Textural and adsorption properties of mesoporous silicophosphate

Low-temperature nitrogen adsorption-desorption and electron microscopy are employed to investigate the textural and adsorption properties of a silicophosphate material produced by the sol-gel method under the influence of two factors, pH of the sol-gel transition and the presence of a template, which predetermine the physical characteristics of the material. It is shown that the mesoporous structure of silicophosphate is composed of rather uniform bottle-shaped mesopores with necks the average diameter of which can be regulated in a targeted fashion in a narrow range of 3–5 nm. Templation with cetylpyridinium chloride leads to flattening the amorphous walls of the pores in silicophosphate and the formation of mesopores with large average diameters. The features of the supramolecular structure, which are revealed at different scale levels by electron microscopy and the analysis of the external and internal surface areas of silicophosphate, are not reflected in the pore-size distribution curves calculated from sorption isotherms, because they are governed by the interconnection of the mesopores rather than their individual shapes.