(中南大学 材料科学与工程学院,长沙 410083)
摘 要: 以正硅酸乙酯和硝酸镍为原料、乙二醇为还原剂,采用溶胶−凝胶法和超临界干燥工艺制备负载金属Ni纳米线的SiO2复合气凝胶。通过BET、XRD、TEM、TPR和H2-TPD等技术,对其物相组成和活性比表面进行表征。结果表明:负载Ni主要以金属Ni单质纳米线的形态均匀分布在SiO2气凝胶三维网络骨架结构上,该纳米线直径为1~5 nm、长度为10~80 nm,载体骨架结构上存在尚未还原完全的Ni;随Ni负载量的增加,Ni与载体SiO2 之间的相互作用逐渐减弱,催化剂的Ni活性中心点增多;负载Ni纳米线显示出较强的热稳定性。
关键字: 复合气凝胶;微观结构;金属纳米线;原位法;热稳定性
(School of Materials Science and Engineering, Central South University, Changsha 410083, China)
Abstract:The silica composite aerogels doped with Ni nanowire were prepared by sol-gel and supercritical drying technique using orthosilicate ethyl ester and nickel nitrate as raw materials and ethylene glycol as reductant. The phase component and activity of specific surface of Ni-based catalysts were characterized with BET, XRD, TEM, TPR and H2-TPD techniques. The results show that, Ni nanowire and unreduced pure nickel distribute homogenously in the tri-dimensional SiO2 aerogel skeleton, the size of nanowire is 1−5 nm in diameter and 10−80 nm in length. With the increase of Ni content, the interaction between nickel species and SiO2 becomes weaker, and the active specific surface area of the catalyst increases. Ni nanowire/SiO2 aerogel catalysts have good thermal stability.
Key words: composite aerogel; microstructure; Ni nanowires; in-situ method; thermal stability