Hydrothermal synthesis and adsorption property of porous spherical Al2O3 nanoparticles

Spherical porous Al2O3 nanoparticles were synthesized by hydrothermal method using C6H5(NH4)(3)O-7 center dot 2H2O and Al(NO3)(3)center dot 9H(2)O as raw materials. The morphology and size of the Al2O3 particles were significantly influenced by hydrothermal temperature, time, and the molar ratio of Al3+ to (C6H5O7)(3-). The interphase Al(OH)(3) is a key factor on the preparation of gamma-Al2O3. Under the hydrothermal conditions of high temperatures, Al(OH)(3) decomposes into the precursor gamma-AlOOH instead of the exothermic reaction between Al(OH)(3) and H+. In the form of hydrogen bonds, (C6H5O7)(3-) adsorbs on the surface of gamma-AlOOH nanoparticles to form some nano-chains, which interweave and tangle each other to become spheres. During calcination, the precursor gamma-AlOOH converts to gamma-Al2O3 nanoparticles while the spherical morphology is retained. Gas outrush during calcination should be the formative cause of the porous structure. The as-prepared spherical porous Al2O3 nanoparticles can be used as a catalyst or carrier due to the favorable adsorption property.