Inhibition effect of H2O on decomposition of nitrogen monoxide over ion-exchanged copper zeolites

The catalytic decomposition of NO in the presence and in the absence of water vapor was studied over ion exchanged copper zeolites. It was found that the rate of the formation of N2 in the decomposition of NO decreases greatly in the presence of H2O, whereas the rate of the formation of N2O is weakly hindered by the presence of H2O. By TPD method, it was shown that H2O inhibits the formation of NO3 intermediates and promotes the decomposition of the NO3 species. By comparison of these results, it was suggested that the inhibition effect of H2O on the decomposition of NO is ascribed to the decrease in the formation of NO3 intermediate species.