Influence of the amount of titania on the texture and structure of titania supported on silica

Samples obtained by grafting various amounts of titania over silica using titanium IV isopropoxide in isopropyl alcohol were studied using SBET, pore volume, XRD, ESCA, DRS, and zeta potential measurements. Very good dispersion of TiO2 over silica approaching monolayer dispersion was observed for TiO2 content lower than about 15 wt%. At higher TiO2 content, TiO2 crystallites were formed. A strong oxide-oxide interaction with the formation of the Ti-O-Si bend was observed. For a part of TiO2, the intensity of this interaction increases with the calcination temperature, but for other parts, formed crystallites. (C) 1996 Academic Press, Inc.