【作者】 曹莉；

【导师】 陈开勋；

【作者基本信息】 西北大学 ， 应用化学， 2004， 硕士

【摘要】 TiO₂气凝胶是指由TiO₂纳米粒子相互聚结构成纳米多孔网状结构，并在孔隙中充满气态分散介质的一种高分散固态材料，也属于纳米材料的一种。以其独特的性质，TiO₂气凝胶可广泛瘟用于传感器、介电材料、催化剂及催化剂载体等重要领域。超临界干燥技术是制备气凝胶材料重要的方法之一，用超临界干燥TiO₂湿凝胶制备轻质多孔大比表面积的TiO₂纳米材料具有重要理论研究价值和实用意义。 本研究以钛酸正丁酯为原料，乙醇和水为溶剂，经过溶胶—凝胶过程制得湿凝胶。采用超临界CO₂干燥工艺，制得了TiO₂块状气凝胶：采用超临界乙醇干燥制得了TiO₂纳米粉体。 研究了溶胶—凝胶过程中，水和乙醇用量及溶液pH值对凝胶化时间的影响，通过实验确定了室温下制备TiO₂湿凝胶的优化工艺条件。讨论了溶胶—凝胶反应机理。对超临界干燥过程的影响因素进行了分析，并对超临界CO₂干燥过程中部分可控因素进行了正交实验，确定了其影响。 对TiO₂产品的性能进行了研究。用X射线衍射分析（XRD）、低温液氮吸附法（BET）、扫描电镜（SEM）、透射电镜（TEM）、红外光谱分析等手段对块状气凝胶和纳米粉体产品的结构分别进行了表征。 结果表明，用超临界CO₂干燥得到的TiO₂气凝胶是一种多小孔、孔径分布较窄、大比表面积、具有纳米网络结构的非晶固体材料；用超临界乙醇干燥得到了纳米级、大比表面积的锐钛矿型TiO₂粉体产品。更多还原

【Abstract】 Titanium aerogels are advanced nanometer materials that have high porosity and specific surface area, varied chemical structures, fascinating and useful properties. Supercritical fluid drying technique is one of important methods for aerogels’ preparation.In this thesis, titanium aerogels were prepared with sol-gel method by supercritical drying technique. The titanium dioxide alcogels were made from titanium tetrabutoxide, water and ethanol at certain molar ratio. Monolithic aerogels were prepared by supercritical carbon dioxide drying technique, and nanometer powder was prepared by supercritical ethanol drying technique.The sol-gel process has been studied under different conditions, and the optimum condition for preparing titanium hydrogels at room temperature was given. Besides, the influence factors and mechanism of sol-gel process has been discussed. In the process of supercritical drying, some of the main influence factors were analyzed.The structural and other physical properties of the products have been characterized by means of XRD, BET, SEM, TEM and IR analysis. The results show that the monolithic aerogels were coherent, non-crystalline, low density, high specific surface areas, nanosized porous solid materials. The titanium dioxide powder was anatase and consists of nanometer particles with great specific surface areas.Cao Li (Applied Chemistry) Directed by professor Chen Kaixun更多还原