不同酸催化条件下Ta_2O_5气凝胶的制备  

Preparation of Ta_2O_5 aerogels catalyzed by different kinds of acids

作　　者：杨静[1] 任洪波[1] 毕于铁[1] 

机构地区：[1]中国工程物理研究院激光聚变研究中心,四川绵阳621900

出　　处：《强激光与粒子束》2012年第2期338-342,共5页High Power Laser and Particle Beams

基　　金：高温高密度等离子体国家重点实验室基金资助项目(9140C6806020609);国家高技术发展计划项目

摘　　要：采用溶胶-凝胶技术,以乙醇钽为前躯体,乙醇为溶剂,分别以盐酸、硝酸、硫酸为催化剂,结合CO2超临界干燥技术制备了Ta2O5气凝胶。研究发现:硫酸作催化剂的体系,其胶凝时间远远小于其他体系,且溶剂交换及超临界干燥过程中的收缩开裂现象明显改善;扫描电镜分析结果显示,硫酸为催化剂制备的Ta2O5气凝胶骨架颗粒间存在较严重的团簇现象,比表面积约167m2/g,明显低于以盐酸、硝酸为催化剂的体系。X射线光电子能谱测试结果显示,Ta2O5气凝胶中无相应的Cl元素或N元素残留,而S元素则基本上滞留在Ta2O5气凝胶中。说明S元素进入了Ta-O-Ta交联结构,正是因为这种结构的引入,Ta2O5气凝胶的收缩龟裂现象得以明显改善并呈现出相对较高的力学性能。Ta2O5 aerogels are prepared by sol-gel technique in the presence of different kinds of acid catalysts such as HC1, HNOa and H2SO4. The gelation time of H2SO4 system is far less than that of HC1 and HNOa systems. Moreover, the shrinkage and cracking phenomena of Ta2O5 gels in solvent exchanging process and supercritical drying process, which are unavoidable in HC1 and HNO3 systems, are obviously inhibited in Ta2O5 system. The SEM observations find that the particles of Ta2O5 aerogels catalyzed by H2SO4 are much bigger due to the cluster effect of nano particles. The BET analysis finds that Ta2O5 aerogels catalyzed by H2SO4 exhibit the BJH surface area of 167 m^2/g, which is much lower due to the cluster phenomenon. XPS estimating results reveal that all the S but no CI or N elements remain in Ta2O5 aerogels, indicating that S element is in the Ta- O-Ta crosslinking structure. Due to this particular structure, the shrinkage and cracking phenomena of Ta2O5 aerogels are significantly prevented, and better mechanical properties are achieved.

关 键 词：酸催化 Ta2O5气凝胶 溶胶凝胶 水解 

分 类 号：TL69[核科学技术—核技术及应用]