US3922333A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for preparing mullite powder and fabrication of structural bodies therefrom
Assignee: United States Department of the Air Force
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Filing: 1974-10-23
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Granted: 1975-11-25
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Expires: 1994-10-23
Abstract
Abstract A process is provided for preparing high purity, submicron, mullite powder (3Al2O3.2SiO2) by hydrolytically decomposing aluminum tris isopropoxide and silicon tetrakis isopropoxide in the presence of ammonium hydroxide or a very dilute mineral acid. The powder as prepared as well as that subjected to calcination has an orthorhombic crystal structure. Structural bodies of near theoretical density can be fabricated by vacuum hot pressing the powder. Because of its large surface area, the mullite powder is an excellent catalyst and catalyst carrier, especially for hydrocarbon cracking catalysts.
Inventors
- 👤 Khodabakhsh S Mazdiyasni
- 👤 Leanne M Brown
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 16:15
CPC Classifications
C; C01; C01B; C01B33/00; C01B33/20; C01B33/36; C01B33/38; C01B33/42; C01B33/26; C01B33/40; C01B33/46; C04; C04B; C04B35/00; C04B35/01; C04B35/16; C04B35/18; C10; C10G; C10G47/00; C10G47/02; C10G47/10; C10G47/12
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
178 words
A PROCESS FOR PREPARING MULLITE WHICH COMPRISES THE STEPS OF: A. ADDING A MIXTURE OF ALUMINUM TRIS ISOPROPOXIDE AND A SILICON ALKOXIDE IN A MOL RATION OF 3 TO 1 AN ALCOHOL, THE SILICON ALKOXIDE BEING SELECTED FROM THE GROUP CONSISTING OF THOSE HAVING THE FORMULA SI(OR)4, WHEREIN R IS METHYL, ETHYL, ISOPROPYL OR N-BUTYL AND THE ALCOHOL BEING SELECTED FROM THE GROUP CONSISTING OF THOSE HAVING THE FORMULA ROH, THE ALCOHOL SELECTED HAVING THE SAME R GROUP AS THE SELECTED SILICON ALKOXIDE; B. REFLECTING THE RESULTING SOLUTION FOR FROM ABOUT 8 TO 24 HOURS; C. ADDING THE SOLUTION TO A DILUTE SOLUTION OF A WEAK BASE OR MINERAL ACID, THEREBY FORMING HYDROXYALUMINOSILICATE, THE SOLUTION OF THE WEAK BASE CONTAINING FROM ABOUT 0.25 TO 5 MILLILITERS OF A SATURATED SOLUTION OF THE WEAK BASE PER MOL OF WATER AND THE SOLUTION OF THE MINERAL ACID CONTAINING ABOUT 2 TO 5 DROPS OF ACID PER MOL OF WATER; D. WASHING THE HYDROXYALUMINOSILICATE WITH ISOJPROPYL ALCOHOL; AND E. DRYING THE WASHED HYDROXYALUMINOSILICATE UNDER A VACUUM, THEREBY CONVERTING IT TO MULLITE.
Claim 2
Dependent Claim
178 words
A PROCESS FOR PREPARING MULLITE WHICH COMPRISES THE STEPS OF: A. ADDING A MIXTURE OF ALUMINUM TRIS ISOPROPOXIDE AND A SILICON ALKOXIDE IN A MOL RATION OF 3 TO 1 AN ALCOHOL, THE SILICON ALKOXIDE BEING SELECTED FROM THE GROUP CONSISTING OF THOSE HAVING THE FORMULA SI(OR)4, WHEREIN R IS METHYL, ETHYL, ISOPROPYL OR N-BUTYL AND THE ALCOHOL BEING SELECTED FROM THE GROUP CONSISTING OF THOSE HAVING THE FORMULA ROH, THE ALCOHOL SELECTED HAVING THE SAME R GROUP AS THE SELECTED SILICON ALKOXIDE; B. REFLECTING THE RESULTING SOLUTION FOR FROM ABOUT 8 TO 24 HOURS; C. ADDING THE SOLUTION TO A DILUTE SOLUTION OF A WEAK BASE OR MINERAL ACID, THEREBY FORMING HYDROXYALUMINOSILICATE, THE SOLUTION OF THE WEAK BASE CONTAINING FROM ABOUT 0.25 TO 5 MILLILITERS OF A SATURATED SOLUTION OF THE WEAK BASE PER MOL OF WATER AND THE SOLUTION OF THE MINERAL ACID CONTAINING ABOUT 2 TO 5 DROPS OF ACID PER MOL OF WATER; D. WASHING THE HYDROXYALUMINOSILICATE WITH ISOJPROPYL ALCOHOL; AND E. DRYING THE WASHED HYDROXYALUMINOSILICATE UNDER A VACUUM, THEREBY CONVERTING IT TO MULLITE.
Claim 3
Dependent Claim
32 words
The process according to claim 1 in which the solution of the mixture of aluminum tris isopropoxide and silicon alkoxide in the alcohol is added to a dilute solution of ammonium hydroxide.
Claim 4
Dependent Claim
21 words
The process according to claim 2 in which the silicon alkoxide is silicon tetrakis methoxide and the alcohol is methyl alcohol.
Claim 5
Dependent Claim
21 words
The process according to claim 2 in which the silicon alkoxide is silicon tetrakis ethoxide and the alcohol is ethyl alcohol.
Claim 6
Dependent Claim
21 words
The process according to claim 2 in which the silicon alkoxide is silicon tetrakis isopropoxide and the alcohol is isopropyl alcohol.
Claim 7
Dependent Claim
32 words
The process according to claim 1 in which the solution of the mixture of aluminum tris isopropoxide and silicon alkoxide in the alcohol is added to a dilute solution of nitric acid.
Claim 8
Dependent Claim
21 words
The process according to claim 6 in which the silicon alkoxide is silicon tetrakis isopropoxide and the alcohol is isopropyl alcohol.
Claim 9
Dependent Claim
21 words
The process according to claim 6 in which the silicon alkoxide is silicon tetrakis butoxide and the alcohol is n-butyl alcohol.
Claim 10
Dependent Claim
44 words
The process according to claim 1 in which the hydroxyaluminosilicate is dried by heating same under a vacuum at a temperature ranging from about 55* to 65*C for a period of time sufficient to distill off any isopropyl alcohol and water that is formed.
Claim 11
Dependent Claim
41 words
The process according to claim 1 in which the mullite is calcined at a temperature in the range of about 500* to 700*C for a period of about 1 to 24 hours, thereby providing acicular particulates having an orthorhombic crystalline structure.
Claim 12
Dependent Claim
58 words
The process according to claim 10 in which the calcined mullite particulates are compressed under a vacuum for a period of about 15 to 60 minutes under a pressure of about 3 to 5 thousand pounds per square inch and at a temperature of about 1300* to 1600*C, thereby producing a highly dense, translucent, polycrystalline body of mullite.
Claim 13
Dependent Claim
25 words
The process according to claim 11 in which the vacuum ranges from about 5 X 10 4 to 5 X 10 3 mm of Hg.
References Cited (Backward Citations)
US2389352A
Cited
US3336108A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-11-24 | 1979-05-26 | 1979-11-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-24 | 1983-05-26 | 1983-11-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-24 | 1987-05-26 | 1987-11-25 | $7700.00 | Window Closed / Lapsed |