METHOD FOR MAKING HYDROPHOBIC ORGANOSILICATE-MODIFIED SILICAGELS UNDER NEUTRAL CONDITIONS

摘要

The present invention is hydrophobic organosilicate-modified silica gels and a method for their preparation under neutral conditions. The method comprises two steps, where in the first step the pH of an organosilicate-modified silica hydrosol is adjusted with a base to within a range of pH 3 to pH 7 to facilitate formation of an organosilicate-modifie d silica hydrogel. In the second step, the organosilicate-modified silica hydrogel is contacted with an organosilicon compound in the presence of a catalytic amount of a strong acid to effect hydrophobing of the organosilicate-modified silica hydrogel to form a hydrophobic organosilicate-modified silica gel having a surface area within a range of 100 m2/g to 850 m2/g in the dry state. In a preferred process, the hydrophobic organosilicate-modified silica hydrogel is contacted with a sufficient quantity of a water-immiscible organic solvent to convert the hydrophobic organosilicate-modified silica hydrogel into a hydrophobic organosilicate-modified silica organogel. A water soluble compou nd of cerium or iron may be added in the second step to improve the heat stability of the hydrophobic organosilicate-modified silica gel.