Manufacture of porous carbon membranes
First Claim
1. 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., andcarbonizing said membrane in a temperature range of 600°
to 3000°
C., whereby clogging of the pores in said membrane is prevented.
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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.
28 Citations
11 Claims
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1. 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:
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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., andcarbonizing said membrane in a temperature range of 600°
to 3000°
C., whereby clogging of the pores in said membrane is prevented. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification