US5686031A
Expired / Lapsed
US
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Method for rapidly producing microporous and mesoporous materials
Assignee: University of California
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Filing: 1995-01-05
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Granted: 1997-11-11
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Expires: 2015-01-05
Abstract
Abstract An improved, rapid process is provided for making microporous and mesoporous materials, including aerogels and pre-ceramics. A gel or gel precursor is confined in a sealed vessel to prevent structural expansion of the gel during the heating process. This confinement allows the gelation and drying processes to be greatly accelerated, and significantly reduces the time required to produce a dried aerogel compared to conventional methods. Drying may be performed either by subcritical drying with a pressurized fluid to expel the liquid from the gel pores or by supercritical drying. The rates of heating and decompression are significantly higher than for conventional methods.
Inventors
- 👤 Paul R. Coronado
- 👤 John F. Poco
- 👤 Lawrence W. Hrubesh
- 👤 Robert W. Hopper
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 01:40
CPC Classifications
C; C01; C01B; C01B33/00; C01B33/113; C01B33/12; C01B33/14; C01B33/157; C01B33/158; C01B33/1585; B; B01; B01J; B01J13/00; B01J13/02; B29; B29C; B29C67/00; B29C67/20; B29C67/202; C03; C03B; C03B19/00; C03B19/08; C03B19/12; C03C; C03C11/00; C04; C04B; C04B38/00; C04B38/0045
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
53 words
A process for rapidly producing open-pore microporous or mesoporous materials, comprising: heating a gel precursor solution or a pre-formed gel while confining its physical expansion by providing a sealed vessel having interior walls with the gel or gel precursor substantially filling the vessel's entire internal volume, controllably releasing internal pressure from the vessel.
Claim 2
Dependent Claim
53 words
A process for rapidly producing open-pore microporous or mesoporous materials, comprising: heating a gel precursor solution or a pre-formed gel while confining its physical expansion by providing a sealed vessel having interior walls with the gel or gel precursor substantially filling the vessel's entire internal volume, controllably releasing internal pressure from the vessel.
Claim 3
Dependent Claim
15 words
The process as recited in claim 1, wherein the precursor comprises a metal alkoxide solution.
Claim 4
Dependent Claim
22 words
The process as recited in claim 1, wherein the gel precursor forms a gel in situ in the sealed vessel during heating.
Claim 5
Dependent Claim
31 words
The process as recited in claim 3, wherein the pre-formed gel or in situ gel expands slightly during heating to form a seal against the internal walls of the sealed vessel.
Claim 6
Dependent Claim
25 words
The process as recited in claim 3, wherein the pre-formed gel or in situ gel is selected from the group consisting of alcogels and hydrogels.
Claim 7
Dependent Claim
35 words
The process as recited in claim 3, wherein the pre-formed gel or in situ gel contains a liquid in its pores, and further comprising removing the pore liquid to form the microporous or mesoporous material.
Claim 8
Dependent Claim
31 words
The process as recited in claim 6, wherein the microporous or mesoporous material is selected from the group consisting of inorganic aerogels, organic aerogels, porous glasses, xerogels, polymer foams, and pre-ceramics.
Claim 9
Dependent Claim
52 words
The process as recited in claim 6, wherein removing the pore liquid is carried out by heating the gel to a subcritical point of the pore liquid, applying a pressurized fluid to at least one side of the gel to replace the pore liquid, and removing the pore liquid from the vessel.
Claim 10
Dependent Claim
24 words
The process as recited in claim 8, further comprising removing the pressurized fluid from the gel and the vessel to form the porous material.
Claim 11
Dependent Claim
23 words
The process as recited in claim 9, further comprising purging with a gas or evacuating the porous material after removing the pressurized fluid.
Claim 12
Dependent Claim
52 words
The process as recited in claim 9, wherein the pressurized fluid is a liquid, and removing the pressurized fluid is carried out by heating the liquid to above the supercritical point to form a supercritical fluid, and removing the supercritical fluid from the gel and the vessel to form the porous material.
Claim 13
Dependent Claim
23 words
The process as recited in claim 8, wherein the pressurized fluid is selected from the group consisting of gases, liquids, and supercritical fluids.
Claim 14
Dependent Claim
27 words
The process as recited in claim 8, wherein the pressurized fluid is selected from the group consisting of carbon dioxide, nitrous oxide, air, helium, propane, and freons.
Claim 15
Dependent Claim
33 words
The process as recited in claim 8, wherein the pressurized fluid is a supercritical fluid, and further comprising removing the supercritical fluid from the gel and the vessel to form the porous material.
Claim 16
Dependent Claim
25 words
The process as recited in claim 6, wherein the porous material is selected from the group consisting of cracked gels, pellets, monoliths, powders, and granules.
Claim 17
Dependent Claim
49 words
The process as recited in claim 6, wherein removing the pore liquid is carried out by heating the gel to above the supercritical point of the pore liquid to form a supercritical fluid, and removing the supercritical fluid from the gel and the vessel to form the porous material.
Claim 18
Dependent Claim
32 words
The process as recited in claim 16, wherein the supercritical fluid is selected from the group consisting of water, carbon dioxide, nitrous oxide, propane, freons, alcohols, ketones, ethers, amines, and nitrated hydrocarbons.
Claim 19
Dependent Claim
23 words
The process as recited in claim 16, further comprising purging with a gas or evacuating the porous material after removing the supercritical fluid.
Claim 20
Dependent Claim
25 words
The process as recited in claim 16, wherein the average rate of removing the supercritical fluid from the vessel exceeds three (3) psi per minute.
Claim 21
Dependent Claim
59 words
A process for rapidly producing open-pore microporous or mesoporous materials, comprising: heating a gel precursor solution or a pre-formed gel while confining its physical expansion by providing a mold of desired dimensions within a sealed vessel, wherein the mold and the gel or gel precursor substantially fill the vessel's entire internal volume, controllably releasing internal pressure from the vessel.
Claim 22
Dependent Claim
59 words
A process for rapidly producing open-pore microporous or mesoporous materials, comprising: heating a gel precursor solution or a pre-formed gel while confining its physical expansion by providing a mold of desired dimensions within a sealed vessel, wherein the mold and the gel or gel precursor substantially fill the vessel's entire internal volume, controllably releasing internal pressure from the vessel.
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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) | 2000-11-10 | 2001-05-12 | 2001-11-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-11-10 | 2005-05-12 | 2005-11-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-11-10 | 2009-05-12 | 2009-11-11 | $7700.00 | Window Closed / Lapsed |