Abstract: Highly dispersed mesoporous alumina fibers were successfully synthesized through urea hydrothermal-uniform precipitation method using rosin-based quaternary ammonium salt as a structure directing agent. Their structures were characterized with X-ray diffraction, N₂ adsorption and desorption, field-emission scanning electron microscope and transmission electron microscope. The results indicated that well dispersed fibrous ammonium aluminium carbonate hydroxide precursors were formed under the hydrothermal treatment. After the calcinations at 823 K for 4 h, fibrous mesoporous γ-Al₂O₃ were obtained. The temperatures of the hydrothermal treatments had significant influence on the textural properties of the samples. The increase of the temperatures resulted in the increase of crystallinities. However, after the calcinations, all the samples transformed into γ-Al₂O₃ phase. No distinct difference of crystal structure could be observed among the samples. When the hydrothermal temperature was 373 K, the sample possessed a larger surface area (241.18 m²/g) with a smaller pore diameter(7.21 nm). The increase or decrease of the hydrothermal temperatures led to the decrease of surface areas, and the increase of pore diameters. The length of the precursor fibers was about 5 μm, and the width of which was about 200 nm. After the calcinations, the morphology of the sample kept intact with porocity increased.

Key words: rosin-based quaternary ammonium salt, fibrous, ammonium aluminium carbonate hydroxide, mesoporous alumina