reaction of NO with NH3 on V2O5, V2O5/TiO2, V2O5/Al2O3, and V2O4 catalysts. As for the N̄O-NH3 reaction (N̄ represents the labeled nitrogen atom) on the V2O5, V2O5/TiO2 and V2O5/Al2iO3 catalysts at temperatures below 300°C, NN̄ was selectively produced while NN̄O, N̄N̄, N̄N̄O, NO, NN, and NNO were not. These data strongly support the previously proposed mechanism for the NO-NH3 reaction on V2O5 and assure its application to supported V2O5 catalysts. As for the N̄O-NH3 reaction on V2O5 at temperatures above 300°C, NN̄O, NN, NO, and NNO were produced in addition to NN. The conversion of N̄O went through a maximum at 400°C, which is similar to the behavior found for the conversion of NO in the NO-NH3 reaction in the presence of O2 under the dilute gas condition. The N̄O-NH3 reaction on the V2O4 catalyst produced N̄N̄ and N̄N̄O in addition to NN̄ and NNO, and the selectivities to NN̄, NN̄O, N̄N̄, and N̄N̄O were determined as functions of reaction temperature and catalyst weight. The mechanisms of the NO-NH3 reaction on V2O5 catalyst at high temperatures and that on V2O4 catalyst are proposed.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry