Synthesis of nano-ceria powder of high thermal stability

A new method is studied for preparing nano-ceria by acid leaching MgO from CeO₂−MgO mixed powder made by calcining a gel. The MgO in the mixed powder can be leached completely with acetic acid solution at room temperature, but the CeO₂ remains unaffected. The surface area (Sg) of the resulting CeO₂ increases with Mg/Ce ratio, but approaches constant after the ratio is larger than a given value which is higher for the higher gel calcining temperature. When Mg/Ce is 8 (molar ratio) and the calcining temperature is 1253 K, the Sg of the resulting ceria remains 25.1 m²/g even after annealed at 1253 K for 4 h. In comparison with the conventional methods, CeO₂ from the new method shows higher surface area and higher thermal stability.