Preparation of SiO2 Microspheres by Two-step Catalytic Sol-Gel Method

Micrometer SiO2 microspheres were prepared by two-step catalytic Sol-Gel method with tetraethoxysilane (TEOS) as starting material and N,N-Dimethylformamide (DMF) as template. The effects of some factors on the diameter and particle size distribution of the SiO2 microspheres were discussed, such as H2O quantity and ethanol quantity during the first catalytic process, the electrolyte concentration and stirring speed during the secondary catalytic process. SiO2 microspheres were characterized by SEM, Zetasizer, BET measurements and microscope-particle image analysis system. Results show that SiO2 microspheres are mostly regular-ball with no particle agglomeration. The mean particle size (D-50) is 8.9 mu m, and the particle size distribution follows typical Gaussian distribution. The specific surface area is 546.67m(2)/g, and pore volume is 0.7142m(3)/g, with a narrow pore size varied from 2nm to 8nm. Also the particle size increases with water quantity, ethanol quantity and NaCl concentration increaing, but decreases with stirring speed acceleration.