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Selective catalytic oxidation of ammonia to nitrogen over Mg-Al, Cu-Mg-Al and Fe-Mg-Al mixed metal oxides doped with noble metals

Paper ID Volume ID Publish Year Pages File Format Full-Text
45826 46423 2013 11 PDF Available
Title
Selective catalytic oxidation of ammonia to nitrogen over Mg-Al, Cu-Mg-Al and Fe-Mg-Al mixed metal oxides doped with noble metals
Abstract

Mg-Al, Cu-Mg-Al and Fe-Mg-Al mixed oxides, were obtained by thermal decomposition of synthetic hydrotalcite-like materials and, in the next step, were modified with selected noble metals (Pt, Pd, Rh) by incipient wetness impregnation method. The process of thermal decomposition of hydrotalcite-like materials into metal oxide systems was studied by thermogravimetry method combined with the on-line analysis of gaseous products of the sample decomposition (TG–DTA-QMS). The obtained catalysts were studied with respect to chemical composition (EDS), structure (XRD, UV–vis–DRS), morphology (STEM), surface area (BET) and redox properties (H2-TPR). Metal oxide catalysts obtained from the hydrotalcite-like precursors were characterized by high dispersion of transition metals (Cu, Fe), which were present mainly in the form of monomeric or small aggregated species dispersed in the Mg-Al oxide matrix. Noble metals, as it was shown by STEM studies, were rather uniformly dispersed on the surface of the samples. The obtained samples were tested as catalysts of the selective catalytic oxidation (SCO) of ammonia to nitrogen. The Cu-Mg-Al oxide catalyst was active in the low-temperature SCO process, while the Fe-containing sample was found to operate in the high temperature range. Modification of these catalysts with noble metals significantly decreased temperature of the ammonia oxidation but also decreased the selectivity to nitrogen. The best catalytic properties were obtained for the Cu-Mg-Al oxide catalyst modified with small amount of platinum (0.2 wt%), which operated at relatively low temperature with high selectivity to nitrogen.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Calcined Cu-Mg-Al hydrotalcite is active catalyst for low-temperature SCO of NH3 to N2. ► Calcined Fe-Mg-Al hydrotalcite is active catalyst for high-temperature SCO of NH3 to N2. ► Doping of the catalysts with Pt, Pd and Rh increased their activity and decreased selectivity to N2. ► Performance of catalyst is determined by its activity in NH3 oxidation to NO and NO reduction by NH3.

Keywords
Selective catalytic oxidation (SCO) of ammonia; Hydrotalcite-like materials; Mixed metal oxides; Noble metals
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Selective catalytic oxidation of ammonia to nitrogen over Mg-Al, Cu-Mg-Al and Fe-Mg-Al mixed metal oxides doped with noble metals
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volumes 130–131, 7 February 2013, Pages 152–162
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us