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EP-4735408-A1 - RECYCLING OF CATALYTIC COATED MEMBRANE COMPONENTS FROM FUEL CELLS AND REFORMERS

EP4735408A1EP 4735408 A1EP4735408 A1EP 4735408A1EP-4735408-A1

Abstract

The present invention relates to a method for recycling a membrane electrode assembly from a fuel cell or a reformer. Further, the present invention relates to a polymer or a polymer solution obtained from the method according to the invention and to the use of the obtained polymer or polymer solution.

Inventors

  • DEDECI, Orhun

Assignees

  • Hensel Recycling GmbH

Dates

Publication Date
20260506
Application Date
20240619

Claims (15)

  1. 1. Method for recycling a membrane electrode assembly from a fuel cell or a reformer, wherein the membrane electrode assembly comprises a polymer film and a supported noble metal catalyst coated on at least one side of the polymer film, wherein the method comprises the steps of (a) contacting the membrane electrode assembly with a fluid containing at least one Ci to Ce alkanol to obtain a slurry; (b) heating the slurry at a temperature of 90°C to 160°C and at a pressure of 2 bar to 25 bar; (c) receiving a mixture of a solid phase and a liquid phase; and (d) separating the solid phase and the liquid phase.
  2. 2. Method according to claim 1, characterized in that the Ci to Ce alkanol is Ethanol; or characterized in that the fluid consists of the Ci to Ce alkanol and water, wherein preferably the ratio of the Ci to Ce alkanol to water (alkanol/water) is from 95/5 to 50/50, more preferred from 90/10 to 55/45, even more preferred from 85/15 to 75/25.
  3. 3. Method according to claim 1 or claim 2, characterized in that the membrane electrode assembly comprises a fluorocarbon-containing polymer essentially being devoid of cross-links.
  4. 4. Method according to claim 1 or claim 3, characterized in that step (b) heating the slurry is performed at a temperature of 110°C to 150°C, preferably 125°C to 145°C; and/or the pressure amounts to 5 bar to 15 bar, preferably 8 to 10 bar.
  5. 5. Method according to any one of claims 1 to 4, characterized in that step (b) is performed under mixing; or characterized in that step (b) is performed for a duration of 1 minute to 120 minutes, preferably 5 minutes to 60 minutes; more preferred 15 minutes to 30 minutes.
  6. 6. Method according to any one of claims 1 to 5, characterized in that step (d) is performed by centrifugation, sedimentation, decantation or filtration, preferably centrifugation.
  7. 7. Method according to any one of claims 1 to 5, characterized in that step (d) is performed by centrifugation followed by filtration.
  8. 8. Method according to any one of claims 1 to 7, characterized in that the method further comprises the steps of (d) separating the solid phase and the liquid phase to receive the liquid phase being a polymer solution; and (e-1) at least partially separating the fluid from the polymer solution to obtain a recovered polymer and a recovered fluid, wherein preferably the at least partially separating the fluid from the polymer solution is performed by evaporating at least part of the fluid.
  9. 9. Method according to any one of claims 1 to 8, characterized in that the method comprises the step of (f-1) reusing the recovered fluid in method step (a).
  10. 10. Method according to any one of claims 1 to 7, characterized in that the method comprises the steps of (d’) separating the solid phase and the liquid phase to receive the solid phase comprising a recovered supported noble metal catalyst; and (e-2) subjecting the recovered supported noble metal catalyst to a refining method to recover the noble metal.
  11. 11. A polymer or a polymer solution obtained from a method for recycling a membrane electrode assembly from a fuel cell or a reformer, wherein the membrane electrode assembly comprises a polymer film and a supported noble metal catalyst coated on at least one side of the polymer film, wherein the method comprises the steps of (a) contacting the membrane electrode assembly with a fluid containing at least one Ci to Ce alkanol to obtain a slurry; (b) heating the slurry at a temperature of 90°C to 160°C and at a pressure of 2 bar to 25 bar; (c) receiving a mixture of a solid phase and a liquid phase; and (d) separating the solid phase and the liquid phase to receive the liquid phase being a polymer solution.
  12. 12. Polymer or polymer solution according to claim 11, characterized in the method further comprises the step of (e-1) at least partially separating the fluid from the polymer solution to obtain a recovered polymer and a recovered fluid.
  13. 13. Polymer or polymer solution according to claim 11, characterized in the method further comprises the step of (e-1) at least partially separating the fluid from the polymer solution to obtain a recovered polymer and a recovered fluid, wherein the at least partially separating the fluid from the polymer solution is performed by evaporating at least part of the fluid.
  14. 14. Polymer or polymer solution according to claim 11, characterized in the method further comprises the step of (e’-1) at least partially separating the fluid from the polymer solution to obtain a recovered polymer and a recovered fluid, wherein the at least partially separating the fluid from the polymer solution is performed by ultrafiltering or dialyzing the polymer solution prior to evaporating at least part of the fluid.
  15. 15. Use of a polymer or a polymer solution according to any one of claims 11 to 14 for manufacturing a membrane electrode assembly for a fuel cell or a reformer.

Description

RECYCLING OF CATALYTIC COATED MEMBRANE COMPONENTS FROM FUEL CELLS AND REFORMERS The present invention relates to a method for recycling a membrane electrode assembly from a fuel cell or a reformer. Further, the present invention relates to a polymer or a polymer solution obtained from the method according to the invention and to use of the obtained polymer or polymer solution. A fuel cell is an electrochemical cell that converts the chemical energy of a fuel, such as hydrogen or lower hydrocarbons, and an oxidizing agent, such as oxygen, into electricity through a pair of redox reactions. Fuel cells play a crucial role in the supply of energy on the way of a more sustainable economy with a less severe ecological footprint. Fuels can be produced from regenerative energy, stored in large quantities and converted in a fuel cell to electrical power as needed. Fuel cells thus belong to the “green” technology for energy supply as long as the fuel is produced by green techniques. Hydrogen as the fuel for fuel cells is becoming more and more important in the area of green technology. Excess electrical power may be used in so called reformers or electrolyzers to produce hydrogen as energy storing medium. The hydrogen may also be produced by reformers which transform natural gas, thus mostly methane, together with steam to hydrogen and carbon dioxide. The hydrogen produced by electrolyzers or reformers can be used for operating fuel cells in vehicles or stationary power generators to generate electricity. The predominantly used fuel cell is the proton exchange membrane fuel cells (PEMFC). In these PEMFC as well as in reformers, catalysts - predominantly platinum and noble metals of the platinum group - are supported on carbon black materials which are deposited on membranes. These membranes are polymeric materials mostly comprising fluorinated polymers which are called ionomers. Many attempts were pursued to recover the materials of fuel cells and reformers after the expiry of their life span. Most efforts concerned the recovery of the noble metals as they are most valuable materials in fuel cells. State of the art methods for the recovery of the noble metals are pyrometallurgical and hydrometallurgical methods. The pyrometallurgical method is conducted as follows: The combustion of the supporting film including the noble metal supported carbon produces an ash residue with the precious metals. This can be further processed into pure precious metal in the usual further treatment steps in precious metal refineries. The disadvantage is that the polymeric material is converted into carbon dioxide and other harmful substances including fluorine containing substances. In the hydrometallurgical method, alcohols are used for dissolving the membrane. The solids are separated from the solution by filtration and further processed pyrometallurgically. Such a method is disclosed in the US 2007 0292745 A1. However, here again a pyrometallurgical step is required. The polymeric materials of the membranes have as well a high value. Furthermore, it is a contribution to environmental protection to fully recover the polymeric materials. The recovery of the materials for an arbitrary purpose is a first issue. However, the recovery of the polymeric materials such that they can be reused in rebuilt fuel cell membranes is a further and more interesting issue. The invention’s underlaying problem relates to the provision of a method for recycling materials of fuel cells and reformers. The invention’s underlaying problem preferably refers to the provision of a method for recycling the noble metals and the polymeric materials of the membrane electrode assembly. A more preferred invention’s underlaying problem relates to the provision of a recycling method, which enables the reuse of the polymeric material for the purpose of rebuilding membranes for a fuel cell or a reformer. In particular, it is an object to provide the method as environmentally friendly as possible. The invention’s underlaying problems are solved by the subject-matter of claim 1. Thus, according to a first aspect, the invention relates a method for recycling a membrane electrode assembly from a fuel cell or a reformer, wherein the membrane electrode assembly comprises a polymer film and a supported noble metal catalysts coated on at least one side of the polymer film, wherein the method comprises the steps of (a) contacting the membrane electrode assembly with a fluid containing at least one Ci to Ce alkanol to obtain a slurry; (b) heating the slurry to a temperature of 90°C to 160°C at a pressure of 2 bar to 25 bar; (c) receiving a mixture of a solid phase and a liquid phase; and (d) separating the solid phase and the liquid phase. By use of a short chain alkanol and under mild conditions of temperature and pressure, it is possible to dissolve ionomers and to obtain a solubilized polymeric phase and a solid phase. The obtained solution residue, i.e. the solid phase, contai