乙醇为溶剂超临界干燥法制备纳米Al2O3

以硝酸铝为原料，柠檬酸为分散剂，无水乙醇为溶剂，采用溶胶-凝胶结合超临界干燥的方法制备了纳米AlOOH。经过500～900℃焙烧后得到纳米γ-Al₂O₃。考察了溶液pH值、硝酸铝与柠檬酸物质的量比对AlOOH粉体，以及焙烧温度对γ-Al₂O₃两者形貌和尺寸的影响。采用TEM、XRD、IR对超细粒子的粒径、形貌进行了表征。结果表明，制备溶胶时的pH值和柠檬酸的〖JP2〗加入对经超临界干燥所得的AlOOH的形貌和尺寸有明显影响。在pH=3，n(C₆H₈O₇)∶n(Al(NO₃)₃)=1∶2的条件下可得到纤维状纳米AlOOH(直径为1～10nm, 长为30～40nm)。该AlOOH经500～900℃焙烧后可得纤维状纳米γ-Al₂O₃，其直径为1～10nm，长为30～70nm。

Use of anhydrous ethanol as solvent to prepare nano AL2O3 by a supercritical drying method

Nanosized AlOOH has been prepared by a combination of sol-gel and supercritical drying methods, using aluminum nitrate as the raw material, citric acid as dispersant and anhydrous ethanol as solvent. Nano γ-Al₂O₃ was obtained after calcination of the AlOOH at 500-900?℃. The effects of varying the pH of the synthesis solution and the ratio of aluminium nitrate to citric acid on the particle size of AlOOH as well as the effect of varying the calcination temperature on the particle size of γ-Al₂O₃ were investigated. The morphology, particle size and structure of the products were characterized by TEM, IR and XRD. It was found that both the pH of the solution during the preparation of the sol-gel and addition of citric acid significantly affected the morphology and size of the AlOOH particles. At pH=3 with n(citric acid)∶n(aluminum nitrate)=1∶2, fibrous nano AlOOH particles (with a diameter of 1-10nm and a length of 30-40nm) were obtained. Calcination of the resulting nano AlOOH at 500-900℃ afforded fibrous nano γ-Al₂O₃ particles with a diameter of 1-10nm and a length of 30-70nm. 