US3761571A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Production of ceria
Assignee: United Kingdom Atomic Energy Authority
•
Filing: 1971-02-04
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Granted: 1973-09-25
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Expires: 1991-02-04
Abstract
Abstract Control over physical characteristics of product ceria is provided by a new process in the manufacture of ceria from cerium IV hydroxide. A slurry of the cerium IV hydroxide in water is treated with nitric acid and heated until the pH, which is controlled to be ultimately less than 5.4, reaches a steady value. The slurry thus conditioned is dried to give a dry gel powder.
Inventors
- 👤 J Woodhead
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 11:04
CPC Classifications
C; C01; C01F; C01F17/00; C01F17/20; C01F17/206; C01F17/224; C01F17/235; C01P; C01P2004/00; C01P2004/30; C01P2004/32; C01P2004/60; C01P2004/61; C01P2006/00; C01P2006/10; C01P2006/60
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
56 words
A process as claimed in claim 1, wherein the cerium IV hydroxide is prepared for use in the process by precipitation from a solution of a cerium salt, and washing until the final wash water has a specific conductivity of not greater than 5 X 103 Mu mhos and a pH value between 7 and 8.5.
Claim 2
Dependent Claim
30 words
A process as claimed in claim 1, wherein the nitric acid is in a quantity for the steady value of pH reached after heating to be not less than 3.8.
Claim 3
Dependent Claim
30 words
A process as claimed in claim 1, wherein the nitric acid is in a quantity for the steady value of pH reached after heating to lie between 3.8 and 4.4.
Claim 4
Dependent Claim
29 words
A process as claimed in claim 1, wherein the nitric acid is in a quantity for the steady value of pH reached after heating to be less than 1.5.
Claim 5
Dependent Claim
25 words
A process as claimed in claim 1, wherein heating of the slurry is carried out in the region of 100*C for at least 1 hour.
Claim 6
Dependent Claim
25 words
A process as claimed in claim 1, wherein, prior to drying, the conditioned slurry is allowed to settle and is separated from the supernatant liquor.
Claim 7
Dependent Claim
30 words
A process as claimed in claim 1, wherein the quantity of nitric acid lies in the range 0.25 to 1.00 mole of nitric acid per mole of cerium IV hydroxide.
Claim 8
Dependent Claim
28 words
A process as claimed in claim 1, wherein the dry gel powder is treated with more nitric acid, heated and evaporated to dryness to give a gel product.
Claim 9
Dependent Claim
39 words
A process as claimed in claim 9, wherein said gel product is dispersed in water, the nitric acid concentration is adjusted to cause coagulation, the supernatant liquor is removed, and the coagulated material dried to give a transparent gel.
Claim 10
Dependent Claim
37 words
A process as claimed in claim 10, wherein said transparent gel is dispersed in water to form a sol, the sol is suspended in an organic phase and water extracted from the suspended sol to produce spheres.
Claim 11
Dependent Claim
35 words
A process as claimed in claim 10, wherein said transparent gel is dispersed in water to form a sol, and nitric acid is extracted from the sol to produce as a precipitate an acid-deficient gel.
Claim 12
Dependent Claim
31 words
A process as claimed in claim 12, wherein prior to extraction of nitric acid, the sol is suspended in an organic phase, whereby, upon extraction of nitric acid, spheres are produced.
Claim 13
Dependent Claim
17 words
A process as claimed in claim 1 wherein the dry gel powder is calcined to give ceria.
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) | 1976-09-24 | 1977-03-26 | 1977-09-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-24 | 1981-03-26 | 1981-09-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-24 | 1985-03-26 | 1985-09-25 | $7700.00 | Window Closed / Lapsed |