Nitrous oxide decomposition active sites

Despite several decades of studies devoted to the characterization of Fe-ZSM-5 zeolite materials, the nature of the active sites in N20 direct decomposition (Fe species nuclearity, coordination, etc.) is still a matter of debate [1], The difficulty in understanding the Fe-ZSM-5 reactivity justifies a quantum chemical approach. Apart from mononuclear models which have been extensively investigated [2-5], there are very few results on binuclear iron sites in Fe-ZSM-5 [6-8], These DFT studies are essentially devoted to the investigation of oxygen-bridged binuclear iron structures [Fe-0-Fe]2+, while [FeII(p-0)(p-0H)FeII]+ di-iron core species have been proposed to be the active species from spectroscopic results [9]. We thus performed DFT based calculations to study the reactivity of these species exchanged in ZSM-5 zeolite and considered the whole nitrous oxide catalytic decomposition cycle [10],... 

The behaviour of the system in the transient experiment at low temperature proves that catalyst Cu sites are able to convert nitric oxide into nitrous oxide at low temperature, until all copper is re-oxidised to Cu". The phenomenon is activated by temperature, but at higher temperatures (> 300°C) the formation of gaseous N2O is less observable, since the kinetics of its decomposition becomes significant, as shown in Fig.4. 

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