Modification of surface and catalytic properties of Fe 2O 3 due to doping with rare-earth oxides Sm 2O 3 and Y 2O 3

Abstract

The effects of Sm 2O 3 and Y 2O 3 doping of Fe 2O 3 on its surface and catalytic properties were investigated using nitrogen adsorption at −196 °C, oxidation of CO by O 2 at 225–275 °C and decomposition of H 2O 2 at 30–50 °C. Fe 2O 3 was prepared by thermal decomposition of ferric carbonate at 350 °C. The treated ferric oxide solid was prepared by wet impregnation method using finely powdered Fe 2(CO 3) 3 solid followed by doping with different amounts of samarium nitrate or yttrium nitrate. Pure and doped Fe 2O 3 solids were calcined at 350–650 °C. The extent of dopant added was varied between 1.0 and 6.0 mol%. The results obtained revealed that doping of Fe 2O 3 solids with different amounts of Sm 2O 3 and Y 2O 3 decreased the degree of crystallinity and particle size of Fe 2O 3 phase. This doping process led to a progressive increase in the specific surface area of the treated Fe 2O 3 solids to an extent proportional to the amount of Sm 2O 3 and Y 2O 3 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 H 2O 2 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.