大孔容γ-Al_2O_3的制备研究

Preparation of Macroporousγ-Al_2O_3

以硫酸铝为铝源、碳酸氢铵为沉淀剂,采用分步老化法,使用L9(34)正交实验考察了碳酸氢铵物质的量浓度、反应温度、pH和n(HCO-3)/n(Al 3+)等因素对制备γ-Al2O3的影响,并对所得Al2O3进行了N2物理吸附表征和堆积密度测量,对Y5样品进行了X射线衍射和电镜扫描,由正交实验结果分析得出温度和pH对γ-Al2O3的结构影响很大。大孔容氧化铝的制备最佳条件为:反应温度为75℃,pH为8.5,碳酸氢铵物质的量浓度为2mol/L,n(HCO-3)/n(Al 3+)为0.75。其中,样品Y5孔容达2.02mL/g,具有双峰孔分布,粒子呈纤维状,大小均匀,粒径为1μm左右。

Alumina were prepared with aluminium sulfate as aluminium source,ammonium bicarbonate as precipitant,using substep aging method and L9 （34 ） orthogonal table.Factors inculding ammonium bicarbonate concentration, reaction temperature,pH and n（HCO-3 ）/n（Al3＋）were studied.The alumina were characterized by the N2 physisorption and bulk density measurement,XRD and SEM as well.After orthogonal analysis,reaction temperature and pH have significant effect on textile properties ofγ-Al2 O3 .Optimum preparation conditions were determined by macropore formation,and they were as follows：reaction temperature 75 ℃,pH 8.5,the concentration of ammonium bicarbonate 2 mol/L,n（HCO-3 ）/n（Al3＋）ratio 0.75.Besides that,Y5 has big pore volume up to 2.02 mL/g,bimodal pore distribution and fibrous particles which have uniform size around 1μm.