Research On Preparation And Application Of Nano-SiO₂

Nanometer technology changes with each passing day , nanometer material science is also unceasing and progressive. Nanometer SiO2 , as one of nanometer materials , its preparation method emerges continuously, its application scope is also extended continuously ,it has become an important inorganic nanometer material gradually. That we do further research for the preparation methods of nanometer SiO2 , for the fields of its application, will have very important economic meaning and realistic meaning.First, this paper prepares SiO2 with homo- precipitation method, used low-priced water glass as one major raw material, used ethyl acetate as hide reagent. Later we carry out symptom with modern detection means for it, make the formless nanometer SiO2 out. The results indicated that the prepared the powder SiO2 was spherical approximately,the average particle size is about 40 nanometer and the specific surface area is about 137m2/g .Then , the nano-SiO2 ultrafine powder was prepared with chemical precipitation method as raw materials of sodium silicate and ammonium chloride, and as a solvent of ethanol-water solution in this experiment by chemical precipitation.The basic performance of powder had been characterized by means of TEM, SEM , XRD , DTA and IRThe results indicated that the prepared the powder SiO2 was even,the average particle size is about 40 nanometer and the specific surface area is about 235m2/g.In the course of experiment, this paper studies and analyses the density of raw material, surface activator, reaction temperature and solution and roast temperature that affect sediment generation, and have sought the reaction condition of the best. With the reaction condition of the suitable control, this paper does it as generation of one step sediment , which not only reduces production cost, and still makes sediment handling greatly easier later.This paper also makes general introduction about the application of nanometer SiO2 on the base of experiment, acting as carrier of strong solid acid, which deepens the knowledge for the application of nanometre SiO2. We have prepared a solid acid catalyst SO42-/TiO2-ZrO2-La2O3, supported by nano- SiO2. It substitutes oil of vitriol for esterification. In the existence of carrier SiO2 , the effects of different Zr/Ti ratios and different sintering temperatures on the percent conversion of the acetic acid are discussed .Compared with the catalyst SO42-/TiO2-ZrO2, we investigate the La3+ dependence of the solid acid. Themeasurement shows that the add of porous nanoscale SiO: increases specific surface area of the catalyst and the attractive force strengthens the active center of the catalyst because of strong electronegativity value of Si .We conclude that the optimal sintering temperature is 450C and the optimal Zr/Ti ratio is 0.5.