Synthesis and application study of α-Al 2 O 3 with large specific surface area at high-temperature by hydrothermal-assisted freeze-drying

gamma-AlOOH nanopowder synthesized using hydrothermal-assisted freeze-drying was employed as a precursor, with AlF3 as a sintering aid, to explore the preparation of alpha-Al2O3 with a high specific surface area at elevated temperatures. The gamma-AlOOH nanopowder produced in this study exhibited superior dispersion, achieving a specific surface area of 198.06 m2/g and a zeta potential of 45.8 mV. At a calcination temperature of 1200 degrees C, the resulting alpha-Al2O3, synthesized from gamma-AlOOH and AlF3, maintained a specific surface area of 27.72 m2/g, significantly higher than the typical values reported in the literature (generally below 10 m2/g). The alpha-phase purity exceeded 99 %, and the [AlO6] proportion was 95.07 %. Furthermore, at a calcination temperature of 1150 degrees C, the specific surface area of the alpha-Al2O3 reached 50.48 m2/g. Using this alpha-Al2O3 as a carrier, a composite TiO2 catalyst was prepared via a sol-gel and hydrothermal method. This catalyst demonstrated a photocatalytic degradation rate of over 98 % for rhodamine B (10 mg/L) within 30 min of irradiation, under the illumination of a 300 W mercury lamp in proximity to the light source.