Method for producing porous silica material
View Patent ↗A method of producing a porous silica material includes: preparing a raw material solution containing silicon alkoxides including diisobutyldimethoxysilane and tetramethoxysilane in such a mass ratio that a mass of the diisobutyldimethoxysilane is 0.25 or more and 1 or less per mass of the tetramethoxysilane, and a solvent; obtaining a wet gel by adding, to the raw material solution, an aqueous solution containing a catalyst for promoting hydrolysis and condensation polymerization of the silicon alkoxides, the aqueous solution having a pH of 8.9 or more and 11.3 or less; washing the wet gel; and drying the washed wet gel under supercritical conditions.
1. A method of producing a porous silica material, comprising:
preparing a raw material solution containing
silicon alkoxides including diisobutyldimethoxysilane and tetramethoxysilane in such a mass ratio that a mass of the diisobutyldimethoxysilane is 0.25 or more and 1 or less per mass of the tetramethoxysilane, and
a solvent;
obtaining a wet gel by adding, to the raw material solution, an aqueous solution containing a catalyst for promoting hydrolysis and condensation polymerization of the silicon alkoxides, the aqueous solution having a pH of 8.9 or more and 11.3 or less;
washing the wet gel; and
drying the washed wet gel under supercritical conditions.
2. The method of producing a porous silica material according to claim 1 , wherein the raw material solution contains the silicon alkoxides and the solvent in such a mass ratio that a mass of the solvent is 0.24 or more and 7.1 or less per mass of the silicon alkoxides.
3. The method of producing a porous silica material according to claim 1 , wherein the pH of the aqueous solution containing the catalyst is 9.2 or more and 10.2 or less.
4. The method of producing a porous silica material according to claim 1 , wherein the pH of the aqueous solution containing the catalyst is 8.8 or more and 11.3 or less.
5. The method of producing a porous silica material according to claim 1 , wherein the pH of the aqueous solution containing the catalyst is 8.9 or more and 10.4 or less.
6. The method of producing a porous silica material according to claim 1 , further comprising, between the drying and the washing, hydrophobizing the wet gel.
7. The method of producing a porous silica material according to claim 1 , wherein the solvent of the raw material solution comprises ethanol.
8. The method of producing a porous silica material according to claim 1 , wherein the catalyst comprises at least one kind selected from the group consisting of ammonia, a quaternary ammonium salt, an amine, sodium hydroxide, and potassium hydroxide.
9. The method of producing a porous silica material according to claim 1 , wherein an amount of the aqueous solution containing the catalyst is 3.5 or more and 4.5 or less per mole of the silicon alkoxides.
10. The method of producing a porous silica material according to claim 1 , wherein the obtaining a wet gel comprises holding the raw material solution having added thereto the aqueous solution containing the catalyst at a temperature of 40° C. or more and 70° C. or less.