Kinetic Modelling of the Dynamic Interaction between NO and N2O over Cu-ZSM5

A kinetic model has been developed to describe the interaction between NO and N2O over Cu-ZSM5. The spontaneous and isothermal oscillations of N2O decomposition rate, observed in the absence of NO, disappear in the presence of even very low amount of nitric oxide in the gas phase, and also the overall reaction rate significantly increases. N2O decomposition kinetics is based on a reaction mechanism assuming that N2O is converted by both reduced and oxidised copper sites of Cu-ZSM5 while NO quickly converts the less active Cu+2 species into reduced copper sites (Cu+), through the formation of gaseous NO2. Numerical simulations show that the hypothesised reaction mechanism results in a good description of the experimental results. In absence of NO, the model expect oscillations of reactant and product concentrations, while in the presence of NO, even in very low amount, the oscillations disappear and N2O conversion significantly increases, due to the consequent strong increase of Cu+ sites concentration.