Modification of surface and catalytic properties of Fe2O3 due to doping with rare-earth oxides Sm2O3 and Y2O3

The effects of Sm2O3 and Y2O3 doping of Fe2O3 on its surface and catalytic properties were investigated using nitrogen adsorption at -196 degreesC, oxidation of CO by O-2 at 225-275 degreesC and decomposition of H2O2 at 30-50 degreesC. Fe2O3 was prepared by thermal decomposition of ferric carbonate at 350 degreesC. The treated ferric oxide solid was prepared by wet impregnation method using finely powdered Fe-2(CO3)(3) solid followed by doping with different amounts of samarium nitrate or yttrium nitrate. Pure and doped Fe2O3 solids were calcined at 350-650 degreesC. The extent of dopant added was varied between 1.0 and 6.0 mol%. The results obtained revealed that doping of Fe2O3 solids with different amounts Of Sm2O3 and Y2O3 decreased the degree of crystallinity and particle size of Fe2O3 phase. This doping process led to a progressive increase in the specific surface area of the treated Fe2O3 solids to an extent proportional to the amount Of Sm2O3 and Y2O3 added. The doping process led also to a progressive increase in the catalytic activities of the investigated solids towards CO oxidation by O-2 and H2O2 decomposition. Also, the doping process did not modify the mechanism of the catalytic reactions but increased the concentration of catalytically active sites involved in the catalyzed reactions. (C) 2004 Elsevier B.V. All rights reserved.