Structural, Textural, and Catalytic Properties of Ti(IV)-Fe(III) Mixed Oxides Prepared by a Modified Sol-Gel Route

Iron(III) titanates and Fe(III)-modified titania were prepared via a modified sol-gel method. Structures, texture and phase transformations after calcination at different temperatures were investigated. Fe(III) ions below 10 % were well dispersed in the titania lattice. Pseudorutile (Fe₂Ti₃O₉) was prepared starting with a solution containing 40 % Fe(III) and calcining the product at 500 °C. Starting with equal concentrations of both metal ions resulted in a mixture of pseudorutile and pseudobrookite, Fe₂TiO₅. However, using 66.7 % Fe(III) to prepare pseudobrookite resulted in segregation of trace amounts of iron(III) oxide and rutile. All mixed oxides possessed significantly higher surface areas (178-217 m²/g), larger pore volumes (0.16-0.27 cc/g), and more homogeneous mesopores compared with the parent single metal oxides. Fe₂TiO₅ showed promising catalytic activity in the catalytic oxidation of toluene. A conversion of 100 % to CO₂ was obtained at temperatures ≥300 °C and its catalytic activity correlates with its enhanced reducibility as studied by H₂-temperature programmed reduction (H₂-TPR).