We demonstrated the formation of monodispersed spherical aluminum hydrous oxide precursors with tunable sizes by controlling the variables of a forced hydrolysis method. The particle sizes of aluminum hydrous oxide precursors were strongly dependent on the molar ratio of the Al3+ reactants (sulfates and nitrates). In addition, the systematic phase and morphological evolutions from aluminum hydrous oxide to γ-alumina (Al2O3) and finally to α-Al2O3 through thermal dehydrogenation were characterized by X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). After annealing the amorphous aluminum hydrous oxide in air at 900°C and 1100 °C for 1 h, we observed complete conversion to phase-pure γ- and α-Al2O3, respectively, while maintaining monodispersity (125 nm, 195 nm, 320 nm, and 430 nm diameters were observed). Furthermore, both γ- and α-Al2O3 were found to be mesoporous in structure, providing enhanced specific surface areas of 102 and 76 m2 g-1, respectively, based on the Brunauer-Emmett-Teller (BET) measurement.
ASJC Scopus subject areas
- Inorganic Chemistry