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1656776 
Journal Article 
Effect of Ag2O doping on surface and catalytic properties of cobalt-magnesia catalysts 
Deraz, NAM 
2001 
1 
Materials Letters
ISSN: 0167-577X
EISSN: 1873-4979 
51 
6 
470-477 
WOS:000172299500003 
Magnesia-supported Co3O4 catalyst, doped with 0.7-3.5 wt.% Ag2O, was prepared by wet impregnation method then calcined in air at 500 degreesC and 700 degreesC. The produced phases were identified by XRD analysis. The surface properties of the pure and doped solids were studied by using N-2 adsorption at -196 degreesC and their catalytic activities were determined by studying the oxidation of CO by O-2 at 150-300 degreesC.



The obtained results revealed that pure and doped mixed solids preheated in air at 500 degreesC and 700 degreesC consist of MgO and poorly crystalline Co3O4 phases. Doping with silver oxide resulted in a decrease in the specific surface areas for the treated solids calcined at 700 degreesC and an increase in their values for doped solids fired at 500 degreesC. However, this treatment brought about a significant modification in the catalytic activity of the doped solids. Doping with 0.7 wt.% Ag2O at 500 degreesC led to an increase of about 78% in the specific catalytic activity which was found to decrease on increasing the percentage of Ag2O above this limit, falling to values smaller than that measured for the undoped catalyst. Doping at 700 degreesC led to a progressive decrease in the activity of the treated solids to an extent proportional to the amount of dopant present. The doping process at 500 degreesC and 700 degreesC did not modify the mechanism of the catalytic reaction but altered the number of catalytically active sites contributing in the catalysis of CO oxidation by O-2 without changing their energetic nature. (C) 2001 Elsevier Science B.V. All rights reserved. 
Ag2O doping; cobalt-magnesia catalyst; CO oxidation