Method for recycling ion conducting membranes

Patent metadata

Field	Value
Publication number	US-2025144576-A1
Application number	US-202418934959-A
Country	US
Kind code	A1
Filing date	Nov 1, 2024
Priority date	Nov 2, 2023
Publication date	May 8, 2025
Grant date	—

Abstract

Disclosed herein is a method for dissolving ion exchange membranes to provide dissolved polymers, particularly at low temperatures and/or pressures, that can be recast to regenerate ion exchange membranes exhibiting reduced defects compared to the initial ion exchange membrane. In some aspects of the disclosure, the polymer exchange membranes include a perfluorosulfonic acid polymer. In some aspects of the disclosure, the method involves dissolving the membranes in one or more aprotic solvents, particularly at temperatures below 80° C.

First claim

We claim:

1 . A method for recycling an ion exchange membrane, comprising:
exposing a first ion exchange membrane comprising a polymer to a solvent at a temperature of no greater than 80° C.; dissolving the first ion exchange membrane to form a polymer dispersion; and recasting the polymer dispersion to form a recycled ion exchange membrane.

2 . The method of claim 1 , wherein the recycled ion exchange membrane comprises a lower concentration of voids, tears, pores, or any combination thereof, as compared to the first ion exchange membrane.

3 . The method of claim 1 , wherein the recycled ion exchange membrane comprises a lower concentration of oxygen radicals or a lower concentration of metal ions than the first ion exchange membrane.

4 . The method of claim 1 , wherein the first ion exchange membrane is a cation exchange membrane.

5 . The method of claim 1 , wherein the polymer is a perfluorosulfonic acid polymer.

6 . The method of claim 5 , wherein the perfluorosulfonic acid polymer comprises:
a polyfluorocarbon backbone; a sulfonic acid group or a fluoro-sulfone group; and a side chain connecting the sulfonic acid group or the fluoro-sulfone group to the polyfluorocarbon backbone.

7 . The method of claim 5 , wherein the perfluorosulfonic acid polymer has a structure according to Chemical Formula I, Chemical Formula II, or Chemical Formula III, or wherein the perfluorosulfonic acid polymer comprises a mixture of two or more compounds having structures according to Chemical Formula I, Chemical Formula II, or Chemical Formula III,
wherein Chemical Formula I is

wherein values of x, y, and z are selected from integers that provide an equivalent weight for the perfluorosulfonic acid polymer ranging from 100 g/mol to 2000 g/mol;
Chemical Formula II is

wherein values of m and n are selected from integers that provide an equivalent weight for the perfluorosulfonic acid polymer ranging from 100 g/mol to 2000 g/mol; and
Chemical Formula III is

wherein values of x, y, and z are selected from integers that provide an equivalent weight for the perfluorosulfonic acid polymer ranging from 100 g/mol to 2000 g/mol.

8 . The method of claim 1 , wherein the solvent has a flashpoint of 65° C. or greater.

9 . The method of claim 1 , wherein the solvent comprises a phosphate, a phosphonate, a phosphite, a sulfoxide, an amide, or any combination thereof.

10 . The method of claim 9 , wherein the solvent comprises trimethyl phosphate, tripropyl phosphate, tributyl phosphate, triethyl phosphate, dimethyl methylphosphonate, diethyl ethylphosphonate, triethyl phosphite, dimethyl sulfoxide, N,N-dimethylformamide, or any combination thereof.

11 . The method of claim 1 , wherein the solvent is triethyl phosphate.

12 . The method of claim 1 , wherein the temperature ranges from 40° C. to 70° C.

13 . The method of claim 1 , wherein the temperature is less than or equal to 50° C.

14 . The method of claim 1 , wherein the method is conducted at ambient pressure.

15 . The method of claim 1 , wherein the first ion exchange membrane comprises a perfluorosulfonic acid polymer, the solvent is triethyl phosphate, and the temperature is less than or equal to 50° C.

16 . A method, comprising:
exposing a first ion exchange membrane comprising a perfluorosulfonic acid polymer to a polar, aprotic solvent at a temperature ranging from 30° C. to 60° C.; dissolving the first ion exchange membrane to form a perfluorosulfonic acid polymer dispersion; and recasting the perfluorosulfonic acid polymer dispersion to form a recycled ion exchange membrane exhibiting reduced defects as compared to the first ion exchange membrane.

17 . The method of claim 16 , wherein the method is conducted at ambient pressure.

18 . The method of claim 16 , wherein the temperature ranges from 30° C. to 50° C.

19 . A device, comprising:
a positive electrode; a negative electrode; a recycled polymer membrane disposed between the positive electrode and the negative electrode, wherein the recycled polymer membrane is obtained by exposing a first ion exchange membrane comprising a polymer to a solvent at a temperature of no greater than 80° C., dissolving the first ion exchange membrane to form a polymer dispersion, and recasting the polymer dispersion to form the recycled ion exchange membrane; and an electrical load in electrical communication with the positive electrode and the negative electrode.

20 . The device of claim 19 , wherein the device is a fuel cell, an electrolyzer, or a flow battery.

Assignees

• Battelle Memorial Institute

Inventors

• Shao Yuyan
• Yan Litao
• Wu Bingbin

Classifications

• B01D2325/42

  Ion-exchange membranes · CPC title

• B01D2323/54

  Recycling of scrap material from production process or membrane fragments · CPC title

• B01D71/32

  containing fluorine atoms · CPC title

• B01D71/82

  characterised by the presence of specified groups, e.g. introduced by chemical after-treatment · CPC title

• B01J47/12

  characterised by the use of ion-exchange material in the form of ribbons, filaments, fibres or sheets, e.g. membranes (electrodialysis or electro-osmosis B01D61/42) · CPC title