Process for the preparation of hydrophobic sìlica with reduced area of superfìcie under neutral conditions

摘要

Invention patent: " b the process for the preparation of hydrophobic su00eclica with reduced area of superfu00eccie under neutral conditions' ' d .The present invention relates to a hydrophobic silica gels having a reduced surface area and a method for their preparation under neutral conditions.The method consists of two steps, where in the first step, the pH of a mixture containing silica hidrossol and colloidal silica is adjusted with a base to within a range of pH 3 and pH 6 to facilitateThe formation of a silica hydrogel having a colloidal silica incorporated therein.In the second step,The silica hydrogel is placed in contact with a organossilu00edcio compound in the presence of a catalytic amount of a strong acid to make the hidrofobilizau00e7u00e3o of silica hydrogel to form a su00edlICA gel and a hydrophobic surface area within a range of about 100 m2 / g to 450 m2 / g in the dry state.A preferred process the hydrophobic silica gel is brought into contact with a sufficient quantity of an organic solvent insoluble in water to convert the silica hydrogel into a hydrophobic silica org.Anogel hydrophobic. A compound of cerium or iron soluble in water can be added during the driving of the second stage to improve the heat stability of hydrophobic silica gel.