| abstract |
The invention process provides a metal oxide, or oxides of more than one more metal, wherein the oxides have a mean particle size less than 1 micron. The oxides are made by steps including (1) reacting an aqueous solution of a metal salt (or salts) that form insoluble carbonate(s), thereby to form a carbonate precipitate, followed by (b) recovering the precipitate, e.g., by filtration; (c) redispersing the precipitate in water to form a second very dilute slurry; (d) spray-drying said second slurry; (e) calcining the spray-dried product at a low temperature (e.g., 540° C.), followed by a final calcination in atmosphere consisting of flowing oxygen initially under reduced pressure (e.g., 2 Torr). The spray-dried spheroids comprise particles having a mean particle size less than one micron, a property carried over into the products of both calcinations. |