| 摘要 |
PROBLEM TO BE SOLVED: To obtain an alumina or alumina hydrate having an ultralow bulk density, a high specific surface area and a high fine pore volume, by making the alumina or aluminal hydrate have a specific composition, and have a surface area, a fine pore volume, a bulk density and an average particle diameter in specific ranges, respectively, and further have an open-cell porous structure. SOLUTION: This alumina or alumina hydrate has a composition expressed by the formula: Al2 O3 .nR wherein R is water and/or an alcohol; (n) is <=2 and includes zero. The alumina or alumina hydrate has a specific surface area of >=350m<2> /g by a BET method, a fine pore volume of >=1.0ml/g by a BET method, and a bulk density of 0.02-0.12g/ml measured by an iron cylinder method. The alumina or alumina hydrate has an average particle diameter of 0.5-40μm measured by a call counter method, clear open-cells in the particles and a cell diameter of 100-3000 angstrom. |
