The Studies Of Nano-sized Cerium Base Materials With Special Morphologies

CeO₂-based mixed oxides are widely used in catalytic field because of the high special oxygen-storage,oxygen-removal capacity and the fast oxygen vacancy transfer ability. Due to its unique redox properties and high oxygen storage capability, highly stability and low temperature catalytic activity, Ce_xZr_1-xO₂ are attracting much attention. Compared with the noble metal, Copper-cerium oxide catalysts have been extensively comparable or even higher activity and selectivity for CO oxidation. At the same time, because different exposed crystal surfaces show much difference in surface atom densities, electronic structures, and chemical reactivities,so the diverse shapes and sizes of nanomaterials may largely influence their physical and chemical properties. A lot of attention was paid for the nano cerium with controllable structure because of its unique property.In present study, Ce_xZr_1-xO₂ and the CuO-CeO₂ catalyst with different morphologies were prepared by different methods or controlling conditions and the ratio of different materials. The resulted samples were used for catatlytic reaction.Ce_xZr_1-xO₂ solid solution with different morphologies was prepared via Kirkendall Effect. The catalysts were characterized and their catalytic activities were testted. The Ce_xZr_1-xO₂ nanocubes were synthesized successfully by alkali-themal conditions. A series of Ce_xZr_1-xO₂ catalysts were prepared. It was found that the morphology of the particles will be affectted by the amount of zirconium. Nano-rods Ce-Zr catalysts were prepared by controlling conditions. the alkali content, reaction time, reaction temperature will affect the dispersion and the sizes of the nanorods in the preparation process.CuO-CeO₂ catalysts with different morphologies were prepared by different methods. A series of nearly spherical CuO-CeO₂ catalysts with high BET surface area were prepared via a hydrolysis process in glycol, and particle morphology changes from the spherical shape to a cube by controlling the conditions in the preparation process. These catalysts were found to be very active for CO oxidation reaction. Nanocube CuO-CeO₂ catalyst were successfully prepared by alkali-themal conditions. it was found that the alkali content had strong influence on the size and the dispersion of the particle. The sample where Ce, Cu molar ratio was 1:0.1 showed the highest catalytic activity for CO oxidation. CuO was loaded on Ce_xZr_1-xO₂ solid solution synthesized via Kirkendall Effect by a hydrolysis process in glycol. the morphology has no change with the loading of CuO.