Hydrolytic and calcination method for forming hollow silica particles

Patent metadata

Field	Value
Publication number	US-12139411-B2
Application number	US-202418660358-A
Country	US
Kind code	B2
Filing date	May 10, 2024
Priority date	Jun 1, 2018
Publication date	Nov 12, 2024
Grant date	Nov 12, 2024

Abstract

A method for forming hollow silica spheres by dissolving a hydrolyzable aryl silane in an aqueous solution of water and an acid to form a hydrolyzed silane solution, mixing the hydrolyzed silane solution with a hydroxide base to form a precipitate, and calcining the precipitate in a multi-stage calcination procedure that includes (a) heating to a first temperature of 180 to 240° C. with a first ramp rate of 3 to 10° C./min and holding the first temperature for 2 minutes to 2 hours, then (b) heating to a second temperature of 600 to 740° C. at a second ramp rate of 0.1 to 4° C./min, and holding the second temperature for 2 to 24 hours.

First claim

The invention claimed is:

1. A hydrolytic and calcination method for forming hollow silica spheres, the method comprising:
dissolving a trialkoxy (aryl) silane in an aqueous solution comprising water and a mineral acid to form a hydrolyzed silane solution;
mixing the hydrolyzed silane solution with a hydroxide base to form a precipitate in a suspension;
centrifuging the suspension to separate the precipitate from the suspension; then
washing the precipitate with an organic solvent and water; then
calcining the precipitate to form hollow silica spheres, wherein the calcining is performed by
heating to a first temperature of 180 to 240° C. with a first ramp rate of 3 to 10° C./min and holding the first temperature for 2 minutes to 2 hours, then
heating to a second temperature of 600 to 740° C. at a second ramp rate of 0.1 to 4° C./min, and holding the second temperature for 2 to 24 hours,
wherein a template is not employed for forming the hollow silica spheres.

2. The method of claim 1 , wherein the trialkoxy (aryl) silane is trimethoxy (phenyl) silane.

3. The method of claim 1 , wherein the first temperature is 195 to 210° C.

4. The method of claim 1 , wherein the second temperature is 650 to 670° C.

5. The method of claim 1 , wherein the second temperature is held for 12 to 20 hours.

6. The method of claim 1 , wherein the hollow silica spheres comprise a silica-containing shell surrounding a core, wherein the silica-containing shell has a higher density of silica compared to the core.

7. The method of claim 6 , wherein the hollow silica spheres have an average degree of hollowness, defined as a maximum peak intensity of the core divided by a minimum peak intensity of the silica-containing shell, each measured with transmission electron microscopy, of 3 to 8.

8. The method of claim 6 , wherein the silica-containing shell has a thickness of about 150 to 210 nm, and the core has a diameter of about 100 to 230 nm.

9. The method of claim 1 , wherein the hollow silica spheres have an average diameter of 500 to 530 nm.

10. The method of claim 9 , wherein the hollow silica spheres are monodisperse with a coefficient of variation, defined as a ratio of the standard deviation to the mean diameter of the hollow silica spheres, of less than 5%.

11. The method of claim 1 , wherein the hollow silica spheres have an average pore diameter of 1.7 to 8 nm with a cumulative pore volume of 0.02 to 0.035 cm 3 /g.

Assignees

• Univ Imam Abdulrahman Bin Faisal

Inventors

• Bozkurt Ayhan
• Anil Seyda Tugba Gunday
• Almessiere Munirah Abdullah
• Akhtar Sultan

Classifications

• C01P2004/88

  Thick layer coatings · CPC title

• C01P2006/14

  Pore volume · CPC title

• C01P2006/12

  Surface area · CPC title

• C01P2006/16

  Pore diameter · CPC title

• C01P2004/34

  hollow · CPC title