SiO_2干凝胶制备及其煅烧特性的研究

Preparation of SiO_2 Xerogel and Investigation of Its Calcining Characteristic

采用溶胶-凝胶法结合共沸蒸馏干燥工艺制备了SiO2干凝胶.探讨了共沸蒸馏过程对在常压干燥下凝胶多孔网络结构形成的影响,研究了煅烧过程中干凝胶物相及孔结构的变化.结果表明:采用共沸蒸馏干燥工艺可以同时完成颗粒表面疏水改性及凝胶中溶剂的替换过程;300℃煅烧后,SiO2干凝胶的比表面积为924.62m2·g-1,孔体积为0.754cm3·g-1,孔径主要分布在10nm以下,其微观结构与气凝胶相似;高温是导致颗粒烧结和孔结构变化的直接因素.

SiO2 xerogel was prepared by sol-gel process and azeotropic distillation drying method. The effect of azeotropic disstillation process on the formation of gel porous network structure under ambient pressure was discussed, and the changes of xerogel phase and pore structure during calcining process were investigated. The results showed that the particle surface hydrophobic modification and solvent replacement can be simultaneously completed during azeotropic distillation drying process. After calcined at 300℃ , the specific surface area and pore volume of SiO2 xerogel is 924.62 m2·g ^-1 and 0. 754 cm3·g^-1 respectively, and the pore size distribution is mainly less than 10 nm, which are similar to aerogel in microscopic structure. High temperature is the direct factor of changing particles sinter and pore structure.