| 摘要 |
<p>It is known to prepare silica particles by the known sol-gel method. However silica particles prepared by the known method have a lower bulk crush strength and a lower water resistivity than desired. These properties of silica particles may be improved by the present invention which provides a process for the preparation of globular silica particles having a water resistivity of at least 80% and a bulk crushing strength of at least 12 kg/cm2, which process comprises the following successive steps: a) preparing a silica hydrosol by mixing an aqueous solution of an alkalimetal silicate wit an aqueous solution of an acid, b) converting the hydrosol into droplet form, c) gelling the droplets in a liquid which is not miscible with water, d) removing at least 25% of the amount of water present in the hydrogel particles by evaporation, e) decreasing the alkalimetal content of the hydrogel particles in an aqueous medium to less than 1% w calculated on dry material, and f) drying and calcining the globular silica particles. The so prepared silica particles are useful as catalysts, catalyst carriers, adsorbants, drying agents and ion exchangers.</p> |
