SiO2/TiO2复合气凝胶的孔道结构研究

为了在常压干燥下制备高比表面积且具有多级孔道结构的SiO2/TiO2复合气凝胶,以正硅酸乙酯、钛酸丁酯为原料,利用低聚体聚合将分相平行引入到溶胶凝胶过程中,获得SiO2/TiO2醇凝胶,并通过溶剂替换技术实现气凝胶的常压干燥制备.不同硅钛比气凝胶的内部结构研究表明:合成的气凝胶是由纳米SiO2和TiO2颗粒分散复合而成的介孔块体,其中Ti—O—Ti、Si—O—Si和Ti—O—Si键相互交织.气凝胶的结构变化是分相与溶胶凝胶过程相互竞争的结果.Si含量能显著改善气凝胶的结构,当n(Ti)∶n(Si)为3∶1时,比表面积高达712.2 m2/g,平均孔径为3.36 nm;当n(Ti)∶n(Si)为1.5∶1时,复合气凝胶具有明显双连续孔道,比表面积高,同时孔状结构清晰.

Synthesis and pore structure of porous SiO2/TiO2 composite aerogel

In order to prepare SiO2/TiO2 composite aerogels with high specific surface area and multi?level pore structure under ambient pressure drying, the porous SiO2/TiO2 gel was synthesized via sol?gel process with phase separation using TEOS and TnBT as raw materials. Using the solvent replacement technique, SiO2/TiO2 aerogels were prepared via a drying process at ambient pressure. The effects of silicon titanium content on microstructure were investigated. The as?prepared SiO2/TiO2 aerogel is a composite mesoporous solid bulk formed by dispersed nano?SiO2 and TiO2 particles Ti—O—Ti bonds, Si—O—Si bonds and Ti—O—Si bonds are intertwined in this SiO2/TiO2 aerogel , which make composite aerogels have smaller crystal size, higher specific surface area and better thermal stability. Structure change of the composite aerogel is the result of competition between split phase process and sol?gel process essentially. Proper silicon content can refine the structure TiO2/SiO2 composite aerogels dramatically. The prepared SiO2/TiO2 aerogels with a mole ratio n(Ti)∶n(Si) = 3∶1, have high specific surface area of 712.2 m2/g and small pore diameter of 3.36 nm. When mole ratio n(Ti)∶n(Si)= 1.5∶1, the prepared SiO2/TiO2 aerogels not only have double continuous channel structure, high specific surface area ,but also clear pore structure.