US4452909A
Expired / Lapsed
US
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Process for coating crystalline silica polymorphs
Assignee: EIDP Inc
•
Filing: 1982-09-13
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Granted: 1984-06-05
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Expires: 2002-09-13
Abstract
Abstract Process for coating crystalline silica polymorphs such as silicalites and zeolites with amorphous silica using alkali metal silicates as the source of silica.
Inventors
- 👤 Duck J. Yang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 21:35
CPC Classifications
C; C07; C07C; C07C2/00; C07C2/02; C07C2/04; C07C2/06; C07C2/08; C07C2/12; B; B01; B01J; B01J21/00; B01J21/06; B01J21/08; B01J29/00; B01J29/03; B01J29/035; B01J29/88; B01J37/00; B01J37/02; B01J37/0215; B01J37/0217; C07C2/86; C07C2/862; C07C2/864; B01J2229/00; B01J2229/10; B01J2229/12; B01J2229/30; B01J2229/32; C07C2521/00; C07C2521/06; C07C2521/08; C07C2529/00; C07C2529/03; C07C2529/035; C07C2529/04; C07C2529/06; Y; Y02; Y02P; Y02P20/00; Y02P20/50; Y02P20/52; Y10; Y10S; Y10S423/00; Y10S423/22
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
70 words
A process for coating a crystalline silica polymorph with essentially amorphous silica which comprises contacting the silica having the external part of at least a portion of the channels in the crystalline silica polymorph occupied with a blocking compound with an aqueous solution of an alkali metal silicate for a period of about 5 minutes to about 11/2 hours while maintaining the pH of the solution in the range 7.5-11.5.
Claim 2
Dependent Claim
70 words
A process for coating a crystalline silica polymorph with essentially amorphous silica which comprises contacting the silica having the external part of at least a portion of the channels in the crystalline silica polymorph occupied with a blocking compound with an aqueous solution of an alkali metal silicate for a period of about 5 minutes to about 11/2 hours while maintaining the pH of the solution in the range 7.5-11.5.
Claim 3
Dependent Claim
12 words
The process of claim 1 wherein the crystalline silica is a silicalite.
Claim 4
Dependent Claim
11 words
The process of claim 1 wherein the silica is a zeolite.
Claim 5
Dependent Claim
14 words
The process of claim 1 wherein the pH is maintained in the range 7.5-10.5.
Claim 6
Dependent Claim
18 words
The process of claim 1 wherein the blocking compound is the template employed to prepare the silica polymorph.
Claim 7
Dependent Claim
24 words
The process of claims 1, 2, 3, 4 or 5 wherein the temperature of the aqueous solution is maintained in the range 70-90° C.
Claim 8
Dependent Claim
102 words
A process for preparing a crystalline silica polymorph coated with amorphous silica which comprises initiating crystallization of silica in a crystallization medium in the presence of a template compound to produce said polymorph, separating the resulting polymorph from the crystallization medium without removing a significant amount of the template compound from the channels in the polymorph, contacting the thus obtained polymorph with an aqueous solution of an alkali metal silicate for a period up to 11/2 hours while maintaining the pH of the solution in the range 7.5-10.5 and thereafter separating the unreacted silicate from the polymorph and removing the template compound.
Claim 9
Dependent Claim
102 words
A process for preparing a crystalline silica polymorph coated with amorphous silica which comprises initiating crystallization of silica in a crystallization medium in the presence of a template compound to produce said polymorph, separating the resulting polymorph from the crystallization medium without removing a significant amount of the template compound from the channels in the polymorph, contacting the thus obtained polymorph with an aqueous solution of an alkali metal silicate for a period up to 11/2 hours while maintaining the pH of the solution in the range 7.5-10.5 and thereafter separating the unreacted silicate from the polymorph and removing the template compound.
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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) | 1987-06-05 | 1987-12-05 | 1988-06-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-06-05 | 1991-12-05 | 1992-06-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-06-05 | 1995-12-05 | 1996-06-05 | $7700.00 | Window Closed / Lapsed |