US4919860A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Manufacture of porous carbon membranes
Assignee: Akzo NV
•
Filing: 1988-07-13
•
Granted: 1990-04-24
•
Expires: 2008-07-13
Abstract
Abstract The invention relates to a process for making porous carbon membranes and membranes which can made by this process. As starting material, a porous membrane from an acrylonitril-polymer is used. The starting material is pretreated with a hydrazine solution, followed by preoxidation and carbonization. The process enables carbon membranes to be made with selectively adjusted pore sizes and tight pore size distribution. The pore sizes can lie in the ultrafiltration or microfiltration range. The membranes are suitable for separation processes, in which chemically aggressive media are used and for high-temperature processes. They can be used wherever electrical conductivity of the membranes is required.
Inventors
- 👤 Erich Schindler
- 👤 Franz Maier
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 10:43
CPC Classifications
B; B01; B01D; B01D67/00; B01D67/0039; B01D67/0067; B01D69/00; B01D69/02; B01D69/08; B01D69/085; B01D71/00; B01D71/02; B01D71/021; B01J; B01J35/00; B01J35/50; B01J35/58; B01J35/59; C; C04; C04B; C04B35/00; C04B35/515; C04B35/52; C04B35/524; C04B38/00; C04B38/0022; D; D01; D01F; D01F9/00; D01F9/08; D01F9/12; D01F9/14; D01F9/20; D01F9/21; D01F9/22; B01D2323/00; B01D2323/08; B01D2323/081; C04B2111/00; C04B2111/00474; C04B2111/00793; C04B2111/00801
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
107 words
A process for making porous carbon membranes having a porosity of from 10 to 90% and having maximum pore diameter of from 0.005 to 3 microns in the form of capillary, tubular, or flat membranes and comprising more than 75 weight percent of carbon, comprising: pretreating a porous membrane from an acrylonitrile polymer in an aqueous hydrazine solution containing at least 40 weight percent of hydrazine, washing and drying said membrane, heat treating said membrane in a temperature range of 180° to 350° C., and carbonizing said membrane in a temperature range of 600° to 3000° C., whereby clogging of the pores in said membrane is prevented.
Claim 2
Dependent Claim
107 words
A process for making porous carbon membranes having a porosity of from 10 to 90% and having maximum pore diameter of from 0.005 to 3 microns in the form of capillary, tubular, or flat membranes and comprising more than 75 weight percent of carbon, comprising: pretreating a porous membrane from an acrylonitrile polymer in an aqueous hydrazine solution containing at least 40 weight percent of hydrazine, washing and drying said membrane, heat treating said membrane in a temperature range of 180° to 350° C., and carbonizing said membrane in a temperature range of 600° to 3000° C., whereby clogging of the pores in said membrane is prevented.
Claim 3
Dependent Claim
20 words
The process as set forth in claim 1, wherein said aqueous solution contains 50 to 65 weight percent of hydrazine.
Claim 4
Dependent Claim
25 words
The process as set forth in claim 1, wherein the pretreatment lasts 15 to 60 minutes in a temperature range of 60° to 90° C.
Claim 5
Dependent Claim
34 words
The process as set forth in claim 1, further comprising evacuating the pores of the membrane by reduction of pressure and refilling said pores with nitrogen gas at normal pressure prior to the pretreatment.
Claim 6
Dependent Claim
21 words
The process as set forth in claim 1, wherein said membrane from an acrylic polymer is unstretched or only partly stretched.
Claim 7
Dependent Claim
28 words
The process as set forth in claim 1, wherein at least one of the heat treatment and the carbonization is carried out with complete or extensive shrinkage prevention.
Claim 8
Dependent Claim
21 words
The process as set forth in claim 1, wherein the carbonization is carried out in a nitrogen or noble gas atmosphere.
Claim 9
Dependent Claim
21 words
The process as set forth in claim 1, wherein the heat treatment is carried out in an air or oxygen atmosphere.
Claim 10
Dependent Claim
24 words
The process as set forth in claim 1, wherein the heat treatment is carried out in a temperature range of 200° to 250° C.
Claim 11
Dependent Claim
23 words
The process as set forth in claim 1, wherein the carbonization is carried out in a temperature range of 800° to 1600° C.
Claim 12
Dependent Claim
33 words
The process as set forth in claim 1, wherein the carbon membrane produced has a porosity of 50 to 80% and a maximum pore diameter in the range of 0.01 to 1.5 microns.
References Cited (Backward Citations)
US3615024A
Cited
DE1954505A1
Cited
US3674628A
Cited
GB1329245A
Cited
US3769390A
Cited
US3977967A
Cited
US4042359A
Cited
DE2462567A1
Cited
DE2614391A1
Cited
US4073870A
Cited
US4341631A
Cited
JPH05263428A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-04-23 | 1993-10-23 | 1994-04-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-04-23 | 1997-10-23 | 1998-04-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-04-23 | 2001-10-23 | 2002-04-24 | $7700.00 | Window Closed / Lapsed |