TiO2–SiO2 mixed oxide modified with H2SO4: I. Characterization of the microstructure of metal oxide and sulfate Original Research Article

A series of titania and silica mixed metal oxide samples modified by H2SO4 has been characterized by BET, XRD, XPS, FT-IR and compared with non sulfated samples. The XPS results show the appearance of a titanium silicate phase in all samples. After sulfuric acid treatment the decrease of BET surface area, the appearance of the TiO2 crystalline in XRD and the enrichment of Si on the surface in XPS indicate that the strong bond between TiO2 and sulfate ions induces the migration of Ti ions from the titanium silicate phase. The total contents of sulfate ions depend on the TiO2–SiO2 mole ratio. The shift of the SO characteristic peak in FT-IR shows that the bond strength of SO is influenced by the TiO2–SiO2 microstructure.