Various Fe-BEA catalysts have been

Various Fe-BEA catalysts have been synthesized by liquid ion-exchange, varying the iron precursor (nitrate, sulfate or chloride),the iron content (0.2–1.5 wt% Fe), and the conditions of activation, i.e. atmosphere (air or inert) and heating rate (5 or20 K min)1). The catalysts were tested in direct N2O decomposition in the temperature range of 625–825 K. An optimal ironloading of 0.8 wt% Fe was found, with no significant influence of the used Fe-precursor. Activation of the ion-exchanged catalystsin inert gas yields significantly better performance than activation in air. NO adsorption combined with infrared analysis was usedto characterize the various Fe2þ species present in the differently prepared Fe-BEA zeolites. A correlation exists between theabsorption intensity of NO at 1874 cm)1 and the activity of the catalysts in N2O decomposition. This relationship, which can beused as a reliable and fast assessment of catalyst performance, suggests an important role of ferrous ions in the activity of thesecatalysts. Based on these results and previous mechanistic studies using transient techniques, the NO absorption band at 1874 cm)1is tentatively assigned to oligonuclear oxocations in the zeolite channels, with general formula FexOy.

Various Fe-BEA catalysts have been synthesized by liquid ion-exchange varying the, iron precursor (nitrate sulfate or,, Chloride),
the iron content (0.2 - 1.5 wt% Fe), and the conditions, of activation i.e. Atmosphere (air or inert) and heating. Rate (5 or
20 K min) 1). The catalysts were tested in direct N2O decomposition in the temperature range of 625 - 825 K. An. Optimal iron
loading of 0.8 wt% Fe was found with no, significant influence of the used Fe-precursor. Activation of the ion-exchanged catalysts
in. Inert gas yields significantly better performance than activation in air. NO adsorption combined with infrared analysis. Was used
to characterize the various Fe2 þ species present in the differently prepared Fe-BEA zeolites. A correlation exists. Between the
.Absorption intensity of NO at 1874 cm) 1 and the activity of the catalysts in N2O decomposition. This relationship which,, Can be
used as a reliable and fast assessment of catalyst performance suggests an, important role of ferrous ions in the. Activity of these
catalysts. Based on these results and previous mechanistic studies using transient techniques the NO,, Absorption band at 1874 cm) 1
.Is tentatively assigned to Oligonuclear oxocations in the, zeolite channels with general formula FexOy.