Controlled Preparation And Properties Of Nanostructured Ceria

Cerium oxide is an important rare earth functional material,with good mechanical strength and excellent oxygen ion transport performance,in the catalytic,polishing,medium temperature solid oxide fuel cell,UV shielding and many other areas have a wide range of uses.At the nanometer scale cerium oxide relative to the bulk phase material,the electronic structure changes,the specific surface area increases,often showing some new physical properties(such as lattice diffusion,UV absorption blue shift)and higher chemical activity.The development of highly controllable and green CeO2 nanomaterials has been studied,and its relationship with morphology,size,structure and properties will be improved,which will effectively enhance the application value of CeO2 in industrial catalysis.In this paper,the multi-stage cerium oxide octahedral,layered cerium carbonate and ultrafine cerium oxide powders with uniform morphology and uniform size were prepared by Hydrothermal and precipitation method.The cerium oxide octahedron was prepared by hydrothermal method using Ce(NO3)3.6H2 O and polyvinylpyrrolidone PVP as raw materials at pH = 5.The structure of the product was characterized by transmission electron microscopy(TEM).The results showed that the octahedron was self-assembled from ~ 5nm primary particles in the same direction.Further study shows that the size of the hydrothermal reaction system can be obtained by adjusting the pH value of the hydrothermal reaction system.The growth mechanism of the cerium oxide is discussed.The catalytic performance of the catalytic oxidation of CO was investigated.The results show that multi-stage cerium oxide octahedron has a higher catalytic activity,Compared with the size of the single crystal structure cerium oxide octahedral.In this paper,Ce(NO3)3.6H2 O was used as the source of cerium,PVP as the dispersant,ethylene glycol as the solvent and ammonia as the precipitant.The self-assembled lamellar structure of cerium carbonate was prepared by hydrothermal method at about 740 nm The The effects of reaction temperature,reaction time,PVP amount and precipitant concentration on the morphology and phase of the product were investigated.The experimental results show that when the reaction temperature is 180?,the concentration of ammonia is 0.4mol/L,the time is 24 h and the PVP is1.2g,the dispersion of the basic structure cerium carbonate is the best,and the possible reaction mechanism is discussed.The effect of different bursting temperature,injection method,aging temperature and aging time on the morphology of the product was studied by using CeCl3 as the raw material and ammonium bicarbonate as the precipitant to obtain high density rare earth carbonate.The experimental results show that the best blasting temperature is900~950?,aging temperature is 900~1000?,aging time is 2 ~ 4h,the product morphology is the best and the agglomeration is the least.