Alumina nanotubes: preparation and textural, structural and morphological characterization

Alumina nanotube was synthesized by hydrolysis of aluminum isopropoxide followed by gelation and drying under hypercritical condition. The influence of temperature on the structural, textural, and morphological properties of the material was studied by powder X-ray diffraction, infrared spectroscopy, nitrogen adsorption, thermal analysis, scanning and transmission electronic microscopy. The as-prepared alumina (300°C) was formed by boehmite crystallites. Its structure collapsed after heating (500–1200 °C) yielding γ, δ and θ alumina nanophases. The aerogel surface area changed from 254 to 99 m2 g−1 in this heating range. The formation of alumina nanotubes was verified by transmission microscopy analysis at the heating range.