Cerium dioxide(CeO2) has attracted much attention and has wide applications such as automotive exhaust catalysts,polishing materials for optical glasses and additives for advanced glasses,as well as cosmetic materials.The particle size and its distribution are key factors to the performance of the materials in the functional applications.However,control of particle size is still a challenge in materials synthesis.Therefore,continuous precipitation of cerium oxalate(precursor of ceria) was carried out at different operational conditions such as reactant concentration,agitation speed,feeding rate and reaction temperature,and their effect on the particle size distribution,distribution width and morphology of cerium oxalate were investigated.The optimum conditions for preparing cerium oxalate with large particle size were determined based on orthogonal test as follows:[Ce(NO3)]=0.02 mol/L,agitation speed:200 r/min,feeding rate of solutions of cerium nitrate and oxalic acid:10 ml/min,reaction temperature:80 ℃.The results showed that the shape of cerium oxalate was sheet and the phase structure was amorphous.The median particle size of the final product was 27.60 μm,the particle size distribution width was very narrow and the micrograph was still sheet-like.Some attempts were made to explain the experimental phenomena in terms of agglomeration,disrupt,and precipitation kinetics.
The large particle CeO2 and Y2O3 were prepared using oxalic acid as precipitator. The effects of operational parameters such as stirring velocity, precipitation temperature, feeding speed, aging time, precipitation method, and calcination temperature on particle size and loose density of CeO2 were studied. Under the particular conditions, particle median size of D50≥30μm, loose density of ≥2.0 g/ml of CeO2, and particle median size of D50≥20 μm of Y2O3 were prepared. This technology had advantages of simple process, less equipment investment, ease of use, and suitability for industrialization products.
