Method for recovering catalyst from catalyst coating film

Abstract

A method for recycling anode and / or cathode catalysts from a catalyst coating film, comprising a proton exchange membrane, a continuous non-porous crosslinked polymer electrolyte multilayer coating containing alternating layers of polycationic polymer and polyanionic polymer, an anode coating layer containing anode catalyst particles, a cathode coating layer containing cathode catalyst particles, and optionally a second continuous non-porous crosslinked polymer electrolyte multilayer coating between the second surface of the proton exchange membrane and the cathode coating layer. The crosslinked polymer electrolyte multilayer coating between the proton exchange membrane and the anode and / or cathode catalyst coating layer is dissolved in an aqueous solution with a pH greater than 7. The catalyst coating film is peeled off and the anode and / or cathode catalysts are recovered.

Description

[Technical Field]

[0001] (Priority statement) This application claims priority to U.S. Patent Application No. 18 / 451,327, filed on 17 August 2023, which is incorporated herein by reference in its entirety. [Background technology]

[0002] Hydrogen as an energy vector for grid balancing or power-to-gas and power-to-liquid processes plays a crucial role in the path toward an environmentally friendly, low-carbon energy structure. Water electrolysis produces high-quality hydrogen by electrochemically decomposing water into hydrogen and oxygen, the reaction occurring according to Equation 1 below. Water electrolysis is an endothermic process, and electricity is the energy source. If the process is powered by renewable energy sources such as wind, solar, or geothermal energy, the carbon footprint of water electrolysis is zero. Major water electrolysis technologies include alkaline electrolysis, proton exchange membrane (PEM) water electrolysis (PEM-WE shown in Figure 1), anion exchange membrane (AEM) water electrolysis (AEM-WE shown in Figure 2), and solid oxide water electrolysis.

[0003] As shown in Figure 1, in the PEM-WE system 100, the anode 105 and cathode 110 are separated by a solid PEM electrolyte 115, such as a sulfonated tetrafluoroethylene-based cofluoropolymer sold by Chemors under the trademark name Nafion®. The anode catalyst and cathode catalyst typically contain IrO2 and Pt, respectively. At the positively charged anode 105, pure water 120 is oxidized to produce oxygen gas 125, electrons (e-), and protons, and the reaction is shown by Equation 2. The protons are transported from the anode 105 to the cathode 110 through the proton-conducting PEM 115. At the negatively charged cathode 110, a reduction reaction occurs, in which electrons from the cathode 110 are donated to the protons to form hydrogen gas 130, and the reaction is shown by Equation 3. PEM115 not only conducts protons from the anode 105 to the cathode 110, but also separates the H2 gas 130 and O2 gas 125 produced in the water electrolysis reaction. PEM water electrolysis is one of the preferred methods for converting renewable energy into high-purity hydrogen, offering advantages such as high differential pressure, high current density, high efficiency, fast response, low footprint, low temperature (20-90°C) operation, and a compact system design with high-purity oxygen byproducts. However, one of the major challenges of PEM water electrolysis is the high capital cost of the cell stack, which includes expensive acid-resistant stack hardware such as Pt-coated Ti bipolar plates, expensive precious metal catalysts required for the electrodes, and expensive PEMs. Water electrolysis reaction: 2 H2O → 2 H2 + O2 (1) Oxidation reaction of PEM-WE at the anode: 2H2O → O2 + 4H + 4e (2) Reduction reaction at the cathode of PEM-WE: 4H++4e- → 2H2 (3)

[0004] PEM-WE and AEM-WE systems integrate several components to generate environmentally friendly H2, including a current collector plate, a bipolar plate (BP), two porous transport layers (PTL), a membrane, an anode layer, and a cathode layer, which are also called a catalyst-coated membrane (CCM) or membrane electrode assembly (MEA). Of the main components, the CCM is the most important because the electrochemical water electrolysis reaction takes place within the CCM.

[0005] In a CCM for an electrochemical cell, the anode, coated on one surface of the membrane, is the electrode where the dominant reaction is oxidation (e.g., a hydroxide / oxygen evolution electrode in a water electrolytic cell). The cathode, coated on the other surface of the membrane, is the electrode where the dominant reaction is reduction (e.g., a proton reduction / hydrogen evolution electrode in a water electrolytic cell). Both the anode and cathode are important components in a CCM. Typically, in the case of PEM-WE, unsupported or supported iridium (Ir)-based rare platinum group electrode catalysts are used for the oxygen evolution reaction (OER) on the anode, and carbon-supported platinum electrode catalysts (Pt / C) are used for the hydrogen evolution reaction (HER) on the cathode. Both Ir and Pt-based platinum group metal (PGM) catalysts are very expensive and rare. As GW-scale PEM-WE installation projects increase, a significant reduction in the amount of PGM catalyst supported on the catalyst coating layer will be necessary. Methods for reducing the amount of PGM catalyst, as well as methods for recycling the PGM catalyst, are important for improving the market penetration of PEM-WE technology for environmentally friendly H2 production.

[0006] Significant progress is needed to find cost-effective and sustainable PGM recovery methods for spent CCMs. [Brief explanation of the drawing]

[0007] [Figure 1] This is a diagram of one embodiment of the PEMWE cell. [Figure 2] This is a diagram of one embodiment of the catalyst coating film of the present invention. [Figure 3A] This is a diagram illustrating an embodiment of a method for recovering a catalyst from a catalyst coating film. [Figure 3B] This is a diagram illustrating an embodiment of a method for recovering a catalyst from a catalyst coating film. [Figure 3C] This is a diagram illustrating an embodiment of a method for recovering a catalyst from a catalyst coating film. [Modes for carrying out the invention]

[0008] The present invention relates to an innovative and simple method for recovering PGM catalysts, particularly Ir-containing anode catalysts, from spent catalyst coatings (CCMs) for PEM-WEs. This catalyst recovery method can be used to recover and recycle PGM catalysts from PEM electrolytic cell stacks containing CCMs. This catalyst recovery method is particularly suitable for recovering anode catalysts from, for example, the CCM for PEM-WEs described in U.S. Patent Application No. 17 / 451,227, filed October 18, 2021, entitled Polyelectrolyte Multilayer Coated Proton Exchange Membrane for Electrolysis and Fuel Cell Applications, which is incorporated herein by reference in its entirety, and from the CCM for PEM-WEs described in U.S. Provisional Patent Application No. 63 / 476,983, filed December 23, 2022, entitled Multilayer Ion-Exchange Membrane for Electrolysis Applications, which is incorporated herein by reference in its entirety.

[0009] Current catalytic recycling methods differ from conventional incineration methods, which release highly toxic and corrosive hydrogen fluoride (HF) gas. This method involves a crosslinked polymer electrolyte (CCM) comprising: a proton exchange membrane having a first surface and a second surface; a first continuous nonporous crosslinked polymer electrolyte multilayer coating on the first surface of the proton exchange membrane, the first continuous polymer electrolyte multilayer coating comprising alternating layers of polycationic polymer and polyanionic polymer; an anode coating layer comprising anode catalyst particles on the continuous nonporous crosslinked polymer electrolyte multilayer coating on the first surface of the proton exchange membrane; a cathode coating layer comprising cathode catalyst particles on the second surface of the proton exchange membrane; and optionally, a second continuous nonporous crosslinked polymer electrolyte multilayer coating between the second surface of the proton exchange membrane and the cathode coating layer. From this CCM, the crosslinked polymer electrolyte multilayer coating between the proton exchange membrane and the anode and / or cathode catalyst coating layer, for example, an ion-crosslinked sulfonated poly(etheretherketone) (SPEEK) / poly(allylamine hydrochloride) (PAH) polymer electrolyte layer, is converted into an aqueous solution with a pH greater than 7, for example, 1M. Anode and / or cathode catalysts, such as IrO2 anode catalysts, are recycled by dissolving them in an aqueous NaOH solution, stripping the catalyst coating film, and recovering the anode and / or cathode catalyst from the CCM. Furthermore, ion-crosslinked polymer electrolytes can be used as ionomers in the anode and cathode catalyst coating layers. The ion-crosslinked polymer electrolyte ionomer may also be dissolved to facilitate catalyst recovery.

[0010] This method avoids the formation of toxic and corrosive gases (HF) because it does not involve the incineration of CCM. Furthermore, it preserves important membrane materials such as the proton exchange membrane and the hydrogen recombination layer (if present). This method also has a high catalyst recovery yield, and since the anode and cathode catalysts can be recovered separately, it eliminates the need to separate the anode and cathode catalysts.

[0011] One aspect of the present invention is a method for recovering a catalyst from a catalyst coating film. In one embodiment, the method includes providing a catalyst coating film comprising: a proton exchange membrane having a first surface and a second surface; a first continuous nonporous crosslinked polymer electrolyte multilayer coating on the first surface of the proton exchange membrane, the first continuous polymer electrolyte multilayer coating comprising alternating layers of polycationic polymer and polyanionic polymer; an anode coating layer comprising anode catalyst particles on the continuous nonporous crosslinked polymer electrolyte multilayer coating on the first surface of the proton exchange membrane; a cathode coating layer comprising cathode catalyst particles on the second surface of the proton exchange membrane; and optionally, a second continuous nonporous crosslinked polymer electrolyte multilayer coating between the second surface of the proton exchange membrane and the cathode coating layer. The catalyst coating film is brought into contact with an alkaline solution to dissolve the first continuous nonporous crosslinked polymer electrolyte multilayer coating or the first and second continuous nonporous crosslinked polymer electrolyte multilayer coatings. The anode and / or cathode catalyst particles are recovered. When recovering both anode catalyst particles and cathode catalyst particles, it is preferable to recover them separately.

[0012] The pH of an alkaline solution is typically greater than 7, or greater than 8, or greater than 9, or greater than 10, or greater than 11, or greater than 12, or greater than 13.

[0013] The catalyst coating film may be brought into contact with the alkaline solution while heating the catalyst coating film and / or the alkaline solution, while ultrasonically treating the catalyst coating film and / or the alkaline solution, or while heating the catalyst coating film and / or the alkaline solution and ultrasonically treating it. The catalyst coating film may be heated at temperatures in the range of 30°C to 150°C, or 30°C to 100°C, or 50°C to 150°C, or 50°C to 100°C.

[0014] The alkaline solution may be added to the anode side, the cathode side, or both sides of the catalyst coating film. Alternatively, the catalyst coating film may be added to the alkaline solution to recover the catalyst, in which case the anode and cathode catalyst particles will be mixed together.

[0015] The anode catalyst particles can include, but are not limited to, platinum group metals (PGMs), PGMs supported on different PGM carriers, PGMs supported on non-PGM carriers, their alloys, their oxides, their carbides, their phosphides, or combinations thereof. The term "platinum group metal" means six noble metal elements including ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), and platinum (Pt). The anode catalyst particles can include, but are not limited to, iridium, iridium supported on a non-PGM carrier, platinum, platinum supported on a non-PGM carrier, ruthenium, ruthenium supported on a non-PGM carrier, osmium, rhodium, palladium, tin, tungsten, vanadium, cobalt, silver, gold, copper, nickel, molybdenum, iron, chromium, their alloys, their oxides, their carbides, their phosphides, or combinations thereof. The anode catalyst particles can include, but are not limited to, iridium, iridium supported on platinum, iridium supported on a non-PGM carrier, platinum, platinum supported on a non-PGM carrier, ruthenium, ruthenium supported on a non-PGM carrier, their oxides, or combinations thereof.

[0016] The cathode catalyst particles can include, but are not limited to, platinum group metals (PGMs), PGMs supported on a non-PGM carrier, their alloys, or combinations thereof. The cathode catalyst particles can include, but are not limited to, platinum, platinum supported on a non-PGM carrier, ruthenium, ruthenium supported on a non-PGM carrier, osmium, rhodium, palladium, tin, tungsten, vanadium, cobalt, silver, gold, nickel, molybdenum, iron, copper, chromium, their alloys, their carbides, their phosphides, or combinations thereof. The cathode catalyst particles can include, but are not limited to, platinum, platinum supported on a carbon carrier, platinum supported on a graphene carrier, platinum supported on an oxidized graphene carrier, ruthenium, ruthenium supported on a carbon carrier, ruthenium supported on a graphene carrier, ruthenium supported on an oxidized graphene carrier, platinum and ruthenium supported on a carbon carrier, or combinations thereof.

[0017] The polycationic polymer layer of the first continuous non-porous crosslinked polyelectrolyte multilayer coating is in contact with the first surface of the proton exchange membrane. When a second continuous non-porous crosslinked polyelectrolyte multilayer coating is present, the polycationic polymer layer of the first continuous non-porous crosslinked polyelectrolyte multilayer coating is in contact with the first surface of the proton exchange membrane, and the polycationic polymer layer of the second continuous non-porous crosslinked polyelectrolyte multilayer coating is in contact with the second surface of the proton exchange membrane.

[0018] Any suitable alkaline solution can be used. Suitable alkaline solutions can include, but are not limited to, KOH, NaOH, LiOH, CsOH, KHCO3, K2CO3, LiHCO3, Li2CO3, NaHCO3, Na2CO3, or combinations thereof.

[0019] Figure 2 shows one embodiment of the catalyst coating film 300. The catalyst coating film 300 includes a proton exchange membrane 305. The proton exchange membrane may include a cation exchange polymer, or a mixture of a cation exchange polymer and an inorganic filler containing covalently bonded acidic functional groups. The proton exchange membrane 305 has a negative ionic charge -SO3 - , -COO - , -PO3 2- , or -PO3H - It contains cation exchange functional groups. The proton exchange polymer may be selected from, but is not limited to, perfluorinated ionomers such as Nafion®, Flemion®, Fumion®, Aciplex®, or Aquivion®, crosslinked perfluorinated cation exchange polymers, partially fluorinated polymers, crosslinked partially fluorinated cation exchange polymers, non-fluorinated hydrocarbon polymers, crosslinked non-fluorinated hydrocarbon cation exchange polymers, or combinations thereof. The proton exchange membrane 305 has high mechanical strength, good chemical and thermal stability, and good proton conductivity. Compared to the proton exchange membrane 305 without a catalyst layer and polymer electrolyte multilayer coating, the catalyst coating membrane 300 has lower membrane area resistivity, less swelling, significantly reduced H2 and O2 crossover, and enhanced proton conductivity.

[0020] The proton exchange membrane 305 may be a composite proton conductive membrane as described in U.S. Patent Application No. 17 / 162,421, filed January 29, 2021, titled Composite Proton Conductive Membranes, which is incorporated herein by reference in whole. The application describes covalently bonded acidic functional groups and at least 150 m 2 A novel type of composite proton-conducting film is disclosed, comprising an inorganic filler having a high surface area of ​​1 / g and a water-insoluble ion-conducting polymer.

[0021] The inorganic filler containing covalently bonded acidic functional groups in the proton exchange membrane 305 may be selected from, but is not limited to, silica gel, precipitated silica, fumed silica, colloidal silica, alumina, silica-alumina, zirconium oxide, molecular sieves, metal-organic skeletons, zeolite imidazolate skeletons, covalently bonded organic skeletons, or combinations thereof. The filler contains covalently bonded acidic functional groups and 150m 2 / g or more, or 300m 2 / g or more, or 400m 2It may include both high surface area of ​​1 / g or more. Molecular sieves have a skeletal structure that can be characterized by a distinctive wide-angle X-ray diffraction pattern. Zeolites are a subclass of molecular sieves based on aluminosilicate compositions. Non-zeolite molecular sieves are based on other compositions such as aluminophosphates, silicoaluminophosphates, and silica. Molecular sieves can have a variety of chemical compositions and skeletal structures. Molecular sieves may be microporous or mesoporous molecular sieves and need to be stable in aqueous solutions with a pH of less than 6. The acidic functional group covalently bonded to the inorganic filler may be selected from, but is not limited to, -H2PO3, -R-H2PO3, -SO3H, -R-SO3H, -COOH, -R-COOH, -C6H5OH, -R-C6H5OH, or a combination thereof, where R represents a linear alkyl group, a branched alkyl group, a cycloalkyl group, an organic amino group, an acid-substituted organic amino group, or an aryl group, and the number of carbon atoms in these groups is preferably 1 to 20, more preferably 1 to 10. The inorganic filler may be in the form of particles, fine beads, sheets, rods, or fibers, but is not limited to these forms. The size of the inorganic filler is in the range of 2 nm to 200 μm, or 10 nm to 100 μm, or 50 nm to 80 μm. In some embodiments, the inorganic filler is aminopropyl-N,N-bis(methylphosphonic acid) functionalized silica gel such as SilicaMetS® AMPA, aminopropyl-N,N-bis(methylphosphonic acid) functionalized fumed silica, n-propylphosphonic acid functionalized silica gel, n-propylphosphonic acid functionalized fumed silica, p-toluenesulfonic acid functionalized silica gel, p-toluenesulfonic acid functionalized fumed silica, 4-ethylbenzenesulfonic acid functionalized silica gel such as SilicaBond® tosylic acid, 4-ethylbenzenesulfonic acid functionalized fumed silica, n-propylsulfonic acid functionalized silica gel, n-propylsulfonic acid functionalized fumed silica, or a combination thereof.

[0022] Suitable cation exchange polymers include, but are not limited to, perfluoro-sulfonic acid polymers, perfluoro-carboxylic acid polymers, sulfonated aromatic hydrocarbon polymers, crosslinked sulfonated aromatic hydrocarbon polymers, or combinations thereof. Suitable cation exchange polymers include copolymers of tetrafluoroethylene and perfluoro-3,6-dioxa-4-methyl-7-octen-sulfonic acid, copolymers of tetrafluoroethylene and perfluoro-5-oxa-6-heptene-sulfonic acid, copolymers of tetrafluoroethylene and perfluoro-4-oxa-5-hexene-sulfonic acid, copolymers of tetrafluoroethylene and perfluoro-3-oxa-4-pentene-sulfonic acid, and perfluoro-3 Copolymer of ,6-dioxa-4-methyl-7-octen-sulfonic acid and perfluoro(2,2-dimethyl-1,3-dioxol), copolymer of perfluoro-5-oxa-6-heptene-sulfonic acid and perfluoro(2,2-dimethyl-1,3-dioxol), copolymer of perfluoro-4-oxa-5-hexene-sulfonic acid and perfluoro(2,2-dimethyl-1,3-dioxol), copolymer of perfluoro-3-oxa-4-pentene-sulfonic acid and perfluoro Copolymer with (2,2-dimethyl-1,3-dioxol), copolymer of perfluoro-3,6-dioxa-4-methyl-7-octenosulfonic acid and perfluoro(2-methylene-4-methyl-1,3-dioxolane), copolymer of perfluoro-5-oxa-6-heptenesulfonic acid and perfluoro(2-methylene-4-methyl-1,3-dioxolane), copolymer of perfluoro-4-oxa-5-hexenesulfonic acid and perfluoro(2-methylene-4-methyl-1 Copolymer of perfluoro-3-oxalane, perfluoro-3-oxa-4-pentene-sulfonic acid and perfluoro(2-methylene-4-methyl-1,3-dioxolane), perfluoro-3,6-dioxa-4-methyl-7-octen-sulfonic acid and 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxol, perfluoro-5-oxa-6-heptene-sulfonic acid and 2,2,4-trifluoro-5-trifluoromethoxy-1,Copolymer with 3-dioxole, copolymer with perfluoro-4-oxa-5-hexene-sulfonic acid and 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxole, copolymer with perfluoro-3-oxa-4-pentene-sulfonic acid and 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxole, sulfonated poly(ether ether ketone) (SPEEK), sulfonated polyether sulfone, sulfonated polyphenyl sulfone, sulfonated poly(2,6-dimethyl-1,4-phenylene oxy Examples include, but are not limited to, poly(phenylene)(side), sulfonated poly(4-phenoxybenzoyl-1,4-phenylene), sulfonated polyphenylene oxide, sulfonated poly(phenylene), sulfonated poly(phthalazinone), crosslinked SPEEK, crosslinked sulfonated polyethersulfone, crosslinked sulfonated polyphenylsulfone, crosslinked poly(phenylene sulfide sulfone nitrile), sulfonated polystyrene, sulfonated poly(vinyltoluene), crosslinked sulfonated polystyrene, crosslinked sulfonated poly(vinyltoluene), or combinations thereof.

[0023] The catalyst coating film includes a first polymer electrolyte multilayer coating 310 comprising alternating layers of polycationic polymer 315 and polyanionic polymer 320. A second polymer electrolyte multilayer coating (not shown) comprising alternating layers of polycationic polymer and polyanionic polymer may be present on the opposite side of the proton exchange film 305.

[0024] The first layer of the polymer electrolyte layer deposited on the proton exchange membrane must be a polycationic polymer layer 315 having a positive ionic charge. Then, a polyanionic polymer layer 320 having the opposite charge is deposited on the surface of the first polycationic polymer coating layer 315 via electrostatic interaction to form the second portion of the first polymer electrolyte bilayer. The polymer electrolyte multilayer coating can be formed according to the same alternating deposition process. This results in the formation of a stable polymer electrolyte multilayer coating 310 via electrostatic interaction between the proton exchange membrane 305 and the first polymer electrolyte multilayer coating 310.

[0025] Polymer electrolyte multilayer coatings can be formed following the same alternating deposition process.

[0026] The thickness of each polyanion or polycation layer may be less than 50 nm, less than 20 nm, less than 10 nm, or less than 5 nm.

[0027] The first polymer electrolyte multilayer coating 310 may be thinner than the proton exchange membrane 305. Furthermore, the first polymer electrolyte multilayer coating 310 and the second polymer electrolyte multilayer coating (not shown) may be thinner than the proton exchange membrane 305.

[0028] An anode coating layer 325 containing anode particles 330 is located on the first polymer electrolyte multilayer coating 310, and a cathode coating layer 335 containing cathode particles 340 is located on the opposite side of the proton exchange membrane 305. If a second polymer electrolyte multilayer coating is present, it will be located between the proton exchange membrane 305 and the cathode coating layer 335. The anode coating layer 325 and the cathode coating layer 335 may be thinner than the proton exchange membrane 305 and thicker than the first polymer electrolyte multilayer coating 310.

[0029] Optionally, a continuous non-porous hydrogen recombination catalyst coating layer 345 may be present between the proton exchange membrane 305 and the first polymer electrolyte multilayer coating 310. The hydrogen recombination catalyst coating layer 345 may contain a catalyst and an ionomer. The catalyst is for the hydrogen recombination reaction and may be Pt, Pt / Co, Pd, Pd / Co, or mixtures thereof. The ionomer may be a proton-conducting fluorinated or non-fluorinated polymer ionomer.

[0030] The hydrogen recombination catalyst coating layer 345 may further contain additives such as CeO2, Ce(OH)4, CeO2 / ZrO2, Ce(OH)4 / ZrO2, or mixtures thereof. These additives such as CeO2, Ce(OH)4, CeO2 / ZrO2, Ce(OH)4 / ZrO2, or mixtures thereof are radial scavengers having an active redox pair of Ce(IV) / Ce(III). The catalytic H2 recombination reaction in the H2 recombination catalyst layer 345 and the catalytic reaction at the cathode 110 in the presence of O2 also produce hydrogen peroxide and radical intermediates, such as hydroperoxyl radicals (HOO · ), and hydroxyl radicals (HO · ). These reactive oxygen species degrade the membrane and the ionomer. By incorporating a radical scavenger into the H2 recombination catalyst layer, the durability of the multilayer ion exchange membrane is improved.

[0031] Figures 3A - 3C show one embodiment of a method for recovering a catalyst from a catalyst-coated film. The system 400 includes a tank 405, a tank 410, and a cell 415 including a catalyst-coated film 300 with the anode catalyst coating layer 325 side connected to the tank 410. As shown in Figures 3A - 3B, when the catalyst-coated film at the end of the life of the PEM electrolyzer is incorporated into the cell 415, an alkaline solution 420 such as an aqueous KOH solution is placed in the tank 410 and contacts the anode side of the catalyst-coated film 300. The alkaline solution 420 dissolves the first polyelectrolyte multilayer coating 310, releases the anode coating particles 330, and then these can be recovered. The proton exchange membrane 305 and the cathode catalyst coating layer 335 remain.

[0032] As shown in Figure 3C, when the alkaline solution is added to the tank 410 and the tank 405, the polyelectrolyte layers on both sides of the proton exchange membrane 305 dissolve, releasing the anode catalyst particles 330 and the cathode catalyst particles 340. The proton exchange membrane 305 remains. The anode particles 330 and / or the cathode particles 340 can be recovered.

[0033] The proton exchange membrane may include a reinforced proton exchange membrane or an unreinforced proton exchange membrane. The proton exchange membrane may be reinforced using polytetrafluoroethylene (PTFE), polyphenylene sulfide (PPS), polyvinylidene difluoride (PVDF), polychlorotrifluoroethylene (PCTFE), polyetheretherketone (PEEK), polyimide (PI), polyetherimide (PEI), polybenzoxazole (PBO), polybenzimidazole (PBI), polysulfone (PSF), polyethersulfone (PES), polyaramid, polypropylene (PP), polyethylene (PE), co-PP-PE, or a combination thereof. A suitable reinforced proton exchange membrane is described in U.S. Provisional Patent Application No. 63 / 509,806, which is incorporated herein by reference in its entirety.

[0034] The catalyst coating film may further include a continuous nonporous hydrogen recombination catalyst coating layer between the proton exchange film layer and the first continuous nonporous crosslinked polymer electrolyte multilayer coating. The continuous nonporous hydrogen recombination catalyst coating layer may include a mixture of a hydrogen recombination catalyst and a proton-conducting ionomer.

[0035] The hydrogen recombination catalyst may include any suitable hydrogen recombination catalyst. Suitable hydrogen recombination catalysts include, but are not limited to, Pt, Pt or PtCo supported on carbon or silica, PtCo supported on carbon or silica, Pd, Pd or PdCo supported on carbon or silica, or mixtures thereof.

[0036] The proton-conducting ionomer may include any suitable proton-conducting ionomer. Suitable proton-conducting ionomers include copolymers of tetrafluoroethylene and perfluoro-3,6-dioxa-4-methyl-7-octen-sulfonic acid, copolymers of tetrafluoroethylene and perfluoro-5-oxa-6-heptene-sulfonic acid, copolymers of tetrafluoroethylene and perfluoro-4-oxa-5-hexene-sulfonic acid, copolymers of tetrafluoroethylene and perfluoro-3-oxa-4-pentene-sulfonic acid, and perfluoro-3,6-dioxa-4-methyl-7 -Octen-sulfonic acid copolymer of perfluoro(2,2-dimethyl-1,3-dioxol), perfluoro-5-oxa-6-heptene-sulfonic acid copolymer of perfluoro(2,2-dimethyl-1,3-dioxol), perfluoro-4-oxa-5-hexene-sulfonic acid copolymer of perfluoro(2,2-dimethyl-1,3-dioxol), perfluoro-3-oxa-4-pentene-sulfonic acid copolymer of perfluoro(2,2-dimethyl-1,3-dioxol), perfluoro Copolymer of oro-3,6-dioxa-4-methyl-7-octen-sulfonic acid and perfluoro(2-methylene-4-methyl-1,3-dioxolane), copolymer of perfluoro-5-oxa-6-heptene-sulfonic acid and perfluoro(2-methylene-4-methyl-1,3-dioxolane), copolymer of perfluoro-4-oxa-5-hexene-sulfonic acid and perfluoro(2-methylene-4-methyl-1,3-dioxolane), copolymer of perfluoro-3-oxa-4-pentene-sulfonic acid and perfluoro(2 Copolymer of -methylene-4-methyl-1,3-dioxolane), copolymer of perfluoro-3,6-dioxa-4-methyl-7-octen-sulfonic acid and 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxol, copolymer of perfluoro-5-oxa-6-heptene-sulfonic acid and 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxol, copolymer of perfluoro-4-oxa-5-hexene-sulfonic acid and 2,2,4-trifluoro-5-trifluoromethoxy-1,Perfluorosulfonic acid (PFSA) polymers selected from copolymers with 3-dioxole, or copolymers of perfluoro-3-oxa-4-pentene-sulfonic acid and 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxole, sulfonated poly(ether ether ketone) (SPEEK), sulfonated polyethersulfone, sulfonated polyphenylsulfone, sulfonated poly(2,6-dimethyl-1,4-phenylene oxide), sulfonated poly(4-phenoxybenzoyl-1,4- Examples include, but are not limited to, non-PFSA polymers selected from phenylene, sulfonated polyphenylene oxide, sulfonated poly(phenylene), sulfonated poly(phthalazinone), crosslinked SPEEK, crosslinked sulfonated polyethersulfone, crosslinked sulfonated polyphenylsulfone, crosslinked poly(phenylene sulfide sulfone nitrile), sulfonated polystyrene, sulfonated poly(vinyltoluene), crosslinked sulfonated polystyrene, or crosslinked sulfonated poly(vinyltoluene), or combinations thereof.

[0037] The continuous nonporous hydrogen recombination catalyst coating layer may further contain radical scavengers. Any suitable radical scavenger may be used. Suitable radical scavengers include, but are not limited to, CeO2, Ce(OH)4, CeO2 / ZrO2, Ce(OH)4 / ZrO2, or mixtures thereof.

[0038] Polyanionic polymers in the first and / or second continuous nonporous crosslinked polymer electrolyte multilayer coating include sulfonated poly(ether ether ketone), sulfonated polyethersulfone, sulfonated polyphenylsulfone, sulfonated poly(2,6-dimethyl-1,4-phenylene oxide), sulfonated poly(4-phenoxybenzoyl-1,4-phenylene), sulfonated polyphenylene oxide, sulfonated poly(phenylene), sulfonated poly(phthalazinone), sulfonated polystyrene, sulfonated poly(vinyltoluene), poly(acrylic acid), poly(sodium vinylsulfonate), poly(sodium phosphate); sodium alginate, potassium alginate, calcium alginate, ammonium alginate, and alginic acid. Examples include, but are not limited to, negatively charged polysaccharide polyanionic polymers selected from the group consisting of sodium hyaluronate, potassium hyaluronate, calcium hyaluronate, ammonium hyaluronate, hyaluronic acid, κ-carrageenan, λ-carrageenan, ι-carrageenan, carboxymethyl curdlan, sodium carboxymethyl curdlan, potassium carboxymethyl curdlan, calcium carboxymethyl curdlan, ammonium carboxymethyl curdlan, carboxymethyl cellulose, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose, calcium carboxymethyl cellulose, ammonium carboxymethyl cellulose, and pectinic acid, or combinations thereof.

[0039] Polycation polymers in the first and / or second continuous nonporous crosslinked polymer electrolyte multilayer coating include protonated chitosan; polybiguanide, quaternary ammonium polyethyleneimine, quaternary ammonium polypropyleneimine, quaternary ammonium polyamidoamine (PAMAM), poly(vinylamine hydrochloride) (PVH), poly(allylamine hydrochloride) (PAH), poly(amidoamine hydrochloride), poly(N-isopropylallylamine hydrochloride), and poly(N-tert-butylallylamine hydrochloride). Poly(N-1,2-dimethylpropylallylamine hydrochloride), poly(N-methylallylamine hydrochloride), poly(N,N-dimethylallylamine hydrochloride), poly(2-vinylpiperidine hydrochloride), poly(4-vinylpiperidine hydrochloride), poly(diallyldimethylammonium chloride), poly(acrylamide-co-diallyldimethylammonium chloride), poly(diallylmethylamine hydrochloride), 2-propen-1-amine-hydrochloride and N-2-propenyl-2-propenyl Copolymer with pen-1-amine hydrochloride, poly(N-alkyl-4-vinylpyridinium) salt, polylysine, polyornithine, polyarginine, poly(ethylene oxide)-block-poly(vinylbenzyltrimethylammonium chloride), poly(ethylene oxide)-block-poly(l-lysine), poly(2-methacryloyloxyethyl phosphorylcholine methacrylate)-block-poly(vinylbenzyltrimethylammonium chloride), poly[2-(dimethylamino)-ethyl methacrylate, poly[3-(dimethylamino) Examples include, but are not limited to, amine-based linear, superbranched, or dendritic polycationic polymers selected from the group consisting of [dimethylamino)-propyl methacrylate], poly[2-(dimethylamino)-ethyl methacrylamide], poly[3-(dimethylamino)propyl methacrylamide], poly[2-(trimethylamino)ethyl methacrylate chloride], poly[2-(diethylamino)ethyl methacrylate], poly[2-(dimethylamino)ethyl acrylate], and poly(4-vinylpyridine). [Examples]

[0040] The following embodiments are provided to illustrate one or more embodiments of the present invention, but are not intended to limit them. Numerous modifications can be made to the following embodiments which fall within the scope of the present invention.

[0041] Example 1: Catalyst recycling from a two-layer catalyst coating film by heating and stirring A 30 cm³ layer comprising a polymer electrolyte multilayer, an H2 recombination catalyst layer, and a multilayer cation exchange membrane (PEL-H2RCe-PEM) containing CeO2 in the H2 recombination catalyst layer, as described in Example 3 of U.S. Provisional Patent Application No. 63 / 476,983 filed December 23, 2022. 2 One two-layer anode catalyst coated film and an anode containing an IrO2 catalyst coating the surface of a poly(allylamine hydrochloride) (PAH) and sulfonated poly(ether ether ketone) (SPEEK) polymer electrolyte bilayer, as described in Example 4 of U.S. Provisional Patent Application No. 63 / 476,983 filed December 23, 2022, were added to a bottle containing 250 mL of 1 M KOH aqueous solution. The bottle was heated at 80°C for 24 hours with stirring. The PEL-H2RCe-PEM film without the anode IrO2 catalyst coating was removed from the KOH solution, rinsed with ultrapure water, and recycled. IrO2 catalyst particles were recovered from the KOH aqueous solution by filtration, rinsed with ultrapure water, and recycled.

[0042] Example 2: Catalyst recycling from a two-layer catalyst coating film by heating and ultrasonic treatment A 30cm² film containing a PEL-H2RCe-PEM film, as described in Example 3 of U.S. Provisional Patent Application No. 63 / 476,983, filed December 23, 2022. 2One two-layer anode catalyst coated film and an anode containing an IrO2 catalyst coating the surface of the PAH / SPEEK polymer electrolyte bilayer of a PEL-H2RCe-PEM film, as described in Example 4 of U.S. Provisional Patent Application No. 63 / 476,983 filed December 23, 2022, were added to a bottle containing 250 mL of 1 M KOH aqueous solution. The bottle was heated in an ultrasonic bath at 50°C for 2-3 hours. The PEL-H2RCe-PEM film without the anode IrO2 catalyst coating was removed from the KOH solution, rinsed with ultrapure water, and recycled. IrO2 catalyst particles were recovered from the KOH aqueous solution by filtration, rinsed with ultrapure water, and recycled.

[0043] Example 3: Catalyst recycling from a 3-layer catalyst coating film using a continuous recycling process (SPEEK-PAH) as described in Example 1 of U.S. Patent Application No. 17 / 451,227, filed October 18, 2021. n / Nafion(registered trademark)-212 / (PAH-SPEEK) n One three-layer catalyst coating film including a membrane, and (SPEEK-PAH) as described in Example 5 of U.S. Patent Application No. 17 / 451,227 filed on October 18, 2021. n / Nafion(registered trademark)-212 / (PAH-SPEEK) n an anode containing an IrO2 catalyst coating one surface of the film and (SPEEK-PAH) n / Nafion(registered trademark)-212 / (PAH-SPEEK) n The cathode, which contains a Pt / C catalyst coating the other surface of the membrane, was incorporated into a catalyst recycling circulation system heated to 50-80°C, as shown in Figure 3. The system consisted of two separate chambers connected to two circulation pumps, and two containers containing a 1M KOH aqueous solution for recycling the anode IrO2 catalyst and the cathode Pt / C catalyst. The KOH aqueous solution, heated to 50-80°C, was continuously circulated separately to the anode and cathode sides for 12-20 hours. The recycled IrO2 and Pt / C catalysts in the KOH containers were filtered and dried to recover the catalysts.

[0044] Example 4: Catalyst recycling from a spent PEM electrolytic cell stack containing a 3-layer catalyst coating film using a continuous recycling process. (SPEEK-PAH) as described in Example 1 of U.S. Patent Application No. 17 / 451,227, filed October 18, 2021. n / Nafion(registered trademark)-212 / (PAH-SPEEK) n Numerous three-layer catalyst coating films including a film, and (SPEEK-PAH) as described in Example 5 of U.S. Patent Application No. 17 / 451,227 filed October 18, 2021 n / Nafion(registered trademark)-212 / (PAH-SPEEK) n an anode containing an IrO2 catalyst coating one surface of the film and (SPEEK-PAH) n / Nafion(registered trademark)-212 / (PAH-SPEEK) n A spent PEM electrolytic cell stack, including a cathode containing a Pt / C catalyst coating the other surface of the membrane, was connected to two circulation pumps and two containers containing a 1M KOH aqueous solution for recycling the anode IrO2 catalyst and the cathode Pt / C catalyst. The KOH aqueous solution, heated to 50-80°C, was continuously circulated separately to the anode and cathode sides of the spent PEM electrolytic cell stack for 12-20 hours. The recycled IrO2 and Pt / C catalysts in the KOH containers were filtered and dried to recover the catalysts.

[0045] Specific Embodiments The following will be explained in conjunction with specific embodiments, but it should be understood that this explanation is intended to illustrate the scope of the preceding explanation and the attached claims, and is not intended to limit them.

[0046] A first embodiment of the present invention provides a method for recovering a catalyst from a catalyst coating film, comprising: a proton exchange membrane having a first surface and a second surface; a first continuous nonporous crosslinked polymer electrolyte multilayer coating on the first surface of the proton exchange membrane, the first continuous polymer electrolyte multilayer coating comprising alternating layers of polycationic polymer and polyanionic polymer; an anode coating layer comprising anode catalyst particles on the continuous nonporous crosslinked polymer electrolyte multilayer coating on the first surface of the proton exchange membrane; a cathode coating layer comprising cathode catalyst particles on the second surface of the proton exchange membrane; and optionally, a second continuous nonporous crosslinked polymer electrolyte multilayer coating between the second surface of the proton exchange membrane and the cathode coating layer; and a method comprising: contacting the catalyst coating film with an alkaline solution to dissolve the first continuous nonporous crosslinked polymer electrolyte multilayer coating or the first and second continuous nonporous crosslinked polymer electrolyte multilayer coatings; and recovering the anode catalyst particles, or recovering both the anode catalyst particles and the cathode catalyst particles separately. Embodiments of the present invention are any or all of the embodiments described in the first to prior embodiments of this paragraph, wherein contacting the catalyst coating film in the presence of an alkaline solution further includes heating the catalyst coating film and / or the alkaline solution, ultrasonically treating the catalyst coating film and / or the alkaline solution, or heating and ultrasonically treating the catalyst coating film and / or the alkaline solution. Embodiments of the present invention are any or all of the embodiments described in the first to prior embodiments of this paragraph, wherein the catalyst coating film is heated at a temperature in the range of 30°C to 150°C. Embodiments of the present invention are any or all of the embodiments described in the first to prior embodiments of this paragraph, wherein the alkaline solution is added to the anode side of the catalyst coating film, or to the cathode side of the catalyst coating film, or to both the anode and cathode sides of the catalyst coating film. Embodiments of the present invention include anode catalyst particles comprising platinum group metals (PGMs), PGMs supported on different PGM supports, PGMs supported on non-PGM supports, alloys thereof, oxides thereof, carbides thereof, phosphides thereof, or combinations thereof.The embodiments of the present invention are one, any, or all of the embodiments described in the first embodiment of this paragraph to the preceding embodiments of this paragraph. The embodiments of the present invention are one, any, or all of the embodiments described in the first embodiment of this paragraph to the preceding embodiments of this paragraph, wherein the anode catalyst particles include iridium, iridium supported on different PGM supports, iridium supported on non-PGM supports, platinum, platinum supported on non-PGM supports, ruthenium, ruthenium supported on non-PGM supports, osmium, rhodium, palladium, tin, tungsten, vanadium, cobalt, silver, gold, copper, nickel, molybdenum, iron, chromium, alloys thereof, oxides thereof, carbides thereof, phosphides thereof, or combinations thereof. Embodiments of the present invention are any or all of the embodiments described in the first to prior embodiments of this paragraph, wherein the anode catalyst particles include iridium, iridium supported on different PGM supports, iridium supported on non-PGM supports, platinum, platinum supported on non-PGM supports, ruthenium, ruthenium supported on non-PGM supports, oxides thereof, or combinations thereof. Embodiments of the present invention are any or all of the embodiments described in the first to prior embodiments of this paragraph, wherein the cathode catalyst particles include platinum group metals (PGMs), PGMs supported on non-PGM supports, alloys thereof, or combinations thereof. Embodiments of the present invention are any or all of the embodiments from the first embodiment of this paragraph to the preceding embodiments of this paragraph, wherein the cathode catalyst particles include platinum, platinum supported on a non-PGM support, ruthenium, ruthenium supported on a non-PGM support, osmium, rhodium, palladium, tin, tungsten, vanadium, cobalt, silver, gold, nickel, molybdenum, iron, copper, chromium, alloys thereof, carbides thereof, phosphides thereof, or combinations thereof. Embodiments of the present invention are any or all of the embodiments from the first embodiment of this paragraph to the preceding embodiments of this paragraph, wherein the cathode catalyst particles include platinum, platinum supported on a carbon support, platinum supported on a graphene support, platinum supported on a graphene oxide support, ruthenium, ruthenium supported on a carbon support, ruthenium supported on a graphene support, ruthenium supported on a graphene oxide support, platinum and ruthenium supported on a carbon support, or combinations thereof.The embodiment of the present invention is one, any, or all of the embodiments described in the first embodiment of this paragraph to the preceding embodiments of this paragraph. The embodiment of the present invention is one, any, or all of the embodiments described in the first embodiment of this paragraph to the preceding embodiments of this paragraph, wherein the polycation polymer layer of the first continuous nonporous crosslinked polymer electrolyte multilayer coating is in contact with the first surface of the proton exchange membrane, or the polycation polymer layer of the first continuous nonporous crosslinked polymer electrolyte multilayer coating is in contact with the first surface of the proton exchange membrane, and the polycation polymer layer of the second continuous nonporous crosslinked polymer electrolyte multilayer coating is in contact with the second surface of the proton exchange membrane. The embodiment of the present invention is one, any, or all of the embodiments described in the first embodiment of this paragraph to the preceding embodiments of this paragraph, wherein the alkaline solution includes KOH, NaOH, LiOH, CsOH, KHCO3, K2CO3, LiHCO3, Li2CO3, NaHCO3, Na2CO3, or a combination thereof. Embodiments of the present invention are any or all of the embodiments from the first embodiment to the prior embodiments of this paragraph, wherein the proton exchange membrane includes a reinforced proton exchange membrane or a non-reinforced proton exchange membrane. Embodiments of the present invention are any or all of the embodiments from the first embodiment to the prior embodiments of this paragraph, wherein the catalyst coating film further includes a continuous non-porous hydrogen recombination catalyst coating layer between the proton exchange membrane layer and a first continuous non-porous crosslinked polymer electrolyte multilayer coating, and the continuous non-porous hydrogen recombination catalyst coating layer includes a mixture of a hydrogen recombination catalyst and a proton-conducting ionomer. Embodiments of the present invention are any or all of the embodiments from the first embodiment to the prior embodiments of this paragraph, wherein the hydrogen recombination catalyst includes Pt, Pt supported on carbon or silica, PtCo, PtCo supported on carbon or silica, Pd, PdCo supported on carbon or silica, or a mixture thereof. Embodiments of the present invention include a proton-conducting ionomer which is a copolymer of tetrafluoroethylene and perfluoro-3,6-dioxa-4-methyl-7-octen-sulfonic acid, a copolymer of tetrafluoroethylene and perfluoro-5-oxa-6-heptene-sulfonic acid,Copolymer of tetrafluoroethylene and perfluoro-4-oxa-5-hexene-sulfonic acid, copolymer of tetrafluoroethylene and perfluoro-3-oxa-4-pentene-sulfonic acid, copolymer of perfluoro-3,6-dioxa-4-methyl-7-octen-sulfonic acid and perfluoro(2,2-dimethyl-1,3-dioxol), copolymer of perfluoro-5-oxa-6-heptene-sulfonic acid and perfluoro(2,2-dimethyl-1,3-dioxol), copolymer of perfluoro-4-oxa-5-hexene-sulfonic acid and Copolymer with perfluoro(2,2-dimethyl-1,3-dioxol), copolymer of perfluoro-3-oxa-4-pentene-sulfonic acid and perfluoro(2,2-dimethyl-1,3-dioxol), copolymer of perfluoro-3,6-dioxa-4-methyl-7-octen-sulfonic acid and perfluoro(2-methylene-4-methyl-1,3-dioxolane), copolymer of perfluoro-5-oxa-6-heptene-sulfonic acid and perfluoro(2-methylene-4-methyl-1,3-dioxolane), perfluoro-4-oxa-5 Copolymer of -hexene-sulfonic acid and perfluoro(2-methylene-4-methyl-1,3-dioxolane), copolymer of perfluoro-3-oxa-4-pentene-sulfonic acid and perfluoro(2-methylene-4-methyl-1,3-dioxolane), copolymer of perfluoro-3,6-dioxa-4-methyl-7-octen-sulfonic acid and 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxol, copolymer of perfluoro-5-oxa-6-heptene-sulfonic acid and 2,2,4-trifluoro-5-trifluoromethoxy-1 Perfluorosulfonic acid (PFSA) polymers selected from copolymers with ,3-dioxole, copolymers of perfluoro-4-oxa-5-hexene-sulfonic acid and 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxole, or copolymers of perfluoro-3-oxa-4-pentene-sulfonic acid and 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxole, sulfonated poly(etheretherketone) (SPEEK), sulfonated polyethersulfone, sulfonated polyphenylsulfone,One, any, or all of the first embodiments of this paragraph to the prior embodiments of this paragraph include non-PFSA polymers selected from sulfonated poly(2,6-dimethyl-1,4-phenylene oxide), sulfonated poly(4-phenoxybenzoyl-1,4-phenylene), sulfonated polyphenylene oxide, sulfonated poly(phenylene), sulfonated poly(phthalazinone), crosslinked SPEEK, crosslinked sulfonated polyethersulfone, crosslinked sulfonated polyphenylsulfone, crosslinked poly(phenylene sulfide sulfone nitrile), sulfonated polystyrene, sulfonated poly(vinyltoluene), crosslinked sulfonated polystyrene, or crosslinked sulfonated poly(vinyltoluene), or combinations thereof. Embodiments of the present invention are one, any, or all of the first embodiments of this paragraph to the prior embodiments of this paragraph, wherein a continuous nonporous hydrogen recombination catalyst coating layer further comprises a radical scavenger. Embodiments of the present invention are one or all of the embodiments described in the first to prior embodiments of this paragraph, wherein the radical scavenger comprises CeO2, Ce(OH)4, CeO2 / ZrO2, Ce(OH)4 / ZrO2, or a mixture thereof. Embodiments of the present invention include polyanionic polymers such as sulfonated poly(ether ether ketone), sulfonated polyethersulfone, sulfonated polyphenylsulfone, sulfonated poly(2,6-dimethyl-1,4-phenylene oxide), sulfonated poly(4-phenoxybenzoyl-1,4-phenylene), sulfonated polyphenylene oxide, sulfonated poly(phenylene), sulfonated poly(phthalazinone), sulfonated polystyrene, sulfonated poly(vinyltoluene), poly(acrylic acid), poly(sodium vinylsulfonate), poly(sodium phosphate); sodium alginate, potassium alginate, calcium alginate, ammonium alginate, alginic acid, sodium hyaluronate, potassium hyaluronate, calcium hyaluronate, ammonium hyaluronate, hyaluronic acid, κ-carrageenan, λ-carrageenan, ι-carrageenan, carboxymethyl curdlan, sodium carboxymethyl curdlan, potassium carboxymethyl curdlan, calcium carboxymethyl curdlan,Carboxymethylcurdranammonium, carboxymethylcellulose, sodium carboxymethylcellulose, potassium carboxymethylcellulose, calcium carboxymethylcellulose, carboxymethylcellulose ammonia One, any, or all of the embodiments described in the first to prior embodiments of this paragraph include a negatively charged polysaccharide polyanionic polymer selected from the group consisting of nium and pectic acid, or a combination thereof.Embodiments of the present invention include polycationic polymers such as protonated chitosan; polybiguanide; quaternary ammonium polyethyleneimine; quaternary ammonium polypropyleneimine; quaternary ammonium polyamidoamine (PAMAM); poly(vinylamine hydrochloride) (PVH); poly(allylamine hydrochloride) (PAH); poly(amidoamine hydrochloride); poly(N-isopropylallylamine hydrochloride); poly(N-tert-butylallylamine hydrochloride); and poly(N-1,2-dimethylpropylallylamine). Poly(N-methylallylamine hydrochloride), poly(N,N-dimethylallylamine hydrochloride), poly(2-vinylpiperidine hydrochloride), poly(4-vinylpiperidine hydrochloride), poly(diallyldimethylammonium chloride), poly(acrylamide-co-diallyldimethylammonium chloride), poly(diallylmethylamine hydrochloride), copolymer of 2-propen-1-amine hydrochloride and N-2-propenyl-2-propen-1-amine hydrochloride, poly(N -Alkyl-4-vinylpyridinium) salt, polylysine, polyornithine, polyarginine, poly(ethylene oxide)-block-poly(vinylbenzyltrimethylammonium chloride), poly(ethylene oxide)-block-poly(l-lysine), poly(2-methacryloyloxyethyl phosphorylcholine methacrylate)-block-poly(vinylbenzyltrimethylammonium chloride), poly[2-(dimethylamino)-ethyl methacrylate, poly[3-(dimethylamino)-propyl methacrylate], poly[2-(di One, any, or all of the embodiments described in the first to prior embodiments of this paragraph, comprising an amine-based linear, hyperbranched, or dendritic polycationic polymer selected from the group consisting of [methylamino)-ethyl methacrylamide], poly[3-(dimethylamino)propyl methacrylamide], poly[2-(trimethylamino)ethyl methacrylate chloride], poly[2-(diethylamino)ethyl methacrylate], poly[2-(dimethylamino)ethyl acrylate], and poly(4-vinylpyridine).

[0047] Without further detail, it is expected that those skilled in the art will be able to utilize the invention to the fullest extent without departing from the spirit and scope of the invention, and will readily identify its essential characteristics, and will be able to make various changes and modifications to the invention to suit various uses and conditions. Accordingly, the prior preferred specific embodiments should be interpreted as merely illustrative and not to limit the remainder of this disclosure in any way, but are intended to cover various modifications and equivalent configurations that fall within the scope of the appended claims.

[0048] In the above, all temperatures are given in degrees Celsius, and all parts and percentages are based on weight unless otherwise indicated.

Claims

1. A method for recovering a catalyst from a catalyst coating film (300), A proton exchange membrane (305) having a first surface and a second surface, A first continuous nonporous crosslinked polymer electrolyte multilayer coating (310) on the first surface of the proton exchange membrane (305), the first continuous polymer electrolyte multilayer coating comprising layers in which polycationic polymer (315) and polyanionic polymer (320) are alternately stacked, The anode coating layer (325) includes anode catalyst particles (330) on the continuous nonporous crosslinked polymer electrolyte multilayer coating (310) on the first surface of the proton exchange membrane (305), A cathode coating layer (335) containing cathode catalyst particles (340) on the second surface of the proton exchange membrane (305), Optionally, a second continuous non-porous crosslinked polymer electrolyte multilayer coating is provided between the second surface of the proton exchange membrane (305) and the cathode coating layer (335), To provide a catalyst coating film (300) containing, The catalyst coating film (300) is brought into contact with an alkaline solution (420) to dissolve the first continuous nonporous crosslinked polymer electrolyte multilayer coating (310) or the first and second continuous nonporous crosslinked polymer electrolyte multilayer coatings (310). Either recover the anode catalyst particles (330), or recover both the anode catalyst particles (330) and the cathode catalyst particles (340) separately. Methods that include...

2. The method according to claim 1, wherein contacting the catalyst coating film (300) with the alkaline solution (420) further includes heating the catalyst coating film (300) and / or the alkaline solution (420), ultrasonically treating the catalyst coating film (300) and / or the alkaline solution (420), or heating and ultrasonically treating the catalyst coating film (300) and / or the alkaline solution (420).

3. The method according to claim 2, wherein the catalyst coating film (300) is heated at a temperature in the range of 30°C to 150°C.

4. The method according to any one of claims 1 to 2, wherein the alkaline solution (420) is added to the anode side of the catalyst coating film (300), or to the cathode side of the catalyst coating film (300), or to both the anode side and the cathode side of the catalyst coating film (300).

5. The method according to any one of claims 1 to 2, wherein the anode catalyst particles (330) include platinum group metals (PGM), PGM supported on different PGM supports, PGM supported on non-PGM supports, alloys thereof, oxides thereof, carbides thereof, phosphides thereof, or combinations thereof.

6. The method according to any one of claims 1 to 2, wherein the anode catalyst particles (330) include iridium, iridium supported on different PGM supports, iridium supported on non-PGM supports, platinum, platinum supported on non-PGM supports, ruthenium, ruthenium supported on non-PGM supports, osmium, rhodium, palladium, tin, tungsten, vanadium, cobalt, silver, gold, copper, nickel, molybdenum, iron, chromium, alloys thereof, oxides thereof, carbides thereof, phosphides thereof, or combinations thereof.

7. The method according to any one of claims 1 to 2, wherein the cathode catalyst particles (340) include platinum group metals (PGM), PGM supported on a non-PGM carrier, alloys thereof, or combinations thereof.

8. The method according to any one of claims 1 to 2, wherein the cathode catalyst particles (340) include platinum, platinum supported on a non-PGM support, ruthenium, ruthenium supported on a non-PGM support, osmium, rhodium, palladium, tin, tungsten, vanadium, cobalt, silver, gold, nickel, molybdenum, iron, copper, chromium, alloys thereof, carbides thereof, phosphides thereof, or combinations thereof.

9. The alkali solution (420) is KOH, NaOH, LiOH, CsOH, KHCO ３ , K ２ CO ３ , LiHCO ３ , Li ２ CO ３ , NaHCO ３ , Na ２ CO ３ The method according to any one of claims 1 to 2, comprising or a combination thereof.

10. The proton exchange membrane (305) includes a reinforced proton exchange membrane or a non-reinforced proton exchange membrane, or The catalyst coating film (300) A continuous nonporous hydrogen recombination catalyst coating layer (345) between the proton exchange membrane layer (305) and the first continuous nonporous crosslinked polymer electrolyte multilayer coating (310), wherein the continuous nonporous hydrogen recombination catalyst coating layer (310) further comprises a continuous nonporous hydrogen recombination catalyst coating layer comprising a mixture of a hydrogen recombination catalyst and a proton-conducting ionomer, and optionally a radical scavenger, or A method according to any one of claims 1 to 2, which is a combination thereof.

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