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 SiO2/TiO2, obtained from the sol-gel process, with phosphoric acid. HPO42- 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 SiO2/TiO2 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).