Preparation Of Sn-Si And Sn-Al Mixed Oxides By Non-Hydrolytic Sol-Gel Route

In the past 10 to 20 years, non-hydrolytic sol-gel method has become a powerful tool for preparing metal oxides, especially the metal mixed oxide and inorganic-organic hybrid materials. It shows great advantages to control the oxides composition, particle size, morphology and crystal structure.In this thesis, the SnO2-SiO2 and SnO2-Al2O3 mixed oxides were prepared via non-hydro lytic sol-gel route.(1) The SnO2-SiO2 mixed oxide were prepared via the reflux process rather than an thermal process, as well as the introduction of FeCl3 as lewis acid for Si precursor. The yield, surface area, pore volume and pore structure of the mixed oxide have greatly changed.The specific surface area increased from 22.58 m2/g to 305.7m2/g, pore volume from 0.047 cm3/gto 0.14 cm3/g, the average pore diameter decreases, and the mixed oxide yield was improved from about 31% to above 60%.The introduction of FeCl3 promoted the formation of the Sn-O-Si bond, which is conducive to the Sn-O-Si bond supersaturated from precipitation. After calcination, among the mixed oxide, tin oxide dispersed in the amorphous silicon oxide with the tetragonal rutile structure.(2) The tin aluminum mixed oxide were prepared via non-hydrolytic sol-gel method with four different oxygen donors:isopropyl ether,ethyl ether, methanol and ethanol.The main results showed, with ether and methanol as oxygen donor, the mixed oxide has higher molecular level mixing degree than which with isopropyl ether and ethanol as the oxygen donor. The stability of the mixed oxide were higher than that of prepared by other methods.