PROCESS FOR PREPARING HIGH PURITY SILICON OXIDE POROUS BEADS DOPED WITH SMALL QUANTITIES OF OTHER OXIDES

摘要

There is disclosed the preparation of high purity, high surface area, porous beads of silicon oxide doped with small quantities of other oxides, which preparation comprises hydrolyzing a silicon alkoxide dissolved in a hydroxyl containing organic solvent with less than a stoichiometric amount of water so as to provide a partially hydrolyzed intermediate product. The resulting partially hydrolyzed intermediate product is then treated with additional water and an immiscible non-polar organic medium so as to form a discontinuous phase of liquid partially hydrolyzed intermediate product dispersed in a continuous phase of organic medium. As a source of dopant oxide, a selected water soluble salt is added to the process at any convenient step prior to the next process step of pH adjustment, e.g. before, during, or after the partially hydrolyzing; before, during, or after the organic medium treatment. The dispersed intermediate product is then treated with a base and a quantity of water sufficient to hydrolyze any residual alkoxy groups in the dispersed intermediate product. The resulting mixture is stirred until the dispersed intermediate is converted to firm, hard, solid, porous beads of silicon oxide doped with at least one other oxide. The beads are typically recovered by filtration and evaporation of non-solid residues or by like method.