Photocatalytic properties of the SBA-15 mesoporous silica molecular sieve modified with titanium

We describe three methods of post-synthesis modification of the SBA-15 mesoporous molecular sieve with titanium: impregnation with Ti(OEt)₄ in an ethanolic solution, grafting with titanocene dichloride, and modification with colloidal titania. The products were characterized using X-ray diffraction (XRD) and N₂ adsorption as well as Fourier-transform infrared and ²⁹Si NMR spectroscopies. All three methods yield materials containing 1.4-4.7 wt.% titanium and with high surface areas. The absorbance at 960 cm^-1 in SBA-15 modified with colloidal titania and SBA-15 grafted with titanocene indicates the formation of Ti-O bonds. All products showed significant activity towards the degradation of p-chlorophenol. UV-vis absorption spectra of SBA-15 samples modified with titanium indicate that the variation in the photocatalytic activity is governed by isolated titanium sites.