US4318896A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Manufacture of alumina particles
Assignee: Honeywell UOP LLC
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Filing: 1981-04-20
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Granted: 1982-03-09
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Expires: 2001-04-20
Abstract
Abstract An alumina particle and a method of its manufacture. The alumina particle comprises a spheroidal alumina particle of about 1/16 inch in diameter and a crush strength of from about 13 to about 16 pounds. The method comprises preparing a mixture of an acidic alumina hydrosol and an ammonia percursor at below gelation temperature, dispersing the mixture as droplets in a water-immiscible liquid at a temperature and for a time to effect at least partial gelation of the hydrosol to form hydrogel particles, contacting the hydrogel particles with a liquid having a pH no greater than about 7 and an osmotic pressure sufficient to prevent disintegration of the hydrogel particles, aging the hydrogel particles in an aqueous solution having a pH greater than 7, and thereafter drying and calcining the hydrogel particles.
Inventors
- 👤 Michael W. Schoonover
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 10:03
CPC Classifications
B; B01; B01J; B01J21/00; B01J21/02; B01J21/04; C; C01; C01F; C01F7/00; C01F7/02; C01F7/021; C01P; C01P2002/00; C01P2002/60; C01P2004/00; C01P2004/30; C01P2004/32; C01P2006/00; C01P2006/12; C01P2006/14; C01P2006/16; C01P2006/17; C01P2006/21
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
275 words
A method of preparing alumina hydrogel particles which comprises: (a) preparing an admixture of an acidic alumina hydrosol and an ammonia precursor at below gelation temperature, said ammonia precursor consisting essentially of a weakly basic material substantially stable at ambient temperature but convertible to ammonia at elevated temperatures; (b) dispersing said mixture as droplets in a water-immiscible bath at a temperature and for a time to effect at least partial gelation of said hydrosol to form alumina hydrogel particles having an internal aqueous phase possessing a salt concentration; (c) contacting said alumina hydrogel particles with an aqueous acidic solution having a pH of no greater than 7 and having a compound in said solution in a concentration substantially different from said salt concentration of said internal aqueous phase of said alumina hydrogel particles, wherein the concentration of said compound of said solution provides an osmotic pressure to prevent substantial osmotic migration of hydrogen and hydroxyl ions of said solution into said alumina hydrogel particles to thereby prevent substantial swelling and disintegration of said alumina hydrogel particles; (d) aging said alumina hydrogel particles of step (c) in said aqueous acidic solution for a period of greater than about one-half hour without gradual reduction of the concentration of said compound in said aqueous acid solution; (e) contacting said aged alumina hydrogel particles with an aqueous alkaline solution having a pH of greater than 7; (f) aging said alumina hydrogel particles to firmness in said aqueous alkaline solution for a period of time of up to about 6 hours, and thereafter recovering firm alumina hydrogel particles; and, (g) drying said firm alumina hydrogel particles recovered in step (f).
Claim 2
Independent Claim
275 words
A method of preparing alumina hydrogel particles which comprises: (a) preparing an admixture of an acidic alumina hydrosol and an ammonia precursor at below gelation temperature, said ammonia precursor consisting essentially of a weakly basic material substantially stable at ambient temperature but convertible to ammonia at elevated temperatures; (b) dispersing said mixture as droplets in a water-immiscible bath at a temperature and for a time to effect at least partial gelation of said hydrosol to form alumina hydrogel particles having an internal aqueous phase possessing a salt concentration; (c) contacting said alumina hydrogel particles with an aqueous acidic solution having a pH of no greater than 7 and having a compound in said solution in a concentration substantially different from said salt concentration of said internal aqueous phase of said alumina hydrogel particles, wherein the concentration of said compound of said solution provides an osmotic pressure to prevent substantial osmotic migration of hydrogen and hydroxyl ions of said solution into said alumina hydrogel particles to thereby prevent substantial swelling and disintegration of said alumina hydrogel particles; (d) aging said alumina hydrogel particles of step (c) in said aqueous acidic solution for a period of greater than about one-half hour without gradual reduction of the concentration of said compound in said aqueous acid solution; (e) contacting said aged alumina hydrogel particles with an aqueous alkaline solution having a pH of greater than 7; (f) aging said alumina hydrogel particles to firmness in said aqueous alkaline solution for a period of time of up to about 6 hours, and thereafter recovering firm alumina hydrogel particles; and, (g) drying said firm alumina hydrogel particles recovered in step (f).
Claim 3
Dependent Claim
14 words
The method of claim 1 wherein the ammonia precursor of step (a) is hexamethylenetetramine.
Claim 4
Dependent Claim
30 words
The method of claim 1 wherein the ammonia precursor of step (a) is utilized in an amount to effect substantially complete neutralization of the acid anion contained in said mixture.
Claim 5
Dependent Claim
55 words
The method of claim 1 wherein the hydrosol of step (a) is an aluminum hydroxychloride hydrosol having an aluminum ion/chloride ion weight ratio of from about 0.9:1 to about 1.5:1, and said ammonia precursor is hexamethylenetetramine in from about a 1:4 to about a 1:1.2 mole ratio with the chloride ion content of said mixture.
Claim 6
Dependent Claim
24 words
The method of claim 1 wherein the water-immiscible bath of step (b) is at a temperature of from about 30° to about 105° C.
Claim 7
Dependent Claim
28 words
The method of claim 1 wherein said aqueous acidic solution of step (c) comprises an aqueous salt solution having a salt concentration of at least about 5 wt.%.
Claim 8
Dependent Claim
27 words
The method of claim 1 wherein said aqueous acidic solution of step (c) comprises an aqueous ammonium chloride solution comprising at least about 5 wt.% ammonium chloride.
Claim 9
Dependent Claim
18 words
The method of claim 1 wherein the pH of step (c) is between about 4 and about 6.
Claim 10
Dependent Claim
26 words
The method of claim 1 wherein said aqueous acidic solution of step (c) is at a temperature of from about 30° C. to about 105° C.
Claim 11
Dependent Claim
25 words
The method of claim 1 wherein the aging of step (d) is performed at a temperature of from about 30° C. to about 105° C.
Claim 12
Dependent Claim
42 words
The method of claim 1 wherein said aqueous alkaline solution of step (e) possesses a compound having a concentration sufficient to provide at least a slight osmotic pressure to ensure the physical integrity of said alumina hydrogel particles recovered in step (f).
Claim 13
Dependent Claim
23 words
The method of claim 1 wherein said aqueous alkaline solution of step (e) comprises between about 0.5% and about 3% by weight ammonia.
Claim 14
Dependent Claim
37 words
The method of claim 1 wherein said aqueous alkaline solution of step (e) comprises an aqueous ammonium chloride solution comprising at least about 5 wt.% ammonium chloride and between about 0.5% and about 3% by weight ammonia.
Claim 15
Dependent Claim
20 words
The method of claim 1 wherein said duration of the aging of step (f) is at least about 5 hours.
Claim 16
Dependent Claim
92 words
The method of claim 1 wherein step (d) occurs for at least about one-half hour and said aqueous acidic solution comprises an aqueous ammonium chloride solution comprising between about 5% and about 25% by weight ammonium chloride and having a pH of between about 2 and about 6, and wherein step (f) occurs for at least about five hours and wherein said aqueous alkaline solution comprises an aqueous ammonium chloride solution comprising between about 5% and about 25% by weight ammonium chloride and between about 0.5% and about 3% by weight ammonia.
Claim 17
Dependent Claim
27 words
The method of claim 1 wherein the hydrogel particles of step (g) are dried and calcined at a temperature of from about 425° to about 750° C.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-03-08 | 1985-09-07 | 1986-03-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-03-08 | 1989-09-07 | 1990-03-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-03-08 | 1993-09-07 | 1994-03-09 | $7700.00 | Window Closed / Lapsed |