Activation of ammonia adsorption by oxygen

In the case of injection of [ NJ-NHs into an ammonia-free He flow over the reduced platinum sponge [Fig. 5(b)], the injected ammonia also travels through the catalyst bed. Gas-phase analysis showed that only NH3 is detected at the reactor outlet, indicating that ammonia does not dissociate under these conditions. The PEP image shows the weak binding of 

As we did not detect N2 at the relatively low temperature of 323 K, atomic nitrogen is probably not formed. However, due to the high surface coverage of the various species (OH, NH2, NH, NO, N), diffusion may be impaired thereby hindering reconstruction to N2. 

The above results indicate that a relatively high oxygen coverage on platinum promotes NO(a) formation. At low temperatures, NO(a) leads to N2O via  

At temperatures higher than 573 K, the NO surface coverage is low due to desorption of NO, resulting in less N2O formation. The dissociation of NO(a) at low temperature ( 400 K) and also in the situation of a high adsorbates coverage is unfavourable.The formation of nitrogen is 

Determination of adsorbed species by temperature programmed desorption 

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