| abstract |
SPHERICAL ALUMINUM OXIDE GELS ARE MADE BY FEEDING DROPS OF A COAGULABLE AQUEOUS SLURRY OF HYDROUS ALUMINA INTO A COLUMN OF A WATER-IMMISCIBLE LIQUID, E.G., MINERAL OIL, WHICH CAN BE MAINTAINED AT CLOSE TO AMBIENT TEMPERATURE. THE HYDROUS ALUMINA IS PREPARED BY HYDROLYSIS OF FINELY DIVIDED ALUMINUM HAVING A SURFACE AREA OF ABOUT 75,000 TO 1,000,000 SQUARE MILLIMETERS PER GRAM, AND THE HYDROLYSIS MEDIUM IS ACIDIC FROM THE PRESENCE OF A NONOXIDIZING ACID FOR INSTANCE, FORMIC ACID. THE HYDROUS ALUMINA FEED HAS A RATIO OF ALUMINA MONOHYDRATE TO AMOR- PHOUS HYDROUS ALUMINA OF AT LEAST 0.5/1 AND THE ALUMINA MONOHYDRATE HAS A CRYSTALLINE SIZE OF LESS THAN 65 A. AMMONIA CAN BE ADDED TO THE COLUMN TO AID THE COAGULATION. OTHER SOLIDS, FOR INSTANCE, CALCINED ALUMINA, ALUMINA TRIHYDRATE, SILICA OR CARBON CAN BE INCORPORATED IN THE AQUEOUS SLURRY AS CAN ALUMINUM OXYUCHLORIDE. DRYING AND CALCINATION OF THE COAGULATED HYDROUS ALUMINA PROVIDES ADSORPTIVE SOLIDS WITH ADVANTAGEOUS CHARACTERISTIC WHEN USED, FOR INSTANCE, AS CATALYST COMPONENTS. |