Selective catalytic reduction of NO to N2 with copper and cobalt exchanged ZSM-5 zeolites: the effect of calcium addition

ZSM-5 catalysts containing either Cu or Co cations individually or Cu/Ca or Co/Ca cation combinations were prepared by ion exchange. These materials were tested as catalysts for the reduction of NO to N2 in the presence of propane or methane. Cu2+ and [Cu-O-Cu]2+ species were identified in ion excha...

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Bibliographic Details
Published in:Journal of the Brazilian Chemical Society 2005-06, Vol.16 (3b), p.589-596
Main Authors: Martins, Leandro, Peguin, Robson Pablo S., Wallau, Martin, Urquieta-González, Ernesto Antonio
Format: Article
Language:English
Subjects:
CHEMISTRY, MULTIDISCIPLINARY
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Summary:ZSM-5 catalysts containing either Cu or Co cations individually or Cu/Ca or Co/Ca cation combinations were prepared by ion exchange. These materials were tested as catalysts for the reduction of NO to N2 in the presence of propane or methane. Cu2+ and [Cu-O-Cu]2+ species were identified in ion exchangeable sites in the copper-containing catalysts. The amount of the latter cation increased with increasing copper content and in the presence of Ca2+ and was the most active in the reduction of NO. However, at temperatures higher than 400 ºC its activity decreased markedly. For cobalt-exchanged zeolites, Co2+ in charge-compensation sites or Co3+ in extra-framework precipitates were present in the catalysts. It was verified that the amount of Co3+ diminished with the presence of Ca2+. For the catalysts prepared in this study no significant differences in specific activity for the reduction of NO or for methane oxidation were observed in the presence of calcium.
ISSN:0103-5053
1678-4790
DOI:10.1590/S0103-50532005000400016