Relations between pore structure parameters and their implications for characterization of MCM-41 using gas adsorption and X-ray diffraction
Relations between pore structure parameters and their implications for characterization of MCM-41 using gas adsorption and X-ray diffraction
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DOI：
10.1021/cm981006e
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发表时间：
1999-02-01
影响因子：
8.6
通讯作者：
Sayari, A
中科院分区：
文献类型：
--
作者：
Kruk, M;Jaroniec, M;Sayari, A
有序介孔材料的结构参数由于其明确的结构而具有很强的相关性。提出了具有均匀孔六边形阵列的介孔材料（例如 MCM-41 和 SBA-15）的方程，该方程可用于基于几个量来计算孔径、孔壁厚度和比表面积，这些量可以从 X 射线衍射和气体吸附数据（即面间距、初级介孔体积和微孔体积）轻松获得。研究了有关孔形状、孔壁密度以及微孔或无序非细观结构域的存在的假设对结构参数评估的影响。这表明，由于许多MCM-41材料具有非常大的比表面积和初生介孔体积，因此存在广泛的无序性。域不是 MCM-41 的共同特征。 X 射线衍射 (XRD) 图案和氮吸附等温线的检查得出的结论是，有序介孔材料的详细表征需要同时应用气体吸附和 XRD，因为这些技术提供了互补的信息。为了便于比较不同实验室的实验结果，对吸附数据的报告及其在比表面积和孔径分布计算中的应用提出了一些建议。
Structural parameters for ordered mesoporous materials are shown to be strongly interrelated as a result of their well-defined structures. Equations for mesoporous materials with hexagonal arrays of uniform pores (e.g., MCM-41 and SBA-15) are presented, which can be used to calculate the pore size, pore wall thickness, and specific surface area on the basis of several quantities, which are easily available from X-ray diffraction and gas adsorption data (i.e., the interplanar spacing, primary mesopore volume, and micropore volume). The influence of assumptions about the pore shape, pore wall density, and the presence of microporosity or disordered nonmesostructured domains on the evaluation of structural parameters is examined. It is suggested that because of very large specific surface areas and primary mesopore volumes for many MCM-41 materials, the existence of extensive disordered. domains is not a common feature of MCM-41. Examination of X-ray diffraction (XRD) patterns and nitrogen adsorption isotherms led to a conclusion that a detailed characterization of ordered mesoporous materials requires application of both gas adsorption and XRD, since these techniques provide complementary information. To facilitate a comparison of experimental results from different laboratories, some recommendations are made for the reporting of adsorption data and their application in the calculations of specific surface areas and pore size distributions.