Yamamoto Takuji, Endo Akira, Inagi Yuki, Ohmori Takao, Nakaiwa Masaru
National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
J Colloid Interface Sci. 2005 Apr 15;284(2):614-20. doi: 10.1016/j.jcis.2004.10.025.
The accuracy of thermoporometry (TPM) in terms of the characterization of SBA-15 is examined based on a model that classifies the water in the mesopores into two different types: freezable pore water, which can form cylindrical ice crystals, and nonfreezable pore water, which cannot undergo a phase transition during a differential scanning calorimetry (DSC) measurement. Applying the empirical relationship between the sizes of the ice crystals formed in the mesopores and the solidification temperature of the freezable pore water to a thermogram (a recording of the heat flux during the solidification of the freezable pore water) yielded a size distribution of the ice crystals. The size of the ice crystals increased slightly with repetitive freezing, indicating that the mesopores were enlarged by formation of the ice crystals. Adding the thickness, t(nf), of the nonfreezable pore water layer to the ice crystal-size distribution calculated from the thermogram allowed for the determination of the porous properties of SBA-15. The porous properties attained from TPM experiments were compared with the results attained through the combination of Ar gas adsorption experiments and nonlocal density functional theory (NLDFT) analysis. The porous properties determined by TPM were confirmed to be quite sensitive to the t(nf) value.
基于一种模型，对热孔率测定法（TPM）在表征SBA - 15方面的准确性进行了研究。该模型将介孔中的水分为两种不同类型：可冻结的孔隙水，它能形成圆柱形冰晶；不可冻结的孔隙水，在差示扫描量热法（DSC）测量过程中不会发生相变。将介孔中形成的冰晶尺寸与可冻结孔隙水的凝固温度之间的经验关系应用于热谱图（可冻结孔隙水凝固过程中热流的记录），得出了冰晶的尺寸分布。随着反复冷冻，冰晶尺寸略有增加，这表明介孔因冰晶的形成而扩大。将不可冻结孔隙水层的厚度t(nf)添加到根据热谱图计算出的冰晶尺寸分布中，就可以确定SBA - 15的多孔性质。将热孔率测定法实验获得的多孔性质与通过氩气吸附实验和非局部密度泛函理论（NLDFT）分析相结合得到的结果进行了比较。结果证实，热孔率测定法确定的多孔性质对t(nf)值非常敏感。
