TiO2/SiO2气凝胶微球的制备及其表征

以TiOSO4和硅溶胶为原料, 加入甲酰胺作为干燥控制化学添加剂, 采用W/O乳状液中的溶胶-凝胶法制备TiO2/SiO2凝胶微球, 通过正硅酸乙酯母液浸泡、溶剂交换、陈化和常压干燥技术制备TiO2/SiO2气凝胶微球, 采用光学显微镜、SEM、TEM和BET比表面及孔分布测定等手段对所得样品进行表征. 典型的气凝胶微球样品是由粒径15 nm左右, 粒度分布相当均匀的球状纳米粒子构成的轻质纳米多孔材料, 表观密度为177 kg•m-3, 比表面积372 m2•g-1, 平均孔径22.78 nm, 孔隙率高达92.0％, 微球的宏观粒径为50 m. 依据制备条件的变化, TiO2/SiO2气凝胶微球的宏观粒径可控在10～200 m之间, 表观密度为150～300 kg•m-3, 比表面积为300～400 m2•g-1, 平均孔径在18.71～22.78 nm之间变化.

Preparation and Characterization of TiO2/SiO2 Aerogel Microspheres

TiO2/SiO2 aerogel microspheres were prepared by using TiOSO4 and silica sols as raw materials, and formamide as a drying control chemical additive, which was used to improve the gel texture and the structure evolution. Wet gel microspheres were formed by sol-gel process in W/O emulsion, and then aged by a successively solvent exchanging of alcohol, tetraethylorthosilicate (TEOS)/alcohol and alcohol at a certain temperature. The aged gel microspheres were dried at ambient pressure to obtain TiO2/SiO2 aerogel microspheres. The aerogel microsphere samples were characterized with optical microscope, SEM, TEM and BET techniques. The results show that the aerogel microsphere samples were comprised of dispersed TiO2, and SiO2 nanoparticles with sizes of about 15 nm. The density of the typical sample is 177 kg•m-3, the specific surface area is 372 m2•g-1 and the average pore size is 22.78 nm with porosity of 92.0%. By changing the preparation condition, the diameters of TiO2/SiO2 aerogel microspheres can be varied in the range of 10 m to 200 m, the densities in the range of 150～300 kg•m-3, the specific surface areas in 300～400 m2•g-1, and the average pore sizes in the range of 18.71～22.78 nm.