Characterization of the porous structure of SBA-15
Characterization of the porous structure of SBA-15
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DOI：
10.1021/cm000164e
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发表时间：
2000-07-01
影响因子：
8.6
通讯作者：
Ryoo, R
中科院分区：
文献类型：
--
作者：
Kruk, M;Jaroniec, M;Ryoo, R
采用Zhao等报道的方法合成了SBA-15有序介孔氧化硅材料，并利用X射线粉末衍射（XRD）、热重分析（TGA）和氮气吸附等手段对材料的结构进行了表征。发现样品表现出与先前报道的那些类似的结构性质。我们的研究证实，可以通过选择合成温度来定制SBA-15的初级介孔的尺寸，并且SBA-15表现出显著量的无序微孔和小介孔。发现这些互补孔的体积和尺寸在一定程度上取决于合成/老化温度。结果表明，在水或乙醇中洗涤合成的SBA-15伴随着明显的结构收缩，并导致除去了显着部分的聚合物模板。因此，如果想要分离SBA-15而没有明显的模板损失，则需要避免洗涤。证实了水洗的SBA-15样品具有完全可及的初级中孔。还发现乙醇洗涤的样品表现出可接近的孔隙度。尽管在水和乙醇洗涤的样品中有可观的模板含量，但它们的孔径通常大于煅烧材料的孔径。所观察到的SBA-15的结构特性和它们对合成温度和洗涤的依赖性归因于SBA-15的硅质壁内的三嵌段共聚物模板的聚（环氧乙烷）链的渗透程度的变化。
SBA-15 ordered mesoporous silicas were synthesized using the method reported by Zhao et al, The structures of these materials were characterized using powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), and nitrogen adsorption. The samples were found to exhibit structural properties similar to those reported earlier. Our study confirmed that the size of primary mesopores of SBA-15 can be tailored by the choice of synthesis temperature and that SBA-15 exhibits a significant amount of disordered micropores and small mesopores, The volume and size of these complementary pores were found to be dependent to some extent on the synthesis/aging temperature. It was shown that the washing of as-synthesized SBA-15 in water or ethanol was accompanied by an appreciable structural shrinkage and led to the removal of a significant part of the polymeric template. Therefore, washing needs to be avoided if one wants to isolate SBA-15 without appreciable loss of the template. It was confirmed that water-washed SBA-15 samples have fully accessible primary mesopores. Ethanol-washed samples also were found to exhibit accessible porosity. Despite an appreciable content of the template in the water- and ethanol-washed samples, their pore sizes were usually larger than those of the calcined materials. The observed structural properties of SBA-15 and their dependence on the synthesis temperature and washing were attributed to the changes in the degree of penetration of the poly(ethylene oxide) chains of the triblock copolymer template within the siliceous walls of SBA-15.