Composite separation membranes and the preparation and use thereof
First Claim
Patent Images
1. A process for repairing a composite membrane suitable for gas, pervaporation or prestructure separations comprising a separation layer that determines the separation characteristics of the membrane and a porous support layer, said separation layer containing imperfections therein, said process consisting essentially of:
- (a) contacting said separation layer with a volatile post-treatment solution system comprising a volatile solvent having essentially non-solvent or mild swelling characteristics with respect to the composite membrane materials, said solvent containing minute amounts of non-volatile additives as it contacts and fills said imperfections; and
(b) evaporating said volatile solvent from the composite membrane, said minute amounts of additives remaining in and serving to plug preferentially and essentially said imperfections only,whereby the post-treatment process serves to effectively repair the separation layer of the composite membrane, enhancing the selectivity thereof and enabling advantageous combinations of selectivity and permeability to be achieved by the use thereof.
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Abstract
Composite membranes are post-treated by contact with a volatile solvent, with or without minute amounts of additives, followed by solvent evaporation, to repair defects in the thin separation layer thereof.
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Citations
28 Claims
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1. A process for repairing a composite membrane suitable for gas, pervaporation or prestructure separations comprising a separation layer that determines the separation characteristics of the membrane and a porous support layer, said separation layer containing imperfections therein, said process consisting essentially of:
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(a) contacting said separation layer with a volatile post-treatment solution system comprising a volatile solvent having essentially non-solvent or mild swelling characteristics with respect to the composite membrane materials, said solvent containing minute amounts of non-volatile additives as it contacts and fills said imperfections; and (b) evaporating said volatile solvent from the composite membrane, said minute amounts of additives remaining in and serving to plug preferentially and essentially said imperfections only, whereby the post-treatment process serves to effectively repair the separation layer of the composite membrane, enhancing the selectivity thereof and enabling advantageous combinations of selectivity and permeability to be achieved by the use thereof. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A post-treated composite membrane suitable for gas, pervaporation or prestructure separations comprising a separation layer that determines the separation characteristics of the membrane and a porous support layer, said separation layer containing imperfections that are plugged by minute amounts of additives, said composite membrane having been post-treated for the repair of said imperfections by a process consisting essentially of:
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(a) contacting said separation layer with a volatile post-treatment solution system comprising a volatile solvent having essentially non solvent or mild swelling characteristics with respect to the composite membrane materials, said solvent containing minute amounts of non-volatile additives as it contacts and fills said imperfections; and (b) evaporating said volatile solvent from the composite membrane, said minute amounts of additives remaining in and serving to plug preferentially and essentially said imperfections only, whereby the post-treatment process serves to repair the separation layer of the composite membrane, enhancing the selectivity thereof and enabling advantageous combinations of selectivity and permeability to be achieved by the use thereof. - View Dependent Claims (18, 19, 20, 21)
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22. An improved process for the separation of a more permeable component of a fluid feed mixture from a less permeable component thereof by gas, pervaporation or perstructure separations, including contacting said feed mixture with the feed side of a composite membrane suitable for gas, pervaporation or prestructure separation operations, and separately withdrawing said more permeable component as a permeate stream and said less permeable component as a non-permeate stream, said composite membrane having a separation layer that determines the separation characteristics of the membrane and a porous support layer, said composite membrane having been post-treated by a process consisting of:
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(a) contacting said separation layer with a volatile post-treatment solution system comprising a volatile solvent having essentially non-solvent or mild swelling characteristics with respect to the composite membrane materials, said solvent containing minute amounts of non-volatile additives as it contacts and fills said imperfections; and (b) evaporating said volatile solvent from the composite membrane, said minute amounts of additives remaining in and serving to plug preferentially and essentially said imperfections only, whereby the post-treatment process serves to repair the separation layer of the composite membrane, enhancing the selectivity thereof and enabling advantageous combinations of selectivity and permeability to be achieved in said separation process. - View Dependent Claims (23, 24, 25, 26, 27, 28)
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Specification