Recycling of catalyst coated membrane components

Abstract

A method of recycling a spent catalyst coated membrane, wherein the spent catalyst coated membrane comprises: a membrane comprising a membrane ionomer; a first catalyst layer disposed on one side of the membrane, the first catalyst layer comprising a first catalyst and a first catalyst layer ionomer; and a second catalyst layer disposed on opposite sides of the membrane, the second catalyst layer comprising a second catalyst and a second catalyst layer ionomer. The method is configured to recover the first catalyst layer ionomer and the second catalyst layer ionomer in addition to the catalyst materials and the membrane ionomer.

Description

TECHNICAL FIELD

[0001] This specification relates to a method for recycling components of membranes for catalyst coating (such as those used in fuel cells and hydrogen-producing water electrolyzers). BACKGROUND ART

[0002] With the investment in the global hydrogen economy, fuel cell and hydrogen-producing water electrolyzer production will grow rapidly. Catalyst-coated membranes (CCMs) are the main functional components of both fuel cells and electrolyzers. Such CCMs typically include a conductive polymer membrane coated with a catalyst-containing layer on either side. The CCM is configured to drive oxidation and reduction reactions and support proton and electron transport, which are required for fuel cell and electrolysis technologies to function.

[0003] Although there are variations in CCM component materials and configurations depending on the functional performance requirements in end-use applications, they typically contain several valuable components, including one or more platinum group metal (PGM) catalysts and one or more proton-conducting polymers.

[0004] Typically, the membrane is formed from one or more ionomers such as perfluorosulfonic acid (PFSA) ionomers. The ionomer can also be provided in one or more of the catalyst layers. The ionomer in the catalyst layer can be the same as or different from the main membrane component and / or the ionomer in other catalyst layers.

[0005] The CCM can contain two different catalysts, one for driving the oxidation reaction on one side of the CCM and one for driving the reduction reaction on the other side of the CCM. The CCM can also contain a recombination catalyst that is provided to catalyze the recombination of hydrogen and oxygen to form water, thereby reducing the amount of hydrogen passing through the membrane and mixing with oxygen to form a potentially explosive mixture. The CCM can also contain multivalent cations delivered as salts or oxides (supported or unsupported), such as metal oxides such as CeO 2 As a peroxide scavenger.

[0006] CCM catalysts can be based on platinum group metals, such as platinum, ruthenium, iridium, palladium, or mixtures thereof. The platinum group metals can be provided in elemental (metallic) form, in compound form (e.g., oxides, such as iridium oxide catalysts), or as PGM-based metal alloys (e.g., PtCo). In addition, the PGM catalyst material can be supported on a substrate material, such as a carbon-containing substrate material (e.g., carbon, such as platinum-on-carbon catalyst or carbon-supported PtCo containing carbon particles with platinum disposed thereon; or an organic material, such as nanostructured thin-film catalyst (NTFC) technology as described in US2020102659 and WO2006089180).

[0007] A catalyst-coated membrane (CCM) can also be combined with additional functional layers to provide a multi-layer membrane electrode assembly (MEA). Such MEAs can have, for example, 3, 5, or 7 layers.

[0008] With the increase in CCM manufacturing for fuel cells and electrolyzers, there is an associated increase in CCM waste, including a large amount of waste formed during CCM manufacturing (e.g., due to quality control failures) and an increase in end-of-life (EoL) CCM. Since CCM contains several rare and / or valuable components, including platinum group metals (especially Pt, Pd, Ir, and Ru) and ionomers (in both the membrane and catalyst layers), there is a growing need for methods to recycle such components from waste CCM materials.

[0009] One current method for recovering PGM from production waste and end-of-life CCM materials involves incineration. The incineration process produces an ash rich in PGM (usually Pt and Ir), which is processed via conventional PGM refining routes. However, the incineration process releases harmful and toxic gases from the polymer that is part of the membrane, such as CO 2 and HF. Both of these gases have negative impacts as they pollute the atmospheric environment, increase the greenhouse effect, and / or have harmful effects on the human body. Therefore, there is a need for a clean process that reduces or eliminates the emissions of these gases.

[0010] In addition to the above, the incineration method destroys the ionomer component, which also has significant value. Therefore, there is also a desire to provide a process that can recover both PGM and the ionomer component and to provide a cleaner, safer, and more environmentally friendly process. Processes for recovering perfluorosulfonic acid ionomers are known. See, for example, WO2016 / 156815 and US7255798. In addition, processes for recovering individual PGM catalyst components are known. For example, see US7709135. Several other prior art documents that disclose methods for recycling CCM components are discussed below.

[0011] EP3275036 discloses a method that includes: immersing the CCM in a glycol solvent; heating to obtain a dispersion containing the solvent, one or more ionomers, and one or more catalyst components; and filtering the dispersion to separate the solvent and the one or more ionomers from the one or more catalyst components.

[0012] The article titled "PEM water electrolysis: Innovative methods for catalyst separation, recovery, and recycling" (International Journal of Hydrogen Energy 44(2019)3450 - 3455) discloses a method for recycling CCM to recover membrane ionomer, iridium oxide catalyst, and Pt / C catalyst. This is achieved by mounting the CCM on a reactor to define two separate chambers, one on the iridium oxide side of the CCM and one on the Pt / C side of the CCM. Then, both sides of the CCM are subjected to the circulation of a solution composed of deionized water and alcohol. It is described that complete delamination of the catalyst layer from the membrane occurs after 10 minutes - 30 minutes. After delamination, the membrane is dried, reused, or reprocessed. The two separate dispersions containing catalyst residues are centrifuged, the solids are collected and dried in an oven to obtain recycled iridium oxide catalyst powder and recycled Pt / C catalyst powder. The recycled catalyst powder is used to fabricate new CCM. It is disclosed that the temperature used when drying the recycled catalyst is not high enough to burn off the ionomer in the catalyst powder, and it is pointed out that the ionomer present when reusing the catalyst powder in a new ink formulation may be the reason for the increase in cell voltage (decrease in performance) in the CCM fabricated using the recycled catalyst material.

[0013] CN106898790 also discloses a method in which an alcohol - water mixture is used to delaminate the catalyst layer from the membrane, and then the solid membrane is separated from the catalyst layer dispersion. Then the catalyst layer dispersion and the solid membrane are processed and recycled separately. Contrary to the article discussed previously, it is described that the catalyst layer dispersion is processed by heating to a sufficient temperature to burn off the catalyst layer ionomer, and then further heated at a higher temperature to remove carbon and extract the noble metal catalyst.

[0014] To enable fuel cells and electrolyzers to become more sustainable technologies, there is still a need for a commercially viable and environmentally friendly route to recover, separate, and recycle both PGM and ionomer components from waste CCM materials (including production waste and end - of - life materials). The objective of this specification is to solve this problem. Summary of the Invention

[0015] As pointed out in the background section, a catalyst - coated membrane (CCM) can include an ionomer membrane coated with a catalyst layer on either side, and these membranes contain both ionomer and catalyst material. One prior - art method for recycling the ionomer and catalyst material in the membrane involves dispersing the ionomer membrane to form a slurry containing ionomer and catalyst material, separating the catalyst material from the ionomer material, and then processing the ionomer and catalyst material separately.

[0016] However, typically, more than 80% of the ionomer to be recycled is present in the membrane and more than 80% of the catalyst material is present in the catalyst layer. The process for delaminating the catalyst layers to separate them from the ionomer membrane enables the bulk of the ionomer to be processed and recycled separately from the bulk of the catalyst material.

[0017] A prior art method for delaminating the catalyst layer from the ionomer membrane without dispersing the ionomer membrane is described in the article entitled "PEM Water Electrolysis: Innovative Approaches to Catalyst Separation, Recovery, and Recycling", which has been discussed in the background section. However, this method results in the recycled catalyst material being contaminated with ionomer from the original catalyst layer, which reduces the performance of the catalyst material when reused to form a new CCM. A solution to this problem is described in CN106898790, which has also been discussed in the background section. This document proposes delaminating the catalyst layer and then processing the catalyst layer material to burn off the catalyst layer ionomer and carbon material to extract the precious metal catalyst that is not contaminated with ionomer from the delaminated catalyst layer.

[0018] However, the inventors have noted problems with this method. Burning off the catalyst layer ionomer releases harmful and toxic gases such as CO 2 and HF. Both of these gases have negative impacts as they pollute the atmospheric environment, increase the greenhouse effect and / or have harmful effects on the human body. Therefore, a clean process for reducing or eliminating the emissions of these gases is needed.

[0019] In addition, the incineration method destroys valuable catalyst layer ionomer components. Therefore, there is also a desire to provide a process that can recycle the PGM catalyst material, the bulk membrane ionomer, and additional ionomer from the catalyst layer, and to provide a cleaner, safer, and more environmentally friendly process.

[0020] According to the present specification, there is provided a method for recycling a waste catalyst-coated membrane, wherein the waste catalyst-coated membrane comprises: a membrane comprising a membrane ionomer; a first catalyst layer disposed on one side of the membrane, the first catalyst layer comprising a first catalyst and a first catalyst layer ionomer; and a second catalyst layer disposed on the opposite side of the membrane, the second catalyst layer comprising a second catalyst and a second catalyst layer ionomer, the method comprising:

[0021] contacting the waste catalyst-coated membrane with a solvent to delaminate both the first catalyst layer and the second catalyst layer from the membrane without dispersing the membrane, wherein the first catalyst layer and the second catalyst layer form a catalyst layer slurry comprising the first catalyst, the first catalyst layer ionomer, the second catalyst, and the second catalyst layer ionomer;

[0022] separating the membrane from the catalyst layer slurry;

[0023] Processing a membrane to recover membrane ionomer; and

[0024] Processing a catalyst layer slurry to disperse and recover a first catalyst layer ionomer and a second catalyst layer ionomer in a solvent, and to separate and recover a first catalyst and a second catalyst or their components.

[0025] Processing of the catalyst layer slurry may include:

[0026] Heating the catalyst layer slurry to disperse the first catalyst layer ionomer and the second catalyst layer ionomer, thereby forming an ionomer dispersion in which solid first catalyst material and solid second catalyst material are disposed;

[0027] an ionomer dispersion;

[0028] Separating the solid first catalyst material and the solid second catalyst material from the ionomer dispersion (e.g., using a solid-liquid separation technique such as filtration);

[0029] Processing the ionomer dispersion to recover the first catalyst layer ionomer and the second catalyst layer ionomer; and

[0030] Processing the solid first catalyst material and the solid second catalyst material to separate and recover the first catalyst material and the second catalyst material or their components.

[0031] The step of heating the catalyst layer slurry to disperse the first catalyst layer ionomer and the second catalyst layer ionomer may be carried out in the same solvent used to delaminate the first catalyst layer and the second catalyst layer from the membrane. Alternatively, the catalyst slurry may be processed to remove the solvent used in the delamination process and then the materials may be repulped in a different solvent to disperse and separate the catalyst layer ionomers. One or more of the catalyst layer components may be leached before and / or after repulping the materials to disperse the catalyst layer ionomer materials.

[0032] A key feature of the method is that, in addition to the bulk membrane ionomer and the catalyst material, it is also suitable for recovering the catalyst layer ionomers. After delaminating the catalyst layer from the membrane to form a catalyst layer slurry, the catalyst layer slurry is processed to form a dispersion of the catalyst layer ionomers in a solvent such that the ionomer dispersion can be separated from the solid catalyst components. This enables the catalyst layer ionomers to be recovered separately from the catalyst material and the bulk membrane ionomer. The process thus reduces or eliminates ionomer contamination in the recovered catalyst material, avoids the ionomer burnout process that releases harmful and toxic gases, and enables the catalyst layer ionomers to be recycled and reused.

[0033] In addition, the solvent used in the above recycling process can be processed through ion exchange, activated carbon, or other active media to reduce the content of low molecular weight ions / soluble compounds. This enables the recycling of the solvent and reduces waste. The low molecular weight contaminants can then be incinerated or treated by other methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] To better understand the present invention and to show how it may be implemented, certain embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which:

[0035] Figure 1 shows a waste CCM recycling process in which the catalyst layer is first separated from the bulk polymer membrane (note that the gas diffusion layer and sealant can be removed prior to processing the waste CCM);

[0036] Figure 2 shows a method for further processing the catalyst layer material;

[0037] Figure 3 shows an alternative method for further processing the catalyst layer material;

[0038] Figure 4 shows: (a) a catalyst-coated membrane that has been subjected to size reduction (cutting) and immersed in an alcohol:water mixture (left image); (b) after sonication, where the catalyst layer is dispersed in the alcohol:water mixture (middle image); and (c) a layered, clean, and transparent membrane recovered from the alcohol:water mixture (right image);

[0039] Figure 5 shows images of the dispersion and the recovered membrane after treating the catalyst-coated membrane in a series of different alcohol:water mixtures, indicating that methanol is not effective in delaminating the catalyst layer from the membrane (image a), while the effectiveness order of other alcohols in achieving delamination of the catalyst layer and recovery of a clean and transparent membrane is as follows: n-butanol > n-propanol > isopropanol > ethanol (image b); and

[0040] Figure 6 shows an example of a processing flow for treating waste dispersion medium in the CCM recycling process. DETAILED DESCRIPTION

[0041] The CCM can contain ionomers in one or both of the catalyst layers and in the bulk ionomer membrane on which the catalyst layer is disposed. To optimize the performance parameters of the CCM, different ionomers can be used in the catalyst layer and the bulk ionomer membrane. This specification relates to a method in which the catalyst layer ionomer can be separated from the membrane ionomer, and in which the catalyst layer ionomer and the membrane ionomer are processed separately such that both the membrane ionomer and the catalyst layer ionomer are recovered in addition to the PGM-containing catalyst material.

[0042] As described in the Summary of the Invention section, this specification provides a method for recycling a waste catalyst-coated membrane, wherein the waste catalyst-coated membrane comprises: a membrane comprising a membrane ionomer; a first catalyst layer disposed on one side of the membrane, the first catalyst layer comprising a first catalyst and a first catalyst layer ionomer; and a second catalyst layer disposed on the opposite side of the membrane, the second catalyst layer comprising a second catalyst and a second catalyst layer ionomer, the method comprising:

[0043] Contacting the waste catalyst-coated membrane with a solvent to delaminate both the first catalyst layer and the second catalyst layer from the membrane without dispersing the membrane, wherein the first catalyst layer and the second catalyst layer form a catalyst layer slurry comprising the first catalyst, the first catalyst layer ionomer, the second catalyst, and the second catalyst layer ionomer;

[0044] Separating the membrane from the catalyst layer slurry;

[0045] Processing the membrane to recover the membrane ionomer; and

[0046] Processing the catalyst layer slurry to disperse and recover the first catalyst layer ionomer and the second catalyst layer ionomer in the solvent, and separating and recovering the first catalyst and the second catalyst or their components.

[0047] Processing of the catalyst layer slurry may include:

[0048] Heating the catalyst layer slurry to disperse the first catalyst layer ionomer and the second catalyst layer ionomer, thereby forming an ionomer dispersion in which solid first catalyst material and solid second catalyst material are disposed;

[0049] Material of the ionomer dispersion;

[0050] Separating the solid first catalyst material and the solid second catalyst material from the ionomer dispersion (e.g., using solid-liquid separation techniques such as filtration);

[0051] Processing the ionomer dispersion to recover the first catalyst layer ionomer and the second catalyst layer ionomer; and

[0052] Processing the solid first catalyst material and the solid second catalyst material to separate and recover the first catalyst material and the second catalyst material or their components.

[0053] The step of heating the catalyst layer slurry to disperse the first catalyst layer ionomer and the second catalyst layer ionomer can be carried out in the same solvent used to delaminate the first catalyst layer and the second catalyst layer from the membrane. Alternatively, the catalyst slurry can be processed to adjust the solvent composition or remove the solvent used in the delamination process, and then the material can be repulped in a different solvent to disperse and separate the catalyst layer ionomers. One or more of the catalyst layer components can be leached before and / or after repulping the material to disperse the catalyst layer ionomer material.

[0054] Typically, the step of heating the catalyst layer slurry to disperse the first catalyst layer ionomer and the second catalyst layer ionomer is carried out at a higher temperature than the step of contacting the spent catalyst-coated membrane with a solvent to delaminate both the first catalyst layer and the second catalyst layer from the membrane without dispersing the membrane. This is especially the case if the solvent used for dispersion is the same as the solvent used to delaminate the catalyst layer from the membrane. During delamination, the temperature is kept low enough so that the membrane ionomer is not dispersed, but the catalyst layer delaminates and forms a slurry. Then, after separating the membrane from the slurry, the temperature of the slurry can be raised to disperse the catalyst layer ionomer and separate it from the solid catalyst material. The step of heating the catalyst layer slurry to disperse the first catalyst layer ionomer and the second catalyst layer ionomer in a solvent can also be carried out in an autoclave under high pressure.

[0055] Processing of the catalyst layer slurry can also include converting the first catalyst layer ionomer and the second catalyst layer ionomer into a salt form. Salt formation (e.g., by treatment with a base) protects the sulfonic acid groups of the ionomer during the recovery process, after which the salt forms of the first catalyst layer ionomer and the second catalyst layer ionomer can be converted back to the acid form by proton exchange. The catalyst layer ionomer dispersion is also advantageously subjected to ion exchange to remove metal contaminants.

[0056] The first catalyst layer ionomer and the second catalyst layer ionomer can be recovered from the ionomer dispersion as a blend of the first catalyst layer ionomer and the second catalyst layer ionomer, or alternatively the ionomer dispersion can be processed to separate the first catalyst layer ionomer and the second catalyst layer ionomer.

[0057] In a catalyst-coated membrane having different ionomers in the catalyst layer compared to a bulk ionomer membrane, a process of delaminating the catalyst layer can be used to separate different types of ionomers in the membrane and the catalyst layer such that the different types of ionomers can be processed separately. In this regard, it should be noted that in prior art methods involving both a dispersed catalyst layer ionomer and a bulk membrane ionomer where the ionomer in the catalyst layer is different from the ionomer in the bulk membrane, it may be difficult to separate the mixed ionomer dispersion, especially where a large amount of the ionomer is from the membrane. In the present method, where the catalyst layer is first delaminated and separated from the bulk membrane, the catalyst layer ionomer dispersion is processed separately from the majority of the CCM ionomers retained in the membrane. The different types of ionomers may be more easily separated and the smaller volume of ionomers from only the catalyst layer is more easily processed, e.g., to remove metal contaminants and / or separate different types of ionomers.

[0058] The solvent used to delaminate both the first and second catalyst layers from the membrane can be a mixture of an alcohol and water, where the alcohol in the alcohol and water mixture is selected from n-butanol, n-propanol, isopropanol, or ethanol. It has been found that while methanol and water are ineffective in delaminating the catalyst layer from the ionomer membrane, a mixture of n-butanol, n-propanol, isopropanol, or ethanol with water can effectively delaminate the catalyst layer and disperse the catalyst layer ionomer without dispersing the bulk ionomer membrane. The order of effectiveness of these alcohols in achieving delamination of the catalyst layer and recovery of a clean and transparent membrane is as follows: n-butanol > n-propanol > isopropanol > ethanol. Thus, the alcohol is preferably selected from n-butanol, n-propanol, or isopropanol, more preferably n-butanol or n-propanol, and most preferably n-butanol. Selection can be based on a suitable range of Hansen solubility parameters.

[0059] The alcohol and water mixture can have an alcohol:water volume ratio between 0 and 1, and the volume ratio is advantageously: at least 50:50, 60:40, or 70:30; not greater than 95:5, 90:10, or 85:15; or within a range defined by any combination of the above lower and upper limits. For a given set of processing conditions and CCM feed material for recycling, the ratio can be optimized such that the catalyst layer can be effectively delaminated to form a catalyst layer slurry without dispersing the bulk ionomer membrane.

[0060] The solvent (e.g., a mixture of alcohol and water) can be stirred to assist in the delamination of the catalyst layer, for example, by ultrasound. It has been found that sonication can be effectively used in this method. Additionally, during the step of contacting the membrane with the solvent to delaminate the catalyst layer, the solvent can be maintained at a temperature below 150 °C, 100 °C, 80 °C, 60 °C, or 40 °C, optionally greater than 5 °C, 10 °C, or 15 °C, and optionally within the range defined by any one of the foregoing upper and lower limits. The temperature can be low enough such that the catalyst layer delaminates without dispersing the fluoropolymer membrane, which remains in a solid, undispersed form.

[0061] Contacting the spent catalyst-coated membrane with the solvent to delaminate the catalyst layer can be carried out for a time of at least 10 minutes, 20 minutes, 30 minutes, or 1 hour; not exceeding 5 hours, 3 hours, or 2 hours; or within the range defined by any combination of the above lower and upper limits. The specific time of the delamination step will depend on a given set of processing conditions (e.g., type / concentration of alcohol, temperature, pressure, stirring, etc.) and the type of CCM feed material used for recycling.

[0062] Advantageously, before contacting with the solvent to delaminate the catalyst layer, the spent catalyst-coated membrane is processed (e.g., by cutting) into multiple pieces. This can assist in the clean delamination of the catalyst layer from the bulk ionomer membrane and make it easier to handle and process large areas of spent catalyst-coated membrane material (e.g., an amount within the range of 5% to 100% of the original membrane).

[0063] Typically, the first catalyst can comprise platinum, palladium, and / or ruthenium (optionally on a support material such as a carbon support material) and the second catalyst can comprise iridium (e.g., iridium oxide material). The method is particularly suitable for recycling catalyst-coated membranes where the membrane ionomer is different from one or both of the first catalyst layer ionomer and the second catalyst layer ionomer. The catalyst layer ionomers can be the same as or different from each other.

[0064] After delaminating the catalyst layer to produce a solid bulk ionomer membrane in the catalyst layer slurry, solid-liquid separation techniques (e.g., decantation and / or filtration) can be used to separate the solid bulk ionomer membrane from the slurry. The solid bulk ionomer membrane can then be further processed to recover the membrane ionomer without interference from the catalyst layer ionomer. Further processing of the bulk ionomer membrane can include dispersing the membrane ionomer in a solvent and separating the dispersed membrane ionomer from other components of the bulk ionomer membrane such as reinforcing polymers. The recovered membrane ionomer can then be reused to manufacture new membrane materials.

[0065] The catalyst layer slurry is processed separately to recover the first catalyst layer ionomer and the second catalyst layer ionomer, as well as the first catalyst material and the second catalyst material. For example, the first catalyst and the second catalyst can be filtered from the dispersion of the catalyst layer ionomer, and then subjected to selective dissolution and purification steps to recover the individual platinum group metals. The processing of the catalyst layer slurry can also include crushing the catalyst layer material to recover the individual platinum group metals before the selective dissolution and refining steps. The remaining catalyst layer ionomer dispersion can be recycled for manufacturing new catalyst layer ink.

[0066] An example of the processing flow is illustrated in Figure 1 . The first stage of the process involves separating the catalyst layer from the membrane. The CCM material can be immersed in an alcohol-water mixture and sonicated or otherwise agitated for a period of time, where the catalyst layer separates and disperses into the solvent. Once the membrane and the catalyst layer are cleanly separated, the membrane can be further processed to recover the membrane ionomer component. To recover the PGM and ionomer in the catalyst layer, there are two options A and B, as Figure 2 and Figure 3 shown.

[0067] Process Option A: The catalyst layer material is subjected to HCl / oxidant (e.g., chlorine) treatment to leach platinum. Then the liquid from this treatment can be purified from the base metals (using, for example, cation exchange resin), Ru removal occurs via distillation or other processes, and then it directly enters the Pt refining stream. The remaining Ir-containing residue from the leaching can undergo a process involving heating / high-pressure sterilization of the material in an alcohol solvent to dissolve / disperse the ionomer. The ionomer dispersion is separated from the Ir-containing solution via filtration or centrifugation (as an alternative, Ir can be leached before or after the ionomer dispersion). Then further processing of the ionomer dispersion continues for recycling back to manufacturing new CCM. The Ir-containing residue can be processed to directly reuse the Ir catalyst, or the residue can be refined to recover Ir metal.

[0068] Process Option B: Alternatively, the catalyst layer material can be heated to an elevated temperature in a solvent (e.g., an alcohol solvent) and optionally autoclaved to disperse the catalyst layer components. The resulting slurry is then subjected to solid / liquid separation by filtration or centrifugation. The supernatant / filtrate contains the dispersed ionomer, which can then be further processed to recycle back into the manufacture of new CCM. The PGM residue is dried to ensure complete removal of the (organic) solvent prior to being subjected to the HCl / chlorine leaching process. The liquid from this leaching process can then be purified from the base metals (using, for example, cation exchange resins), Ru removal occurs via a distillation process, and then it goes directly into the Pt refining stream. The residue from the leaching process still contains the Ir catalyst, which remains largely unchanged due to its stability. It can be processed to directly reuse the Ir catalyst, or the residue can be refined to recover the Ir metal.

[0069] Common features of the above catalyst layer recycling processes are the use of oxidative acid leaching to extract platinum (and / or palladium and / or ruthenium) materials, and the extraction of iridium via reductive acid leaching or solid-liquid separation after the extraction of platinum and the ionomer dispersion. The Pt leaching can be carried out before or after the ionomer dispersion and before or after the iridium leaching. The processing sequence can be: (i) iridium leaching; (ii) platinum leaching; (iii) processing the remaining catalyst layer ionomer. Alternatively, the processing sequence can be: (i) platinum leaching; (ii) iridium leaching; (iii) processing the remaining catalyst layer ionomer. Still alternatively, iridium leaching is not required to separate iridium from the ionomer. Instead, the iridium-containing material is separated from the catalyst layer ionomer material by dispersing the ionomer material and using solid / solution separation to remove the ionomer. In this case, solid / liquid separation can be used to separate the insoluble materials / alloys containing Ir, Pt, Ru, and / or Rh. As Figure 2 shown, the platinum leaching step can be carried out before the step of dispersing the ionomer. Alternatively, the ionomer dispersion step can be carried out before the platinum leaching step, as Figure 3 shown. In either case, the process first separates the catalyst layer from the bulk polymer membrane, and then applies the processing steps to the catalyst layer material, where the bulk ionomer membrane is processed separately.

[0070] The specific method utilized will depend on the operator requirements, the need for components, and the desired form of the materials recovered through the process. For example, if it is desired to extract a certain component early in the recycling process, e.g., due to a shortage of that particular component, an appropriate processing flow can be selected to obtain the desired component early in the process rather than retaining large amounts of the component for an extended period during the recycling process. For example, if it is desired to recover the bulk of the ionomer early in the process, the process of this specification can be selected because the initial step of removing the catalyst layer from the bulk ionomer membrane ensures that the bulk ionomer membrane can be quickly recovered and processed while the ionomer and PGM in the catalyst layer undergo further processing for various separation steps.

[0071] Processes for recycling ionomers have been described in US7255798 and WO2016 / 156815, and such processes can be integrated into the processing flow of this specification as described above. As discussed above, typically, different ionomers can be used in one or both of the catalyst layers compared to the ionomer in the bulk membrane. Different ionomers can be selected to provide performance improvements in the final application. Blends of ionomers or layers with different ionomers within the bulk polymer membrane can also be used. In such cases, the processing flow of this specification can be used to separate the bulk polymer membrane from the catalyst layer at the start of the processing flow. If different ionomers are used in the catalyst layer compared to the bulk membrane, such separation can be used to separate the different ionomers prior to further processing.

[0072] Catalyst layer lamination process

[0073] The spent catalyst-coated membrane can be contacted and agitated with a mixture of alcohol and water so that both the first catalyst layer and the second catalyst layer are delaminated from the membrane without dispersing the membrane. The first catalyst layer and the second catalyst layer are dispersed in the alcohol and water mixture, forming a catalyst layer dispersion containing the first catalyst, the first catalyst layer ionomer, the second catalyst, and the second catalyst layer ionomer.

[0074] Figure 4 Shown are: (a) a catalyst-coated membrane (left image) that has been size-reduced (cut) and immersed in an 80:20 alcohol:water mixture; (b) after sonication, where the catalyst layer is dispersed in the solution (middle image); and (c) the delaminated, clean, and transparent membrane recovered from the alcohol:water mixture (right image).

[0075] The alcohol in the mixture of alcohol and water is selected from n-butanol, n-propanol, isopropanol or ethanol. It has been found that while methanol and water are ineffective in delaminating the catalyst layer from the ionomer membrane, a mixture of n-butanol, n-propanol, isopropanol or ethanol with water can effectively delaminate the catalyst layer and disperse the catalyst layer ionomer without dispersing the bulk ionomer membrane. The order of effectiveness of these alcohols in achieving delamination of the catalyst layer and recovery of a clean and transparent membrane is as follows: n-butanol > n-propanol > isopropanol > ethanol. Thus, the alcohol is preferably selected from n-butanol, n-propanol or isopropanol, more preferably n-butanol or n-propanol, and most preferably n-butanol. Figure 5 Images of the dispersion and the recovered membrane after treating the catalyst-coated membrane in a series of different alcohol:water mixtures are shown, indicating that methanol is not effective in delaminating the catalyst layer from the membrane (image a), while the order of effectiveness of the other alcohols in achieving delamination of the catalyst layer and recovery of a clean and transparent membrane is as follows: n-butanol > n-propanol > isopropanol > ethanol (image b).

[0076] The mixture of alcohol and water can have an alcohol:water volume ratio between 0 and 1, and this volume ratio is advantageously: at least 50:50, 60:40 or 70:30; not greater than 95:5, 90:10 or 85:15; or within a range defined by any combination of the above lower and upper limits. For a given set of processing conditions and the CCM feed material used for recycling, this ratio can be optimized such that the catalyst layer ionomer can be effectively dispersed without dispersing the bulk ionomer membrane.

[0077] The mixture of alcohol and water can be agitated by ultrasound. It has been found that ultrasonic treatment can be effectively used in this method. The contact of the spent catalyst-coated membrane with the mixture of alcohol and water to delaminate the catalyst layer can be carried out for the following times: at least 10 minutes, 20 minutes, 30 minutes or 1 hour; not exceeding 5 hours, 3 hours or 2 hours; or within a range defined by any combination of the above lower and upper limits. The specific time of the delamination step will depend on a given set of processing conditions (type / concentration of alcohol, temperature, pressure, agitation, etc.) and the type of CCM feed material used for recycling.

[0078] Advantageously, before contact with the mixture of alcohol and water, the spent catalyst-coated membrane is processed (e.g., by cutting) into multiple pieces. This can contribute to a clean delamination of the catalyst layer from the bulk ionomer membrane and make it easier to handle and process large-area spent catalyst-coated membrane materials.

[0079] Regarding the above, it should be noted that some existing methods for recycling CCMs have used pure ethylene glycol and heating, where the CCM undergoes complete dispersion of the ionomer in both the bulk film and the catalyst layer. Some prior art methods also mention generally using an alcohol / water mixture to recycle the catalyst material. The difference in this document is that a solvent system such as an alcohol / water system is used and the conditions are adjusted to selectively separate and recycle different ionomers in the bulk film and the catalyst layer.

[0080] Further processing for recovering ionomer from catalyst layer materials

[0081] The processing steps for recovering the ionomer from the catalyst layer material may include:

[0082] ● Optionally convert the ionomer to a salt form

[0083] ● Heat to disperse the ionomer

[0084] ○ A high temperature sufficient to optionally disperse in an autoclave,

[0085] ○ Separate the catalyst and catalyst support from the ionomer dispersion by:

[0086] ■ Centrifugation, and / or

[0087] ■ Filtration, for example,

[0088] ● Ultrafiltration

[0089] ● Membrane filtration and / or

[0090] ● Cross-flow filtration

[0091] ● Ion exchange to remove metal contaminants

[0092] ● Optionally convert back to the acid form

[0093] Further processing for recovering ionomer from membrane

[0094] The processing steps for recovering the ionomer from the bulk film may include:

[0095] ● Optionally convert the ionomer to a salt form (e.g., before dispersing the film ionomer)

[0096] ● Disperse in water (using the hydrothermal method of an autoclave), an aqueous solution, an alkaline aqueous solution, an organic solvent (e.g., alcohol, diol, phosphate ester, ketone, DMSO, DMF, NMP)

[0097] or a mixture thereof.

[0098] ● Filter particles

[0099] ● Ion exchange to remove metal contaminants

[0100] ● Optionally convert back to the acid form

[0101] ● Optionally treat the spent solvent by ion exchange or contact with an active medium such as activated carbon / charcoal.

[0102] Further processing of ionomer

[0103] The ionomer recovered from the bulk film and / or catalyst layer according to the above processing can be further purified by undergoing an ultrafiltration process and undergoing a separation and / or blending process.

[0104] Processing steps of catalyst layer materials

[0105] The catalyst layer material separated from the bulk polymer film using the foregoing process typically contains an ionomer, at least one catalyst containing platinum, palladium, and / or ruthenium, and at least one catalyst containing iridium. The material can be processed using the following general methods to recover PGM and ionomer:

[0106] (a) Treat the material with a heated solution containing an acid and an oxidizing agent, wherein platinum, palladium, and / or ruthenium are leached from the material into the solution, and the solution is separated from the remaining solid components of the material;

[0107] (b) Treat the material with a solvent to disperse the ionomer and recover a dispersion of the ionomer, wherein the dispersion of the ionomer is carried out before or after the leaching of platinum, palladium, and / or ruthenium; and

[0108] (c) Treat the material by one or both of the following to extract iridium:

[0109] (i) After the leaching of platinum, palladium, rhodium, and / or ruthenium and the dispersion of the ionomer, separate the remaining solid iridium-containing catalyst material from the dispersion of the ionomer; and

[0110] (ii) Leach iridium from the material using a heated solution containing an acid and a reducing agent, and separate the solution containing the leached iridium from the remaining solid components of the material, wherein the iridium leaching is carried out before or after the leaching of platinum, palladium, and / or ruthenium.

[0111] The method steps can be carried out in any order to recover Pt, Ir, and the ionomer. That is: Pt - Ir - ionomer; Ir - Pt - ionomer; ionomer - Pt - Ir; ionomer - Ir - Pt; Pt - ionomer - Ir; or Ir - ionomer - Pt.

[0112] The following description will focus on examples including a platinum catalyst and an iridium-based catalyst (e.g., IrOx). However, the same method can be used if the platinum catalyst is replaced with a palladium catalyst, a ruthenium catalyst, a mixed PGM catalyst comprising a combination of at least two of platinum, palladium, and ruthenium, or a catalyst comprising at least one PGM and at least one non-PGM metal (e.g., PtCo).

[0113] The acid used in one or both of iridium leaching and platinum leaching is optionally hydrochloric acid. Additionally, preferably one or both of the solutions for leaching platinum and iridium are heated to the following temperatures: at least 50 °C, 60 °C, or 70 °C; not exceeding 160 °C, 100 °C, or 90 °C; or within a range defined by any combination of the aforementioned lower and upper limits, wherein if the solution is heated above 100 °C, this is carried out in a pressurized vessel. The oxidizing agent for platinum leaching can include, for example, chlorates such as sodium chlorate solution or chlorine gas (e.g., in-situ electrolytically generated). The oxidizing agent can be added to the hydrochloric acid solution after heating to the aforementioned temperature. The solution can contain concentrated HCl, for example, about 6M HCl.

[0114] Separation of the solution containing leached platinum can be achieved via filtration. The separated solution can be concentrated to a suitable PGM concentration for further processing by boiling the solution. Alternatively, the leachate can be recycled to leach platinum from additional waste catalyst-coated membrane materials, repeating the recycling as needed until the target concentration of PGM is reached. Then the PGM-containing leachate is further processed using known techniques to extract platinum from the acidic solution. The remaining solid components of the waste catalyst layer material can be processed separately.

[0115] The method further includes the step of extracting iridium from the waste catalyst layer material. This can be achieved by leaching Ir species from the waste catalyst layer material via a reductive dissolution process using an acid (such as 8M to 12M HCl) and a reducing agent (such as hydrazine, NaBH 4 or ammonium oxalate), thereby producing an Ir-containing acidic liquid. WO2021083758 describes several examples of such processes for dissolving Ir in a reductive HCl environment. Since the aforementioned oxidative acidic platinum leaching does not leach iridium to any significant extent, such a reductive acidic leaching process step for iridium can be carried out after the oxidative acidic leaching step for platinum. However, it is also contemplated that iridium leaching can be carried out before platinum leaching. Thus, the route proposed according to this example is a two-step process involving the selective leaching of Ir and Pt species from the waste CCM without the need for incineration or other destructive processing. These steps are as follows and can be carried out in any order:

[0116] 1. The Ir material is leached via a reductive dissolution process using an acid (such as HCl or nitric acid) and a reducing agent (such as hydrazine), thereby producing an acidic Ir-containing liquid and an undissolved residue.

[0117] 2. The Pt material is leached via an oxidative dissolution process using an acid (such as HCl) and an oxidizing agent (such as chlorate or Cl 2 ). The resulting acidic Pt-containing liquid and an undissolved residue are produced.

[0118] The liquids generated from Step 1 and Step 2 can then be directed to their respective purification processes (if there are significant impurities) or directly used as precursors for new catalyst materials. The solid residues can then be subjected to further leaching to remove the remaining PGM materials, and the resulting ionomer residues are recycled.

[0119] This process selectively recovers PGM from the waste catalyst layer material, thereby allowing for a further simple recycling process of the remaining catalyst layer ionomer. Thus, this process provides a complete recovery and recycling route for both PGM and ionomer. The two-step method involving Pt and Ir leaching achieves a simple and rapid route to separate and recover both Ir and Pt, with the possibility of directly feeding the metal solution back into the catalyst manufacturing process. By 2040, the estimated demand for fuel cell and electrolyzer CCMs is approximately 800 kOzt Pt and 160 kOzt Ir. The compact and customized nature of this process will shorten the delivery cycle and increase metal mobility. This process enables the generation of a closed-loop cycle for waste CCM materials, not only for PGM but also for ionomer. This process also achieves an open-loop recycling of end-of-life CCMs.

[0120] As an alternative to leaching iridium as described above, the iridium (or iridium oxide) material can be separated from the catalyst layer ionomer by dispersing the ionomer. In this case, platinum can be leached from the waste catalyst layer material as previously described, and then the remaining waste catalyst layer material containing solid ionomer and iridium material can be subjected to ionomer dispersion, thereby producing a slurry containing an ionomer dispersion with solid iridium material disposed therein. The ionomer dispersion can be separated from the solid iridium material using solid / liquid separation (e.g., filtration or centrifugation) to produce an ionomer dispersion for recycling. The remaining solid iridium material can be directly reused in the CCM manufacturing process or can be refined before reuse. Alternatively, the catalyst layer ionomer can be dispersed prior to platinum leaching to produce a mixed PGM residue for further processing.

[0121] In one such example, the spent catalyst layer material is subjected to HCl / oxidant (e.g., chlorine) treatment to leach platinum, and optionally also ruthenium if present in the spent catalyst layer material. The liquid from this treatment can then be processed to remove base metals such as nickel and cobalt (using, for example, cation exchange resin), Ru removal occurs via distillation or other processes, and then it directly enters the Pt refining process stream to recover Pt. The residual spent catalyst layer material from the leaching can undergo a process involving heating / high-pressure sterilization of the material in a solvent (e.g., an alcohol solvent) to disperse the ionomer. The ionomer dispersion can then be separated from the Ir-containing solid via filtration or centrifugation. Further processing of the ionomer dispersion can then be continued to recycle back into the manufacture of new CCMs as pure materials or blended materials. Examples of processes for recycling perfluorosulfonic acid ionomers are described in US7255798 and WO2016 / 156815. Due to its inherent stability, the Ir catalyst can be reused without further processing, or the Ir solid can be refined to recover Ir metal.

[0122] In the above process, a platinum leaching step is performed on the spent catalyst layer material prior to the step of dispersing the ionomer. However, in an alternative method, the ionomer dispersion is performed prior to the platinum leaching step. In this case, the spent catalyst layer material is heated to an elevated temperature in a solvent (e.g., an alcohol solvent) and optionally high-pressure sterilized to disperse the ionomer. Solid / liquid separation is performed on the resulting slurry (e.g., by filtration or centrifugation). The solution will contain the dispersed ionomer, which will then be further processed to recycle back into the manufacture of new CCMs. The PGM residue can be dried to ensure complete removal of the organic solvent prior to being subjected to the HCl / chlorine leaching treatment as previously described. The liquid from the leaching can be processed to remove base metals such as Ni and / or Co (e.g., cation exchange resin), Ru removal occurs (e.g., via a distillation process), and then the remaining platinum-containing solution is provided to the Pt refining process stream to recover Pt, as previously described. The residue from the leaching process still contains the Ir catalyst, which is largely unchanged due to its stability. It can be processed to directly reuse the Ir catalyst material (e.g., IrOx), or the residue can be refined to recover Ir.

[0123] Processing of waste dispersion medium

[0124] After processing the membrane to recover the membrane ionomer and / or after processing the catalyst layer slurry to disperse and recover the first catalyst layer ionomer and the second catalyst layer ionomer, a waste dispersion medium is generated. The waste dispersion medium contains a solvent and fluorine-containing substances such as soluble fluorinated organic compounds, soluble fluoride substances, and / or insoluble fluorine-containing substances such as insoluble metal fluorides. The waste dispersion medium can be treated to reduce the concentration of fluorine-containing substances in the solvent, after which the solvent can be safely discarded or recycled for reuse in processing additional membrane and / or catalyst layer slurry materials. Treatment of the waste dispersion medium can include contacting the waste dispersion medium with a solid adsorbent and / or an ion exchange medium to reduce the concentration of fluorine-containing substances in the solvent, and optionally also to reduce the concentration of residual metal cations in the solvent. For example, the waste dispersion medium can also be subjected to crossflow filtration or ultrafiltration before contacting the waste dispersion medium with an adsorbent such as activated carbon and / or with one or more ion exchange media.

[0125] According to the above, the present specification also provides a method for treating a dispersion medium (e.g., water, basic aqueous solution, or water / alcohol mixture) for recycling ionomers from CCM membrane components and / or catalyst layer components. The used dispersion medium can be contacted with a cation exchange resin and optionally an anion exchange resin and / or a capture medium such as activated carbon. The resulting treated used dispersion medium has a reduced content of low molecular weight soluble organic compounds such as fluorinated or partially fluorinated sulfonic or carboxylic acids and (optionally) a reduced content of residual cations such as iron, nickel, copper, and chromium. The treated dispersion medium can then be reused in a closed-loop system or safely discarded. Optionally, the waste dispersion medium can first be subjected to a crossflow filtration or ultrafiltration step to concentrate impurities before capturing and treating the fluorine-containing impurities. The resin after ion exchange can be regenerated. The waste stream can be concentrated and discarded by pyrolysis (e.g., using a thermal oxidizer). The activated carbon column can also be pyrolyzed at the end of its life.

[0126] Figure 6 An example of a processing flow for treating the waste dispersion medium is shown. Advantages of this waste dispersion medium processing method include reduced emissions resulting from ionomer recycling from production waste and / or end-of-life fuel cells and / or CCM components of water electrolyzers. Reducing water consumption is also beneficial.

[0127] Examples of solid media that can be used to extract fluorine-containing substances from the waste dispersion medium include adsorbents such as carbon-based adsorbents such as activated carbon, silica-based adsorbents, metal-based adsorbents, and / or ion exchange resins that can adsorb F / react with F. Ion exchange resins include, for example, zirconium or aluminum pre-loaded chelating resins having an amino-methylphosphonic acid functional group, strongly basic anion exchange resins containing a quaternary ammonium functional group, pre-loaded metal ions (such as Fe 3+ 、Al 3+ 、Ce 3+ and / or La3+ ) or an iminodiacetic acid-functionalized cation exchange resin of a cavitand ligand. The adsorbent can be a silica-based adsorbent, such as a glass material, such as a barium silicate glass material that can be provided in the form of glass powder. The fluorine-containing waste dispersion medium can be passed through a packed column or bed of such an adsorbent to remove fluorine-containing substances. The adsorbent can be periodically replaced and / or treated to remove fluorine and regenerated for reuse.

[0128] Summary

[0129] This method combines operations to produce a process for recovering ionomers and PGMs from CCMs, which includes delaminating (and optionally crushing) the catalyst layer from the body film to produce a more concentrated ionomer-containing membrane stream and a more concentrated PGM-containing catalyst layer stream, from which the PGM can be more effectively leached while also being able to recover the catalyst layer ionomers.

[0130] An alcohol / water solvent system is provided, and by adjusting conditions (type / concentration of alcohol, temperature, pressure, time, stirring), it is possible to treat CCMs (or MEAs) to achieve one or more of the following results:

[0131] 1. Only delamination of the catalyst layer.

[0132] 2. Delamination of the catalyst layer and dispersion of ionomers selective for the catalyst layer ionomers.

[0133] 3. Delamination of the catalyst layer and complete dispersion of ionomers in all three components (membrane, anode, and cathode catalyst layers).

[0134] This process can be before and / or after one or more of the following steps:

[0135] 4. Leaching of PGM from the catalyst layer.

[0136] 5. Dispersion of ionomers in the catalyst layer leached of PGM.

[0137] 6. Dispersion of ionomers from the membrane.

[0138] The conditions can be adjusted to achieve the desired results. A particular point to note in this specification is the purpose of using an alcohol / water mixture. Previous work has focused on the selective separation and recycling of PGMs, such as keeping the anode PGM separated from the cathode PGM. In contrast, herein we have determined that certain alcohol / water mixtures can be used for ionomer / ionomer separation. Most ionomer recycling processes for CCMs focus on the complete dispersion of all ionomers in the CCM, which means that the separation of ionomer from ionomer must be addressed in another way. It is likely that future CCMs will contain multiple ionomers. This method of delaminating the catalyst layer ionomer from the membrane provides an industrially viable way to handle such multi-ionomer CCMs and, if different ionomers are used in the catalyst layer and the bulk membrane, represents a potentially optimal / only way to separate ionomers in a scaled-up industrial CCMM recycling process.

[0139] The drivers for PFSA recycling are generally:

[0140] 1. Legislation - more stringent regulations on the use of PFA due to its persistence in the environment.

[0141] 2. Finance - the cost of the ionomer can be comparable to the cost of the precious metals in the PEM product.

[0142] 3. Environmental sustainability - current routes for recycling PGMs involve incineration releasing high levels of the toxic and corrosive HF and associated CO 2 footprint.

[0143] Establishing an industrially viable PFSA recycling process enhances the attractiveness of hydrogen technologies using CCMs and provides an opportunity for a closed-loop recycling route for hydrogen technology products. More specifically, the present invention provides a method for mixed ionomer recycling that has scale-up challenges and flexibility in recycling future waste streams.

[0144] While the invention has been specifically shown and described with reference to certain examples, those skilled in the art will understand that various changes in form and detail may be made without departing from the scope of the invention as defined by the appended claims.

Claims

1. A method of recycling a waste catalyst-coated membrane, wherein the waste catalyst-coated membrane comprises: a membrane comprising a membrane ionomer; a first catalyst layer disposed on one side of the membrane, the first catalyst layer comprising a first catalyst and a first catalyst layer ionomer; and a second catalyst layer disposed on the opposite side of the membrane, the second catalyst layer comprising a second catalyst and a second catalyst layer ionomer, the method comprising: contacting the waste catalyst-coated membrane with a solvent to delaminate both the first catalyst layer and the second catalyst layer from the membrane without dispersing the membrane, wherein the first catalyst layer and the second catalyst layer form a catalyst layer slurry comprising the first catalyst, the first catalyst layer ionomer, the second catalyst, and the second catalyst layer ionomer; separating the membrane from the catalyst layer slurry; processing the membrane to recover the membrane ionomer; and processing the catalyst layer slurry to disperse and recover the first catalyst layer ionomer and the second catalyst layer ionomer in a solvent, and to separate and recover the first catalyst and the second catalyst or their components.

2. The method according to claim 1, wherein the processing of the catalyst layer slurry comprises: heating the catalyst layer slurry to disperse the first catalyst layer ionomer and the second catalyst layer ionomer, thereby forming an ionomer dispersion in which solid first catalyst material and solid second catalyst material are disposed; separating the solid first catalyst material and the solid second catalyst material from the ionomer dispersion; processing the ionomer dispersion to recover the first catalyst layer ionomer and the second catalyst layer ionomer; and processing the solid first catalyst material and the solid second catalyst material to separate and recover the first catalyst material and the second catalyst material or their components.

3. The method according to claim 2, wherein the step of heating the catalyst layer slurry to disperse the first catalyst layer ionomer and the second catalyst layer ionomer is carried out in the same solvent used to delaminate the first catalyst layer and the second catalyst layer from the membrane.

4. The method according to claim 2, wherein the step of heating the catalyst layer slurry to disperse the first catalyst layer ionomer and the second catalyst layer ionomer is carried out in a solvent different from the solvent used to delaminate the first catalyst layer and the second catalyst layer from the membrane.

5. The method according to any one of claims 2 to 4, wherein the step of heating the catalyst layer slurry to disperse the first catalyst layer ionomer and the second catalyst layer ionomer is carried out at a higher temperature than the step of contacting the waste catalyst-coated membrane with the solvent to delaminate both the first catalyst layer and the second catalyst layer from the membrane without dispersing the membrane.

6. The method according to any one of claims 2 to 5, The step of heating the catalyst layer slurry to disperse the first catalyst layer ionomer and the second catalyst layer ionomer in the solvent is carried out in an autoclave under high pressure.

7. The method according to any one of the preceding claims, wherein the processing of the catalyst layer slurry further comprises converting the first catalyst layer ionomer and the second catalyst layer ionomer into a salt form.

8. The method according to claim 7, the method further comprises converting the salt form of the first catalyst layer ionomer and the second catalyst layer ionomer back to the acid form by proton exchange.

9. The method according to any one of the preceding claims, wherein the ionomer dispersion is subjected to ion exchange to remove metal contaminants.

10. The method according to any one of the preceding claims, wherein the first catalyst layer ionomer and the second catalyst layer ionomer are recovered from the ionomer dispersion as a blend of the first catalyst layer ionomer and the second catalyst layer ionomer.

11. The method according to any one of claims 1 to 9, wherein the ionomer dispersion is processed to separate the first catalyst layer ionomer and the second catalyst layer ionomer.

12. The method according to any one of the preceding claims, wherein the solvent for delaminating both the first catalyst layer and the second catalyst layer from the membrane is a mixture of an alcohol and water, and wherein the alcohol in the mixture of alcohol and water is selected from n-butanol, n-propanol, isopropanol or ethanol.

13. The method according to claim 12, wherein the mixture of alcohol and water has an alcohol:water volume ratio of at least 50:50, 60:40 or 70:30; not greater than 95:5, 90:10 or 85:15; or within a range defined by any combination of the above lower and upper limits.

14. The method according to any one of the preceding claims, wherein the solvent for delaminating both the first catalyst layer and the second catalyst layer from the membrane contains a base, optionally a metal hydroxide or an ammonium solution, to convert the first catalyst layer ionomer, the second catalyst layer ionomer and the membrane ionomer into a salt form.

15. The method according to any one of the preceding claims, wherein when the spent catalyst-coated membrane is contacted with the solvent to delaminate both the first catalyst layer and the second catalyst layer from the membrane, the solvent is optionally agitated by sonication.

16. The method according to any one of the preceding claims, wherein the membrane ionomer is different from one or both of the first catalyst layer ionomer and the second catalyst layer ionomer.

17. The method according to any one of the preceding claims, wherein the first catalyst layer ionomer is different from the second catalyst layer ionomer.

18. The method according to any one of the preceding claims, wherein the first catalyst comprises platinum, palladium and / or ruthenium.

19. The method according to any one of the preceding claims, wherein the second catalyst comprises iridium.

20. The method according to any one of the preceding claims, The step of processing the solid first catalyst material and the solid second catalyst material includes treatment with a heated solution comprising an acid and an oxidizing agent, wherein platinum, palladium, rhodium, and / or ruthenium are leached into a solution separated from the remaining solid components.

21. The method according to any one of the preceding claims, wherein the step of processing the solid first catalyst material and the solid second catalyst material includes treatment with a heated solution comprising an acid and a reducing agent, wherein iridium is leached into a solution separated from the remaining solid components.

22. The method according to claim 20, wherein the solid iridium-containing catalyst material is recovered after the leaching of the platinum, palladium, and / or ruthenium and the dispersion of the ionomer.

23. The method according to any one of the preceding claims, wherein after processing the membrane to recover the membrane ionomer and / or after processing the catalyst layer slurry to disperse and recover the first catalyst layer ionomer and the second catalyst layer ionomer, a waste dispersion medium comprising a solvent and a fluorinated substance is generated, and wherein the waste dispersion medium is treated to reduce the concentration of the fluorinated substance in the solvent, after which the solvent is discarded or recycled for reuse in processing additional membrane and / or catalyst layer slurry materials.

24. The method according to claim 23, wherein treating the waste dispersion medium to reduce the concentration of the fluorinated substance in the solvent includes one or both of the following: contacting the waste dispersion medium with a solid adsorbent; and contacting the waste dispersion medium with one or more ion exchange media.

25. The method according to claim 23 or 24, wherein the waste dispersion medium is subjected to crossflow filtration or ultrafiltration.

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