Method for making hollow silica particles
AssigneeImam Abdulrahman Bin Faisal University
InventorsAyhan BOZKURT, Seyda Tugba Gunday ANIL, Munirah Abdullah ALMESSIERE, Sultan AKHTAR
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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.
Claims17
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 nitric acid to form a hydrolyzed silane solution;
- mixing the hydrolyzed silane solution with ammonium 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.
(canceled)
3:
- The method of claim 1, wherein the trialkoxy(aryl) silane is trimethoxy(phenyl) silane.
4-5. (canceled)
6:
- The method of claim 1, wherein the first temperature is 195 to 210° C.
7-8. (canceled)
9:
- The method of claim 1, wherein the second temperature is 650 to 670° C.
(canceled)
11:
- The method of claim 1, wherein the second temperature is held for 12 to 20 hours.
(canceled)
13:
- 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.
14:
- The method of claim 13, 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.
15:
- The method of claim 13, 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.
16:
- The method of claim 1, wherein the hollow silica spheres have an average diameter of 500 to 530 nm.
17:
- The method of claim 16, 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%.
18-19. (canceled)
20:
- 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 cm3/g.
Dependencies are inferred from the claim text.