Study On The Synthesis Of Silicon Dioxide Pellets And Its Potential Uses For Nano-sized TS-1 Zeolites Support

The organic-inorganic materials not only have the variety of organic species, but also have the inorganic species'advantages of stability. This area is currently arouse much attention of researchers especially its uses in the area of adsorption, magnetic materials, chromatography and optical.Silica spheres have been gradually attracted much attention at home and abroad for their unique features, such as low intensity, big BET, high thermal stability. But the main applications of silica spheres are using as supporters of catalysts.The main synthesizing methods of silica spheres at present are Sol-gel, micro emulsion, lyotropic liquid crystal and PICA. Compare with the other methods, PICA can control the size of these organic-inorganic hybrid silica spheres, distribution and shape. We adapt method of PICA to synthesize mesoporous silica spheres which sizes between 1-30μm with colloidal silica, formaldehyde, urea, diluted hydrochloric acid as raw materials. It is found that through optimizing the conditions of synthesis (eg. Temperature, pH value, dilute times of colloidal silica, F/U molar ratio and reaction time) and add NaCl or CTAB and Tween-80 can regulate the size of silica spheres and their uniformities. XRD,SEM,UV-VIS,IR,N2 adsorption,scale microscope are used to characterize these silica spheres.5%,10%,20%,30% of silica dioxide(calculate on the SiO2 in colloidal silica) of纳米TS-1 (including classical methods and low-cost methods)are loaded on silica spheres to study the performance of propylene epoxidation. It turns out that silica spheres with in-situ纳米TS-1 loaded to underway the propylene have better function compare to纳米TS-1 raw powders for the reason that active sites of纳米TS-1 are highly dispersed on the silica spheres to make the in-situ loaded纳米TS-1 has the better catalytic performance. The method of PICA has much potential applications in preparing catalysts.