Hierarchical macro-mesoporous structures in the system TiO2–Al2O3, obtained by hydrothermal synthesis using Tween-20® as a directing agent

Macro-mesoporous powders of titania, alumina, and mixed titania–20%alumina systems were obtained by hydrothermal synthesis employing surfactant Tween-20® as structural directing agent in order to promote the textural properties of titania. The effect of the alumina in the titania phase and on textural properties was analyzed. The obtained powders presented a macroporous channel structure that was characterized by X-ray diffractometry, scanning and transmission electron microscopy, N2 adsorption–desorption analysis, pore size distribution, Fourier transform infrared spectrometry, and thermogravimetric analysis. It was found that alumina content retarded the anatase phase crystallization and increased the Brunauer–Emmet–Teller surface area from 136 to 210 m2/g. The powders calcined at 400 °C are thermally stable and possess an interconnected macro-mesoporous hierarchical structure; the results indicate that this synthesis can be employed to prepare mixed titania–alumina with good textural properties.