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Title:
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Evaluation of Fe-zeolite catalysts prepared by different methods for the decomposition of N2O
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Author(s):
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Published by:
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Publication date:
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ECN
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1-6-2003
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ECN report number:
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Document type:
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ECN-RX--03-064
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Other
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Number of pages:
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Full text:
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31
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Download PDF
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Abstract:
Zeolite supported iron catalysts were prepared by different methodsand their catalytic performance was studied in the N2O decomposition
reaction. Iron-zeolite was prepared in accordance with the best-known
recipes described in literature, not only at ECN, but also at other
independent institutes to ensure that the best available expertise in
the field was applied for each method. The preparation methods subject
to investigation were the wet ion-exchange (WIE), chemical vapour deposition/sublimation
and ex-framework method. All catalysts were subjected to similar reaction
conditions representative of exhaust emissions from nitric acid factories
and the total conversion of N2O by decomposition reaction were compared.
With respect to the catalytic activity and ease of catalyst
manufacture, the wet ion-exchange based preparation method to prepare
iron-zeolite is slightly favoured over alternative methods. WIE based
Fe-zeolite catalysts combine high N2O decomposition (and SCR) activity
with good hydro-thermal stability. The pH of the suspension of the iron
salt and the zeolite during WIE is a key factor in achieving catalysts
with high activity in N2O decomposition. The topology of the zeolite
is also a key factor for both activity and stability under realistic
practical conditions. However, over-exchange (Fe/Al = 1), which can
be achieved with the CVD method, but which is also a goal in studies
on WIE preparation, is not a key factor in gaining high activity. Wet
ion exchange yields a catalyst with less than 50% of the exchange sites
occupied by Fe.
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