非表面活性剂合成CeO_2介孔材料

Synthesis of Mesoporous Ceria Using a Non-Surfactant Template Approach

以非表面活性剂三乙胺(TEA)和聚乙二醇(PEG)为模板剂,合成了具有立方莹石晶相结构的介孔CeO2材料,通过XRD,HRTEM,BET,FTIR和选区电子衍射(SAED)等手段对介孔CeO2进行了表征。考察了模板剂在CeO2介孔结构的形成过程中所起的作用及其对比表面、孔径分布、热稳定性的影响,并对模板剂的作用机制进行了分析。结果表明,三乙胺在CeO2介孔结构的形成中起关键作用,聚乙二醇对介孔结构热稳定性有明显的改善作用,经600℃焙烧3h的样品仍能保持较好的介孔结构,其介孔呈直通型的六方型孔道,比表面积>200m2·g-1,孔分布呈双孔型分布,其中介孔孔径约为5nm左右,微孔孔径在1～2nm之间,介孔占较大比例,并且微孔数量随焙烧温度的升高逐渐减少,直至600℃消失。

A non-surfactant template approach, TEA(triethylamine) and PEG(polyethylene glycol) as the pore-forming agents, was used to synthesis mesoporous ceria with crystalline pore walls of cubic fluorite structure. The material was characterized by small and large angle X-ray diffraction, nitrogen physisorption, high-resolution transmission electron microscopy (HRTEM) and FT-IR spectra. The results show that TEA plays the key role as pore-forming agent in the formation of mesoporous ceria, and the addition of PEG in the synthesis can improve the mesoporous structure thermal stability and the mesoporous structure can retain after calcined in 600 ℃ for 3 h. HRTEM microscopy shows ordered hexagonal pore array with pore size around 5 nm. Surface areas larger than 200 m^2·g^(-1) are obtained after dried at room temperature, and drop to 40 m^2·g^(-1) after calcination at T>873 K. The pore distribution of the sample prepared using TEA as a template indicated that there exists some micropore in the mesoporous structure, and the number of micropore decreases as the rise of calcination temperatund, and disappears at around 600 ℃.