Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6454106 | Applied Catalysis B: Environmental | 2017 | 12 Pages |
â¢Ag(Ga)yCu5Mg66âyAl29 with y = 0.25 gave best performances for NH3-SCO.â¢Redox properties determined performances of catalysts with y = 0.25.â¢Bulk and surface segregated phases varied activity of catalysts with y â¥Â 0.25.â¢Gallium modified Cu-Mg-Al-Ox selectively oxidized ammonia into N2.
Ag-, Ce- and Ga-promoted Cu-Mg-Al hydrotalcite derived mixed metal oxides were obtained by standard coprecipitation, followed by calcination. The obtained Ag(Ce, Ga)-Cu-Mg-Al-Ox mixed metal oxides were characterized with respect to their crystalline structure (XRD, TEM), texture (BET), surface acidity (NH3-TPD), redox properties (H2-TPR), chemical surface composition (XPS), and tested in the selective catalytic oxidation of ammonia into nitrogen and water vapour (NH3-SCO). The loading of Agy-, Cey-, or Gay-Cu5-Mg66ây-Al29 (y = 0-1) had a clear effect on the catalytic performances. For materials with low metal loadings (y â¤Â 0.25), the redox properties determined the catalytic performances in NH3-SCO. The formation of easily reducible CuOx played a crucial role for enhanced catalytic activity at lower temperatures, with a drop in the selectivity to N2 at higher temperatures. Higher metal loading (y â¥Â 0.5) led to the formation of surface and bulk copper oxide species, and other aggregated metal oxide phases, which enhanced the catalytic activity for Ag-Cu-Mg-Al-Ox, and diminished activity for Ce(Ga)-Cu-Mg-Al-Ox.
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