Detailed Kinetic Model for NO Oxidation

NO was observed when exposing the catalyst to NO2 thus, it is important to add a reaction step whereby nitrites are oxides by NO2, to simultaneously produce nitrates and NO (see Eq. 12.15). Experimentally, we observe that when increasing the temperature and exposing the catalyst to Ar only, nitrates are decomposing. However, the reverse reaction in Eq. (12.15) requires NO in the gas phase and will not take place in pure Ar. Since this is not the case experimentally, an additional step was added in which nitrates decompose directly. In order to make the model thermodynamically consistent, this reaction was also reversible [11]. 

The results of the experiment (solid line) and the kinetic model (dashed line) for the NO2 TPD at 150 °C over (Tu-ZSM-5 are shown in Fig. 12.9 [11]. The model describes the experimental features adequately. In the lower panel of Fig. 12.9, the coverage on the surface is shown. Based on these results, it becomes evident that nitrites are initially formed on the copper sites and are later converted to nitrates. 

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