Effect of Synthesis Conditions on Textural Properties of Silica MCM-41

Several samples of mesoporous silica were prepared via sol-gel chemistry in the presence of CTAB as template with variation of stirring intensity and aging time, ratios of CTAB/SiO2 and NH4OH/H2O in synthesis mixture. Effects of aging temperature, hydrothermal treatment and ter-Butanol addition to the synthesis mixture on the textural properties of obtained samples were also studied. Results of XRD, SEM, and N2 adsorption isotherm analyses showed that particle size and morphology of the mesoporous silica were affected by the synthesis conditions; although, no significant change of the pore size ( 5 Å) was observed. Thermal effect on the pore size, unit cell and particle morphology was more pronounced than other parameters. The main morphological variations observed in the synthesized samples were transforming the shape of particles from spherical to larger worm-like particles, the crystallinity of mesoporous structure and intensity of the aggregation. MCM-41 samples of particles size in the range of 50 nm to 1 μm with reduction of aging temperature were obtained. Hydrothermal treatment resulted in the formation of large symmetrical hexagonal shape particle of 500 nm. While stirring intensity led to too smaller particle size, very long wormlike particles (up to 2 μm) were formed by using the ter-butanol in the synthesis.