Formation of uniform colloidal ceria in polyol

Well-dispersed uniform spheres of crystalline CeO2 were prepared by calcining precursor particles obtained by heating cerium(III) acetate in 1,2 propane diol (propylene glycol, PG) at the boiling point of the polyol (∼187 °C) for several hours. The first precipitated amorphous spherical particles consist of a complex mixture of ceria, ceria hydrate, cerium hydroxide, cerium glycolate complex and residual PG. To convert these precursors to pure CeO2, the solids were calcined at 500 °C in air at a slow heating rate (≤0.1 °C/min). The purification of the precursor particles depended strongly on the solvent used. By washing with water, much of the organic material was leached out resulting in smaller spheres, while rinsing with methanol showed little effect. The TGA, FTIR, XRD, EDX analyses of the different purified particles revealed the stages in the formation of the final pure well-defined CeO2 powder.