The Synthesis Of MCM-41 Mesoporous Molecular Sieve Under Ultrasonic

The research of the influence of ultrasonic on crystallization was developed in recent years, which was called sonocrystallization, while the mechanism isn't clear. It is a method of controlling the process of crystallizes using ultrasonic energy. As catalyzer or supporter, MCM-41 mesporous material has been proved having many advantages. The investigation of applying ultrasonic to synthesize process is a valuable theme.MCM-41 was successfully synthesized in acid and basic system under ultrasonic condition using cetyltrimethylammonium bromide (CTAB) as the template and tetraethylorthosilicate (TEOS) as the source of silicate. The influence of reaction time and ultrasonic power were discussed and the samples were characterized by XRD, N2 adsorption, IR and SEM measurements. It was shown that ultrasonic synthesis is an effective process to produce sampleswith higher crystallinity within shorter time compared with the conventional room temperature hydrothermal synthesis method. In acid systerm, the ultrasonic synthesis follows the Cooperative Organiation Mechanism (COM). The results also showed that, in basic systerm the appliance of ultrasonic could improve the velocity of crystallize, shorten the incubation period and minish the particle size. The effects of NaOH, CTAB, TEOS and H2O contents on the MCM-41 mesostucture, as well as the mechanistic involved in the formation of the mesophase were also investigated. It was found that the contents of NaOH, CTAB, TEOS and H2O have optimistical ranges. The reaction time isn't favorable to mesostucture if it is too long or too shorter and the same is ultrasonic power. The process of synthesis is following the second pathway of Liquid Crystal Templating Mechanism (LCT).