The catalytic decomposition of nitric oxide by metallic oxides

The catalytic activity of 40 metallic oxides has been examined for the decomposition of NO to N2 and O2. Under conditions where the O2 formed was continuously removed (as NO2) the reaction was first order with respect to NO pressure. Proposed kinetics involve a rate-determining attack by NO upon a surface R2-center (adjacent anion vacancies each containing a trapped electron) followed by desorption of O2 thus reforming the R2-center. The parameters and rate at a given temperature of the NO decomposition are found to depend closely upon those of the O2-desorption step, which is itself the rate-determining step in the isotopic exchange reaction between O2 and the surface, previously studied on the same oxides. The reaction shows general similarity to the N2O decomposition.