Preparation of alumina nanoparticles by supercritical antisolvent process

The supercritical antisolvent (SAS) process Is a novel technique for micronization and has a promising prospect in the production of thermosensitive explosives, polymer microspheres, medicines, superconductors, catalysts, and dyestuffs. Using carbon dioxide as the antisolvent medium and anhydrous ethanol as the solvent, nanoparticles of the aluminum nitrate precursor were prepared by the SAS process. The effects of preparation conditions including precipitation temperature and solution concentration on the SAS process were investigated. Spherical nanoparticles of alumina were prepared through calcination of the aluminum nitrate precursor. The nanoparticles were characterized by thermogravity-mass spectroscopy, X-ray diffraction, transmission electron microscopy, and field emission gun transmission electron microscopy. The reduction properties of nickel supported by SAS alumina nanoparticles were studied by temperature-programmed reduction. It is found that alumina nanoparticles show better dispersion properties for the active component nickel than the commercial gamma-Al2O3 sample.