无外加酸体系中高温合成Al-SBA-15

Direct Synthesis of Al-SBA-15 at High Aging Temperature without Mineral Acid

在无外加酸的体系中,以三嵌段共聚物P123为模板剂,一步合成有序介孔材料Al-SBA-15。考查了高温和硅/铝源物种共水解对产物形貌和结构性质的影响。XRD,N2吸附脱附,IR,SEM,TEM等结果表明,在无外加酸的体系中,升高晶化温度至423 K促使Al-SBA-15的短棒状颗粒分散、卷曲成环状。与较低晶化温度下得到的样品对比,孔径增大,比表面积明显降低。当晶化温度低于423 K,样品铝含量基本保持不变。研究还发现,硅源/铝源物种共水解时间超过20 h后,所得样品中铝含量明显降低。

Al-SBA-15 with a rod-like morphology and well-ordered mesostructure was hydrothermally synthesized through a one-step approach in an environmentally friendly medium by using triblock eopolymer Pluronic P123 as a structure-directing agent. The influence of aging temperature and silica-alumina species co-hydrolysis on the morphologies and structural properties of the resultant materials were investigated by XRD, IR, SEM, TEM and nitrogen adsorption-desorption techniques at 77 K. Compared to silica-alumina co-hydrolysis, the aging temperature plays an important role in the formation of the ordered mesostructure. The mesopores are widened and the wall thickness becomes thinner when the aging temperature is increased. The particles have well-defined rod-like morphology with the uniform particle size from 2 to 4 μm and the diameter in the range of 400-600 nm. The Si/Al molar ratio of the final Al-SBA-15 samples will be obviously higher if the time for silica-alumina co- hydrolysis is longer than 20 h.