Study on properties of composite oxides TiO2/SiO2

The nanometer particles of TiO2 and TiO2/SiO2 oxides were prepared by sol-gel and supercritical fluid drying method. The properties of TiO2 and TiO2/SiO2 were characterized by means of BET (Brunner-Emmett-Teller method), TEM(transmission electron microscopy), SEM(scanning electron microscopy), XRD(X-ray diffraction) and FTIR(Fourier transform-infrared) techniques. The effects of different preparation route, prehydrolysis and non-prehydrolysis, on the properties of TiO2/SiO2 oxide were also examined, Experimental results show that the thermal stability of pure TiO2 is improved greatly when it is mixed with SiO2 in nanometer level. The composite TiO2/SiO2 oxides form Ti-O-Si chemical bonds, which creates new Bronsted acidity sites. The acidity character is related to TiO2/SiO2 chemical composition and preparation methods. The acidity of TiO2/SiO2 oxides by prehydrolysis is greater than that of by non-prehydrolysis. Ti atom is rich on the surface of TiO2/SiO2.