TiO 2–SiO 2 mixed oxide modified with H 2SO 4: I. Characterization of the microstructure of metal oxide and sulfate

Abstract

A series of titania and silica mixed metal oxide samples modified by H 2SO 4 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 TiO 2 crystalline in XRD and the enrichment of Si on the surface in XPS indicate that the strong bond between TiO 2 and sulfate ions induces the migration of Ti ions from the titanium silicate phase. The total contents of sulfate ions depend on the TiO 2–SiO 2 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 TiO 2–SiO 2 microstructure.