PRODUCTION OF HYDROPHILIC SILICA GEL HAVING HIGH PORE VOLUME

• Main Authors: SHEPHARD KIERSTEN LYNN, DENG QIN, HAHN JAMES RICHARD
• Format: Patent
• Language: English
• Published: 23.01.2001
• Edition: 7
• Subjects: CHEMISTRY; COMPOUNDS THEREOF; INORGANIC CHEMISTRY; METALLURGY; NON-METALLIC ELEMENTS

PROBLEM TO BE SOLVED: To obtain a hydrophilic silica gel having high porosity without relying on a conventional method for producing an aerogel by heating a hydrophobic silica hydrogel having bonded organic substituents in an oxidizing atmosphere at a sufficiently high temperature to lower the hydrophobicity of the hydrophobic silica hydrogel by the oxidation of the organic substituents. SOLUTION: A silica hydrogel is brought into contact with a catalytic amount of a strong acid and a organosilicon compound selected from an organosilane of formula I, an oganosiloxane of formula II and an organodisilazane of formula III, preferably hexamethylsiloxane or dimethyldichlorosilane to form a hydrophobic silica hydrogel. This hydrophobic silica hydrogel is heated in an oxidizing atmosphere at a sufficiently high temperature (300-1,000 deg.C) to lower the hydrophobicity of the hydrophobic silica hydrogel to obtain the objective hydrophilic silica gel. In the formulae, R1 is a 1-12C (organofunctional) hydrocarbon, X is a halogen or a 1-12C alkoxy, (a) is 0, 1 or 2 and (b) is 0 or 1.