Preparation of xTiO2·(1 − x)Al2O3 catalytic supports by the sol-gel method: physical and structural characterisation

A series of xTiO2·(1 − x)Al2O3 mixed oxides has been prepared by the sol-gel method with variable amounts of TiO2, from pure alumina to pure titania. Textural, bulk and surface characterisation of the samples has been carried out by nitrogen physisorption (SBET, porosity), thermal analysis (TGA, DTA), X-ray diffraction (XRD), zero point charge (ZPC) and surface acidity. The textural results show that at low titania contents, higher surface areas than those of pure alumina are obtained, and in the titania-rich samples, higher surface areas than for pure titania are stabilised. The titanium content also affects the crystallization process. Furthermore, the strength and distribution of the acid sites may be varied by changing the composition of the mixed oxide.