Hydrothermal synthesis of V-MCM-41 mesoporous molecular sieves and synthesis mechanism

V-MCM-41 mesoporous materials were synthesized by the hydrothermal method using cetyltrimethylammonium bromide (CTAB) as the template and industrial Na2O center dot 3.3SiO(2) as the silica source, which is much cheaper than conventional organic precursors. The effects of synthesis conditions on the structure of V-MCM-41 were investigated and the synthesis mechanism was studied by N-2 adsorption. The results indicated that many factors affected the synthesis, including the molar ratio of Si source and CTAB, pH value, crystallization temperature and time, aging time, calcination atmosphere, and feeding mode. The most important factors involved crystallization temperature, pH value, and molar ratio of Si to CTAB. X-ray diffraction results showed that the samples had a highly ordered hexagonal structure. Fourier transform infrared and ultraviolet visible spectra provided strong evidence that most vanadium ions were incorporated into the framework of mesoporous siliceous MCM-41.