Hydrotermal stability and volumetric properties of mesoporous organic-inorganic composite materials based on MCM-41 according to the low-temperature adsorption / desorption of nitrogen and X-ray analysis

Abstract

The processes of silylation of MCM-41 using trimethylchlorosilane, dimetoxydimetylsilane,
trimetoxyoktylsilane, and dichlorometylphenylsilane are studied. Based on the data of the low-temperature nitrogen
adsorption/desorption the surface properties, the porosity of high ordered mesoporous materials is considered. It is
noted that the degree of grafting and, consequently, the pore size, as well as other bulk material properties vary with
conditioning of temperature and modifying agent concentration. X-ray diffraction data indicates significant structural
changes of MCM-41 after hydrothermal treatment. The partial destruction of the hexagonal structure of mesoporous
materials takes place. Hydrothermal treatment of mesoporous composites based on MCM-41 does not change the
structure of the silica matrix. Silylation of mesoporous silica results in higher stability of matrix of MCM-41
analogues