Spherical TiO2 /Cr2O3 Composites Synthesized Using Ion-Exchange Resins as a Template

Two samples of TiO2 /Cr2O3 composites were synthesized as spherical grains by stepwise thermal treatment of ion-exchange resins, which were preliminarily saturated with chromium cations Cr3+ and dichromate anions Cr2O7 2– and covered with a film-forming solution of titania. The modes of calcination were based on thermal analysis and determined by the type of ion-exchange resin chosen as a template. The obtained composites consist mostly of the α-Cr2O3 phase, while the content of the TiO2 phase does not exceed 4 %. The composites retain the spherical grain shape of the initial ion-exchange resins with the size from 370 to 660 μm. Grains of the sample based on cationite, which adsorbs Cr3+ ions, have a pore structure with swells and voids. Grains of the sample based on anionite have fractures and cracks over the entire surface due to nonuniform distribution of adsorbed Cr2O72– anions in the initial anionite. The composites exhibit the catalytic activity in the complete oxidation of p-xylene. The sample based on cationite is more active. This may be related to a smaller accessible specific surface area of titania in the anionite-based sample due to formation of the Ti3+ solid solution in α-Cr2O3.