Polybenzimidazole hollow fiber membranes and method for making an asymmetric hollow fiber membrane

Patent metadata

Field	Value
Publication number	US-10071345-B2
Application number	US-201615190011-A
Country	US
Kind code	B2
Filing date	Jun 22, 2016
Priority date	Jun 23, 2015
Publication date	Sep 11, 2018
Grant date	Sep 11, 2018

Abstract

This disclosure concerns methods for formation of a novel PBI asymmetric hollow fiber membrane and its application for gas separations, gas/vapor separations, gas/liquid separations (i.e., pervaporation), and liquid separations including solute molecule removal from organic solvents and water.

First claim

We claim:

1. A method for making an asymmetric polybenzimidazole hollow fiber membrane, comprising:
(a) preparing a polymer dope comprising (i) a polybenzimidazole (PBI) polymer; (ii) a dope stabilizing agent; and (iii) a mixture of a primary solvent A and acetonitrile;
(b) preparing a bore fluid comprising a solvent/non-solvent C, a solvent/non-solvent D, or a mixture thereof;
(c) extruding the polymer dope and the bore fluid through an annulus and an inner tube, respectively, of a tube-in-orifice spinneret to form an extruded hollow fiber;
(d) optionally subsequently passing the extruded hollow fiber through an air gap, wherein the air gap comprises an atmosphere with relative humidity in the range of 0-100%; and
(e) coagulating the extruded hollow fiber in a coagulation bath comprising a solvent/non-solvent E and/or a solvent/non-solvent F to provide an asymmetric PBI hollow fiber membrane comprising an integral selective layer in intimate contact with a porous support structure.

2. The method for making an asymmetric polybenzimidazole hollow fiber membrane of claim 1 , wherein:
the PBI polymer comprises recurring units of Formula 1, Formula 2, or a combination thereof, wherein Formula 1is

wherein R 1 is a tetravalent aromatic moiety and the nitrogen atoms of Formula I form a benzimidazole moiety with adjacent carbon atoms of R 1 , and R 2 is (1) an aromatic ring, (2) an alkylene group, or (3) a heterocyclic ring from the group consisting of a) pyridine, b) pyrazine, c) furan, d) quinolone, and e) thiophene, and
wherein Formula 2 is:

wherein Z is an aromatic moiety and the nitrogen atoms of Formula 2 form a benzimidazole moiety with adjacent carbon atoms of Z.

3. The method for making an asymmetric polybenzimidazole hollow fiber membrane of claim 2 , wherein:
R 1 is phenyl, diphenyl, diphenylsulfone, diphenylether, diphenyl hexafluoropropane, naphthalene,

 and
R 2 and Z independently are phenyl, diphenyl, diphenylsulfone, diphenylether, diphenyl hexafluoropropane, naphthalene, cyclohexene,

4. The method for making an asymmetric polybenzimidazole hollow fiber membrane of claim 1 , wherein the PBI polymer has a chemical structure

wherein n is any integer >0.

5. The method for making an asymmetric polybenzimidazole hollow fiber membrane of claim 1 , wherein the polymer dope comprises:
(i) 10-26wt. % of the PBI polymer;
(ii) 0.1-10wt. % of the dope stabilizing agent, wherein the dope stabilizing agent is an inorganic salt, an ionic liquid, or an organic polymer; or
(iii) both (i) and (ii).

6. The method for making an asymmetric polybenzimidazole hollow fiber membrane of claim 1 , wherein:
(i) the primary solvent A comprises a polar aprotic solvent;
(ii) the solvent/non-solvent C comprises a ketone, an organic nitrile, an alcohol, or a combination thereof, and the solvent/non-solvent D comprises a polar aprotic solvent, an ionic liquid, or a combination thereof;
(iii) the solvent/non-solvent E comprises an alcohol, a ketone, an ester, a C6 alkane, an organic nitrile, water, or any combination thereof, and the solvent/non-solvent F comprises a polar aprotic solvent, an ionic liquid, or any combination thereof; or
(iv) any combination of (i), (ii), and (iii).

7. The method for making an asymmetric polybenzimidazole hollow fiber membrane of claim 1 , wherein the bore fluid and the polymer dope have a flow rate ratio in a range of 0.5 to 5.

8. The method for making an asymmetric polybenzimidazole hollow fiber membrane of claim 1 , wherein a length of the air gap and a flow rate of the extruded hollow fiber through the spinneret are selected to provide a residence time of the extruded hollow fiber in the air gap of from greater than 0 seconds to 20 seconds.

9. The method for making an asymmetric polybenzimidazole hollow fiber membrane of claim 1 , further comprising:
performing one or more sequential solvent exchanges with one or more solvents/non-solvents E, one or more solvents/non-solvents, F, or any combination thereof; and
drying the PBI hollow fiber membrane.

10. A method for making an asymmetric polybenzimidazole hollow fiber membrane, comprising:
(a) preparing a polymer dope comprising (i) a polybenzimidazole (PBI) polymer; (ii) a dope stabilizing agent; and (iii) a mixture of a primary solvent A and a secondary solvent/non-solvent B;
(b) preparing a bore fluid comprising a solvent/non-solvent C, a solvent/non-solvent D, or a mixture thereof;
(c) extruding the polymer dope and the bore fluid through an annulus and an inner tube, respectively, of a tube-in-orifice spinneret to form an extruded hollow fiber;
(d) optionally subsequently passing the extruded hollow fiber through an air gap, wherein the air gap comprises an atmosphere with relative humidity in the range of 0-100%;
(e) coagulating the extruded hollow fiber in a coagulation bath comprising a solvent/non-solvent E and/or a solvent/non-solvent F to provide an asymmetric PBI hollow fiber membrane comprising an integral selective layer in intimate contact with a porous support structure; and
(f) depositing a sealing layer on the integral selective layer, the sealing layer comprising a protective PBI polymer having a higher gas permeability than the PBI polymer of the polymer dope.

11. The method for making an asymmetric polybenzimidazole hollow fiber membrane of claim 10 , further comprising annealing the PBI hollow fiber membrane at a temperature within a range of 300 to 450° C. before depositing the sealing layer.

12. The method for making an asymmetric polybenzimidazole hollow fiber membrane of claim 10 , wherein the protective PBI polymer comprises a plurality of repeating units of Formula 1, Formula 2, or a combination thereof, wherein Formula 1 is

wherein R 1 is a tetravalent aromatic moiety and the nitrogen atoms of Formula I form a benzimidazole moiety with adjacent carbon atoms of R 1 , and R 2 is (1) an aromatic ring, (2) an alkylene group, or (3) a heterocyclic ring from the group consisting of a) pyridine, b) pyrazine, c) furan, d) quinolone, and e) thiophene, and
wherein Formula 2 is:

wherein Z is an aromatic moiety and the nitrogen atoms of Formula 2 form a benzimidazole moiety with adjacent carbon atoms of Z.

13. The method for making an asymmetric polybenzimidazole hollow fiber membrane of claim 12 , wherein the protective PBI polymer comprises a plurality of repeating units of Formula I and at least one of R 1 and R 2 is

14. The method for making an asymmetric polybenzimidazole hollow fiber membrane of claim 1 , further comprising:
(i) annealing the PBI hollow fiber membrane at a temperature within a range of 250 to 600° C.;
(ii) crosslinking the PBI hollow fiber membrane with a crosslinking agent comprising 1,4-C 6 H 4 XY, where X and Y independently a

Assignees

• Los Alamos Nat Security Llc

Inventors

• Berchtold Kathryn A
• Dudeck Kevin W
• Singh Rajinder P
• Dahe Ganpat J

Classifications

• B01D2323/30

  Cross-linking · CPC title

• C02F1/448

  by pervaporation · CPC title

• B01D2325/20

  Specific permeability or cut-off range · CPC title

• B01D2257/504

  Carbon dioxide · CPC title

• B01D2325/022

  Asymmetric membranes · CPC title