甲酸铈煅烧制备二氧化铈北大核心CSCD

以硝酸亚铈与甲酸反应后的甲酸铈为煅烧原料,在不同条件下煅烧后进行表征,分析煅烧产物的粒径、比表面积、形貌、碳含量、氮含量和氧与铈原子比(简称O/Ce比)。结果表明,煅烧后的颗粒粒径和形貌与煅烧前的颗粒粒径和形貌有关。16 mol/L甲酸与硝酸亚铈反应制备的甲酸铈颗粒煅烧前为棒状结构的团聚体,煅烧后形貌不变,粒径稍有减少,在煅烧温度高于700℃时产生大量粒径小于0.100μm细颗粒;而20 mol/L甲酸与硝酸亚铈反应制备的甲酸铈颗粒煅烧前为接近球体的团聚体,煅烧后形貌不变,但煅烧后即产生大量粒径小于0.100μm细颗粒。比表面积的降低是由孔结构减少引起的,随着煅烧温度的升高,晶体结构重新排列,晶格内缺陷减少,造成孔结构不断减少。煅烧后颗粒的碳含量和氮含量主要与煅烧温度有关,升高煅烧温度能有效降低碳含量和氮含量,而煅烧时间对碳含量和氮含量的影响较小。二氧化铈的晶体结构稳定,O/Ce比基本上维持在2.000±0.010之间。两种甲酸铈的煅烧工艺均选择煅烧温度为700℃,煅烧时间为1 h,煅烧时需要通入足量空气或氧气。

Preparation of Cerium Dioxide by Calcination of Cerium Formate

Cerium formate after the reaction of cerium nitrate with formic acid was used as raw material for calcination. The calcined products were characterized under different conditions, and the particle size, specific surface area, morphology, carbon content, nitrogen content and ratio of oxygen to cerium(abbreviated as O/Ce ratio) of the products were analyzed. The results show that the particle size and morphology after calcination are related to those before calcination. Cerium formate particles prepared by the reaction of 16 mol/L formic acid with cerium nitrate are agglomerates with rodlike structure before calcination. After calcination, the morphology remains unchanged and the particle size decreases slightly, and a large number of fine particles less than 0-100 μm are produced when the calcination temperature is higher than 700 ℃. While cerium formate particles prepared by the reaction of 20 mol/L formic acid with cerium nitrate are agglomerates close to spheres before calcination, and the morphology remains the same after calcination, but a large number of fine particles less than 0-100 μm are produced after calcination. The decrease of the specific surface area is caused by the decrease of the pore structure. With the increase of the calcination temperature, the crystal structure is rearranged and the defects in the lattice are reduced, resulting in the continuous reduction of pore structure. The C and N contents of the particles after calcination are mainly related to the calcination temperature. Increasing the calcination temperature can effectively reduce the C and N contents. The calcination time has little effect on the C and N contents. The crystal structure of cerium dioxide is stable, and the O/Ce ratio is basically maintained in the range of 2.000±0.010. Finally, for the two kinds of calcination processes of cerium formate, the calcination temperature is 700 ℃, the calcination time is 1 h, and sufficient amount of air or oxygen is introduced during the calcination.