Ultrasonic synthesis of mesoporous molecular sieve

Abstract

The ultrasonic irradiation synthesis of mesoporous molecular sieve (MMS) was investigated by using cationic surfactant and organic silica source in acidic condition. Mesoporous silica that is analogous to the hexagonal MCM-41 could be synthesized over a range of irradiation power from 0 to 250 W within a short synthesis time about 20 min and a quiescent time of 5 h. The material has large BET surface area over 1100 m 2/g, primary pore size in the range of 22–30 Å, pore volume around 1 cm 3/g and wall thickness from 14 to 25 Å. Ultrasonic irradiation has a particular effect on MMS structural uniformity. Generally, the BET surface area increases as the ultrasonic power, time, temperature, solution acidity and quiescent time increasing. The pore volume and primary pore size increase as the ultrasonic power, but decrease as the ultrasonic time and solution acidity increasing. Further more, the strong acidity and long quiescent time are favorable for obtaining higher yield in this research work. Experimental results indicate that this method is satisfactory for saving time and energy than the hydrothermal processing in basic condition although its structural uniformity is slight lower.