Highly Dispersed Phosphate Supported in a Binary Silica−Titania Matrix: Preparation and Characterization

Titanium phosphate supported in a mixed oxide matrix was prepared by reacting SiO 2 /TiO 2, obtained from the sol−gel process, with phosphoric acid. HPO 4 2 - is the species present in the matrix, and it is immobilized by the Ti−O−P bond on the surface. The titanium phosphate is highly and homogeneously dispersed in the SiO 2 /TiO 2 matrix, with the domain of titanium oxide particles about 1 nm, estimated from the UV absorption band threshold. The specific surface areas, determined by the BET multipoint method, changed between 397 and 755 m 2 g - 1 and the average pore volumes between 0.38 and 0.63 mL g - 1 for samples prepared with different contents of titanium phosphate. The titanium hydrogenphosphate is thermally very stable and showed a high proton exchange capacity between 0.50 and 1.10 mmol g - 1 .