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The NH 3 and H 2 O adsorption and desorption, and the NH 3 oxidation was studied using detailed kinetic modeling and flow reactor experiments. Ammonia storage and ammonia oxidation are important for the NH 3 SCR application. In this study, both ammonia storage and oxidation are investigated, with and without the presence of water. Four sites were included in the model. On each copper atom was one active site introduced, denoted S1a, where NH 3 , H 2 O, NO 2 and O 2 can adsorb. However, electron paramagnetic resonance studies (EPR) and also DFT calculations in the literature suggest that [Cu(NH 3 ) 4 ] 2+ complex are formed in copper zeolites. We therefore introduced three additional sites (S1b) that ammonia can adsorb on in order to add up to the four ammonia adsorbed per copper atom. It was important to separate between S1a and S1b since it is not possible for four NO 2 to adsorb per copper and also in order to describe the ammonia TPD and SCR reactions simultaneously. The Cu-ZSM-5 catalyst also contains Bro ¨nsted acid sites (S2), and in order to account for the large amount stored at ambient temperature, sites for weakly bound species (S3) were included as well. The Bro ¨nsted sites were investigated using NH 3 and H 2 O TPD experiments on H-ZSM-5. Water and ammonia TPD experiments on Cu-ZSM-5 were also used in the model development and the model was able to describe the experiment well. An NH 3 TPD experiment with storage performed in the presence of water was used for model validation, and the model was able to predict the experimental results adequately. The model was then extended to include steps for oxygen adsorption, desorption, dissociation, recombination and two summary steps for ammonia oxidation. Ammonia oxidation in both the presence and absence of water was used in the model development. The resulting model was able to predict ammonia storage, desorption and oxidation accurately, both in the presence and absence of water.

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