Characterization of V-MCM-41 Mesoporous Materials

A series of vanadosilicate V-MCM-41 mesoporous materials with various compositions have been synthesized using vanadium sulfate as the source of vanadium. Hexadecyltrimethylammonium bromide was used as a surfactant in the synthesis. The samples were characterized with nitrogen sorption, X-ray diffraction, framework FTIR, diffuse reflectance UV-visible spectroscopy, differential thermal analysis, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy. The results show that the solid products had the MCM-41 structure and contained only atomically dispersed vanadium consistent with framework vanadium in V-MCM-41. N₂ sorption measurements and TEM demonstrated the high mesoporosity of V-MCM-41. The incorporation of vanadium into MCM-41 decreased the surface area to some extent. The morphology of V-MCM-41 was plate with stepped and smooth surfaces. TEM reveals a regular hexagonal array of uniform channels with curved and rectilinear morphologies. The hexagonal array structure of uniform pore size was observed by TEM. It is proved that the pores were highly aligned.