Synthesis and textural-structural characterization of magnesia, magnesia–titania and magnesia–zirconia catalysts

Several pure magnesium oxides together with some mixed systems (magnesia–titania and magnesia–zirconia) were synthesised, using the sol–gel technique. Chemical, textural and structural characterisation of the solids was carried out through a wide range of physical techniques. In all the cases, the presence of titanium or zirconium led to an increase in surface area as compared to pure magnesia. X-ray diffraction (XRD) revealed that no mixed phases were observed, but MgO (periclase), TiO2 (anatase) and ZrO2 (tetragonal) phases. As for mixed oxides, surface and bulk composition is quite similar in Mg–Zr system, whereas titanium tends to accumulate in the surface of Mg–Ti solids. The surface of the catalysts appears clearly carbonated as revealed by the XPS and diffuse reflectance infrared (DRIFT) spectra, revealing the basic character of the catalysts prepared.