| 摘要 |
<p>Silica gels having narrow pore diameter distribution in the range of 300-600 A and surface areas in the range from 200-500 m.2/g., and the process of preparing such silica gels directly from water, comprising critically controlled steps of precipitation of the silica gel, heat aging the precipitated silica hydrogel slurry, washing the aged product with solutions of salts having a displacing effect on sodium, disintegrating the gel and freeze drying the hydrogel so as to remove substantially all of the water i.e., vacuum subliming the water from the gel after freezing said hydrogel particles at a temperature sufficient to maintain the water in the pores in the frozen state.</p> |
