Gamma-alumina octahedral particle and preparation method thereof

The invention discloses gamma-alumina octahedral particles and a preparation method thereof. The gamma-alumina particle provided by the invention has a polycrystalline structure and presents an octahedral morphology, the edge length of the octahedron is 50-700nm, and the particle size of the gamma-alumina octahedron is 70-950nm. The preparation method comprises the following steps: (1) doping alumina precursor powder into inorganic sodium and/or inorganic potassium salt, grinding the powder by using a ball mill to prepare turbid liquid with a certain concentration, adding organic acid, and properly evaporating redundant water to form a wet material; (2) tabletting and molding the wet material obtained in the step (1), then drying, slightly roasting, crushing molded blocks, and screening particles with proper granularity; and (3) carrying out normal-pressure reflux hydrothermal reaction on the material screened in the step (2), and after the reaction is finished, drying and roasting to obtain the product. The