Comparative textural study of highly ordered silicate and aluminosilicate mesoporous mesophase materials having different pore sizes

Honeycomb structure model was applied for describing surface properties in the MCM-41 and SEA-15 types of highly ordered silicas and aluminosilicates with different nominal mesopore diameters: about 4 nm and about 10 nm. As s hown, calculations of internal specific surface area A(me) require a hetero geneity of this surface to be taken into account, the latter being quantifi ed by the roughness coefficient beta. These calculations at the condition b eta = 1.0 will allow to estimate the lower limit of specific surface area o f the materials only. which will correspond to the perfectly smooth walls o f mesopores. This description seems to be valid for the MCM-41 type systems , for which beta is about 1.1-1.2. On the contrary, beta is found to exceed 1.5 for the SEA-15 type materials. This fact is probably due to an essenti al non-smoothness of the mesopore surface in these systems and may be assoc iated with their synthesis conditions. (C) 2001 Elsevier Science B.V. All r ights reserved.