Compound fluorinated sulfonyl fluoride polymer and ion exchange membrane made therefrom

Abstract

The present invention relates to a composition comprising, based on the total weight of the composition, about 90% to about 99.99% by weight of one or more non-crosslinked fluorinated sulfonyl fluoride polymers and about 0.01% to about 10% by weight of one or more noble metal catalysts, wherein the one or more noble metal catalysts are uniformly distributed throughout the one or more non-crosslinked fluorinated sulfonyl fluoride polymers. Such compositions can be formed, for example, by extrusion into cation exchange precursors and, after treatment, into cation exchange membranes. The resulting films and membranes have noble metal catalysts uniformly distributed throughout the entire layer of catalyst-containing polymers.

Description

[Technical Field]

[0001] (Cross-reference of related applications) This application claims priority to U.S. Provisional Application No. 63 / 454,927, filed on 27 March 2023, and U.S. Provisional Application No. 63 / 527,614, filed on 19 July 2023, the disclosures of which are incorporated herein by reference in their entirety.

[0002] (Field of invention) This invention describes a compounded fluorinated sulfonyl fluoride polymer, an ion exchange membrane precursor, an ion exchange membrane, and a process for producing such materials. The compounded polymer and ion exchange membrane have an improved gas recombination catalyst dispersed throughout the resin and can be used to form catalyst-coated membranes, fuel cells, and electrolytic systems, including water electrolysis systems. [Background technology]

[0003] Precious metal compounds can be added to electrolytic systems as gas recombination catalysts (GRCs) to help reduce hydrogen (H2) in oxygen passing through cation exchange membranes during operation. Due to the cost and resource limitations of these precious metal compounds, a key objective is to optimize the reduction of hydrogen crossover while minimizing the amount of precious metal compounds used.

[0004] The most common technique used in the industry is to cast a dispersion of an ionomer having noble metal catalyst particles in a dispersion (such as a Nafion™ ion exchange resin dispersion). This dispersion is cast onto a backing or into a reinforcing material, and then the solvent is removed, leaving behind an ionomer membrane having GRCs. However, the drawbacks of this approach are that the GRC particles may aggregate during casting and that the polymer entanglement in the final cast membrane is low and it swells very much. The casting process is described, for example, in U.S. Patent Application Publication No. 2021 / 0135244 and U.S. Patent Application Publication No. 2008 / 0161429.

[0005] Other processes for incorporating GRCs into a membrane include chemically treating the membrane before swelling it and immersing the membrane in a GRC solution, as proposed in U.S. Patent Application Publication No. 2008 / 0003479. However, this process involves multiple steps and liquid media, which is not ideal for product efficiency. Also, this process does not allow for the exact composition and placement of the GRC material.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Means for Solving the Problems

[0007] The present invention provides a novel method for strategically positioning GRCs in extruded cation exchange membranes via a processing method. One finding of the present invention is that the strategic positioning of GRCs offers performance advantages, product composition advantages, optimizes polymer entanglement and membrane swelling, limits the amount of raw materials required, and reduces post-processing steps for incorporating GRCs. The present invention describes compounded fluorinated sulfonyl fluoride polymers, ion exchange membrane precursors, ion exchange membranes, and processes for producing such materials. The compounded polymers and ion exchange membranes have improved gas recombination noble metal catalysts dispersed throughout the resin and can be used to form catalyst-coated membranes, fuel cells, and electrolytic systems, including water electrolysis systems.

[0008] The present invention relates to a composition comprising, based on the total weight of the composition, about 90% to about 99.99% by weight of one or more non-crosslinked fluorinated sulfonyl fluoride polymers and about 0.01% to about 10% by weight of one or more noble metal catalysts, wherein the one or more noble metal catalysts are uniformly distributed throughout the one or more non-crosslinked fluorinated sulfonyl fluoride polymers. The present invention also relates to a cation exchange membrane precursor comprising at least one proton exchange precursor layer, wherein the at least one proton exchange precursor layer comprises, based on the total weight of the composition, about 90% to about 99.99% by weight of one or more non-crosslinked fluorinated sulfonyl fluoride polymers and about 0.01% to about 10% by weight of one or more noble metal catalysts, wherein the one or more noble metal catalysts are uniformly distributed throughout the at least one proton exchange precursor layer. The present invention further relates to a cation exchange membrane comprising at least one cation exchange layer, wherein the at least one proton exchange layer comprises, based on the total weight of the composition, about 90% to about 99.99% by weight of one or more non-crosslinked fluorinated sulfonic acid polymers and about 0.01% to about 10% by weight of one or more noble metal catalysts, wherein the one or more noble metal catalysts are uniformly distributed throughout the entire at least one cation exchange layer.

[0009] The process for producing such materials is also described in the present invention. In one embodiment, the present invention relates to a method for producing a solid composition, the method is a. Melting at least one non-crosslinked fluorinated sulfonyl fluoride polymer, b. Distributing at least one noble metal catalyst uniformly within at least one molten non-crosslinked fluorinated sulfonyl fluoride polymer in an amount that forms a composition comprising at least 90% to about 99.99% by weight of one or more non-crosslinked fluorinated sulfonyl fluoride polymers and at least 0.01% to about 10% by weight of one or more noble metal catalysts, based on the total weight of the composition. c. Cooling the mixture from step b to form a solid composition, and

[0010] In another aspect, the present invention relates to a method for producing a cation exchange membrane, wherein this method is d. Melting at least one non-crosslinked fluorinated sulfonyl fluoride polymer, e. Based on the total weight of the composition, the composition comprises one or more non-crosslinked fluorinated sulfonyl fluoride polymers in an amount of about 90% to about 99.99% by weight and one or more noble metal catalysts in an amount of about 0.01% to about 10% by weight, wherein at least one noble metal catalyst is uniformly distributed using at least one molten non-crosslinked fluorinated sulfonyl fluoride polymer. f. Forming a layer of material from the composition of step e, wherein the noble metal catalyst is uniformly distributed throughout the entire layer. g. This includes converting the non-crosslinked fluorinated sulfonyl fluoride polymer from the layer of step f into a non-crosslinked fluorinated sulfonic acid polymer. A cathode exchange membrane produced by the above method is also conceivable. [Brief explanation of the drawing]

[0011] [Figure 1] This is a scanning electron micrograph (SEM) image of Example 6. [Figure 2] This is an SEM image of Example 8. [Figure 3] This is an SEM image of Example 9. [Figure 4]This is an SEM image of Example 9 showing the thickness of the precious metal catalyst layer. [Figure 5] This is an SEM image of Example 17. [Figure 6] This is an SEM image of Example 18. [Figure 7] This is an SEM image of comparative example A. [Modes for carrying out the invention]

[0012] The features of the embodiments of the present invention described in "Modes for Carrying Out the Invention" can be combined in any way. All trade names are specified by capitalizing the brand name.

[0013] definition As used herein, the term “uniformly distributed” means that the noble metal catalyst is uniformly distributed throughout the entire volume in all three dimensions. The “process of uniform distribution” means distributing (or rather, redistributing) a material uniformly throughout all three dimensions.

[0014] As used herein, the term “uniformly dispersed” refers to a noble metal catalyst in a deaggregated form, such as discrete particles. The “uniform dispersion process” refers to reducing the particle size of the original material by deaggregating the original particles into smaller particles, such as primary particles with a larger surface area.

[0015] As used herein, the term "non-crosslinked fluorinated sulfonyl fluoride polymer" refers to a fluorinated sulfonyl fluoride polymer that does not have intentionally crosslinkable monomers or repeating units and has no crosslinking agents added. The term "non-crosslinked fluorinated sulfonic acid" refers to a fluorinated sulfonic acid polymer that does not have intentionally crosslinkable monomers or repeating units, has no crosslinking agents added, and whose sulfonic acid units are not bonded to other polymer units.

[0016] As used herein, "ion exchange ratio (IXR)" refers to the number of carbon atoms in the polymer backbone relative to the number of sulfonyl fluoride groups.

[0017] As used herein, "cation exchange membrane precursor" refers to a film that can be converted into a cation exchange membrane by hydrolysis and optional acidification. In this case, the cation exchange membrane precursor is a film containing a fluorinated sulfonyl fluoride polymer. By the same means, the cation exchange resin precursor is a polymer or resin that can be converted into a cation exchange polymer by hydrolysis and optional acidification.

[0018] The present invention relates to a composition comprising, based on the total weight of the composition, about 90% to about 99.99% by weight of one or more non-crosslinked fluorinated sulfonyl fluoride polymers and about 0.01% to about 10% by weight of one or more noble metal catalysts, wherein the one or more noble metal catalysts are uniformly distributed throughout the one or more non-crosslinked fluorinated sulfonyl fluoride polymers.

[0019] The precious metal catalyst may be any precious metal catalyst typically found in electrolytic cell applications. The precious metal may be, but is not limited to, platinum, ruthenium, osmium, rhodium, iridium, palladium, or mixtures thereof. The precious metal may also be mixed with additional compounds, as long as the precious metal content is in the range of about 0.01 to 10% by weight of the total composition. The precious metal catalyst may be unsupported or may be supported by an inorganic support. The inorganic support may be in any form, such as inorganic support particles. The inorganic material constituting the inorganic support may be any suitable material, including, but is not limited to, carbon or inorganic materials, such as those described in U.S. Patent Application Publication No. 20080161429 or European Patent No. 1929574, which are incorporated herein by reference, or mixtures thereof. The precious metal catalyst may have a high surface area to enhance its effectiveness, and as a result, they may have at least 10 m 2 / g, in another embodiment, at least 30m 2 / g, in another aspect, at least 45 m 2 / g of noble metal surface area. In one aspect, the noble metal catalyst has an average particle size D50 of less than about 5 μm, in another aspect, an average particle size D50 of about 75 nm, in another aspect, an average particle size D50 of less than about 50 nm, and in another aspect, an average particle size D50 of less than about 25 nm.

[0020] The ion exchange membrane can be made from various ion exchange polymers. Preferred ion exchange polymers, fluorinated sulfonic acids and fluorinated sulfonates, can be made by hydrolyzing a fluorinated sulfonyl fluoride polymer and then optionally protonating it. Fluorinated sulfonic acids, fluorinated sulfonates, and fluorinated sulfonyl fluoride polymers may or may not be chemically stabilized by fluorinating the polymer end groups. Suitable fluorinated sulfonyl fluoride polymers are obtained from free radical polymerization of at least one fluorinated sulfonyl fluoride monomer and optionally one or more monomers, and include at least one fluorinated sulfonyl fluoride repeating unit and optionally one or more repeating units. For example, the fluorinated ionomer can include the repeating unit: -[CF2-CF((CF2) b -(O-(CF2CFR f ) c ) a -O-(CF2CFR’ f ) d SO2F)]-, and where b is 0 or 1, c is an integer from 1 to 8, a is 0, 1, or 2, d is an integer from 1 to 8, and R f and R’ f are independently selected from F, Cl, or a perfluorinated alkyl group having 1 to 10 carbon atoms. For clarity, the segment ((CF2) b -(O-(CF2CFR f ) c ) a -O-(CF2CFR’ f ) dSO2F) is a pendant chain derived from a perfluorinated polymer main chain. Branched pendant chains containing multiple sulfonyl fluoride groups are also included.

[0021] In one embodiment, the sulfonyl fluoride polymer is a copolymer made from two or more monomers. In addition to sulfonyl fluoride monomers, suitable comonomers include, but are not limited to, tetrafluoroethylene (TFE), hexafluoropropylene, vinyl fluoride, vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, perfluoro(alkyl vinyl ether), and mixtures thereof. For example, it may be a copolymer of a sulfonyl fluoride-containing monomer with TFE or another comonomer that yields repeating units -[CF2-CF2]-. Monomers having pendant phosphonic acid groups can also be incorporated into the fluorinated sulfonyl fluoride polymer to produce a fluorinated ionomer containing both sulfonic acid groups and phosphonic acid groups after conversion.

[0022] The preferred class of fluorinated sulfonyl fluoride polymers is given by formula (O-CF2CFR f ) a -O-CF2CFR ’f It comprises a highly fluorinated, most preferably perfluorinated, carbon skeleton having a side chain represented by SO2F, where R f and R' f a is independently selected from F, Cl, or a perfluorinated alkyl group having 1 to 10 carbon atoms, where a = 0, 1, or 2. These polymers are converted to sulfonates or sulfonic acids, for example, as disclosed in U.S. Patent No. 3,282,875, U.S. Patent No. 4,358,545, or U.S. Patent No. 4,940,525.

[0023] One preferred fluorinated sulfonyl fluoride polymer comprises a perfluorocarbon backbone and a side chain represented by the formula -O-CF2CF(CF3)-O-CF2CF2SO2F. Fluorinated ionomers of this type containing sulfonate or sulfonic acid groups are disclosed in U.S. Patent No. 3,282,875 and can be prepared by copolymerization of tetrafluoroethylene (TFE), perfluorinated vinyl ether CF2=CF-O-CF2CF(CF3)-O-CF2CF2SO2F, and perfluoro(3,6-dioxa-4-methyl-7-octenulfonyl fluoride) (also known as PSEPVE, long side chain, or LSC (long side-chain)), followed by hydrolysis of the sulfonyl fluoride groups to convert them to sulfonic acid groups, and, if desired for a particular application, conversion to a protonate form. Another preferred fluorinated sulfonyl fluoride polymer is of the type disclosed in U.S. Patent Nos. 4,358,545 and 4,940,525, which has a side chain -O-CF2CF2SO2F. This polymer can be prepared by copolymerization of tetrafluoroethylene (TFE), perfluorinated vinyl ether CF2=CF-O-CF2CF2SO2F, and perfluoro(3-oxa-4-pentenesulfonyl fluoride) (also known as PFSVE, short side chain, or SSC (short side-chain)), followed by hydrolysis and, if desired for a particular application, conversion to a protonated form.

[0024] Following hydrolysis and optional conversion to proton form, a fluorinated sulfonate or sulfonic acid polymer is formed. As used herein, the sulfonate group or sulfonic acid group refers to either a sulfonic acid group or a salt of sulfonic acid, preferably an alkali metal or ammonium salt. A preferred functional group is represented by the formula -SO3X, where X is H, Li, Na, K, or N(R) 1 )(R 2 )(R 3 )(R 4 ) and in the formula, R 1 , R 2 , R 3 , and R 4These are either identical or different, and are H, CH3, or C2H5. In exemplary embodiments, the fluorinated sulfonate or sulfonic acid polymer is of a type available under the trade name Nafion® (The Chemours Company FC, LLC, Wilmington, DE).

[0025] For example, fluorinated ionomers have repeating units: -[CF2-CF((CF2) b -(O-(CF2CFR f ) c ) a -O-(CF2CFR' f ) d SO3X) can be included. In the formula, b is 0 or 1, c is an integer from 1 to 8, a is 0, 1, or 2, d is an integer from 1 to 8, R f and R' f X is independently selected from F, Cl, or a perfluorinated alkyl group having 1 to 10 carbon atoms, and X is H, Li, Na, K, or N(R) 1 )(R 2 )(R 3 )(R 4 ) and in the formula, R 1 , R 2 , R 3 , and R 4 These are either the same or different, and are H, CH3, or C2H5. For clarity, the segment ((CF2) in the above structure b -(O-(CF2CFR f ) c ) a -O-(CF2CFR' f ) d SO3X) is a pendant chain derived from a perfluorinated polymer main chain. Branched pendant chains with multiple sulfonic acid groups are also included.

[0026] In some embodiments, the fluorinated sulfonyl fluoride polymer has an ion exchange ratio of less than about 13.2. As used herein, “ion exchange ratio (IXR)” refers to the number of carbon atoms in the polymer back chain relative to the number of sulfonyl fluoride groups. In some embodiments, the IXR of the fluorinated sulfonyl fluoride polymer is given by the formula EW (equivalent weight) = (50 × IXR) + MW sc -19 can be associated with the equivalent weight (EW) of the corresponding fluorinated sulfonate or sulfonic acid polymer, where MW sc ∫ is the molecular weight of the side chain of the fluorinated sulfonate or sulfonic acid polymer. In one embodiment, the fluorinated sulfonyl fluoride polymer has an IXR of less than about 13.2, in another embodiment, less than about 12.7, in another embodiment, less than about 12.1, in another embodiment, less than about 11.7, or any value, range, or partial range in between. In one embodiment, the fluorinated sulfonyl fluoride polymer has an IXR of at least 7.1, in another embodiment, at least 8.1, in another embodiment, at least 9.1, in another embodiment, at least 10.1, or any value, range, or partial range in between.

[0027] In some embodiments, the fluorinated sulfonyl fluoride polymer and the corresponding fluorinated sulfonate or sulfonic acid polymer have an EW of less than about 1000, or less than about 980, or less than about 950, or less than about 930, or any value, range, or partial range in between. In one embodiment, the corresponding fluorinated sulfonate or sulfonic acid polymer has an EW of at least about 530, or at least about 580, or at least about 630, or at least about 680, or any value, range, or partial range in between. As used herein, (EW) refers to the weight in proton form of the corresponding fluorinated sulfonic acid polymer required to neutralize one equivalent of NaOH.

[0028] In one embodiment, the fluorinated sulfonyl fluoride polymer and its corresponding fluorinated sulfonate or sulfonic acid polymer contain long side chains and have an EW of less than about 1000, or less than about 980, or less than about 950, or less than about 930, or any value, range, or partial range in between. In one embodiment, the fluorinated sulfonyl fluoride polymer and its corresponding fluorinated sulfonate or sulfonic acid polymer have an EW of at least about 700, or at least about 750, or at least about 800, or at least about 950, or any value, range, or partial range in between. The IXR of fluorinated polymers with side chains of -O-CF2-CF(CF3)-O-CF2-CF2-SO3H, i.e., those produced from copolymers of TFE and PSEPVE, can be associated with EW using the formula: 50 IXR + 344 = EW.

[0029] In another embodiment, the fluorinated sulfonyl fluoride polymer and its corresponding fluorinated sulfonate or sulfonic acid polymer contain short side chains and have an EW of less than about 840, or less than about 810, or less than about 785, or less than about 765, or any value, range, or partial range in between. In one embodiment, the fluorinated sulfonyl fluoride polymer and its corresponding fluorinated sulfonate or sulfonic acid polymer have an EW of at least about 530, or at least about 580, or at least about 630, or at least about 680, or any value, range, or partial range in between. The IXR of fluorinated polymers with side chains of -O-CF2CF2SO3H, i.e., those produced from copolymers of TFE and PFSVE, can be related to equivalents using the formula: 50 IXR + 178 = EW.

[0030] In the present invention, the noble metal catalyst is particularly combined with a fluorinated sulfonyl fluoride type polymer, rather than a corresponding fluorinated sulfonate or fluorinated sulfonic acid. By directly blending the noble metal catalyst into the fluorinated sulfonyl fluoride, it is possible to more uniformly distribute and disperse the catalyst throughout the polymer, resulting in a more uniformly distributed or dispersed catalyst in materials made from the composition, such as fluorinated sulfonyl fluoride films, corresponding fluorinated sulfonate polymer materials, corresponding fluorinated sulfonic acid polymer materials, and films or membranes thereof. In one embodiment, the noble metal catalyst is uniformly dispersed throughout the composition.

[0031] The precious metal catalyst is present in the composition in an amount sufficient to provide a gas recombination effect, but not in an amount so large as to alter the conductivity (or lack thereof) of the non-crosslinked fluorinated sulfonyl fluoride polymer, or its corresponding fluorinated sulfonate polymer or fluorinated sulfonic acid polymer. In one embodiment, the composition comprises, based on the total weight of the composition, about 90% to about 99.99% by weight of one or more non-crosslinked fluorinated sulfonyl fluoride polymers and about 0.01% to about 10% by weight of one or more precious metal catalysts. In another embodiment, the composition comprises about 92% to about 99.9% by weight of one or more non-crosslinked fluorinated sulfonyl fluoride polymers and about 0.1% to about 8% by weight of one or more noble metal catalysts; in another embodiment, about 95% to about 99.7% by weight of one or more non-crosslinked fluorinated sulfonyl fluoride polymers and about 0.3% to about 5% by weight of one or more noble metal catalysts, about 97% to about 99.5% by weight of one or more non-crosslinked fluorinated sulfonyl fluoride polymers and about 0. The composition includes one or more precious metal catalysts in an amount of 5% to approximately 3% by weight, one or more non-crosslinked fluorinated sulfonyl fluoride polymers in an amount of approximately 98% to approximately 99.3% by weight, and one or more precious metal catalysts in an amount of approximately 0.7% to approximately 2% by weight, one or more non-crosslinked fluorinated sulfonyl fluoride polymers in an amount of approximately 98.5% to approximately 99.3% by weight, and one or more precious metal catalysts in an amount of approximately 0.7% to approximately 1.5% by weight, or any value, range, or partial range between these, all based on the total weight of the composition.

[0032] Additional compounds may be present in the composition, but preferably the composition contains any additional compounds in less than about 5% by weight, based on the total weight of the composition. In another embodiment, the composition contains less than about 3% by weight of additional compounds, in another embodiment, the composition contains less than about 2% by weight of additional compounds, in another embodiment, the composition contains less than about 1% by weight of additional compounds, in one yet another embodiment, the composition contains less than about 0.5% of additional compounds, or any value, range, or partial range in between, all based on the total weight of the composition. Suitable additional compounds include, but are not limited to, radical scavenger compounds, coupling agents, or other resin additives.

[0033] In one embodiment, the composition contains less than 5% by weight of solvent or liquid carrier, in another embodiment, less than 2% by weight of solvent or liquid carrier, in another embodiment, less than 1% by weight of solvent or liquid carrier, in another embodiment, less than 0.1% by weight of solvent or liquid carrier, in another embodiment, 0% of solvent or liquid carrier, or any value, range, or sub-range in between, all based on the total weight of the composition. In one embodiment, no solvent or liquid carrier is present in the composition such that the total weight of the composition is equal to the total dry weight of the composition.

[0034] The composition may be a solid composition. a. Melting at least one non-crosslinked fluorinated sulfonyl fluoride polymer, b. Distributing at least one noble metal catalyst uniformly within at least one molten non-crosslinked fluorinated sulfonyl fluoride polymer in an amount that forms a composition comprising at least 90% to about 99.99% by weight of one or more non-crosslinked fluorinated sulfonyl fluoride polymers and at least 0.01% to about 10% by weight of one or more noble metal catalysts, based on the total weight of the composition. c. It may be prepared by a method comprising cooling the mixture from step b to form a solid composition.

[0035] In this method, the noble metal catalyst is combined with a non-crosslinked fluorinated sulfonyl fluoride polymer in a molten material. Suitable noble metal catalysts, non-crosslinked fluorinated sulfonyl fluoride polymers, compositions, and component amounts are the same as those listed above. Suitable temperatures for steps a and b can be assumed by those skilled in the art, but include temperatures above the melting point of the non-crosslinked fluorinated sulfonyl fluoride polymer, and these temperatures produce a polymer with a viscosity suitable for enabling extrusion.

[0036] The noble metal catalyst is uniformly distributed in the non-crosslinked fluorinated sulfonyl fluoride polymer, and in one embodiment, the noble metal catalyst is uniformly dispersed throughout the non-crosslinked fluorinated sulfonyl fluoride polymer in step b. The uniform distribution step b can be carried out by any mixing method suitable for distributing or dispersing the noble metal catalyst in the resin, for example, any mixing method that applies high mixing and / or shear to the components. These methods include, but are not limited to, mixing in a single-screw extruder or a twin-screw extruder, and may also include screw elements such as a kneading block or gear mixer. In one embodiment, the process further includes a step of mixing a solid non-crosslinked fluorinated sulfonyl fluoride with a solid noble metal catalyst prior to the melting step a, so that the non-crosslinked fluorinated sulfonyl fluoride polymer is melted together with the already present noble metal catalyst in step a. However, other methods of introducing the noble metal catalyst into the composition may also be used, including, but are not limited to, supplying the noble metal catalyst to the molten non-crosslinked fluorinated sulfonyl fluoride polymer in a mixing apparatus.

[0037] To prevent aggregation of the precious metal catalyst, it is desirable to highly disperse the precious metal catalyst within its layer in the film. In one embodiment, a low surface energy molten polymer resin is mixed with a high surface energy filler, and the process is carried out at a high temperature to reduce the polymer viscosity and use a high shear force. By operating under these conditions, a (highly active) precious metal catalyst that is sufficiently dispersed within the cation exchange film layer should be obtained. After step b, the precious metal catalyst may have an average particle size D50 of less than approximately 5 μm, in another embodiment, an average particle size D50 of about 75 nm, in another embodiment, an average particle size D50 of less than approximately 50 nm, and in another embodiment, an average particle size D50 of less than approximately 25 nm.

[0038] To form a solid composition, the mixture of step b is cooled by any preferred method that reduces its temperature. For example, the mixture may be simply cooled by removing heat, such as after being removed from a heated container. Active cooling methods may also be applied to accelerate the solidification process. In one embodiment, the process further includes a step of shaping the mixture of step b before cooling. For example, the mixture of step b may be extruded, pelletized, and cooled. In another embodiment, the mixture of step b may be extruded into a film, melt-cast, or injected and then cooled. Without being bound by one particular theory, the act of cooling or quenching the polymer resin mixture after mixing is thought to work to fix the noble metal catalyst compound in place and prevent aggregation and sedimentation, which is particularly difficult to obtain from the current state of the art using GRC mixed in a PFSA dispersion, where metal catalyst particles are known to sediment over time.

[0039] Another aspect of the present invention relates to a cation exchange membrane precursor comprising at least one cation exchange precursor layer, wherein the at least one proton exchange precursor layer comprises, based on the total weight of the composition, about 90% to about 99.99% by weight of one or more non-crosslinked fluorinated sulfonyl fluoride polymers and about 0.01% to about 10% by weight of one or more noble metal catalysts, wherein the one or more noble metal catalysts are uniformly distributed throughout the at least one proton exchange precursor layer. Preferred noble metal catalysts, non-crosslinked fluorinated sulfonyl fluoride polymers, composition components, and component amounts are the same as those listed above.

[0040] The cation exchange membrane precursor may include at least one additional layer. In another embodiment, the cation exchange membrane precursor includes at least two additional layers, the two layers being referred to as the additional layer and the third layer, and in another embodiment, the cation exchange membrane precursor includes at least three additional layers, the three layers being referred to as the additional layer, the third layer, and the fourth layer. The additional layers may contain an ion exchange resin precursor, such as but not limited to a fluorinated sulfonyl fluoride polymer. Such an ion exchange resin precursor may be crosslinkable, crosslinked, or uncrosslinked. In one embodiment, the ion exchange resin precursor falls within the range of IXR or EW described above. The additional layers may be present in the same film as the original cation exchange precursor layer, or they may be one or more separate films that are later joined to form a cation exchange membrane.

[0041] At least one additional layer may also independently contain additives including radical scavengers, noble metal catalysts, other additives, or mixtures thereof. In one embodiment, radical scavengers, noble metal catalysts, and other additives are present in the additional layer in the amounts described above. The composition of the additional layers may be the same as or different from that of the first cation exchange precursor layer, and they may also be the same as or different from each other. In one embodiment, the additional layers do not contain noble metal catalysts. In one embodiment, there are three additional layers, two of which do not contain noble metal catalysts, and in another embodiment, there are three additional layers, and the total four-layer structure has alternating layers of layers containing noble metal catalysts and layers that do not contain noble metal catalysts.

[0042] GRC is thought to be most active at a specific location in the film, i.e., at a location close to either the anode or the cathode, depending on the operation of the battery. Therefore, in one aspect of the present invention, a noble metal catalyst is packed into a specific location in the film closest to the anode or cathode, while other locations are not packed with the noble metal catalyst.

[0043] In one aspect of the present invention, the cation exchange membrane precursor is not reinforced. However, in another aspect of the present invention, a reinforcing layer is present to provide additional mechanical strength to the entire membrane precursor structure. The reinforcing layer can be any material suitable for providing this additional mechanical strength while also allowing cations to move freely through the structure. For example, the reinforcing material may be a porous film, woven fabric, or porous scrim material composed of materials including, but not limited to, polytetrafluoroethylene (PTFE), polyarylether ketone (PAEK), liquid crystal polymer, polyphenylene sulfide (PPS), PTFE-perfluoroalkyl vinyl ether copolymer (PFA), glass, quartz, and polyolefins including polyethylene or polypropylene. Specific PTFE reinforcing materials include expanded PTFE (ePTFE) and woven PTFE. Examples of materials with a high tensile modulus suitable as reinforcing materials include liquid crystal polymer, polyphenylene sulfide, glass, quartz, or PAEK. Specific examples of polyaryl ether ketones include, but are not limited to, polyether ketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK), or polyether ketone ether ketone ketone (PEKEKK).

[0044] In one embodiment, the final cation exchange membrane precursor may have an average thickness of approximately 25–150 μm; in another embodiment, an average thickness of approximately 30–120 μm; in yet another embodiment, an average thickness of approximately 30–100 μm; in yet another embodiment, an average thickness of approximately 30–80 μm; and in yet another embodiment, an average thickness of approximately 30–60 μm. Thinner thicknesses may be desirable to achieve high efficiency, while thicker thicknesses may be desirable to achieve high durability. To increase the efficiency of the GRC material while minimizing the amount of GRC material required, it may be desirable to have a specific layer of GRC within the membrane where the highest concentrations of hydrogen and oxygen are present. In one embodiment, the layer within the membrane containing the noble metal catalyst may have a thickness of approximately 3 μm to approximately 150 μm; in yet another embodiment, a thickness of approximately 7 μm to approximately 150 μm; and in yet another embodiment, a thickness of approximately 17 to approximately 150 μm. When other cation exchange layers are present in the membrane, the layer within the membrane containing the noble metal catalyst may have a thickness of approximately 3 μm to approximately 100 μm, in another embodiment, approximately 7 μm to approximately 50 μm, and in another embodiment, approximately 17 to approximately 25 μm.

[0045] Accordingly, the present invention also relates to a cation exchange membrane comprising at least one cation exchange layer, the at least one cation exchange layer comprising, based on the total weight of the composition, about 90% to about 99.99% by weight of one or more non-crosslinked fluorinated sulfonic acid polymers or non-crosslinked fluorinated sulfonate polymers, and about 0.01% to about 10% by weight of one or more noble metal catalysts, wherein the one or more noble metal catalysts are uniformly distributed throughout the at least one cation exchange layer. In one embodiment, the one or more noble metal catalysts are uniformly distributed. The cation exchange membrane is prepared by hydrolyzing a cation exchange membrane precursor and optionally protonating it, where the non-crosslinked fluorinated sulfonyl fluoride polymer is converted to a non-crosslinked fluorinated sulfonate polymer or non-crosslinked fluorinated sulfonic acid polymer. Preferred noble metal catalysts, non-crosslinked fluorinated sulfonyl fluoride polymers and their corresponding non-crosslinked fluorinated sulfonates and sulfonic acids, compositions, component amounts, and layer structures are the same as those listed above.

[0046] The cation exchange membrane may also have one or more additional layers, as described above. In this case, the one or more additional layers may include, but are not limited to, cation exchange resins, fluorinated sulfonate polymers or fluorinated sulfonic acid polymers, rather than ion exchange precursors. Such ion exchange resins may be crosslinkable, crosslinked, or non-crosslinked. In one embodiment, the cation exchange resin falls within the range of IXR or EW described above. The additional layers may be in the same film as the original cation exchange layer, or they may be one or more separate films that are later joined to form the cation exchange membrane. As described for the cation exchange membrane precursor, the cation exchange membrane may not be reinforced. However, in another embodiment of the invention, a reinforcing layer is present to provide additional mechanical strength to the entire membrane precursor structure. The reinforcing layer may be any material suitable for providing this additional mechanical strength while also allowing cations to move freely through the structure. Suitable reinforcing materials are described above.

[0047] Cation exchange membranes are d. Melting at least one non-crosslinked fluorinated sulfonyl fluoride polymer, e. Based on the total weight of the composition, the composition comprises one or more non-crosslinked fluorinated sulfonyl fluoride polymers in an amount of about 90% to about 99.99% by weight and one or more noble metal catalysts in an amount of about 0.01% to about 10% by weight, wherein at least one noble metal catalyst is uniformly distributed using at least one molten non-crosslinked fluorinated sulfonyl fluoride polymer. f. Forming a layer of material from the composition of step e, wherein the noble metal catalyst is uniformly distributed throughout the entire layer. g. The non-crosslinked fluorinated sulfonyl fluoride polymer from the layer of step f can be converted to a non-crosslinked fluorinated sulfonic acid polymer or a non-crosslinked fluorinated sulfonate polymer. Cathode exchange membranes prepared by the above method are also conceivable. The cation exchange membrane precursor is generated from the above process and terminates before conversion step g. Suitable noble metal catalysts, non-crosslinked fluorinated sulfonyl fluoride polymers and their corresponding non-crosslinked fluorinated sulfonates and sulfonic acids, compositions, component amounts, and layer structures are the same as those listed above.

[0048] As described above in the process for the solid composition, suitable temperatures for steps d and e may be assumed by those skilled in the art, but include temperatures above the melting point of the non-crosslinked fluorinated sulfonyl fluoride polymer, and these temperatures produce a polymer with a viscosity suitable for enabling extrusion. The noble metal catalyst is uniformly distributed in the non-crosslinked fluorinated sulfonyl fluoride polymer, and in one embodiment, the noble metal catalyst is uniformly dispersed throughout the non-crosslinked fluorinated sulfonyl fluoride polymer in step e. The uniform distribution step e can be carried out by any mixing method suitable for distributing or dispersing the noble metal catalyst in the resin, for example, any mixing method that adds high mixing and / or shear to the components. These methods include, but are not limited to, mixing in a single-screw extruder or a twin-screw extruder, and may also include screw elements such as a kneading block or gear mixer. In one embodiment, the process further includes a step of mixing a solid non-crosslinked fluorinated sulfonyl fluoride with a solid noble metal catalyst prior to the melting step d, so that the non-crosslinked fluorinated sulfonyl fluoride polymer is melted together with the already present noble metal catalyst in step d. However, other methods of introducing the noble metal catalyst into the composition may also be used, including, but are not limited to, supplying the noble metal catalyst to the molten non-crosslinked fluorinated sulfonyl fluoride polymer in a mixing apparatus.

[0049] In one embodiment, the composition of step e is cooled before forming a layer of material in step f. In another embodiment, the method further includes step e1, in which the composition of step e is molded and cooled before step f. The mixture of step e is cooled by any preferred method that reduces the temperature. For example, the mixture may be simply cooled by removing heat, such as after being removed from a heating vessel. Active cooling methods may also be applied to accelerate the solidification process. In one embodiment, the process further includes a step of molding the mixture of step e before cooling. For example, the mixture of step e may be extruded, pelletized, cooled, and remelted before step f. In another embodiment, the mixture of step e may be extruded or injected directly into a film and then cooled.

[0050] In step f, the formation of a layer of composition may be carried out by any preferred means, including extrusion, melt casting, injection, or pressing of the solid composition at high temperature. In one embodiment, the composition of step e is extruded into a film during step f. The extrusion may be carried out using a single-screw extruder or a twin-screw extruder before extruding into a film shape, and may include screw elements such as a kneading block or a gear mixer.

[0051] The additional layer may be formed by any preferred means, including extrusion, injection, or pressing of a solid composition at high temperature. The additional layer may be combined with the layer of material from step f by any preferred process, including co-extrusion or lamination. In one embodiment, at least one additional layer is formed by co-extrusion with the layer of step f to form a single film. Such co-extrusion can be carried out, for example, by providing separate feedstocks for the layer of step f and at least one additional layer, and then joining the feedstocks during extrusion. In another embodiment, at least one additional layer is formed separately and pressed at high temperature together with the film having the layer of step f.

[0052] As described above, the reinforcing layer can be used in the cation exchange membrane precursor and the cation exchange membrane. When a reinforcing material is used, the process includes applying the composition of step e to the reinforcing material either during or after the layering step f. If the composition of step e is applied to the reinforcing material during the layering step f, it can be extruded and melt-laminated onto the reinforcing material by any preferred process, including but not limited to extrusion lamination. In another embodiment, if the composition of step e is applied to the reinforcing material after the layering step f, it can be laminated by any preferred process, including but not limited to double-belt lamination, nip-roll lamination, and vacuum lamination. The extruded film can then be laminated with the woven reinforcing material at a high temperature to fuse the polymer and the woven layer together to form a composite film, according to a typical lamination method, such as using a lamination roll or vacuum lamination process.

[0053] The non-crosslinked fluorinated sulfonyl fluoride in the layer of step f may then be converted to a non-crosslinked fluorinated sulfonate or non-crosslinked fluorinated sulfonic acid in step g. Any convertible polymer from additional layers may be converted simultaneously as part of the same film or composite film. The film or composite film may be hydrolyzed in an aqueous alkali metal hydroxide solution and acidified with an acid such as nitric acid to convert the sulfonyl fluoride groups to sulfonic acid or sulfonate groups. Examples of alkali metal hydroxides include, but are not limited to, NaOH or KOH. During the hydrolysis process, water-soluble organic solvents such as dimethyl sulfoxide (DMSO), N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidinone, N-ethyl-2-pyrrolidone, methanol, ethanol, isopropanol, butanol, methoxyethoxyethanol, butoxyethanol, butylcarbitol, hexyloxyethanol, octanol, propylene glycol methyl ether, ethylene glycol, ethanolamine, N-methylethanolamine, N-ethylethanolamine, 1-amino-2-propanol, 1-amino-3-propanol, 2-aminoethoxyethanol, 2-aminoethoxyethanol, and 2-amino-2-methyl-1-propanol may be used in the hydrolysis solution.

[0054] In one embodiment, the final reinforcing ion exchange membrane may have an average thickness of approximately 30 to 150 μm; in another embodiment, an average thickness of approximately 30 to 120 μm; in yet another embodiment, an average thickness of approximately 30 to 100 μm; in yet another embodiment, an average thickness of approximately 30 to 80 μm; and in yet another embodiment, an average thickness of approximately 30 to 60 μm.

[0055] Cation exchange membranes can be used in catalyst coatings having multiple layers of functional material. Such catalyst coatings can be used in electrolytic systems, such as water electrolysis systems. In one embodiment, the present invention relates to a catalyst coating including a cation exchange membrane, wherein the catalyst coating includes a cathode catalyst layer on one side of a reinforcing ion exchange membrane and an anode catalyst layer on the other side of the reinforcing ion exchange membrane. The catalyst coating may include a cathode catalyst layer (CCL) on one side of the ion exchange membrane and an anode catalyst layer (ACL) on the other side of the ion exchange membrane. For example, the cathode catalyst layer may be in direct contact with the cation exchange membrane, and the cation exchange membrane may be in further direct contact with the anode catalyst layer to form a catalyst coating. The cation exchange membrane may include multiple layers, and may also include reinforcing layers. The catalyst coating may include multiple layers of the same material, or it may include additional layers of functional material such as a gas diffusion layer, a porous transport layer, or a bipolar plate.

[0056] CCL and ACL can be applied to ion exchange membranes in the form of catalytic inks. The catalytic ink composition often comprises a catalytic component and a polymer binder, the polymer binder often comprising a fluorinated ionomer such as those mentioned above. The polymer used in CCL and ACL may be the same as or different from the polymer used as the fluorinated ionomer of the ion exchange membrane. The catalytic component may, but is not limited to, metal particles or carbon-supported metal particles. Specific metals may, but are not limited to, platinum, ruthenium, gold, silver, palladium, iridium, rhodium, iron, cobalt, nickel, chromium, tungsten, manganese, vanadium, and alloys thereof. Solvents, such as those mentioned for use in ion exchange dispersions, may be used to assist in the application of the catalytic ink to the ion exchange membrane. CCL and ACL materials can be applied to ion exchange membranes by any preferred means, including brushing, spraying, notch bar coating, fluid die coating, rod coating, slot feed knife coating, 3-roll coating, or decal transfer. [Examples]

[0057] The following test methods and materials were used in the examples described herein.

[0058] The present invention is illustrated in the following examples, which do not limit the scope of the invention as described in the claims. The following test methods and materials were used in the examples herein.

[0059] All solvents and reagents are available from Sigma-Aldrich (St. Louis, MO) unless otherwise specified.

[0060] HSAPB (High Surface Area Platinum Black) has a Pt crystallite size of 5.0-7.5 nm and a Pt surface area ECSA of 50 m². 2 / g, and total catalyst surface area of ​​50m 2 It is a high-surface-area platinum black with a weight of / g, and is available from The Fuel Cell Store (College Station, TX). Platinum Black TA HSTDP is available from Heraeus Precious Metals (Santa Fe Springs, CA), 27m 2 It was a platinum black product with a BET Pt surface area of ​​ / g.

[0061] The catalyst ink component IrO2 was available from Alpha Aesar Premium (registered trademark) (Ward Hill, MA), and the catalyst ink component Pt / C was TKK TEC10E50E, available from Tanaka Precious Metals (Tokyo, Japan).

[0062] The TiO2-supported Pt catalyst was available from Ishifuku Metal Industry Company (Tokyo, Japan).

[0063] The carbon-platinum catalyst TEC10V50E has a Pt content of 46.8 wt%, a particle size of 23A as measured by XRD, and 106.8 m2 It had a BET Pt surface area of ​​1 / g and was available from TKK (Tokyo, Japan).

[0064] Nafion® D2020 is an ionomer dispersion available from The Chemours Company (Wilmington, DE).

[0065] The PEEK reinforcement fabric used was IEM 17-195 / 70, a plain weave fabric with fibers approximately 38 μm in diameter, an inter-center fiber spacing of approximately 195 μm, and an opening area of ​​approximately 70%, and was available from SEFAR (Thal, Switzerland).

[0066] Test method thickness Three thickness measurements were performed using a ProGage thickness gauge, available from Thwing-Albert Instrument Company (West Berlin, NJ). The reported thickness represents the average of the three measurements.

[0067] Hydrogen / Oxygen Crossover The catalyst coating film was prepared by spraying catalyst ink onto a film formed on a vacuum plate heated to 80°C. The anode catalyst ink concentration was 0.4 mg / cm³. 2 The cathode catalyst ink contains IrO2 and Nafion® D2020 (0.84:0.16 by weight ratio), and the concentration is 0.1 mg / cm³. 2 It contained Pt / C and Nafion(trademark) D2020 (weight ratio of 0.15:0.85).

[0068] The H2:O2 ratio in the cell's anode exhaust stream was quantified using gas chromatography (GC). At the cell outlet, the mixture contained liquid water, oxygen, hydrogen, and water vapor. N2 gas was also added to ensure the mixture remained below the flammability limit. The mixture was passed through a series of components designed to condense and remove liquid water to protect the GC. Samples were taken continuously for typically 5–15 minutes until the H2:O2 ratio reached equilibrium.

[0069] SEM images of compounded resins and films To help minimize the charging effect in electron microscopy, the samples were sputter-coated with osmium and then analyzed using the backscatter mode with an Auriga 60 CrossBeam SEM. Cross-sections of the films were prepared using a microtome.

[0070] (Example 1) 6.0 kg of 920 equivalent sulfonyl fluoride fluoropolymer resin pellets (chemically stabilized PTFE / CF2=CF-O-CF2CF(CF3)-O-CF2CF2SO2F copolymer with an EW of 920 g / mol, available from The Chemours Company (Wilmington, DE)) were mixed in a 1-gallon polyethylene container. 60 g of HSAPB was added to these pellets. This mixture was roll-tumbled at room temperature for 10 minutes to coat the fluoropolymer resin pellets with platinum. The platinum-coated sulfonyl fluoride-containing fluoropolymer resin pellets were then fed into a 1-inch diameter twin-screw extruder using a loss-in-weight feeder at a polymer feed rate of 2.27 kg / hour and a screw speed of 150 RPM. The twin-screw extruder included a kneading block screw element to assist in the distribution and mixing of platinum within the fluoropolymer molten material. The temperature profile rose from 190°C at the feed port to 230°C at the discharge end. The pellets were strand-cut to create black pellets containing 1% by weight of platinum.

[0071] (Example 2) Multilayer films were prepared using a co-extrusion system. Non-platinumized sulfonyl fluoride fluoropolymer resin pellets (chemically stabilized PTFE / CF2=CF-O-CF2CF(CF3)-O-CF2CF2SO2F copolymer with an EW of 920 g / mol, available from The Chemours Company (Wilmington, DE)) were fed into a feed block to a first extruder with a 1.5-inch uniscrew. Platinumized sulfonyl fluoride-containing fluoropolymer resin pellets from Example 1 were fed into a satellite extruder with a 1-inch uniscrew. The feed block combined the flows from these two extruders into separate layers and fed them through a die to create a final film with separate layers of platinumized sulfonyl fluoride resin and unused non-platinumized sulfonyl fluoride fluoropolymer resin. The extruders were operated at 275°C, melt-cast from a 10-mil die, and stretched to a final thickness of 2 mils in the machine direction. The film was hydrolyzed in a DMSO / KOH / water solution as taught in the art. The film was then acidified in a 20% nitric acid aqueous solution and dried to remove excess water.

[0072] (Example 3) (The preliminary hydrolysis film from Example 2 was melt-laminated with a PEEK-reinforced fabric to form a composite film. The laminated film was hydrolyzed in a DMSO / KOH / water solution as taught in the art. The PEEK-reinforced fabric used was a plain weave fabric with fibers approximately 38 μm in diameter, an inter-center fiber spacing of approximately 195 μm, and an opening area of ​​approximately 70%. The film was then acidified in a 20% nitric acid aqueous solution and dried to remove excess water.)

[0073] (Example 4) Example 1 was repeated, except that a screw speed of 300 RPM was used.

[0074] (Example 5) A co-extrusion system was used in which non-platinumized sulfonyl fluoride-containing fluoropolymer resin pellets (chemically stabilized PTFE / CF2=CF-O-CF2CF(CF3)-O-CF2CF2SO2F copolymer with an EW of 920 g / mol, available from The Chemours Company (Wilmington, DE)) were fed into a feed block to a first extruder having a 2.5-inch uniscrew. Platinumized sulfonyl fluoride-containing fluoropolymer resin pellets from Example 4 were fed into a satellite extruder having a 1.5-inch uniscrew. The feed block combined the flows from these two extruders into separate layers and fed them through a die to create a final film having separate layers of platinumized sulfonyl fluoride resin and unused non-platinumized sulfonyl fluoride fluoropolymer resin. The extruders were operated at 270°C, melt-cast from a 33-mil die, and stretched to a final thickness of 2.3 mil in the machine direction. The film was hydrolyzed in a DMSO / KOH / water solution as taught in the art. The film was then acidified in a 20% nitric acid aqueous solution and dried to remove excess water.

[0075] (Example 6) Example 3 was repeated using the preliminary hydrolysis film from Example 5, and the resulting film was tested for H2:O2 crossover.

[0076] [Table 1]

[0077] As can be seen from Table 1, the sample of the present invention maintains a low crossover value over a long period of time, demonstrating good initial performance and performance durability.

[0078] (Example 7) Two separate 1-gallon polyethylene containers were each filled with 4.5 kg of 920 equivalent sulfonyl fluoride fluoropolymer resin pellets (chemically unstabilized PTFE / CF2=CF-O-CF2CF(CF3)-O-CF2CF2SO2F copolymer with an EW of 920 g / mol, available from The Chemours Company (Wilmington, DE)). 90 g of HSAPB was added to one of the containers. This mixture was roll-tumbled at room temperature for 10 minutes to coat the fluoropolymer resin pellets with platinum. The platinum-coated sulfonyl fluoride-containing fluoropolymer resin pellets were then fed into a 27 mm diameter twin-screw extruder using a loss-in-weight feeder at a polymer feed rate of 9.07 kg / hour and a screw speed of 200 RPM. The twin-screw extruder included a kneading block screw element to assist in the distribution and mixing of platinum within the fluoropolymer molten material. The temperature profile increased from 160°C at the feed port to 190°C at the discharge end. The pellets were strand-cut to create black pellets containing 2% by weight of platinum.

[0079] (Example 8) Example 5 was repeated, except that the fluoropolymer resin pellets of Example 7 were used instead of the resin pellets of Example 4.

[0080] (Example 9) Example 3 was repeated using the preliminary hydrolysis film from Example 8. The resulting film was tested for H2:O2 crossover.

[0081] (Example 10) Example 7 was repeated, except that 45 g of TiO2-supported Pt was used, to obtain a pellet containing 1% by weight of Pt / TiO2.

[0082] (Example 11) Example 5 was repeated, except that the fluoropolymer resin pellets from Example 10 were used instead of the resin pellets from Example 4.

[0083] (Example 12) Example 3 was repeated using the preliminary hydrolysis film from Example 11.

[0084] (Example 13) Two separate 1-gallon polyethylene containers were each filled with 5 kg of 920 equivalent sulfonyl fluoride fluoropolymer resin pellets (chemically stabilized PTFE / CF2=CF-O-CF2CF(CF3)-O-CF2CF2SO2F copolymer with an EW of 920 g / mol, available from The Chemours Company (Wilmington, DE)). Platinum Black TA HSTDP (72.5 g) was added to one of the containers. This mixture was roll-tumbled at room temperature for 10 minutes to coat the fluoropolymer resin pellets with platinum. The platinum-coated sulfonyl fluoride-containing fluoropolymer resin pellets were then fed into a 31 mm diameter twin-screw extruder using a loss-in-weight feeder at a polymer feed rate of 9.07 kg / hour and a screw speed of 200 RPM. The twin-screw extruder included a kneading block screw element to assist in the distribution and mixing of platinum within the fluoropolymer molten material. The temperature profile increased from 160°C at the feed port to 190°C at the discharge end. The pellets were strand-cut to create black pellets containing 1.45% by weight of platinum.

[0085] (Example 14) Example 5 was repeated, except that the fluoropolymer resin pellets from Example 13 were used instead of the resin pellets from Example 4.

[0086] (Example 15) Example 3 was repeated using the preliminary hydrolysis film from Example 14. The resulting film was tested for H2:O2 crossover.

[0087] (Example 16) Example 13 was repeated, except that instead of platinum black, 130.5 g of carbon-superplatinum catalyst TEC10V50E was used along with 9 kg of polymer (chemically stabilized PTFE / CF2=CF-O-CF2CF(CF3)-O-CF2CF2SO2F copolymer with an EW of 920 g / mol, available from The Chemours Company (Wilmington, DE)) to obtain pellets containing 1.45 wt% catalyst.

[0088] (Example 17) Example 5 was repeated, except that the fluoropolymer resin pellets from Example 16 were used instead of the resin pellets from Example 4. The resulting film was tested for H2:O2 crossover.

[0089] (Example 18) Example 3 was repeated using the preliminary hydrolysis film from Example 17.

[0090] (Example 19) Example 13 was repeated, except that 250 g of Platinum Black TA HSTDP was used along with 9 kg of polymer (chemically stabilized PTFE / CF2=CF-O-CF2CF(CF3)-O-CF2CF2SO2F copolymer with an EW of 920 g / mol, available from The Chemours Company (Wilmington, DE)) to obtain pellets containing 2.77 wt% platinum.

[0091] (Example 20) Example 5 was repeated, except that the fluoropolymer resin pellets of Example 19 were used instead of the resin pellets of Example 4.

[0092] (Example 21) Example 3 was repeated using the preliminary hydrolysis film from Example 19.

[0093] (Example 22) The compositions were prepared by dry mixing 60 grams of sulfonyl fluoride fluoropolymer resin pellets (chemically unstabilized PTFE / CF2=CF-O-CF2CF(CF3)-O-CF2CF2SO2F copolymer with an EW of 800 g / mol, available from The Chemours Company (Wilmington, DE)) and 0.6 grams of Platinum Black TA HSTDP, and feeding the mixture into a System 10 batch mixer from Rheometer Services Inc. equipped with a 60 cc capacity mixing bowl containing roller blades. These blends were then mixed at 75 rpm to disperse all components and to the melting point and / or T of the polymer of interest. g The mixture was mixed for 10 minutes at a temperature sufficiently higher than the given temperature. In this case, the temperature was 180°C. The mixture was then removed from the mixer and subsequently cut into pellets containing 1% platinum.

[0094] (Example 23) Two separate 1-gallon polyethylene containers were each filled with 1.5 kg of sulfonyl fluoride fluoropolymer resin pellets (chemically stabilized PTFE / CF2=CF-O-CF2CF(CF3)-O-CF2CF2SO2F copolymer with an EW of 800 g / mol, available from The Chemours Company (Wilmington, DE)). Platinum Black TA HSTDP (54 g) was added to each container. This mixture was roll-tumbled at room temperature for 10 minutes to coat the fluoropolymer resin pellets with platinum. The platinum-coated sulfonyl fluoride-containing fluoropolymer resin pellets were then fed into a 27 mm diameter twin-screw extruder using a loss-in-weight feeder at a polymer supply rate of 6.08 kg / hour and a screw speed of 100 RPM. The twin-screw extruder included a kneading block screw element to assist in the distribution and mixing of platinum within the fluoropolymer molten material. The temperature profile increased from 160°C at the feed port to 190°C at the discharge end. The pellets were strand-cut to create black pellets containing 3.6% by weight of platinum.

[0095] Comparative example A Comparative examples were prepared using two dispersions of fluoroionomers (hydrolyzed, chemically stabilized PTFE / CF2=CF-O-CF2CF(CF3)-O-CF2CF2SO2F copolymer, available from The Chemours Company (Wilmington, DE), at an EW of 800 g / mol), one using HSAPB and the other without platinum. A 50 μm total film with a 12 μm platinum layer was prepared. A doctor blade was set in the gap to obtain a dry film thickness of 12 μm, and the platinumized dispersion was solution-cast onto the substrate. The cast film and substrate were dried in a relative humidity oven at 10% RH for 30 minutes. The film had a dry film thickness of 38 μm and a second layer solution cast by the doctor blade using a non-platinumized dispersion. The sample was dried in a relative humidity chamber at 10% RH for 30 minutes, then placed in an oven set to 175°C for 3 minutes to cure the film, and the film was determined to be 20 μg / cm² based on the weight of the film. 2 A film with a Pt content was obtained. The platinum-containing solid layer had 1% by weight of platinum.

[0096] Comparative example B The process in Example 17 was repeated, and although only a single layer of non-platinumized resin pellets was used, a film with the same total thickness was formed.

[0097] [Table 2]

[0098] As can be seen from Table 2, the sample showed a lower crossover value and better initial performance compared to the sample without platinum content.

[0099] Figures 1-7 show a membrane with two different layers, one containing a GRC precious metal catalyst and the other without additives. From Figures 1-7, it can be seen that the process provides a separate GRC layer in which the precious metal catalyst is uniformly distributed and dispersed throughout the material. This allows for the co-extrusion of different material layers to form a membrane material with a uniformly distributed precious metal catalyst at desired locations, while also minimizing the amount of precious metal catalyst required for the entire membrane. The membrane can be configured to minimize hydrogen and oxygen crossover for multiple end-use applications by intentionally positioning the precious metal catalyst at desired locations. In contrast, Figure 7 shows a membrane with two layers formed by a casting process, where the precious metal catalyst is not uniformly distributed throughout the bottom cast GRC layer. Instead, the precious metal catalyst is aggregated and concentrated on one side of the GRC cast layer so as to come into contact with the non-GRC layer. Therefore, the layering of the precious metal catalyst within the membrane cannot be customized and configured as can be done using the process of the present invention.

Claims

1. A composition comprising, based on the total weight of the composition, about 90% to about 99.99% by weight of one or more non-crosslinked fluorinated sulfonyl fluoride polymers and about 0.01% to about 10% by weight of one or more noble metal catalysts, wherein the one or more noble metal catalysts are uniformly distributed throughout the one or more non-crosslinked fluorinated sulfonyl fluoride polymers.

2. The composition according to claim 1, wherein no solvent or liquid support is present.

3. The composition according to claim 1, wherein one or more of the aforementioned precious metal catalysts are not supported.

4. The composition according to claim 1 or 3, wherein one or more of the aforementioned noble metal catalysts are located on carrier particles.

5. The composition according to claim 4, wherein the carrier particles are carbon, inorganic oxide particles, or a mixture thereof.

6. The composition according to claims 1 to 5, wherein the one or more precious metal catalysts are selected from platinum, ruthenium, osmium, rhodium, iridium, palladium, or mixtures thereof.

7. The composition according to claims 1 to 6, wherein the one or more noble metal catalysts are uniformly dispersed throughout the one or more non-crosslinked fluorinated sulfonyl fluoride polymers.

8. The composition according to claims 4 to 5, wherein the D50 particle size is at most about 5 μm.

9. The composition according to claims 1 to 8, comprising, based on the total weight of the composition, about 92% to about 99.9% by weight of one or more non-crosslinked fluorinated sulfonyl fluoride polymers and about 0.1% to about 8% by weight of one or more noble metal catalysts.

10. The composition according to claims 1 to 9, comprising, based on the total weight of the composition, about 95% to about 99.7% by weight of one or more non-crosslinked fluorinated sulfonyl fluoride polymers and about 0.3% to about 5% by weight of one or more noble metal catalysts.

11. A method for preparing a solid composition, a. Melting at least one type of non-crosslinked fluorinated sulfonyl fluoride polymer, b. Distributing at least one noble metal catalyst uniformly within the at least one molten non-crosslinked fluorinated sulfonyl fluoride polymer in an amount that forms the composition comprising about 90% to about 99.99% by weight of one or more non-crosslinked fluorinated sulfonyl fluoride polymers and about 0.01% to about 10% by weight of one or more noble metal catalysts, based on the total weight of the composition. c. A method comprising cooling the mixture from step b to form a solid composition.

12. The method according to claim 11, wherein the one or more noble metal catalysts are not supported.

13. The method according to claim 11, wherein one or more of the aforementioned precious metal catalysts are located on carrier particles.

14. The composition according to claim 13, wherein the carrier particles are carbon, inorganic oxide particles, or a mixture thereof.

15. The method according to claims 11 to 14, wherein the one or more precious metal catalysts are selected from platinum, ruthenium, osmium, rhodium, iridium, or palladium, or mixtures thereof.

16. The method according to claims 11 to 15, wherein the one or more noble metal catalysts are uniformly dispersed throughout the one or more non-crosslinked fluorinated sulfonyl fluoride polymers during step b.

17. The method according to claims 11 to 16, wherein the D50 particle size is at most about 5 μm.

18. The method according to claims 11 to 17, further comprising step b1 of extruding the composition of step b before step c.

19. A method for fabricating a cation exchange membrane, d. Melting at least one non-crosslinked fluorinated sulfonyl fluoride polymer, e. Distributing at least one noble metal catalyst uniformly using the at least one molten non-crosslinked fluorinated sulfonyl fluoride polymer in an amount that forms the composition comprising about 90% to about 99.99% by weight of one or more non-crosslinked fluorinated sulfonyl fluoride polymers and about 0.01% to about 10% by weight of one or more noble metal catalysts, based on the total weight of the composition, f. Forming a layer of material from the composition of step e, wherein the noble metal catalyst is uniformly distributed throughout the entire layer. g. A method comprising converting the non-crosslinked fluorinated sulfonyl fluoride polymer from the layer of step f into a non-crosslinked fluorinated sulfonic acid polymer or a non-crosslinked fluorinated sulfonate polymer.

20. The method according to claim 19, wherein the one or more noble metal catalysts are not supported.

21. The method according to claim 19, wherein one or more of the aforementioned precious metal catalysts are located on carrier particles.

22. The method according to claims 19 to 21, wherein the one or more precious metals are selected from platinum, ruthenium, osmium, rhodium, iridium, palladium, or mixtures thereof.

23. The method according to claims 19 to 22, wherein the one or more noble metal catalysts are uniformly dispersed throughout the one or more non-crosslinked fluorinated sulfonyl fluoride polymers during step e.

24. The method according to claims 19 to 23, wherein the D50 particle size is at most about 5 μm.

25. The method according to claims 19 to 24, wherein step f is performed by extrusion.

26. The method according to claims 19 to 25, wherein at least one additional layer is present in the cation exchange membrane.

27. The method according to claim 26, wherein the at least one additional layer comprises an ion exchange resin.

28. The method according to claim 27, wherein the ion exchange resin is a fluorinated sulfonic acid polymer or a non-crosslinked sulfonate polymer.

29. The method according to claims 26 to 28, wherein the at least one additional layer comprises one or more precious metal catalysts.

30. The method according to claims 26 to 28, wherein the at least one additional layer does not contain a precious metal catalyst.

31. The method according to claims 26 to 30, wherein the at least one additional layer is formed by co-extruding the at least one additional layer with the layer of step f to form a single film.

32. The method according to claims 26 to 30, wherein a third layer is present, and the third layer comprises an ion exchange resin.

33. The method according to claim 32, wherein a fourth layer is present, and the fourth layer comprises an ion exchange resin.

34. The method according to claims 32 to 33, wherein the third layer or the fourth layer is bonded by pressing the layers together at a high temperature.

35. The method according to claims 19 to 34, further comprising step e1 of molding and cooling the composition of step e before step f.

36. The method according to claims 19 to 35, wherein the composition of step e is applied to the reinforcing material during or after the layering step f.

37. The method according to claims 19 to 35, wherein the cation exchange membrane is not reinforced.

38. A cation exchange membrane prepared by the method described in any one of claims 19 to 37.

39. A cation exchange membrane comprising at least one cation exchange layer, A cation exchange membrane wherein the at least one cation exchange layer comprises, based on the total weight of the composition, one or more non-crosslinked fluorinated sulfonic acid polymers or non-crosslinked fluorinated sulfonate polymers in an amount of about 90% to about 99.99% by weight, and one or more noble metal catalysts in an amount of about 0.01% to about 10% by weight, wherein the one or more noble metal catalysts are uniformly distributed throughout the entire at least one cation exchange layer.

40. The cation exchange membrane according to claim 39, wherein one or more of the aforementioned precious metal catalysts are not supported.

41. The cation exchange membrane according to claim 39, wherein one or more of the aforementioned precious metal catalysts are located on carrier particles.

42. The cation exchange membrane according to claims 39 to 41, wherein the one or more precious metals are selected from platinum, ruthenium, osmium, rhodium, iridium, palladium, or mixtures thereof.

43. A cation exchange membrane according to claims 39 to 42, wherein the D50 particle size is approximately 5 μm at most.

44. The cation exchange membrane according to claims 39 to 43, further comprising at least one additional layer in the cation exchange membrane.

45. The cation exchange membrane according to claim 44, wherein the at least one additional layer comprises an ion exchange resin.

46. The cation exchange membrane according to claim 45, wherein the ion exchange resin is a fluorinated sulfonic acid polymer or a fluorinated sulfonate polymer.

47. The cation exchange membrane according to claims 44 to 46, wherein the at least one additional layer comprises one or more precious metal catalysts.

48. The cation exchange membrane according to claims 44 to 46, wherein the at least one additional layer does not contain a precious metal catalyst.

49. The cation exchange membrane according to claims 44 to 48, further comprising a third layer, the third layer comprising an ion exchange resin.

50. The cation exchange membrane according to claim 49, further comprising a fourth layer, the fourth layer comprising an ion exchange resin.

51. The cation exchange membrane according to claims 49 to 50, wherein at least one of the third layer or the fourth layer contains a noble metal catalyst.

52. The cation exchange membrane according to claims 49 to 50, wherein at least one of the third layer or the fourth layer does not contain a noble metal catalyst.

53. The cation exchange membrane according to claims 39 to 52, further comprising a reinforcing material in the cation exchange membrane.

54. The cation exchange membrane according to claims 39 to 52, wherein the cation exchange membrane is not reinforced.

55. A cation exchange membrane precursor comprising at least one cation exchange precursor layer, The cation exchange membrane precursor comprises, based on the total weight of the composition, one or more non-crosslinked fluorinated sulfonyl fluoride polymers in an amount of about 90% to about 99.99% by weight, and one or more noble metal catalysts in an amount of about 0.01% to about 10% by weight, wherein the one or more noble metal catalysts are uniformly distributed throughout the entire proton exchange precursor layer.

56. The cation exchange membrane precursor according to claim 55, wherein one or more of the aforementioned precious metal catalysts are not supported.

57. The cation exchange membrane precursor according to claim 55, wherein one or more of the aforementioned precious metal catalysts are located on carrier particles.

58. The cation exchange membrane precursor according to claims 55 to 57, wherein the one or more precious metals are selected from platinum, ruthenium, osmium, rhodium, iridium, palladium, or mixtures thereof.

59. A cation exchange membrane precursor according to claims 55 to 58, wherein the D50 particle size is at most about 5 μm.

60. The cation exchange membrane precursor according to claims 55 to 59, further comprising at least one additional layer in the cation exchange membrane precursor.

61. The cation exchange membrane precursor according to claim 60, wherein the at least one additional layer comprises an ion exchange resin precursor.

62. The cation exchange membrane according to claim 61, wherein the ion exchange resin precursor is a fluorinated sulfonyl fluoride polymer.

63. The cation exchange membrane precursor according to claims 60 to 62, wherein the at least one additional layer comprises one or more noble metal catalysts.

64. The cation exchange membrane precursor according to claims 60 to 62, wherein the at least one additional layer does not contain a noble metal catalyst.

65. The cation exchange membrane according to claims 60 to 64, further comprising a third layer, the third layer comprising an ion exchange resin precursor.

66. The cation exchange membrane according to claim 65, further comprising a fourth layer, the fourth layer comprising an ion exchange resin precursor.

67. The cation exchange membrane according to claims 65 to 66, wherein at least one of the third layer or the fourth layer contains a noble metal catalyst.

68. The cation exchange membrane according to claims 65 to 66, wherein at least one of the third layer or the fourth layer does not contain a noble metal catalyst.

69. A cation exchange membrane according to claims 55 to 68, further comprising a reinforcing material.

70. The cation exchange membrane according to claims 55 to 68, wherein the cation exchange membrane is not reinforced.

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