US4250058A
Expired / Lapsed
US
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Method of preparing spheroidal alumina particles
Assignee: Honeywell UOP LLC
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Filing: 1979-05-17
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Granted: 1981-02-10
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Expires: 1999-05-17
Abstract
Abstract A method of preparing spheroidal alumina particles of improved physical stability is disclosed. Alumina hydrogel particles prepared by the oil-drop method are aged in the forming oil at atmospheric pressure conditions and at a temperature of from about 95° to 105° C. until the hydrogel spheres achieve a pH in excess of 6 to about 7.5. The forming oil is thereafter displaced with an ammonium salt-buffered aqueous ammoniacal solution, and the hydrogel spheres aged therein for a brief period. After further aging in an aqueous ammoniacal solution in accordance with prior art practice, the spheres are water-washed, dried and calcined.
Inventors
- 👤 Edward Michalko
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 12:21
CPC Classifications
B; B01; B01J; B01J21/00; B01J21/02; B01J21/04; B01J2/00; B01J2/02; B01J2/06; B01J2/08
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
176 words
A method of preparing spheroidal alumina particles which comprises: (a) commingling an acidic alumina hydrosol with an ammonia precursor at below gelation temperature; (b) dispersing the mixture as droplets in a hot oil bath at a temperature effecting decomposition of said ammonia precursor and gelation of said hydrosol; (c) aging the resulting hydrogel spheres in said oil bath at about atmospheric pressure conditions and at a temperature of from about 95° to about 105° C. until said spheres achieve a pH in excess of 6 to about 7.5; (d) thereafter displacing said oil bath with an ammonium salt-buffered aqueous ammoniacal solution containing from about 0.5 to about 10 wt.% ammonium salt and from about 0.1 to about 1 wt.% ammonia, and retaining the spheres in said solution for at least about 15 minutes; (e) separating and further aging the hydrogel spheres in an aqueous ammoniacal solution containing from about 0.5 to about 3 wt.% ammonia for a period of from about 1 to about 24 hours; and, (f) water-washing, drying and calcining the spheroidal alumina product.
Claim 2
Independent Claim
176 words
A method of preparing spheroidal alumina particles which comprises: (a) commingling an acidic alumina hydrosol with an ammonia precursor at below gelation temperature; (b) dispersing the mixture as droplets in a hot oil bath at a temperature effecting decomposition of said ammonia precursor and gelation of said hydrosol; (c) aging the resulting hydrogel spheres in said oil bath at about atmospheric pressure conditions and at a temperature of from about 95° to about 105° C. until said spheres achieve a pH in excess of 6 to about 7.5; (d) thereafter displacing said oil bath with an ammonium salt-buffered aqueous ammoniacal solution containing from about 0.5 to about 10 wt.% ammonium salt and from about 0.1 to about 1 wt.% ammonia, and retaining the spheres in said solution for at least about 15 minutes; (e) separating and further aging the hydrogel spheres in an aqueous ammoniacal solution containing from about 0.5 to about 3 wt.% ammonia for a period of from about 1 to about 24 hours; and, (f) water-washing, drying and calcining the spheroidal alumina product.
Claim 3
Dependent Claim
19 words
The method of claim 1 further characterized with respect to step (a) in that said ammonia precursor is hexamethylenetetramine.
Claim 4
Dependent Claim
30 words
The method of claim 1 further characterized with respect to step (b) in that said oil bath is maintained at a temperature of from about 50° to about 100° C.
Claim 5
Dependent Claim
46 words
The method of claim 1 further characterized with respect to step (c) in that said hydrogel spheres are aged in said oil bath for a period in excess of about 10 hours and until said spheres achieve a pH in excess of 6 to about 7.5.
Claim 6
Dependent Claim
29 words
The method of claim 1 further characterized with respect to step (f) in that said spheres are calcined at a temperature of from about 425° to about 750° C.
Claim 7
Dependent Claim
37 words
The method of claim 1 further characterized with respect to step (a) in that said acidic alumina hydrosol is an aluminum chloride hydrosol characterized by an aluminum/acid anion weight ratio of from about 1.0 to about 1.5.
Claim 8
Dependent Claim
20 words
The method of claim 1 further characterized with respect to step (d) in that said ammonium salt is ammonium chloride.
References Cited (Backward Citations)
US2620314A
Cited
US3887493A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-02-10 | 1984-08-11 | 1985-02-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-02-10 | 1988-08-11 | 1989-02-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-02-10 | 1992-08-11 | 1993-02-10 | $7700.00 | Window Closed / Lapsed |