Composite fluorinated sulfonyl fluoride polymer and ion exchange membrane prepared therefrom

Abstract

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

Description

[0001] Cross-reference to related applications

[0002] This patent application claims the priority of U.S. Provisional Application No. 63 / 454,927, filed March 27, 2023, and U.S. Provisional Application No. 63 / 527,614, filed July 19, 2023, the disclosures of which are incorporated herein by reference in their entirety. Technical Field

[0003] This invention describes a composite fluorinated sulfonyl fluoropolymer, an ion exchange membrane precursor, an ion exchange membrane, and a method for preparing such materials. The composite polymer and ion exchange membrane have an improved gas recombination catalyst dispersed throughout the resin and can be used to form electrolysis systems, including catalyst-coated membranes, fuel cells, and water electrolysis systems. Background Technology

[0004] Noble metal compounds can be added to electrolysis systems as gas recombination catalysts (GRCs) to help reduce hydrogen (H2) in oxygen passing through the cation exchange membrane during operation. Given the high cost and limited resources of these noble metal compounds, a key objective is to optimize the reduction of hydrogen permeation while minimizing the amount of noble metal compound used.

[0005] The most commonly used technology in industry is casting ionomer dispersions (such as Nafion). TM An ion exchange resin dispersion containing noble metal catalyst particles is used. This dispersion is cast onto a backing or reinforcement, and the solvent is then removed, leaving an ionomer film with GRC (Glass Resin Concentrate). However, a disadvantage of this method is that the GRC particles may agglomerate during casting, resulting in a final cast film with low polymer entanglement and high swelling. Casting processes are described, for example, in US2021 / 0135244 and US2008 / 0161429.

[0006] Other methods for introducing GRC into membranes include chemically treating the membrane before swelling and immersing it in a GRC solution, as suggested in US2008 / 0003479. However, this method involves multiple steps and a liquid medium, which is not ideal for product efficiency. Furthermore, this method does not allow for precise configuration and placement of the GRC material. Summary of the Invention

[0007] The present invention provides a new method of strategically placing GRCs in an extruded cation exchange membrane by a processing method. A finding of the present invention is that strategic placement of GRCs provides performance advantages, product configuration 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 composite fluorinated sulfonic fluoropolymer, ion exchange membrane precursors, ion exchange membranes, and methods of making such materials. The composite polymers and ion exchange membranes improve the dispersion of gas recombination noble metal catalyst throughout the resin and are useful in forming electrolytic systems, including catalyst-coated membranes, fuel cells, and water electrolysis systems.

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

[0009] The present invention also describes methods of making such materials. In one aspect, the present invention relates to a method of making a solid composition, the method comprising:

[0010] a. melting at least one non-crosslinked fluorinated sulfonic fluoropolymer;

[0011] b. uniformly distributing at least one noble metal catalyst in the molten at least one non-crosslinked fluorinated sulfonic fluoropolymer in an amount to form a composition comprising from about 90% to about 99.99% by weight of one or more non-crosslinked fluorinated sulfonic fluoropolymer and from about 0.01% to about 10% by weight of one or more noble metal catalyst, based on the total weight of the composition; and

[0012] c. cooling the mixture of step b to form a solid composition.

[0013] In another aspect, the present application relates to a method of making a cation exchange membrane, the method comprising:

[0014] d. melting at least one non-crosslinked fluorinated sulfonic fluoropolymer;

[0015] e. uniformly distributing at least one noble metal catalyst with the molten at least one non-crosslinked fluorinated sulfonic fluoropolymer in an amount to form a composition comprising from about 90% to about 99.99% by weight of one or more non-crosslinked fluorinated sulfonic fluoropolymer and from about 0.01% to about 10% by weight of one or more noble metal catalyst, based on the total weight of the composition;

[0016] f. forming a layer of material from the composition of step e, wherein the noble metal catalyst is uniformly distributed throughout the layer; and

[0017] g. converting the non-crosslinked fluorinated sulfonic fluoropolymer of the layer from step f to a non-crosslinked fluorinated sulfonic acid polymer. Also contemplated is a cathode exchange membrane made by the above method. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a scanning electron micrograph (SEM) image of Example 6.

[0019] Figure 2 is a SEM image of Example 8.

[0020] Figure 3 is a SEM image of Example 9.

[0021] Figure 4 is a SEM image of Example 9 showing the thickness of the noble metal catalyst layer.

[0022] Figure 5 is a SEM image of Example 17.

[0023] Figure 6 is a SEM image of Example 18.

[0024] Figure 7 is a SEM image of Comparative Example A. DETAILED DESCRIPTION

[0025] The features of the embodiments of the application described in the detailed description of the application can be combined in any manner. All trade names are named in capital letters as brand names.

[0026] Definitions

[0027] As used herein, the term uniformly distributed refers to noble metal catalysts being uniformly distributed throughout the volume in all three dimensions. The process of uniformly distributing refers to uniformly distributing (or more precisely, redistributing) material in all three dimensions.

[0028] As used herein, the term uniformly dispersed refers to noble metal catalysts being in a deagglomerated form, such as discrete particles. The process of uniformly dispersing refers to reducing the particle size of the original material by deagglomerating the original particles into smaller particles, for example, primary particles having a higher surface area.

[0029] As used herein, the term non-crosslinked fluorinated sulfonic fluoropolymer refers to a fluorinated sulfonic fluoropolymer that does not contain intentionally introduced crosslinkable monomers or repeating units and to which no crosslinking agent has been added. The term non-crosslinked fluorinated sulfonic acid refers to a fluorinated sulfonic acid polymer that does not contain intentionally introduced crosslinkable monomers or repeating units, to which no crosslinking agent has been added, and in which the sulfonic acid units are not bonded to other polymer units.

[0030] As used herein, ion exchange ratio (IXR) refers to the relationship between the number of carbon atoms in the polymer backbone and the number of sulfonic fluorine groups.

[0031] As used herein, cation exchange membrane precursor refers to a thin film that is capable of being converted into a cation exchange membrane by hydrolysis and optional acidification. In this case, the cation exchange membrane precursor is a thin film comprising a fluorinated sulfonic fluoropolymer. Likewise, cation exchange resin precursor refers to a polymer or resin that is capable of being converted into a cation exchange polymer by hydrolysis and optional acidification.

[0032] The present invention relates to a composition comprising, based on the total weight of the composition, from about 90% to about 99.99% by weight of one or more non-crosslinked fluorinated sulfonic fluoropolymer and from about 0.01% to about 10% by weight of one or more noble metal catalyst, wherein the one or more noble metal catalyst is uniformly distributed throughout the one or more non-crosslinked fluorinated sulfonic fluoropolymer.

[0033] The noble metal catalyst can be any noble metal catalyst typically found in electrolytic cell applications. The noble metal can be, but is not limited to, platinum, ruthenium, osmium, rhodium, iridium, palladium, or mixtures thereof. The noble metal can also be mixed with additional compounds so long as the noble metal content meets the range of about 0.01% to 10% by weight of the total composition. The noble metal catalyst can be unsupported, or it can be supported by an inorganic support. The inorganic support can be in any form, such as inorganic support particles. The inorganic material making up the inorganic support can be any suitable material, including but not limited to carbon or inorganic materials such as those cited in US20080161429 or EP1929574, which are incorporated herein by reference; or mixtures thereof. The noble metal catalyst can have a high surface area to improve effectiveness, such that their noble metal surface area is at least 10 m 2 / g; in another aspect, at least 30 m 2 / g; and in another aspect, at least 45 m 2 / g. In one aspect, the noble metal catalyst has an average particle size D50 of less than about 5 pm; in another aspect, 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.

[0034] Ion exchange membranes can be made from a variety of ion exchange polymers. Preferred ion exchange polymers, fluorinated sulfonic acids and fluorinated sulfonic acid salts, can be prepared by hydrolyzing a fluorinated sulfonic acid fluoride polymer and then optionally protonating. The fluorinated sulfonic acid, fluorinated sulfonic acid salt, and fluorinated sulfonic acid fluoride polymer can or can not be chemically stabilized by fluorinated polymer end groups. Suitable fluorinated sulfonic acid fluoride polymers include at least one fluorinated sulfonic acid fluoride repeat unit and optionally one or more repeat units resulting from the free radical polymerization of at least one fluorinated sulfonic acid fluoride monomer and optionally one or more monomers. For example, a fluorinated ionomer can comprise repeat units:

[0035] - [CF2-CF((CF2) b -(O-(CF2CFR f ) c ) a -O-(CF2CFR' f ) d SO2F)]-

[0036] 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, CI, or a perfluorinated alkyl group having 1 to 10 carbon atoms. For the sake of clarity, it is noted that the segment ((CF2) b -(O-(CF2CFRf ) c ) a -O-(CF2CFR' f ) d SO2F) are side chains from the perfluorinated polymer backbone. Branched side chains with multiple sulfonyl fluoride groups are also encompassed.

[0037] In one aspect, the sulfonyl fluoride polymer is a copolymer made from two or more monomers. Suitable comonomers in addition to the sulfonyl fluoride monomer 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 can be a copolymer of the sulfonyl fluoride-containing monomer with TFE, resulting in the repeating unit -[CF2-CF2]-, or with other comonomers. Monomers with pendant phosphonic acid groups can also be incorporated into the fluorinated sulfonyl fluoride polymer to produce, upon conversion, a fluorinated ionomer containing both sulfonic acid groups and phosphonic acid groups.

[0038] One preferred class of fluorinated sulfonyl fluoride polymers includes a highly fluorinated, most preferably perfluorinated, carbon backbone with pendant side chains represented by the formula -(O-CF2CFR f ) a -O-CF2CFR 'f SO2F wherein R f and R' f are independently selected from F, CI, or a perfluorinated alkyl group having from 1 to 10 carbon atoms, and a = 0, 1, or 2. These polymers are converted to sulfonic acid salts or sulfonic acids, such as the polymers disclosed in U.S. Patent No. 3,282,875, U.S. Patent No. 4,358,545, or U.S. Patent No. 4,940,525.

[0039] A preferred fluorinated sulfonic fluoropolymer includes a perfluorocarbon backbone and side chains represented by the formula -0-CF2CF(CF3)-0-CF2CF2S02F. Fluorinated ionomers containing sulfonate or sulfonic acid groups of this type are disclosed in U.S. Patent No. 3,282,875 and can be prepared by copolymerization of tetrafluoroethylene (TFE) and perfluorovinyl ether CF2=CF-0-CF2CF(CF3)-0-CF2CF2S02F, perfluoro(3,6-dioxa-4-methyl-7- octenesulfonyl fluoride) (PSEPVE, also known as long side chain or LSC), followed by conversion to sulfonate groups by hydrolysis of the sulfonyl fluoride groups, and to the proton form if desired for a particular application. Another preferred fluorinated sulfonic fluoropolymer is of the type disclosed in U.S. Patent No. 4,358,545 and U.S. Patent No. 4,940,525, which has side chains -0-CF2CF2S02F. Such polymers can be made by copolymerization of TFE and perfluoro vinyl ether CF2=CF-0-CF2CF2S02F, perfluoro(3-oxa-4-pentenesulfonyl fluoride) (PFSVE, also known as short side chain or SSC), followed by hydrolysis, and conversion to the proton form if desired for a particular application.

[0040] After hydrolysis and optional conversion to the proton form, a fluorinated sulfonate or sulfonic acid polymer is formed. As used herein, a sulfonate or sulfonic acid group refers to a sulfonic acid group or a sulfonate, preferably an alkali metal salt or an 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 ), where R 1 , R 2 , R 3 , and R 4 are the same or different and are H, CH3, or C2H5. In exemplary embodiments, the fluorinated sulfonate or sulfonic acid polymer is of the type available under the trade designation Nafion® (The Chemours Company FC, LLC, Wilmington, DE). TM (The Chemours Company FC, LLC, Wilmington, DE).

[0041] For example, a fluorinated ionomer can include repeating units:

[0042] -[CF2-CF((CF2) b -(O-(CF2CFR f ) c ) a -O-(CF2CFR' f ) d SO3X)]-

[0043] 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; R f and R' f are independently selected from F, CI, 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 ), where R 1 , R 2 , R 3 , and R 4 are the same or different and are H, CH3, or C2H5. For the sake of clarity, it is noted that the segment ((CF2) b -(O-(CF2CFR f ) c ) a -O-(CF2CFR' f ) d SO3X) in the above structure is a side chain from the perfluoropolymer backbone. Branched side chains with multiple sulfonic acid groups are also contemplated.

[0044] 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 relationship of the number of carbon atoms in the polymer backbone to the number of sulfonyl fluoride groups. In some embodiments, the IXR of the fluorinated sulfonyl fluoride polymer can be related to the equivalent weight (EW) of the corresponding fluorinated sulfonate or sulfonic acid polymer by the equation EW = (50 x IXR) + MW sc -19, where MW sc is the molecular weight of the side chain of the fluorinated sulfonate or sulfonic acid polymer. In one aspect, the IXR of the fluorinated sulfonyl fluoride polymer is less than about 13.2; in another aspect, less than about 12.7; in another aspect, less than about 12.1 ; and in another aspect, less than about 11.7; or any value, range, or sub-range therebetween. In one aspect, the IXR of the fluorinated sulfonyl fluoride polymer is at least 7.1 ; in another aspect, at least 8.1 ; in another aspect, at least 9.1 ; and in another aspect, at least 10.1 ; or any value, range, or sub-range therebetween.

[0045] In some embodiments, the fluorinated sulfonic fluoride polymer and the corresponding fluorinated sulfonate or sulfonic acid polymer have an equivalent weight (EW) of less than about 1000; alternatively less than about 980; alternatively less than about 950; alternatively less than about 930, or any value, range, or sub-range therebetween. In one aspect, the corresponding fluorinated sulfonate or sulfonic acid polymer has an EW of at least about 530; alternatively at least about 580; alternatively at least about 630; alternatively at least about 680, or any value, range, or sub-range therebetween. As used herein, (EW) refers to the weight of the corresponding fluorinated sulfonic acid polymer in its protonated form required to neutralize one equivalent of NaOH.

[0046] In one aspect, the fluorinated sulfonic fluoride polymer and the corresponding fluorinated sulfonate or sulfonic acid polymer comprise long side chains and have an EW of less than about 1000; alternatively less than about 980; alternatively less than about 950; alternatively less than about 930, or any value, range, or sub-range therebetween. In one aspect, the fluorinated sulfonic fluoride polymer and the corresponding fluorinated sulfonate or sulfonic acid polymer have an EW of at least about 700; alternatively at least about 750; alternatively at least about 800; alternatively at least about 950, or any value, range, or sub-range therebetween. The IXR of a fluorinated polymer bearing side chains -OCF2-CF(CF3)-O-CF2-CF2-SO3H (i.e., a fluorinated polymer produced from a copolymer of TFE and PSEPVE) can be related to the EW using the following equation: 50 IXR + 344 = EW.

[0047] In another embodiment, the fluorinated sulfonic fluoride polymer and the corresponding fluorinated sulfonate or sulfonic acid polymer comprise short side chains and have an EW of less than about 840; alternatively less than about 810; alternatively less than about 785; alternatively less than about 765, or any value, range, or sub-range therebetween. In one aspect, the fluorinated sulfonic fluoride polymer and the corresponding fluorinated sulfonate or sulfonic acid polymer have an EW of at least about 530; alternatively at least about 580; alternatively at least about 630; alternatively at least about 680, or any value, range, or sub-range therebetween. The IXR of a fluorinated polymer bearing side chains -OCF2CF2SO3H (i.e., a fluorinated polymer produced from a copolymer of TFE and PFSVE) can be related to the equivalent weight using the following equation: 50 IXR + 178 = EW.

[0048] In the present invention, the noble metal catalyst is specifically combined with a polymer in the form of fluorinated sulfonic acid fluoride, rather than with the corresponding fluorinated sulfonate salt or fluorinated sulfonic acid. It is believed that directly blending the noble metal catalyst into the fluorinated sulfonic acid fluoride will allow the catalyst to be more uniformly distributed and more uniformly dispersed throughout the polymer, resulting in the catalyst being more uniformly distributed or more uniformly dispersed in materials made from the composition, such as fluorinated sulfonic acid fluoride films, the corresponding fluorinated sulfonate salt polymer materials, the corresponding fluorinated sulfonic acid polymer materials, and their films or membranes. In one aspect, the noble metal catalyst is uniformly dispersed throughout the composition.

[0049] The noble metal catalyst is present in the composition in an amount sufficient to provide a gas recombination effect, but insufficient to alter the conductivity (or lack of conductivity) of the non-crosslinked fluorinated sulfonic acid fluoride polymer or its corresponding fluorinated sulfonate salt polymer or fluorinated sulfonic acid polymer. In one aspect, the composition comprises from about 90% to about 99.99% by weight of one or more non-crosslinked fluorinated sulfonic acid fluoride polymers and from about 0.01% to about 10% by weight of one or more noble metal catalysts, based on the total weight of the composition. In another aspect, the composition comprises from about 92% to about 99.9% by weight of one or more non-crosslinked fluorinated sulfonic acid fluoride polymers and from about 0.1% to about 8% by weight of one or more noble metal catalysts; in another aspect, from about 95% to about 99.7% by weight of one or more non-crosslinked fluorinated sulfonic acid fluoride polymers and from about 0.3% to about 5% by weight of one or more noble metal catalysts; from about 97% to about 99.5% by weight of one or more non-crosslinked fluorinated sulfonic acid fluoride polymers and from about 0.5% to about 3% by weight of one or more noble metal catalysts; from about 98% to about 99.3% by weight of one or more non-crosslinked fluorinated sulfonic acid fluoride polymers and from about 0.7% to about 2% by weight of one or more noble metal catalysts; from about 98.5% to about 99.3% by weight of one or more non-crosslinked fluorinated sulfonic acid fluoride polymers and from about 0.7% to about 1.5% by weight of one or more noble metal catalysts; or any value, range, or sub-range therebetween; all based on the total weight of the composition.

[0050] Additional compounds can be present in the composition, but preferably, the composition comprises less than about 5% by weight of any additional compounds, based on the total weight of the composition. In another aspect, the composition comprises less than about 3% by weight of additional compounds; in another aspect, the composition comprises less than about 2% by weight of additional compounds; in another aspect, the composition comprises less than about 1% by weight of additional compounds; and in another aspect, the composition comprises less than about 0.5% of additional compounds; or any value, range, or sub-range therebetween; all based on the total weight of the composition. Suitable additional compounds include, but are not limited to, free radical scavenger compounds, coupling agents, or other resin additives.

[0051] In one aspect, the composition contains less than 5% by weight of a solvent or liquid carrier; in another aspect, less than 2% by weight of a solvent or liquid carrier; in another aspect, less than 1% by weight of a solvent or liquid carrier; in another aspect, less than 0.1% by weight of a solvent or liquid carrier; and in another aspect, 0% of a solvent or liquid carrier; or any value, range, or sub-range therebetween; all based on the total weight of the composition. In one aspect, 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.

[0052] The composition can be a solid composition and can be prepared by a method comprising:

[0053] a. melting at least one non-crosslinked fluorinated sulfonic fluoropolymer;

[0054] b. uniformly distributing at least one noble metal catalyst in the molten at least one non-crosslinked fluorinated sulfonic fluoropolymer in an amount to form a composition comprising about 90% to about 99.99% by weight of one or more non-crosslinked fluorinated sulfonic fluoropolymers and about 0.01% to about 10% by weight of one or more noble metal catalysts, based on the total weight of the composition; and

[0055] c. cooling the mixture of step b to form a solid composition.

[0056] In this method, the noble metal catalyst is combined with the non-crosslinked fluorinated sulfonic fluoropolymer in a melt. Suitable noble metal catalysts, non-crosslinked fluorinated sulfonic fluoropolymers, compositions, and component amounts are the same as those listed above. Suitable temperatures for step a and step b can be envisioned by one of skill in the art, but include temperatures above the melting point of the non-crosslinked fluorinated sulfonic fluoropolymer, where the temperature results in a polymer having a suitable level of viscosity to allow for extrusion.

[0057] The noble metal catalyst is uniformly distributed in the non-crosslinked fluorinated sulfonic fluoropolymer, and in one aspect, the noble metal catalyst is uniformly dispersed throughout the non-crosslinked fluorinated sulfonic fluoropolymer in step b. The uniformly distributing step b can be performed by any mixing method suitable for distributing or dispersing the noble metal catalyst in the resin, such as 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 mixing in a twin screw extruder, where screw elements such as kneading blocks or gear mixers can also be included. In one aspect, the method further includes the step of mixing the solid non-crosslinked fluorinated sulfonic fluorine with the solid noble metal catalyst prior to the melting step a, such that the non-crosslinked fluorinated sulfonic fluoropolymer is melted in step a in the presence of the noble metal catalyst already. However, other methods of introducing the noble metal catalyst into the composition can also be used, including but not limited to feeding the noble metal catalyst into the molten non-crosslinked fluorinated sulfonic fluoropolymer in the mixing equipment.

[0058] It is desirable that the noble metal catalyst be highly dispersed within this layer of the membrane to prevent agglomeration thereof. In one aspect, a low surface energy molten polymer resin is mixed with a high surface energy filler, operated at high temperature to reduce polymer viscosity, and high shear forces are applied. By operating under these conditions, one should obtain a well dispersed (high activity) noble metal catalyst within the cation exchange membrane layer. After step b, the average particle size D50 of the noble metal catalyst can be less than about 5 pm; in another aspect, about 75 nm; in another aspect, the average particle size D50 is less than about 50 nm; and in another aspect, the average particle size D50 is less than about 25 nm.

[0059] To form a solid composition, the mixture of step b is cooled by any suitable method of reducing temperature. For example, the mixture can simply be cooled by removal of heat, such as after being removed from a heated vessel. Active cooling methods can also be applied to speed up the solidification process. In one aspect, the method further includes the step of shaping the mixture of step b prior to cooling. For example, the mixture of step b can be extruded, pelletized, and cooled. In another aspect, the mixture of step b can be extruded, melt-cast or cast into a thin film and cooled. Without being bound by one particular theory, it is believed that the operation of cooling or quenching the polymer resin mixture after mixing is to lock the noble metal catalyst compound in place to prevent agglomeration and settling, which is a particular difficulty encountered with prior art that mixes the GRC into the PFSA dispersion, where metal catalyst particles are known to settle over time.

[0060] Another aspect of the present application 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 from about 90% to about 99.99% by weight of one or more non-crosslinked fluorinated sulfonic fluoropolymer and from about 0.01% to about 10% by weight of one or more noble metal catalyst, based on the total weight of the composition, wherein the one or more noble metal catalyst is uniformly distributed throughout the at least one proton exchange precursor layer. Suitable noble metal catalysts, non-crosslinked fluorinated sulfonic fluoropolymer, composition components, and component amounts are the same as those listed above.

[0061] The cation exchange membrane precursor can comprise at least one additional layer; in another aspect, the cation exchange membrane precursor comprises at least two additional layers, wherein the two layers are denoted by the terms additional layer and third layer; and in another aspect, the cation exchange membrane precursor comprises at least three additional layers, wherein the three layers are denoted by the terms additional layer, third layer, and fourth layer. The additional layers can comprise ion exchange resin precursors, such as but not limited to fluorinated sulfonic fluoropolymer. Such ion exchange resin precursors can be crosslinkable, crosslinked, or non-crosslinked. In one aspect, the ion exchange resin precursors fall within the IXR or EW ranges described above. The additional layers can be present in the same thin film as the original cation exchange precursor layer, or they can be one or more separate thin films that are subsequently joined to form the cation exchange membrane.

[0062] The at least one additional layer can also independently comprise additives, including radical scavengers, noble metal catalysts, other additives, or mixtures thereof. In one aspect, the radical scavengers, noble metal catalysts, and other additives are present in the additional layers in the amounts described above. The composition of the additional layers can be the same or different from the first cation exchange precursor layer, and they can also be the same or different from each other. In one aspect, the additional layers do not comprise noble metal catalysts. In one aspect, there are three additional layers, wherein two of the additional layers do not comprise noble metal catalysts; and in another aspect, there are three additional layers, wherein the overall four-layer structure has alternating layers comprising noble metal catalysts and layers not comprising noble metal catalysts.

[0063] It is believed that the GRC is most active in certain locations of the membrane, depending on the cell operation, which are closer to the anode or cathode. Therefore, in one aspect of the present application, there is a noble metal catalyst loading in certain locations of the membrane that are closest to the anode or cathode, and there is no noble metal catalyst in other locations.

[0064] In one aspect of the application, the cation exchange membrane precursor is un-reinforced. However, in another aspect of the application, a reinforcing layer is present to provide additional mechanical strength to the overall membrane precursor structure. The reinforcing layer can be any material suitable for providing such additional mechanical strength while also allowing free movement of cations through the structure. For example, the reinforcement can be a porous membrane, a woven fabric, or a porous scrim material constructed of materials including, but not limited to, polytetrafluoroethylene (PTFE), polyaryletherketone (PAEK), liquid crystal polymer, polyphenylene sulfide (PPS), PTFE-perfluoroalkylvinyl ether copolymer (PFA), glass, quartz, and polyolefins including polyethylene or polypropylene. Specific PTFE reinforcements include porous expanded PTFE (ePTFE) and braided PTFE. Examples of materials with high tensile modulus suitable as reinforcing materials include liquid crystal polymers, polyphenylene sulfide, glass, quartz, or PAEK. Specific polyaryletherketones include, but are not limited to, polyetherketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK), or polyether ketone ether ketone ketone (PEKEKK).

[0065] In one aspect, the final cation exchange membrane precursor can have an average thickness of about 25 pm to 150 pm; in another aspect, about 30 pm to 120 pm; in another aspect, about 30 pm to 100 pm; in another aspect, about 30 pm to 80 pm; and in another aspect, about 30 pm to 60 pm. Lower thicknesses can be desired for high efficiency targets, while higher thicknesses can be desired for high durability targets. It can be desirable to have specific GRC layers within the membrane where the highest concentrations of hydrogen and oxygen are present to increase the efficiency of the GRC material while minimizing the amount of GRC material required. In one aspect, the thickness of the layer within the membrane having the noble metal catalyst can be about 3 pm to about 150 pm; in another aspect, about 7 pm to about 150 pm; and in another aspect, about 17 pm to about 150 pm. When other cation exchange layers are present in the membrane, the thickness of the layer within the membrane having the noble metal catalyst can be about 3 pm to about 100 pm; in another aspect, about 7 pm to about 50 pm; and in another aspect, about 17 pm to about 25 pm.

[0066] Accordingly, the present application also relates to a cation exchange membrane comprising at least one cation exchange layer, wherein the at least one cation exchange layer comprises from 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 from about 0.01% to about 10% by weight of one or more noble metal catalysts, based on the total weight of the composition, wherein the one or more noble metal catalysts are uniformly distributed throughout the at least one cation exchange layer. In one aspect, the one or more noble metal catalysts are uniformly distributed. The cation exchange membrane is prepared by hydrolysis and optional protonation of a cation exchange membrane precursor, wherein the non-crosslinked fluorinated sulfonyl fluoride polymer as described above is converted to a non-crosslinked fluorinated sulfonate polymer or non-crosslinked fluorinated sulfonic acid polymer. Suitable noble metal catalysts, non-crosslinked fluorinated sulfonyl fluoride polymers, and their corresponding non-crosslinked fluorinated sulfonate and sulfonic acids, compositions, component amounts, and layer structures are the same as those listed above.

[0067] As described above, the cation exchange membrane can also have one or more additional layers. In this case, the one or more additional layers can comprise a cation exchange resin rather than an ion exchange precursor, including but not limited to a fluorinated sulfonate polymer or fluorinated sulfonic acid polymer. Such ion exchange resins can be crosslinkable, crosslinked, or non-crosslinked. In one aspect, the cation exchange resin falls within the IXR or EW ranges described above. The additional layers can be present in the same film as the original cation exchange layer, or they can be one or more separate films that are subsequently joined to form the cation exchange membrane. As described for the cation exchange membrane precursor, the cation exchange membrane can be unreinforced. However, in another aspect of the present application, a reinforcing layer is present to provide additional mechanical strength to the overall membrane precursor structure. The reinforcing layer can be any material suitable for providing such additional mechanical strength while also allowing the free movement of cations through the structure. Suitable reinforcing materials are described above.

[0068] The cation exchange membrane can be prepared by a method comprising the steps of:

[0069] d. melting at least one non-crosslinked fluorinated sulfonyl fluoride polymer;

[0070] e. uniformly distributing at least one noble metal catalyst with the melted at least one non-crosslinked fluorinated sulfonyl fluoride polymer in an amount to form a composition comprising from about 90% to about 99.99% by weight of one or more non-crosslinked fluorinated sulfonyl fluoride polymers and from about 0.01% to about 10% by weight of one or more noble metal catalysts, based on the total weight of the composition;

[0071] f. forming a layer of material from the composition of step e, wherein the noble metal catalyst is uniformly distributed throughout the layer; and

[0072] g. converting the non-crosslinked fluorinated sulfonyl fluoride polymer of the layer from step f into a non-crosslinked fluorinated sulfonic acid polymer or a non-crosslinked fluorinated sulfonate polymer. Also contemplated are cathode exchange membranes prepared by the above method. The cation exchange membrane precursor is produced by the above method, stopping prior to the conversion step g. The suitable noble metal catalyst, non-crosslinked fluorinated sulfonyl fluoride polymer, and their corresponding non-crosslinked fluorinated sulfonate and sulfonic acid, compositions, component amounts, and layer structure are the same as those listed above.

[0073] As described above for the solid composition method, the skilled artisan can envision suitable temperatures for step d and step e, but include temperatures above the melting point of the non-crosslinked fluorinated sulfonyl fluoride polymer, where the temperature results in a polymer with a suitable level of viscosity to allow for extrusion. The noble metal catalyst is uniformly distributed in the non-crosslinked fluorinated sulfonyl fluoride polymer, and in one aspect, the noble metal catalyst is uniformly dispersed throughout the non-crosslinked fluorinated sulfonyl fluoride polymer in step e. Uniformly distributing step e can be performed by any mixing method suitable for distributing or dispersing the noble metal catalyst in the resin, such as 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 mixing in a twin screw extruder, where screw elements such as kneading blocks or gear mixers can also be included. In one aspect, the method further includes a step of mixing the solid non-crosslinked fluorinated sulfonyl fluoride with the solid noble metal catalyst prior to the melting step d, such that the non-crosslinked fluorinated sulfonyl fluoride polymer is melted in step d with the noble metal catalyst already present. However, other methods of introducing the noble metal catalyst to the composition can also be used, including but not limited to feeding the noble metal catalyst into the molten non-crosslinked fluorinated sulfonyl fluoride polymer in the mixing device.

[0074] In one aspect, the composition of step e is cooled prior to forming the layer of material in step f. In another aspect, the method further includes a step e1 of shaping and cooling the composition of step e prior to step f. The mixture of step e is cooled by any suitable method of reducing temperature. For example, the mixture can simply be cooled by removing heat, such as after removal from a heated vessel. Active cooling methods can also be applied to speed up the solidification process. In one aspect, the method further includes a step of shaping the mixture of step e prior to cooling. For example, the mixture of step e can be extruded, pelletized, cooled, and re-melted prior to step f. In another aspect, the mixture of step e can be extruded or directly cast into a thin film and cooled.

[0075] In step f, a layer of the composition is formed, which formation can be by any suitable means, including extrusion, melt casting, pouring, or pressing a solid composition at elevated temperature. In one aspect, the composition of step e is extruded into a film during step f. The extrusion can be performed using a single screw extruder or a twin screw extruder, where screw elements such as kneading blocks or gear mixers can also be included prior to extrusion into a film shape.

[0076] The additional layer can be formed by any suitable means, including extrusion, pouring, or pressing a solid composition at elevated temperature. The additional layer can be combined with the layer from step f by any suitable method, including co-extrusion or lamination. In one aspect, the 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 performed, for example, by providing separate feedstocks for the layer of step f and the at least one additional layer, which are then joined during extrusion. In another aspect, the at least one additional layer is formed separately and pressed with the film having the layer of step f at elevated temperature.

[0077] As described above, a reinforcement layer can be used in the cation exchange membrane precursor and cation exchange membrane. When a reinforcement is used, the method includes applying the composition of step e to the reinforcement during the layer forming step f or after the layer forming step f. When the composition of step e is applied to the reinforcement during the layer forming step f, it can be extruded and melt laminated to the reinforcement by any suitable method, including but not limited to extrusion lamination. In another aspect, when the composition of step e is applied to the reinforcement after the layer forming step f, it can be laminated by any suitable method, such as but not limited to by double belt lamination, roll lamination, vacuum lamination. The extruded film can then be laminated with the woven reinforcement at elevated temperature to fuse the polymer and woven layers together to form a composite film according to typical lamination methods, such as by using a lamination roll or vacuum lamination process.

[0078] The non-crosslinked fluorinated sulfonic sulfonyl fluoride of the layer of step f can then be converted to a non-crosslinked fluorinated sulfonic acid salt or non-crosslinked fluorinated sulfonic acid in step g. Any convertible polymer from additional layers can be converted simultaneously as part of the same thin film (composite thin film). The thin film or composite thin film can be hydrolyzed in an aqueous alkali hydroxide solution and acidified by an acid such as nitric acid to convert the sulfonyl fluoride groups to sulfonic acid or sulfonic acid salt groups. The alkali hydroxide includes, but is not limited to, NaOH or KOH. During the hydrolysis step, a water soluble organic solvent such as dimethyl sulfoxide (DMSO), N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, methanol, ethanol, isopropanol, butanol, methoxyethoxyethanol, butoxyethanol, butyl carbitol, 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-l-propanol can be used in the hydrolysis solution.

[0079] In one aspect, the final reinforced ion exchange membrane can have an average thickness of about 30 pm to 150 pm; in another aspect, about 30 pm to 120 pm; in another aspect, about 30 pm to 100 pm; in another aspect, about 30 pm to 80 pm; and in another aspect, about 30 pm to 60 pm.

[0080] The cation exchange membrane can be used in a catalyst coated membrane having multiple layers of functional materials. Such catalyst coated membranes can be used in electrolysis systems, for example, water electrolysis systems. In one aspect, the present invention relates to a catalyst coated membrane comprising a cation exchange membrane, wherein the catalyst coated membrane includes a cathode catalyst layer on one side of the reinforced ion exchange membrane and an anode catalyst layer on the other side of the reinforced ion exchange membrane. The catalyst coated membrane can 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 can be in direct contact with the cation exchange membrane, and the cathode exchange membrane can be further in direct contact with the anode catalyst layer to make the catalyst coated membrane. The cation exchange membrane can include multiple layers, and it can also include a reinforcement layer. The catalyst coated membrane can contain multiple layers of the same material, and it can contain additional layers of functional materials such as gas diffusion layers, porous transport layers, or bipolar plates.

[0081] CCLs and ACLs can be applied to ion exchange membranes in the form of catalyst inks. Catalyst ink compositions generally include a catalyst component and a polymer binder, where the polymer binder generally includes a fluorinated ionomer, such as those described above. The polymer used in the CCLs and ACLs can be the same or different from the polymer of the fluorinated ionomer used as the ion exchange membrane. The catalyst component can include, but is not limited to, metal particles or carbon-supported metal particles. Specific metals can include, 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 used in ion exchange dispersions, can be used to aid in the application of the catalyst ink to the ion exchange membrane. The CCL material and ACL material can be applied to the ion exchange membrane by any suitable means, including brush coating, spray coating, notch bar coating, fluid die coating, rod coating, slot-die blade coating, three-roll coating, or decal transfer.

[0082] Examples

[0083] The following test methods and materials were used in the examples herein.

[0084] 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.

[0085] All solvents and reagents were purchased from Sigma-Aldrich, St. Louis, MO, unless otherwise noted.

[0086] HSAPB is high surface area platinum black with Pt crystallite size of 5.0 nm to 7.5 nm, Pt surface area ECSA of 50 m 2 / g, and total catalyst surface area of 50 m 2 / g; all of which were purchased from The Fuel Cell Store, College Station, TX. Platinum black TA HSTDP is a platinum black product with a BET Pt surface area of 27 m2 / g, purchased from Heraeus Precious Metals, Santa Fe Springs, CA.

[0087] Catalyst ink component IrO2 was purchased from Alpha Aesar Ward Hill, MA, and catalyst ink component Pt / C was TKK TEC10E50E, purchased from Tanaka Precious Metals, Tokyo, Japan.

[0088] TiO2supported Pt catalyst was purchased from Ishifuku Metal Industry Company, Tokyo, Japan.

[0089] Carbon supported platinum catalyst TEC10V50E has a Pt content of 46.8% by weight, a particle size of 23 A measured by XRD, and a BET Pt surface area of 106.8 m 2 / g, purchased from TKK, Tokyo, Japan.

[0090] Nafion TM D2020 is an ionomer dispersion, purchased from The Chemours Company, Wilmington, DE.

[0091] The PEEK reinforcing fabric used was IEM 17-195 / 70, a plain weave fabric with a fiber diameter of about 38 pm, a center-to-center fiber spacing of about 195 pm, and an open area of about 70%, purchased from SEFAR, Thal, Switzerland.

[0092] Test Methods

[0093] Thickness

[0094] Three thickness measurements were made with a ProGage thickness gauge, purchased from Thwing-Albert Instrument Company, West Berlin, NJ. The reported thickness represents the average of the three measurements.

[0095] Hydrogen / oxygen permeation

[0096] Catalyst-coated membranes were prepared by spraying catalyst inks onto the formed membranes, which were attached to a vacuum plate heated to 80 °C. The anode catalyst ink contained 0.4 mg / cm 2 of IrO2and Nafion TM D2020 (weight ratio of 0.84:0.16), and the cathode catalyst ink contained 0.1 mg / cm 2 of Pt / C and Nafion TM D2020 (weight ratio of 0.15:0.85).

[0097] The H2:02 ratio in the anode off-gas stream of the cell was quantified using gas chromatography (GC). At the cell outlet, the mixture contains liquid water, oxygen, hydrogen, and water vapor. N2 gas was also added to ensure the mixture remains below the flammability limit. The mixture was directed through a series of components designed to condense and remove the liquid water to protect the GC. Samples were taken continuously until the H2:02 ratio equilibrated, typically between 5 and 15 minutes.

[0098] SEM images of composite resins and films

[0099] The samples were sputter coated with osmium to help minimize charging effects in the electron microscope and then analyzed on an Auriga 60 CrossBeam SEM using backscatter mode. Cross sections of the films were prepared using a microtome.

[0100] Example 1

[0101] 6.0 kg of 920 equivalent weight sulfuryl fluoride containing fluoropolymer resin pellets (chemically stabilized PTFE / CF2=CF-O-CF2CF(CF3)-O-CF2CF2S02F copolymer with an EW of 920 g / mol, available from The Chemours Company, Wilmington, DE) were mixed into a 1 gallon polyethylene container. To these pellets, 60 g of HSAPB was added. The mixture was tumbled for 10 minutes at room temperature to coat the fluoropolymer resin pellets with platinum. The platinum coated sulfuryl fluoride containing fluoropolymer resin pellets were then fed into a 1" diameter twin screw extruder using a loss weight feeder at a polymer feed rate of 2.27 kg / hour and a screw speed of 150 RPM. The twin screw extruder contained a kneading block screw element to help distribute mixing of the platinum within the fluoropolymer melt. The temperature profile was ramped from 190 °C in the feed throat to 230 °C at the discharge end. The pellets were line chopped to produce black pellets containing 1 wt% platinum.

[0102] Example 2

[0103] A multi-layer film was prepared using a co-extrusion system. Non-platinized sulfonlimide fluoropolymer resin (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) pellets were fed to a first extruder with a 1.5" single screw. A satellite extruder with a 1" single screw was fed fluoropolymer resin pellets containing platinized sulfonlimide from Example 1. The feed block combined the streams from the two extruders into discrete layers and was fed through a die to produce a final film with discrete layers of platinized sulfonlimide resin and virgin non-platinized sulfonlimide fluoropolymer resin. The extruders were run at 275 °C and melt cast from a 10 mil die and stretched in the machine direction to a 2 mil final thickness. The film was hydrolyzed in a solution of DMSO / KOH / water as taught in the art. The film was then acidified in a 20% aqueous nitric acid solution and dried to remove excess water.

[0104] Example 3

[0105] A pre-hydrolyzed film of Example 2 was melt laminated with a PEEK reinforcing fabric to form a composite film. The laminated film was hydrolyzed in a solution of DMSO / KOH / water as taught in the art. The PEEK reinforcing fabric used was a plain weave fabric with a fiber diameter of about 38 μιη, a center-to-center fiber spacing of about 195 μιη, and an open area of about 70%. The film was then acidified in a 20% aqueous nitric acid solution and dried to remove excess water.

[0106] Example 4

[0107] Example 1 was repeated except that a screw speed of 300 RPM was used.

[0108] Example 5

[0109] A co-extrusion system was employed in which fluoropolymer resin pellets containing non-platinized sulfonyl fluoride (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 to a first extruder with a 2.5" single screw. Fluoropolymer resin pellets containing platinized sulfonyl fluoride from Example 4 were fed to a satellite extruder with a 1.5" single screw. The feed block combined the streams from the two extruders into discrete layers and was fed through a die to produce a final film with discrete layers of platinized sulfonyl fluoride resin and virgin non-platinized sulfonyl fluoride fluoropolymer resin. The extruders were run at 270 °C and melt cast from a 33 mil die and drawn in the machine direction to a 2.3 mil final thickness. The film was hydrolyzed in a solution of DMSO / KOH / water as taught in the art. The film was then acidified in a 20% aqueous nitric acid solution and dried to remove excess water.

[0110] Example 6

[0111] Example 3 was repeated using the pre-hydrolyzed film of Example 5 and the resulting film was tested for H2:O2 permeation.

[0112] Table 1. H2:02 permeation performance (%) for Example 6

[0113]

[0114] As can be seen in Table 1, the inventive samples maintained low permeation values for many hours, indicating good initial performance and performance durability.

[0115] Example 7

[0116] A 1-gallon polyethylene container was filled with 4.5 kg of 920 equivalent weight sulfuryl fluoride containing fluoropolymer resin pellets (non-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). The HSAPB (90 g) was added to the container. The mixture was tumbled for 10 minutes at room temperature to coat the fluoropolymer resin pellets with platinum. The platinum-coated sulfuryl 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 contained a kneading block screw element to aid in the distributive mixing of the platinum within the fluoropolymer melt. The temperature profile was ramped from 160 °C in the feed throat to 190 °C at the discharge end. The pellets were line-cut to produce black pellets containing 2 wt% platinum.

[0117] Example 8

[0118] Example 5 was repeated except that the fluoropolymer resin pellets of Example 7 were used in place of the resin pellets of Example 4.

[0119] Example 9

[0120] Example 3 was repeated using the pre-hydrolyzed film of Example 8. The resulting film was tested for H2:O2 permeation.

[0121] Example 10

[0122] Example 7 was repeated except that 45 g of TiO2-supported Pt was used, resulting in pellets containing 1 wt% Pt / TiO2.

[0123] Example 11

[0124] Example 5 was repeated except that the fluoropolymer resin pellets of Example 10 were used in place of the resin pellets of Example 4.

[0125] Example 12

[0126] Example 3 was repeated using the pre-hydrolyzed film of Example 11.

[0127] Example 13

[0128] A 1-gallon polyethylene container was filled with 5 kg of 920 equivalent weight sulfuryl 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). Platinum black TA HSTDP (72.5 g) was added to the container. The mixture was tumbled for 10 minutes at room temperature to coat the fluoropolymer resin pellets with platinum. The platinum-coated sulfuryl 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 contained a kneading block screw element to aid in the distributive mixing of the platinum within the fluoropolymer melt. The temperature profile was ramped from 160 °C in the feed throat to 190 °C at the discharge end. The pellets were line-cut to produce black pellets containing 1.45 wt% platinum.

[0129] Example 14

[0130] Example 5 was repeated except that the fluoropolymer resin pellets of Example 13 were used in place of the resin pellets of Example 4.

[0131] Example 15

[0132] Example 3 was repeated using the pre-hydrolyzed film of Example 14. The resulting film was tested for H2:O2 permeation.

[0133] Example 16

[0134] Example 13 was repeated except that 130.5 g of carbon-supported Pt catalyst TEC10V50E was used in place of platinum black 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 produce pellets containing 1.45 wt% catalyst.

[0135] Example 17

[0136] Example 5 was repeated except that the fluoropolymer resin pellets of Example 16 were used in place of the resin pellets of Example 4. The resulting film was tested for H2:O2 permeation.

[0137] Example 18

[0138] Example 3 was repeated using the prehydrolyzed film of Example 17.

[0139] Example 19

[0140] Example 13 was repeated except that 250 g of platinum black TA HSTDP was used with 9 kg of polymer (chemically stabilized PTFE / CF2=CF-O-CF2CF(CF3)-O-CF2CF2SO2F copolymer having an EW of 920 g / mol, available from The Chemours Company, Wilmington, DE) to give pellets containing 2.77 wt% platinum.

[0141] Example 20

[0142] Example 5 was repeated except that the fluoropolymer resin pellets of Example 19 were used in place of the resin pellets of Example 4.

[0143] Example 21

[0144] Example 3 was repeated using the prehydrolyzed film of Example 19.

[0145] Example 22

[0146] A composition was prepared by dry blending 60 grams of sulfuryl fluoride fluoropolymer resin pellets (non-chemically stabilized PTFE / CF2=CF-O-CF2CF(CF3)-O-CF2CF2SO2F copolymer having 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 Rheometer Services Inc. System 10 batch mixer equipped with a 60 cc volume mixing bowl containing a roller blade. These blends were mixed at 75 rpm for 10 minutes at a temperature well above the melting point and / or Tg of the polymer of interest to disperse all components. In this case, the temperature was 180 °C. The mixture was then removed from the mixer and subsequently cut into pellets with 1% platinum. g

[0147] Example 23

[0148] ​Two separate 1 gallon polyethylene containers were each charged with 1.5 kg of sulfonyl fluoride containing 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. The mixture was tumbled for 10 minutes at room temperature 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 6.08 kg / hour and a screw speed of 100 RPM. The twin-screw extruder contained a kneading block screw element to aid in the distributive mixing of the platinum within the fluoropolymer melt. The temperature profile was ramped from 160 °C in the feed throat to 190 °C at the discharge end. The pellets were line-cut to produce black pellets containing 3.6 wt% platinum.

[0149] Comparative Example A

[0150] A comparative example was prepared with two fluorine-containing ionomer dispersions (hydrolyzed, 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), one containing HSAPB and the other not containing platinum. A film was prepared with a total thickness of 50 pm with a 12 pm layer of platinum. The draw down knife was set at the gap to produce a dry film thickness of 12 pm and the platinum-coated dispersion solution was cast onto the substrate. The cast film and substrate were dried in a 10% RH relative humidity oven for 30 minutes. A second layer of solution was cast onto the film by the draw down knife with the non-platinum-coated dispersion with a dry film thickness of 38 pm. The sample was dried in a 10% RH relative humidity chamber for 30 minutes and then introduced into an oven set at 175 °C for 3 minutes to cure the film, resulting in a Pt content of 20 pg / cm2of film. The film was then removed from the oven and allowed to cool to room temperature. 2 The platinum-containing solid layer had 1% platinum by weight.

[0151] Comparative Example B

[0152] Example 17 was repeated using only a single layer of non-platinum-coated resin pellets, but a film of the same total thickness was formed.

[0153] Table 2. H2:02 permeation performance (%) at 0 hours

[0154]

[0155] As can be seen in Table 2, the samples show low permeation values compared to the sample that does not contain a platinum content, indicating good initial performance.

[0156] Figures 1 to 7 A film with two different layers is exemplified, one layer containing GRC noble metal catalyst and the other layer containing no additives. From Figures 1 to 7 As can be seen, the method of the present invention provides for different GRC layers with noble metal catalysts uniformly distributed and dispersed throughout the material. This allows for co-extrusion with different material layers to form a film material with noble metal catalysts uniformly distributed at desired locations, while also minimizing the amount of noble metal catalysts required throughout the film. By purposefully placing noble metal catalysts at desired locations, the film can be configured to minimize hydrogen and oxygen permeation for a variety of end-use applications. In contrast, Figure 7 A film with two layers is shown formed by a casting process, where the noble metal catalyst is not uniformly distributed throughout the bottom cast GRC layer. Rather, the noble metal catalyst agglomerates and concentrates on one side of the GRC cast layer, such that it is in contact with the non-GRC layer. Thus, the stratification of noble metal catalyst within the film cannot be tailored and configured, and the effects that can be accomplished using the method of the present invention cannot be achieved.

Claims

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

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

3. The composition according to claim 1, wherein the one or more noble metal catalysts are unsupported.

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

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

6. The composition according to claims 1 to 5, wherein the one or more noble 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 fluoropolymers.

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, wherein, based on the total weight of the composition, the composition comprises, by weight, about 92% to about 99.9% of one or more non-crosslinked fluorinated sulfonyl fluoropolymers and by weight, about 0.1% to about 8% of one or more noble metal catalysts.

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

11. A method for preparing a solid composition, the method comprising: a. Melting at least one non-crosslinked fluorinated sulfonyl fluoropolymer; b. At least one noble metal catalyst is uniformly distributed in an amount to form a composition in at least one non-crosslinked fluorinated sulfonyl fluoropolymer, wherein, based on the total weight of the composition, the composition comprises about 90% to about 99.99% by weight of one or more non-crosslinked fluorinated sulfonyl fluoropolymer and about 0.01% to about 10% by weight of one or more noble metal catalysts. c. Cool 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 unsupported.

13. The method according to claim 11, wherein the one or more noble metal catalysts are on support particles.

14. The composition of claim 13, wherein the carrier particles are carbon, inorganic oxide particles, or mixtures thereof.

15. The method according to claims 11 to 14, wherein the one or more noble 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 during step b, the one or more noble metal catalysts are uniformly dispersed throughout the one or more non-crosslinked fluorinated sulfonyl fluoropolymers.

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, which involves extruding the composition of step b prior to step c.

19. A method for preparing a cation exchange membrane, the method comprising: d. Melt at least one non-crosslinked fluorinated sulfonyl fluoropolymer; e. A noble metal catalyst is uniformly distributed with at least one molten non-crosslinked fluorinated sulfonyl fluoropolymer in an amount equal to that used to form a composition, wherein, based on the total weight of the composition, the composition comprises about 90% to about 99.99% by weight of one or more non-crosslinked fluorinated sulfonyl fluoropolymers and about 0.01% to about 10% by weight of one or more noble metal catalysts. f. Forming a material layer from the composition of step e, wherein the noble metal catalyst is uniformly distributed throughout the layer; and g. Convert the non-crosslinked fluorinated sulfonyl fluoropolymer from the layer of step f into a non-crosslinked fluorinated sulfonic acid polymer or a non-crosslinked fluorinated sulfonate polymer.

20. The method of claim 19, wherein the one or more noble metal catalysts are unsupported.

21. The method according to claim 19, wherein the one or more noble metal catalysts are on support 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 during step e, the one or more noble metal catalysts are uniformly dispersed throughout the one or more non-crosslinked fluorinated sulfonyl fluoropolymers.

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 of claim 26, wherein the at least one additional layer comprises an ion exchange resin.

28. The method of 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 noble metal catalysts.

30. The method according to claims 26 to 28, wherein the at least one additional layer does not contain a noble 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 of 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 attached by pressing the layers together at an elevated temperature.

35. The method according to claims 19 to 34, further comprising step e1 of shaping and cooling the composition of step e prior to 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 layer formation step f.

37. The method according to claims 19 to 35, wherein the cation exchange membrane is unreinforced.

38. A cation exchange membrane, said cation exchange membrane being prepared by the method according to any one of claims 19 to 37.

39. A cation exchange membrane, said cation exchange membrane comprising at least one cation exchange layer, Based on the total weight of the composition, the at least one cation exchange layer comprises, by weight, about 90% to about 99.99% of one or more non-crosslinked fluorinated sulfonate polymers or non-crosslinked fluorinated sulfonate polymers and by weight, about 0.01% to about 10% 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.

40. The cation exchange membrane according to claim 39, wherein the one or more noble metal catalysts are unsupported.

41. The cation exchange membrane according to claim 39, wherein the one or more noble metal catalysts are on the support particles.

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

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

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

45. The cation exchange membrane of 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 noble metal catalysts.

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

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

50. The cation exchange membrane of claim 49 further comprises a fourth layer, wherein the fourth layer comprises an ion exchange resin.

51. The cation exchange membrane according to claims 49 to 50, wherein at least one of the third layers of the fourth layer comprises 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, wherein the cation exchange membrane further comprises a reinforcing material.

54. The cation exchange membrane according to claims 39 to 52, wherein the cation exchange membrane is unreinforced.

55. A cation exchange membrane precursor, said cation exchange membrane precursor comprising at least one cation exchange precursor layer, Based on the total weight of the composition, the at least one cation exchange precursor layer comprises about 90% to about 99.99% by weight of one or more non-crosslinked fluorinated sulfonyl fluoropolymers 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.

56. The cation exchange membrane precursor according to claim 55, wherein the one or more noble metal catalysts are unsupported.

57. The cation exchange membrane precursor according to claim 55, wherein the one or more noble metal catalysts are on support particles.

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

59. The 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, wherein the cation exchange membrane precursor further comprises at least one additional layer.

61. The cation exchange membrane precursor of 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, wherein the third layer comprises an ion exchange resin precursor.

66. The cation exchange membrane of claim 65 further comprises a fourth layer, wherein the fourth layer comprises an ion exchange resin precursor.

67. The cation exchange membrane according to claims 65 to 66, wherein at least one of the third layers of the fourth layer comprises 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. The cation exchange membrane according to claims 55 to 68 further comprises a reinforcing material.

70. The cation exchange membrane according to claims 55 to 68, wherein the cation exchange membrane is unreinforced.

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