Composite gas separation membranes and making thereof
AssigneeUop LLC
InventorMan-Wing Tse Tang
Life of this patent
Estimating the term…
Abstract
A composite membrane made of an asymmetric porous support and an ultrathin layer having a thickness of less than 100 nm is provided. A method of making the membrane and method for carrying out gas separations using the membrane are also provided.
Claims37
A composite membrane comprising a porous asymmetric support having a first and a second surface area, said first surface area contacting an ultrathin polymer layer with a thickness less than 100 nm, said first surface area having an average pore diameter of about 5 nm to about 20 nm, and said second surface area having a pore diameter greater than that of the first surface area.
A process for making a composite gas separation membrane comprising the following steps:
- (A) Providing a base support having a first planar surface;
- (B) Forming on said first planar surface an asymmetric porous support, such asymmetric porous support comprising mutually coplanar first and second regions, the thickness of said first region being substantially greater than the thickness of said second region, said first region having a microporous structure and being placed adjacent to said first planar surface, said second region having a high density of pores having an average diameter of less than about 1,000 .ANG.ngstroms, said second region comprising a first surface integrally connected to said first region and a second surface;
- (C) Preparing a dissolved polymer solution comprising (1) at least one 6FDA-type polyimide polymer having been formed by the dehydration of the condensation reaction product of at least one aromatic dianhydride and at least one aromatic diamine;
- and (2) a solvent for the polyimide polymer which is immiscible with a selected liquid, said selected liquid being a nonsolvent for the polyimide polymer and having a higher surface tension than said dissolved polymer solution;
- (D) Providing a bath containing a pool of said selected liquid, said pool having a smooth surface with high surface tension;
- means for depositing the dissolved polymer solution onto said smooth surface at a deposition point;
- and means for conveying the smooth surface away from the deposition point;
- (E) Depositing said dissolved polymer solution onto said smooth surface, and removing the solvent from the dissolved polymer solution to yield an ultrathin 6-FDA type polyimide polymer selective membrane film having a leading edge, being the farthest-most edge of said polymer film floating away from said deposition point on said smooth surface, which leading edge is conveyed by the smooth surface away from the deposition point;
- (F) Conveying said asymmetric porous support into a position so that said second surface is adjacent to said leading edge;
- and (G) Picking up said leading edge onto said second surface and conveying said second surface tangentially away from said smooth surface;
- yielding a composite membrane comprising an ultrathin 6FDA-type polyimide polymer selective membrane film.
Dependencies are inferred from the claim text.