Metallopolyimide precursor fibers for aging-resistant carbon molecular sieve hollow fiber membranes with enhanced selectivity

• US 10,143,973 B2
• Filed: 06/30/2016
• Issued: 12/04/2018
• Est. Priority Date: 06/30/2016
• Status: Active Grant

• Current Assignee: L'Air Liquide Societe Anonyme Pour L'Etude et L'Exploitation Des Procedes Georges Claude (L'Air Liquide SA)
• Original Assignee: L'Air Liquide Societe Anonyme Pour L'Etude et L'Exploitation Des Procedes Georges Claude (L'Air Liquide SA)
• Inventors: Swaidan, Raja, Hasse, David J., Kosuri, Madhava R., Ma, Canghai, Gagliano, Robert A., Chevrel, Henri, Kratzer, Dean W.
• Primary Examiner(s): Shumate, Anthony R
• Application Number:
  US15/199,908
• Publication Number:
  US 20180001270A1
• Time in Patent Office: 887 Days
• CPC Class Codes: B01D 2256/24 Hydrocarbons
• CPC Class Codes: B01D 2257/304 Hydrogen sulfide
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2323/21811 Metals
• CPC Class Codes: B01D 2323/21817 Salts
• CPC Class Codes: B01D 2325/28 Degradation or stability over time
• CPC Class Codes: B01D 53/228 characterised by specific membranes
• CPC Class Codes: B01D 67/00111 Polymer pretreatment in the casting solutions
• CPC Class Codes: B01D 67/00113 Pretreatment of the casting solutions, e.g. thermal treatment or ageing
• CPC Class Codes: B01D 67/0067 by carbonisation or pyrolysis
• CPC Class Codes: B01D 69/02 characterised by their properties
• CPC Class Codes: B01D 69/087 Details relating to the spinning process
• CPC Class Codes: B01D 71/021 Carbon
• CPC Class Codes: B01D 71/028 Molecular sieves carbon B01D71/021
• CPC Class Codes: B01D 71/64 Polyimides; Polyamide-imides; Polyester-imides; Polyamide acids or similar polyimide precursors
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

Metallopolyimide precursor fibers for aging-resistant carbon molecular sieve hollow fiber membranes having enhanced selectivity include transition metal cations complexed with electronegative regions of a polyimide. CMS membranes are made by pyrolyzing the metallopolyimide precursor fibers. The cations are introduced by including, in the bore fluid used to extrude the fibers, either a salt of the transition metal and an inorganic anion or a transition metal/organic ligand complex.

Claims

1. A method for producing a metallopolyimide precursor fiber for aging-resistant carbon molecular sieve hollow fiber membrane having improved selectivity, comprising the steps of:

ejecting a bore fluid from a circular opening in a hollow fiber spinneret, cations of a transition metal being dissolved in the bore fluid;

extruding a core spin dope composition from an annular opening that surrounds the circular opening, the core spin dope composition comprising a polyimide dissolved in a solvent;

allowing the extruded core spin dope composition to traverse an air or inert gas gap to produce a nascent hollow fiber;

allowing the nascent hollow fiber to travel through a coagulation bath of a non-solvent where still-dissolved portions of the polyimide in the nascent hollow fiber are solidified via phase inversion to produce a solidified hollow fiber, wherein the transition metal cations diffuse into the solidified hollow fiber and complex with electronegative regions of the polyimide; and

drying the solidified hollow fiber.

2. The method of claim 1, further comprising the step of washing the solidified hollow fiber with a wash liquid so as to remove the solvent from the solidified hollow fiber, wherein the complexed cations are not substantially removed from the solidified hollow fiber by the wash liquid.

3. The method of claim 1, wherein the transition metal is selected from the group consisting of Sc, Ti, Va, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, Pt, and Au.

4. The method of claim 3, wherein the transition metal cations are in a +2 or +3 oxidation state.

5. The method of claim 3, wherein the cation is selected from the group consisting of Fe(ii), Fe(iii), Ag(i) Ag(ii), Ag(iii), Zn(ii), and Zn(iii).

6. The method of claim 1, wherein the bore fluid comprises water and a transition metal salt of the metal cation and an inorganic anion, the inorganic anion being selected from the group consisting of sulfate, nitrate, nitrite, chloride, chlorate, perchlorate, bromide, iodide, cyanate, isocyanate, thiocyanate, tetrafluoroborate, hexafluorophosphate, and molybdate.

7. The method of claim 6, wherein the anion is nitrate.

8. The method of claim 7, wherein the cation is Fe(iii) or Ag(i).

9. The method of claim 1, wherein the bore fluid comprises water and a metalorganic, the metalorganic being a cation of a transition metal complexed with an organic ligand in the bore fluid, the ligand being selected from the group consisting of acetylacetonate, acetate, oxalate, and citrate.

10. The method of claim 9, wherein the ligand is acetylacetonate.

11. The method of claim 10, wherein the cation is Fe(iii), Ag(i) or Zn(ii).

12. The method of claim 11, wherein the polyimide is 6FDA/BPDA:

DAM and the metalorganic in the bore fluid is tris(acetylacetonato) iron(III).

13. A plurality of the dried solidified hollow fibers produced by the method of claim 1.

14. A method for producing an aging-resistant CMS hollow fiber membranes having enhanced selectivity, comprising the step of pyrolyzing the dried solidified hollow fibers of claim 13.

15. The aging-resistant CMS hollow fiber membranes produced by the method of claim 14.

16. A method for separating a gas mixture, comprising the steps of feeding a gas mixture to a CMS membrane module comprising a plurality of the aging-resistant CMS hollow fiber membranes of claim 15, withdrawing a permeate gas from the CMS membrane module that is enriched in at least one gas relative to the gas mixture, and withdrawing a non-permeate gas from the CMS membrane module that is deficient in said at least one gas relative to the gas mixture.