NO AND N2O DECOMPOSITION AND THEIR REDUCTION BY HYDROCARBONS OVER Fe-Zn MANGANITE SPINELS

In this work the catalytic behaviour of zinc manganite-based catalysts doped with iron in small amounts is reported for the reduction of NO by propane and propene. All catalysts are monophasic and are characterized by a spinel structure. On the most representative catalysts the NO and N2O decomposition and the reduction of N2O by propane and propene were also investigated. The NO reduction by hydrocarbons is enhanced by the presence of iron and the catalytic activity increases on increasing the iron loading. On the other hand, the catalytic activity of N2O reduction appears to be less sensitive to either the presence of iron and the type of hydrocarbon. Moreover, it is almost comparable to that of N2O decomposition which, in turn, occurs much easier than the NO decomposition. In all reactions the selectivity to N2 and CO2 is almost 1 at the maximum temperature explored of 873 K. Along the NO and N2O reduction by hydrocarbons iron preserves in some extent the catalyst from reduction which tends to occur in propene at higher temperatures disaggregating the spinel phase into a mixture of ZnO and MnO oxides.