US4248852A
Expired / Lapsed
US
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Process for the production of alumina suitable for use as a catalyst carrier
Assignee: Chiyoda Corp
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Filing: 1979-08-15
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Granted: 1981-02-03
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Expires: 1999-08-15
Abstract
Abstract Improved gamma -alumina suitable for use as a catalyst carrier having high mechanical strength, a large specific surface area, and a substantially uniform pore size distribution in a relatively small portion of the pore size range below 500 A. Said alumina is produced by first establishing a seed aluminum hydroxide hydrogel having a pH of between 6 and 10 and then repetitively and sequentially adding an aluminum compound to adjust the pH to less than 5 or more than 11 to dissolve crystallites of aluminum hydroxide followed by addition of a neutralizing agent to return the hydrogel to the pH range from about 6 to 10 to cause pseudo-boehmite crystallites to grow. After a sufficient number of repetitions of said sequential addition, sparse aggregates of crystallites of the desired structure are formed. These are dried and calcined to produce the said alumina.
Inventors
- 👤 Motoyoshi Wakabayashi
- 👤 Takeo Ono
- 👤 Osamu Togari
- 👤 Munekazu Nakamura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 12:55
CPC Classifications
B; B01; B01J; B01J21/00; B01J21/02; B01J21/04; C; C01; C01F; C01F7/00; C01F7/02; C01P; C01P2004/00; C01P2004/10; C01P2004/50; C01P2004/60; C01P2004/61; C01P2006/00; C01P2006/12; C01P2006/14
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
163 words
A process for the production of an alumina suitable for use as a catalyst carrier comprising establishing a seed aluminum hydroxide hydrogel having a pH of between about 6 and 10 at a temperature of at least about 50° C., sequentially adding (a) an aluminum compound of said hydrogel to adjust the pH of said hydrogel to a value of less than 5 or more than 11 whereby fine crystallites of the aluminum hydroxide are dissolved, and (b) then adding a neutralizing agent to said hydrogel to return the pH of the range of from about 6 to 10 to cause hydrated aluminum oxide crystallites to grow, then repeating at least two additional times said sequential addition of said aluminum compound and of said neutralizing agent to continue the growth of said hydrated aluminum oxide crystallites, and drying and calcining said hydrated aluminum oxide crystallites to form crystalline alumina having a predetermined pore volume ranging from 0.5 to 2 cubic centimeters per gram.
Claim 2
Dependent Claim
163 words
A process for the production of an alumina suitable for use as a catalyst carrier comprising establishing a seed aluminum hydroxide hydrogel having a pH of between about 6 and 10 at a temperature of at least about 50° C., sequentially adding (a) an aluminum compound of said hydrogel to adjust the pH of said hydrogel to a value of less than 5 or more than 11 whereby fine crystallites of the aluminum hydroxide are dissolved, and (b) then adding a neutralizing agent to said hydrogel to return the pH of the range of from about 6 to 10 to cause hydrated aluminum oxide crystallites to grow, then repeating at least two additional times said sequential addition of said aluminum compound and of said neutralizing agent to continue the growth of said hydrated aluminum oxide crystallites, and drying and calcining said hydrated aluminum oxide crystallites to form crystalline alumina having a predetermined pore volume ranging from 0.5 to 2 cubic centimeters per gram.
Claim 3
Dependent Claim
31 words
The process of claim 1 wherein said aluminum compound is an aluminum salt of a strong acid which is added to adjust the pH to a value of less than 5.
Claim 4
Dependent Claim
23 words
The process of claim 2 wherein said aluminum salt is selected from the group consisting of aluminum nitrate, aluminum chloride, and aluminum sulfate.
Claim 5
Dependent Claim
33 words
The process of claims 1, 2 or 3 wherein said neutralizing agent is selected from the group consisting of ammonia, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium aluminate and potassium aluminate.
Claim 6
Dependent Claim
25 words
The process of claim 1 wherein said aluminum compound is an aluminate which is added to adjust the pH to a value larger than 11.
Claim 7
Dependent Claim
14 words
The process of claim 5 wherein said aluminate is sodium aluminate or potassium aluminate.
Claim 8
Dependent Claim
46 words
The process of claims 1, 5 or 6 wherein said aluminum compound adjusts the pH to a value larger than 11 and wherein said neutralizing agent is selected from the group consisting of sulphuric acid, nitric acid, hydrochloric acid, aluminum sulfate, aluminum nitrate and aluminum chloride.
Claim 9
Dependent Claim
24 words
The process of claim 1 wherein said temperature during said sequential additions is between 70° C. to the boiling point of the reaction mixture.
Claim 10
Dependent Claim
33 words
The process of claim 1 wherein said aluminum compound is added in an amount of from 2 to less than 200 molar percent of added aluminum compound based on said seed aluminum hydroxide.
Claim 11
Dependent Claim
34 words
The process of claims 3 or 6 wherein said aluminum compound is added in an amount of from 2 percent up to 100 molar percent of aluminum compound based on said seed aluminum hydroxide.
Claim 12
Dependent Claim
33 words
The process of claim 4 wherein said aluminum compound is added in an amount of between 2 to less than 50 molar percent of added aluminum compound based on said seed aluminum hydroxide.
Claim 13
Dependent Claim
33 words
The process of claim 7 wherein said aluminum compound is added in an amount of between 2 to less than 50 molar percent of added aluminum compound based on said seed aluminum hydroxide.
Claim 14
Dependent Claim
31 words
The process of claims 1, 3, 6, 8, or 9 wherein said sequence of addition of aluminum compound and then addition of neutralizing agent is repeated between 3 and 20 times.
Claim 15
Dependent Claim
48 words
The process of claim 11 wherein said sequence of addition of aluminum compound and then addition of neutralizing agent is repeated between 3 and 20 times and wherein said temperature during said repetitive additions is maintained at between 70° C. and the boiling point of the reaction mixture.
Claim 16
Dependent Claim
48 words
The process of claim 12 wherein said sequence of addition of aluminum compound and then addition of neutralizing agent is repeated between 3 and 20 times and wherein said temperature during said repetitive additions is maintained at between 70° C. and the boiling point of the reaction mixture.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-02-03 | 1984-08-04 | 1985-02-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-02-03 | 1988-08-04 | 1989-02-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-02-03 | 1992-08-04 | 1993-02-03 | $7700.00 | Window Closed / Lapsed |