【摘要】 以正硅酸乙酯(tetraethyl orthosilicate,TEOS)、乙酸铜、乙酸钴、乙酸锰为原料,采用溶胶-凝胶法、常压干燥制备了CuO(CoO,MnO)/SiO2纳米复合气凝胶。分析了过渡金属氧化物MO与SiO2的质量比、温度和pH值对凝胶形成的影响。采用场致发射扫描电镜(FE-SEM)、BET、傅里叶变换红外分析(FTIR)、热重-差热分析(TG-DTA)、电子散射能谱分析(EDS)和化学分析等对CuO(CoO,MnO)/SiO2纳米复合气凝胶的微观结构和组成进行了研究。结果表明,纳米复合气凝胶的颗粒约在20~100nm,比表面积为344~733m2/g,孔径范围为2~22nm,而且过渡金属Cu、Co和Mn能够与氧形成部分—O—M—O—桥键连接,并与Si通过化学键形成三维网络结构;纳米复合气凝胶试样中的多元过渡金属氧化物含量可控制在3%~75%(质量分数)。这种结构和组成既有利于提高催化剂负载量,又可充分发挥过渡金属氧化物的助催化作用。更多还原

【Abstract】 CuO(CoO,MnO)/SiO2 nanocomposite aerogels were prepared from tetraethyl orthosilicate(TEOS) and acetate of Cu,Co and Mn via sol-gel process and ambient pressure drying technique.The effect of mass ratio of transition metal-oxides to SiO2,preparation temperature and pH value on gelation was investigated.The microstructure and composition of CuO(CoO,MnO)/SiO2 nanocomposite aerogels were analyzed by field emission scanning electron microscope,BET,Fourier transform infrared spectrum,thermogravimetric and differential thermal analysis,electron dispersive spectrum and chemical analysis.The results show that CuO(CoO,MnO)/SiO2 nanocomposite aerogels are porous with particle size distribution of 20-100nm,surface area of 344-733m2/g,and pore size distribution of 2-16nm.In addition,bridge bonds of —O—M—O— can be formed to some extent by the chemical bonding of transition metals and oxygen,and three-dimensional network structure is formed by the chemical bonding of Si and —O—M—O—.The mass fraction of transition metal-oxides in the nanocomposite aerogels is in the range of 3%-75wt%.This kind of structure and composition is not only favorable to the increase of the catalysts loading,but also to the effective use of transition metal-oxides as catalyst accelerators.更多还原