Comparative study on synthesis and characterizaton of ceria based composite oxides containing manganese nano-particles

Mn/Ce nano-composite oxides different amounts of manganese [5, 9, 17, 23, 29, 34 wt% as MnO[2]] were prepared by impregnation method at various calcinations temperatures. Effect of both thermal treatment and loading on the structural, surface and microstructure properties of the as prepared nano-composites was determined. The combined effect of manganese oxide and ceria, at different concentrations. Strongly influences the previous properties of the nano-composite oxides, by dispersing the MnO[2] phase and promoting the efficiency of the Ce[4+] - Ce[3+] and Mn[4+] - Mn[3+] redox couples. The thermal treatment and loading influences the interaction between manganese and CeO[2] evidently. The incorporation of Mn ions into CeO[2] cystal lattice resulted in weaker interaction between manganese and ceria on composite surface. Manganese loading at 400 [degree sign]C led to a slight increase in the ceria crystallite size which decreased by increasing the calcinations temperature from 400 to 600 [degree sign] C. The sintering activation energy of ceria was evaluated to be 12KJ/mol for the MnO[2]/Ce[O2] nano-composite

Synthesis and characterization of Co[3]O[4]/CeO[2] nanocomposite

Ceria based nanocoomposite oxides containing different amounts of cobalt [4, 8, 15, 21, 26, 30 wt% ad Co[3]O[4]] were prepared by impregnation method at various calcinations temperatures. The effect of both heat treatment and loading on the structural, textural and morphological properties of the as prepared nanocomposites was determined. The combined effect of cobalt oxide and ceria, at different compositions, strongly influences the properties of the nanocomposite oxide, by dispersing the Co[3]O[4] phase and promoting the efficiency of the Co[3+]-Co[2+] and Ce[4+] - Ce[3+] redox couples. The heat treatment and loading influenced the interaction between cobalt and CeO[2] evidently. The incorporation of Co ions into CeO[2] crystal lattice resulted in weaker interaction between cobalt and ceria on composite surface. Cobalt loading of sample heated at 500 [degree sign]C led to a progressive decrease in the crystallite size, lattice constant and unit cell volume of cerium and cobalt oxides. Co[3]O[4] loading at 500 [degree sign]C brought about a significant increase in the surface area of the investigated system. Opposite behavior was observed by increasing the calcinations temperature from 400 to 600 [degree sign] C. However, the sintering activation energies of cerium and cobalt oxides were evaluated to be 8 and 11 kJ/mol, respectively