共沸精馏法制备氧化铈纳米粉体及其煅烧动力学

用碳酸氢铵做沉淀剂,采用化学共沉淀法制备纳米氧化铈的前驱体,并以正丁醇为共沸剂经过共沸精馏除去前驱体中的水分,然后再烘干、煅烧制备了纳米氧化铈晶体.通过热重和差热分析、X射线衍射和透射电镜等对颗粒结构进行表征,研究了晶体煅烧动力学.结果表明：采用该方法能够很好地抑制粉体的团聚,获得分散均匀的立方晶系结构纳米晶体,粉体的平均粒径为20～30 nm.在煅烧过程中,该体系的表观活化能为68.43 kJ/mol,且晶粒的生长过程主要受扩散作用的控制.

PREPARATION OF CERIA NANOPOWDER BY AZEOTROPIC DISTILLATION AND ITS CALCINATION DYNAMICS

The precursor of ceria was prepared by chemical co-precipitation using ammonium hydrogen carbonate as precipitator. Water in the precursor was removed by azeotropic distillation with n-butyl alcohol as an entrainer, and then it was dried and calcined to get nanocrystalline ceria. The microstructure of particles was characterized by thermogravimetric/differential thermal analysis, X-ray diffraction and transmission electron microscope. The calcination dynamics were investigated. The results indicate that the azeotropic distillation can effectively prevent the aggregation of particles and a well-dispersed nano-ceria powder was obtained. The average diameter of the particles is 20 30 nm. The superficial activation energy of the powder is 68.43 kJ/mol and the grain growth is mainly affected by the diffusion during the process of calcination.