Controlled Synthesis And Property Studying Of Hierarchically Structured Nano-alumina

Nano-alumina with hierarchical structure has recently attracted extensive attention because of special structure and effect of synergism and coupling on micro-nano scales. In this dissertation, hierarchically structured nano-alumina were synthesized using hydrothermal-homogenic hydrolysis method that is of which Al3+ was precipitated accompanying precipitant thermolysis with high temperature in hydrothmal procedure. Two types of hierarchically structured nano-alumina with hollow structure of special form and cluster structure of open form were focused as object of study. The influence of synthesis conditions on morphology and property of result products was investigated. Development of hollow structure and thermostability of cluster structure and also crystallographic facet preferred orientation of secondary module in cluster structure were studied. Requirements of hollow structure formation were proposed and controllable of surface property of result products was achieved.Hierarchically nano-alumina with hollow structure was obtained using alum as aluminum source and homogenic precipitants with urea and hexamethylenetetramine in hydrothermal procedure. The results show that urea is present in reaction process that is not essential for forming hollow structure, if only compounds obtained precipitant thermolysis can build spherical template with SO42- and the relative speed of spherical template growing andγ-AlOOH crystallite nucleating can be reasonable, the hollow structure will be obtained.Hierarchically nano-alumina with cluster structure was obtained using ethanol-water mixture as solvent and method of which aluminum nitrate was precipitated accompanying urea thermolysis in hydrothermal procedure. The results show that using ethanol-water mixture as solvent in reaction process not only improve the yield of result products, but also the thermostability of result products is very well.