Alkaline water electrolysis membrane

Abstract

A membrane suitable for alkaline water electrolysis is disclosed, along with an alkaline water electrolysis device containing the membrane. A method for producing hydrogen and a method for manufacturing a membrane for alkaline water electrolysis are also disclosed.

Description

[Technical Field]

[0001] REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 411209, filed September 29, 2022, and European Patent Application Publication No. 22209371.8, filed November 24, 2022, the entire contents of each of which are incorporated herein by reference for all purposes.

[0002] The present invention relates to a membrane suitable for alkaline water electrolysis, an alkaline water electrolysis device, a method for producing hydrogen, and a method for manufacturing a membrane for alkaline water electrolysis. [Background technology]

[0003] Hydrogen is used in a wide variety of industrial applications, such as petroleum refining, chemical synthesis, metal refining, and stationary fuel cells. Today, the use of hydrogen is expected to expand in hydrogen stations for fuel cell vehicles (FCVs), smart communities, and hydrogen power plants. In light of this, attention is being focused on technologies for producing high-purity hydrogen.

[0004] One industrial method for producing hydrogen is the water electrolysis process, which has the advantage that it can be combined with means for generating energy using renewable resources such as wind and solar power, which are necessary to maintain a balance between supply and demand on the power grid.

[0005] In a typical water electrolysis process, an aqueous solution containing an electrolyte such as sodium hydroxide or potassium hydroxide is used as the electrolyte solution to obtain increased conductivity. A direct current is applied to the electrolyte solution using a cathode and an anode to induce the water electrolysis process.

[0006] The electrolyzer used in the electrolysis process (hereinafter simply referred to as "electrolysis") is divided into an anode compartment and a cathode compartment by a membrane. Oxygen gas is produced in the anode compartment, while hydrogen gas is produced in the cathode compartment. The membrane is required to be gas impermeable to prevent mixing of the oxygen and hydrogen gases, while at the same time having high ion permeability to allow ions to flow within the cell generating electricity. Therefore, a membrane with a porous structure and high ion permeability is required.

[0007] WO 93 / 15529A1 discloses a diaphragm for alkaline water electrolysis, which is a porous membrane formed by incorporating zirconium oxide or magnesium oxide into polysulfone, an aromatic polymer resin, and performing a non-solvent-induced phase separation process. It was observed that as electrolysis continued, inorganic particles tended to detach from the pores, resulting in a decrease in the number of inorganic particles on the surface of the porous membrane. Over the long term, this caused air bubbles to adhere to the surface of the porous membrane, impeding ion permeation and thereby reducing membrane performance.

[0008] Existing technical solutions still leave room for improvement. For example, when a diaphragm in the form of a porous membrane is sandwiched between electrodes (anode and cathode), hydrogen and oxygen generated from the electrodes adhere to the surface of the porous membrane in the form of bubbles, closing the pores on the surface of the porous membrane. This causes an increase in voltage loss through the diaphragm during electrolysis, as ions cannot pass through the pores closed by the bubbles. This problem of increased voltage loss is particularly significant when the surface of the porous membrane is hydrophobic, as bubbles easily adhere to the surface.

[0009] Therefore, there remains a need to provide a membrane for alkaline water electrolysis that is free from a decrease in ion permeability due to bubble adhesion and a decrease in properties due to loss of hydrophilic inorganic particles. Summary of the Invention

[0010] Faced with the problem of providing a membrane suitable for use in alkaline electrolysis that does not have the above-mentioned drawbacks and can be produced in the form of a flat sheet, the applicant has found that the above-mentioned problem can be solved by a membrane comprising at least one poly(aryl ether ketone), said membrane being endowed with a contact angle of at least 155° measured according to the trapped bubble contact angle test and / or characterized by a static contact angle that decreases over time. The membrane is porous. The membrane comprises at least one surface comprising a functionalized poly(aryl ether ketone) polymer having hydroxyl groups attached to aromatic rings of the poly(aryl ether ketone) chains.

[0011] Poly(aryl ether ketone) is a class of semi-crystalline engineering thermoplastics with excellent thermal properties and chemical resistance. Poly(aryl ether ketone) polymers are virtually insoluble in all common solvents at room temperature. These properties make poly(aryl ether ketone) an attractive material for the preparation of porous membranes. DETAILED DESCRIPTION OF THE INVENTION

[0012] In this application: - any description, even if made in relation to a particular embodiment, is applicable to and interchangeable with other embodiments of the present disclosure; - When an element or component is said to be included in and / or selected from a list of enumerated elements or components, in relevant embodiments expressly contemplated in this application, the element or component can also be any one of the individually enumerated elements or components, or can be selected from a group consisting of any two or more of the explicitly enumerated elements or components; it is to be understood that any element or component enumerated in a list of elements or components can be omitted from such list; - Any recitation herein of numerical ranges by endpoints includes all numbers subsumed within the recited range, as well as the endpoints of the range and equivalents thereof.

[0013] A first object of the present invention is a membrane as defined in the appended claims, which membrane has a contact angle of at least 155° measured according to the trapped bubble contact angle test.

[0014] The trapped air bubble (CAB) contact angle test provides a measure of the hydrophilicity of a film. It can be measured by a contact angle goniometer, as described in detail in the experimental section. High hydrophilicity is associated with high contact angles. Herein, a fully wettable surface has a trapped air bubble contact angle test contact angle of 180°.

[0015] Without being bound by theory, it is believed that increasing the hydrophilicity of the membrane, particularly the surface of the membrane, may reduce the tendency of gases such as hydrogen and oxygen to adhere to the surface of the membrane and close the pores of the membrane, preventing the passage of ions during electrolysis.

[0016] The membranes of the present invention are characterized by a contact angle of at least 155°, or even at least 157°, as measured according to the trapped bubble contact angle test. The trapped bubble contact angle test involves immersing the membrane in deionized water at room temperature, dispensing a 2 pL bubble onto the membrane's surface using a J-type syringe, and measuring the contact angle between the bubble and the membrane's surface using an optical tensiometer equipped with a high-quality monochromatic low-temperature LED light and a high-resolution digital camera. The bubble is dispensed onto the surface of a membrane comprising a functionalized poly(aryl ether ketone) polymer.

[0017] Alternatively or additionally, the films of the present invention are characterized by a static contact angle that decreases over time, as measured according to ASTM D 5725-99.

[0018] The membranes of the present invention are characterized by a static contact angle, measured after 60 seconds, that is at least 15° lower than the initial value. In particularly advantageous embodiments, the static contact angle is at least 10° lower after 10 seconds, and even 20° lower after 10 seconds. The expression "initial value" refers to the value of the static contact angle determined at the initial time when a water droplet is placed on the surface of the membrane.

[0019] Determination of the change in static contact angle over time is performed by measuring the static contact angle according to ASTM D 5725-99 at an initial time, waiting a time interval and making a new measurement of the contact angle on the same sample under the same experimental conditions.

[0020] The trapped bubble contact angle and static contact angle are conveniently measured on at least one surface comprising a functionalized poly(aryl ether ketone) polymer.

[0021] The membrane comprises at least one poly(aryl ether ketone) polymer.

[0022] The expression "poly(aryl ether ketone) polymer" refers to a polymer having repeating units (R 1 ) with Ar-C(=O)-Ar' groups, where Ar and Ar' are equal or different and are aromatic groups, preferably phenyl groups. PAEK ) is used herein to refer to any polymer that contains at least 50 mole %.

[0023] The poly(aryl ether ketone) polymer may comprise at least 60 mol%, at least 80 mol%, at least 90 mol%, at least 95 mol%, or at least 98 mol% of repeat units (R PAEK ) has a repeating unit (R PAEK ) is selected from the group consisting of formulas (JA) to (JO) shown herein below: [ka] [ka] [ka] (In the formula, each R' is equal to or different from one another and is selected from the group consisting of halogen, alkyl, alkenyl, alkynyl, aryl, ether, thioether, carboxylic acid, ester, amide, imide, alkali or alkaline earth metal sulfonate, alkyl sulfonate, alkali or alkaline earth metal phosphonate, alkyl phosphonate, amine and quaternary ammonium; - j' is zero or an integer from 1 to 4).

[0024] Repeating unit (R PAEK Each phenylene moiety in R' can independently have a 1,2-, 1,4-, or 1,3-linkage to another moiety in the repeat unit that is different from R'. The phenylene moieties can have a 1,3- or 1,4-linkage. Typically, the phenylene moieties have a 1,4-linkage.

[0025] Additionally, in some embodiments, the repeating unit (R PAEK In some such embodiments, j' in the repeat unit (R PAEK ) can be represented by a formula selected from the group consisting of the following formulas (J'-A) to (J'-O): [ka] [ka]

[0026] The poly(aryl ether ketone) polymer may be a homopolymer, a random, alternating, or block copolymer. When the poly(aryl ether ketone) polymer is a copolymer, it comprises repeat units (R PAEK ), or (ii) one or more repeating units (RPAEK ) and repeating units (R PAEK ) and a repeating unit (R * PAEK ) may be contained.

[0027] Repeating unit (R PAEK ) is advantageously selected from the group consisting of units of formula (JA) to (JD) and (J''-B). [ka]

[0028] The membrane comprises at least one surface comprising a functionalized poly(aryl ether ketone) polymer. In the remainder of this specification, the expression "functionalized poly(aryl ether ketone) polymer" is used to refer to a poly(aryl ether ketone) polymer that includes hydroxyl groups attached to aromatic rings in the poly(aryl ether ketone) polymer backbone. Preferably, the hydroxyl groups are attached directly to carbon atoms in the aromatic rings.

[0029] The functionalized poly(aryl ether ketone) polymer has the following formulae (KA)-(KD): [ka] wherein each Q′ is —OH and each independently i is zero or an integer from 1 to 4, with the proviso that in a given repeat unit, the sum of all i's is different from zero. PAEK-OH ) is included.

[0030] The functionalized poly(aryl ether ketone) polymer comprises repeating units (R ) selected from the group consisting of units of formulae (J'-A) to (J'-D) and (J''-B) defined above. PAEK ) may further include.

[0031] Repeating unit (R PAEK-OH ), the phenylene moieties are independently selected from the repeating units (R PAEK-OH) may have 1,2-, 1,4- or 1,3-linkages to other moieties different from Q'.

[0032] The functionalized poly(aryl ether ketone) polymer comprises at least 50 mole percent repeat units (R aryl ether ketone) based on the total number of repeat units in the functionalized poly(aryl ether ketone) polymer. PAEK-OH ) and repeating units (R PAEK The functionalized poly(aryl ether ketone) polymer typically comprises at least 60 mol%, at least 65 mol%, at least 70 mol%, at least 75 mol%, at least 80 mol%, at least 85 mol%, at least 90 mol%, at least 95 mol%, or at least 99.9 mol% of repeat units (R ) based on the number of repeat units in the functionalized poly(aryl ether ketone) polymer. PAEK-OH ) and repeating units (R PAEK ) total amount.

[0033] In some cases, the functionalized poly(aryl ether ketone) polymer contains 0.001 mol % or more, even 0.005 mol % or more, and in some cases 0.01 mol % or more of repeat units (R ) relative to the number of repeat units in the functionalized poly(aryl ether ketone) polymer. PAEK-OH ).

[0034] Advantageously, the functionalized poly(aryl ether ketone) polymer is selected from the group comprising, preferably consisting of, functionalized poly(ether ether ketone) (f-PEEK) and functionalized copolymers of PEEK and poly(diphenyl ether ketone) (f-PEEK-PEDEK copolymers), and blends thereof.

[0035] The expression "functionalized poly(ether ether ketone) (f-PEEK)" refers to any polymer containing repeating units of the formulae (KA) and (J'-A) above. Preferably, the phenylene moieties in the repeating units (KA) and (J'-A) have 1,4-bonds.

[0036] Preferably, at least 60 mol%, 70 mol%, 80 mol%, 90 mol%, 95 mol%, 99 mol%, and most preferably all of the repeating units are a combination of repeating units (KA) and (J'-A). The amount of repeating units (KA) is different from zero.

[0037] The expression functionalized copolymer of PEEK and poly(diphenyl ether ketone), f-PEEK-PEDEK copolymer, refers to any polymer comprising repeating units of formula (KA) and / or (J′-A) (PEEK repeating units) and repeating units of formula (KD) and / or (J′-D) (poly(diphenyl ether ketone) (PEDEK) repeating units): [ka] (wherein R', j', Q' and i are as defined above.) Preferably, the phenylene moieties in the repeating units (KA), (J'-A), (KD) and (J'-D) have 1,4-bonds.

[0038] The f-PEEK-PEDEK copolymer may comprise PEEK repeat units and PEDEK repeat units in a relative molar ratio ranging from 95 / 5 to 60 / 40. Preferably, the sum of repeat units (KA), (J'-A), (KD) and (J'-D) represents at least 60 mol%, 70 mol%, 80 mol%, 90 mol%, 95 mol%, 99 mol% of the repeat units in the functionalized poly(aryl ether ketone) polymer, provided that the amount of repeat units (KA) + (KD) is different from zero.

[0039] Most preferably, the functionalized poly(aryl ether ketone) polymer is f-PEEK or f-PEEK-PEDEK, or a blend of f-PEEK and f-PEEK-PEDEK as defined above.

[0040] The membranes of the present invention comprise at least one surface comprising at least one functionalized poly(aryl ether ketone) polymer comprising hydroxyl groups attached to aromatic rings of the poly(aryl ether ketone) polymer backbone. The remainder of the membrane can comprise a poly(aryl ether ketone) polymer having the same or a different backbone of the functionalized poly(aryl ether ketone) polymer.

[0041] The membranes of the present invention may have both surfaces comprising at least one functionalized poly(aryl ether ketone) polymer as defined above.

[0042] The membrane of the present invention may have the same composition throughout its thickness, said composition comprising at least one functionalized poly(aryl ether ketone) polymer as defined above.

[0043] The term "membrane" is intended to denote a discrete, generally thin interface that regulates the permeation of chemical species in contact with it, said membrane comprising pores of finite dimensions. The membranes of the present invention are porous membranes.

[0044] Membranes containing pores uniformly distributed throughout their thickness are commonly known as symmetric (or isotropic) membranes. Membranes containing pores non-uniformly distributed throughout their thickness are commonly known as asymmetric (or anisotropic) membranes.

[0045] The membranes of the present invention can be either symmetric or asymmetric. Asymmetric membranes can include a thin selective layer (0.1-1.0 μm thick) and a thick, highly porous layer (100-200 μm thick) that acts as a support and has little effect on the separation properties of the membrane.

[0046] The membrane of the present invention has an average pore size of 50 nm to 200 nm, typically 60 to 150 nm.

[0047] The membrane has a bubble point (i.e., a measurement of the largest pore) of 100 nm to 400 nm, typically 150 nm to 300 nm. The membrane has a minimum pore size of 40 nm to 120 nm, typically 50 to 100 nm.

[0048] Pore ​​size and bubble point can be measured according to ASTM F316.

[0049] Suitable techniques for measuring the average pore size in the porous membranes of the present invention are described, for example, in Handbook of Industrial Membrane Technology, Edited by PORTER, Mark C. Noyes Publications, 1990, pp. 70-78. The pore size of the membrane can be estimated by several techniques, such as scanning electron microscopy (SEM) and / or measurement of bubble point, gas flux, water flux, and molecular weight cutoff.

[0050] The membranes of the present invention can be either free-standing porous membranes consisting of one porous layer, or multi-layer membranes, preferably comprising at least one porous layer supported on a substrate, which is preferably made from a material that minimally affects the selectivity of the porous membrane.

[0051] The membrane of the present invention preferably has a structure in which the porous polymer membrane surrounds the porous substrate, and more preferably has a structure in which the porous polymer membrane is laminated on both sides of the porous substrate. The inclusion of the substrate can increase the strength of the membrane. For example, defects such as cuts, tears, and stretching of the membrane caused by mechanical stress can be prevented.

[0052] The substrate material is preferably, but not limited to, a material that does not substantially reduce the membrane's permeability to ions in the electrolyte solution. Examples of porous substrate materials include, but are not limited to, poly(phenylene sulfide), polyethylene, polypropylene, poly(vinylidene fluoride), polytetrafluoroethylene, polyparaphenylene benzobisoxazole, poly(ether ketone), polyimide, and polyetherimide. Among these, polyphenylene sulfide is preferred. By using poly(phenylene sulfide), the porous substrate can exhibit high resistance to high-temperature, high-concentration alkaline solutions and high chemical stability against active oxygen generated from the anode during the water electrolysis process. Furthermore, by using poly(phenylene sulfide), the porous substrate can be easily processed into various forms, such as woven and nonwoven fabrics, and can therefore be appropriately modified depending on the intended application or intended use environment. The above-mentioned materials can be used alone or in combination of two or more thereof.

[0053] Examples of porous substrates include, but are not limited to, mesh, porous membrane, nonwoven fabric, and woven fabric. These may be used alone or in combination of two or more thereof. A more preferred example of a porous substrate is a mesh substrate made from a poly(phenylene sulfide) monofilament and a composite fabric including a nonwoven fabric and a woven fabric enclosed in the nonwoven fabric.

[0054] Depending on its ultimate intended use, the membrane of the present invention may be flat or tubular in shape.

[0055] Flat membranes are generally preferred for use in electrolytic cells.

[0056] Nevertheless, the scope of the present invention is not limited to flat membranes but also encompasses tubular and hollow fiber membranes, which are particularly advantageous in applications where compact modules with large surface areas are required.

[0057] When the membrane is flat, its thickness is advantageously between 10 and 800 microns, even between 25 and 600 microns, preferably between 200 and 500 microns.

[0058] If the membrane is tubular, its outer diameter can be up to 15.0 mm. If the outer diameter of the membrane is between 0.5 mm and 3.0 mm, it is called a hollow fiber membrane. If the membrane has a diameter less than 0.5 mm, it is called a capillary membrane.

[0059] In certain embodiments, the membrane may comprise a composition comprising at least one poly(aryl ether ketone) polymer and / or at least one functionalized poly(aryl ether ketone) polymer and a radical scavenger, preferably selected from the group of inorganic scavengers, in particular from the group consisting of cerium salts and oxides.

[0060] Method for producing a membrane The membranes of the present invention can be prepared from poly(aryl ether ketone) polymers as defined above.

[0061] In certain embodiments, it can be prepared starting from a functionalized poly(aryl ether ketone) polymer as defined above, i.e., a poly(aryl ether ketone) polymer comprising hydroxyl groups attached to aromatic rings of the poly(aryl ether ketone) polymer backbone.

[0062] In such embodiments, the functionalized poly(aryl ether ketone) polymer can provide only one surface layer of the membrane, both surface layers, or it can be used to fabricate the entire membrane. The functionalized poly(aryl ether ketone) polymer can be used alone or in a composition with another polymer, typically a polymer selected from the group of poly(aryl ether ketone) polymers detailed above.

[0063] Alternatively, in a preferred embodiment, the film is obtained by chemically treating a film (hereinafter "precursor film") that comprises a poly(aryl ether ketone) polymer and has a contact angle of less than 155° measured according to a trapped bubble contact angle test and / or a static contact angle that does not decrease over time. The precursor film has at least one surface made of a poly(aryl ether ketone) polymer. The step of chemically treating the precursor film provides the film with at least one surface that includes hydroxyl groups attached to aromatic rings of the poly(aryl ether ketone) polymer backbone. In other words, the step of chemically treating the precursor film provides the film with at least one surface that includes a functionalized poly(aryl ether ketone) polymer as defined above. The hydroxyl groups are generally directly attached to carbon atoms of the aromatic rings.

[0064] In a first step, the method includes providing a precursor film that includes a poly(aryl ether ketone) polymer and has a contact angle of less than 155° measured according to a trapped bubble contact angle test and / or a static contact angle that does not decrease over time.

[0065] The precursor membrane may be prepared according to any method known in the art for preparing porous membranes comprising poly(aryl ether ketone) polymers.

[0066] Suitable methods for preparing porous membranes by processing poly(aryl ether ketone) polymers are described, for example, in U.S. Pat. Nos. 4,957,817, 5,200,078, 5,205,968, and 4,755,540.

[0067] More advantageously, the precursor film can be prepared according to any method described in WO2018065526A1, WO2021018868A1 or WO2022096373A1.

[0068] In a first embodiment, the precursor film comprises: (i) a poly(aryl ether ketone) polymer and at least 28 wt. %, based on the total weight of the polymer composition, of at least one additive having Formula (I): R a -Ar-X b (I) wherein Ar is selected from the group consisting of substituted or unsubstituted monocyclic or polycyclic aromatic groups having 5 to 18 carbon atoms, and each of R, which may be the same or different from each other, is selected from the group consisting of halogen, hydroxyl, a C1-C18 aliphatic groups, a C1-C18 alicyclic groups, and a C1-C18 aromatic groups; a is 0 or an integer ranging from 1 to 5; and X is (SO3 - ), (M p+ ) 1 / p or (COO - ), (M p+ ) 1 / p where M p+ is a p-valent metal cation; and b is an integer from 1 to 4, (ii) immersing the solid article in water to obtain a porous article; It is prepared according to a method comprising:

[0069] The additive of formula (I) is preferably selected from alkali metal benzoates, methyl benzoate, ethyl benzoate, propyl benzoate, benzenesulfonate, benzenedisulfonate, p-toluenesulfonate, xylenesulfonate, cumenesulfonate, p-cymenesulfonate and dodecylbenzenesulfonate.

[0070] In a preferred embodiment, the precursor film comprises: (I) providing at least one compound comprising at least one poly(aryl ether ketone) polymer, at least one poly(aryl ether sulfone) polymer, and a sulfonate or carboxylate of a metal selected from the group consisting of alkali metals, alkaline earth metals, aluminum, iron, zinc, nickel, copper, palladium, and silver; (II) processing the composition to obtain pellets; (III) melt-extruding the pellets obtained in step (II) to obtain a precursor layer; (IV) contacting the precursor layer with at least one organic solvent or water, and subsequently with at least one organic solvent, thereby obtaining an intermediate porous layer; (V) contacting the intermediate porous layer obtained in step (IV) with water, thereby obtaining a porous membrane. It is prepared according to a method comprising:

[0071] The poly(arylethersulfone) polymer is preferably selected from polyphenylsulfone (PPSU), polyethersulfone (PES) or polysulfone (PSU).

[0072] The sulfonate or carboxylate-containing compound is selected from the group consisting of benzoate, methyl benzoate, ethyl benzoate, propyl benzoate, benzenesulfonate, benzenedisulfonate, p-toluenesulfonate, xylenesulfonate, cumenesulfonate, p-cymenesulfonate and dodecylbenzenesulfonate. Preferably, it is selected from the group consisting of sodium or potassium benzoate, sodium or potassium methylbenzoate, sodium or potassium ethylbenzoate, sodium or potassium butylbenzoate, sodium or potassium benzenesulfonate, sodium or potassium benzene-1,3-disulfonate, sodium or potassium p-toluenesulfonate, sodium or potassium xylenesulfonate, sodium or potassium cumenesulfonate, sodium or potassium para-cymenesulfonate, sodium or potassium n-butylbenzenesulfonate, sodium or potassium iso-butylbenzenesulfonate, sodium or potassium tert-butylbenzenesulfonate and sodium or potassium dodecylbenzenesulfonate.

[0073] In a second step, the method for preparing the membrane of the present invention comprises chemical treatment of the precursor membrane to obtain a contact angle of at least 155° measured according to the trapped bubble contact angle test and / or a static contact angle that decreases over time.

[0074] The chemical treatment provides the membrane with at least one surface comprising hydroxyl groups attached to aromatic rings in the poly(aryl ether ketone) polymer backbone, i.e., at least one surface comprising a functionalized poly(aryl ether ketone) polymer.

[0075] The chemical treatment involves contacting the precursor membrane with peroxide in the presence of an oxidation catalyst comprising iron(II) or iron(III) ions to obtain hydroxyl groups attached to aromatic rings of the poly(aryl ether ketone) polymer backbone, at least at the surface of the membrane.

[0076] The chemical treatment is typically carried out in an aqueous medium and may be conveniently carried out by immersing or dipping the precursor membrane in a bath or tank containing an aqueous solution containing the oxidation catalyst and peroxide.

[0077] The peroxide is typically hydrogen peroxide. The concentration of hydrogen peroxide in the aqueous medium is typically 0.5 to 15.0% by weight, and preferably 1.0 to 10.0% by weight, based on the weight of the aqueous medium.

[0078] The oxidation catalyst is preferably in the form of a salt. Notable examples of suitable salts include Fe(NH4)2(SO4)2 * 6H2O. The concentration of iron(II) or iron(III) ions in the aqueous medium is not critical. It is typically at least 1.0 x 10 -4 I am M.

[0079] The treatment is typically carried out under acidic conditions; preferably at a pH of the aqueous medium of less than 6.0, more preferably at a pH of between 3.0 and 5.0.

[0080] The treatment is typically carried out at a temperature of from 30°C to 95°C, more preferably from 40°C to 90°C.

[0081] When the precursor membrane is immersed, it can remain in the aqueous medium for a period of from 1 second to 10 hours, typically from 5 to 60 minutes.

[0082] The process may further include washing the membrane followed by drying.

[0083] The membranes of the present invention are particularly suitable for use as separators in alkaline water electrolysis systems due to the inherent chemical stability of the poly(aryl ether ketone) polymers, combined with increased hydrophilicity.

[0084] The alkaline water electrolysis device comprises an anode, a cathode, and the porous membrane described above, with the membrane disposed between the anode and the cathode. In a more specific example, the interior of the alkaline water electrolysis device is divided by the porous membrane of the present invention into an anode compartment containing the anode and a cathode compartment containing the cathode, and oxygen gas and hydrogen gas generated from the electrodes are not mixed.

[0085] The configuration of the alkaline water electrolysis device of the present invention is not particularly limited as long as it includes the membrane of the present invention. When used as a separator in an alkaline water electrolysis device, the membrane of the present invention is typically in the form of a flat membrane. Advantageously, it is in the form of a flat membrane comprising a porous substrate. Advantageously, the porous substrate is in the form of a mesh, preferably a poly(phenylene sulfide) mesh.

[0086] The membrane, when used as a separator in an alkaline water electrolysis system, is characterized by a contact angle, measured according to the Trapped Bubble Contact Angle Test, of at least 155°, even at least 157°, and / or a static contact angle that decreases over time, preferably a static contact angle that decreases by 15° relative to the initial value when measured after 60 seconds.

[0087] The electrolysis method and conditions using the alkaline water electrolysis device of the present invention are not particularly limited, and known methods and conditions can be used. For example, an alkaline solution is filled inside the alkaline water electrolysis device, and a direct current is applied between the anode and the cathode. For example, an aqueous solution of sodium hydroxide or potassium hydroxide is used as the electrolyte solution.

[0088] Hydrogen can be industrially produced by a water electrolysis process using the alkaline water electrolysis device of the present invention, in which a variable power supply is applied to the device. That is, the hydrogen production method according to this embodiment includes a step of electrolyzing alkaline water by applying a voltage to the alkaline water electrolysis device of this embodiment using the variable power supply. The hydrogen production method according to this embodiment makes it possible to efficiently and stably convert variable power obtained from renewable energy sources such as large-scale wind power generation or solar power generation into hydrogen and store the hydrogen.

[0089] Thus, an exemplary beneficial use of an electrolyzer incorporating the membrane of the present invention is to enable electricity obtained from renewable energy sources to be converted into hydrogen and stored as hydrogen.

[0090] The porous membranes of the present invention may also be advantageously used in filtration devices such as microfiltration or ultrafiltration devices.

[0091] Therefore, the present invention also provides a method for filtering at least one fluid, comprising contacting said fluid with at least one porous membrane of the present invention. The at least one fluid is a gas or a liquid, preferably selected from the group consisting of biological solutions, buffer solutions, oil / water emulsions, water, hydrocarbons. Among oil / water emulsions, notable examples are fracking water and so-called "produced water", or in other words water from oil wells, water with a high solids content, and wastewater.

[0092] Hereinafter, the present invention will be explained in more detail with reference to examples and comparative examples.

[0093] The above-described embodiments are intended to be illustrative and not limiting. Additional embodiments are within the concept of the present invention. In addition, while the present invention has been described with reference to specific embodiments, those skilled in the art will recognize that changes in form and detail may be made without departing from the spirit and scope of the invention. [Example]

[0094] material The following were obtained from Solvay Specialty Polymers USA, LLC: PEEK: Ketaspire® KT-820 NL PEEK polymer (MFR = 3 g / 10 min measured at 400°C and 2.16 Kg); PSU: Udel® P1700 PSU polymer (MFR = 6.5 g / 10 min measured at 343°C / 2.16 Kg); Dimethyl sulfoxide (DMSO) and isopropyl alcohol (IPA) were obtained from Sigma Aldrich®. Micronized sodium benzoate was obtained commercially from Fluid Energy, Telford, PA.

[0095] Bubble point and pore size determination The membrane bubble point (i.e., measurement of the largest pore), smallest pore size, and average pore size were determined using a capillary flow porometer Porolux™ 1000 (Porometer-Belgium) according to ASTM F316 method. For each test, the membrane sample was first thoroughly wetted with Fluorinert C 43 (a fluorinated fluid with a surface tension of 16 dyn / cm). Nitrogen (inert gas) was used.

[0096] Static contact angle (CA) measurement Static water contact angles were evaluated at 25°C by using a DSA10 instrument (Kruess GmbH, Germany) according to ASTM D 5725-99. Contact angles were measured on only one side of the flat film. The results shown in Table 2 are for an average of at least 10 drops of water. The drop volume was 2 μL. Contact angles were measured immediately after deposition of the water drops and remeasured on the same samples after the times shown in Table 2 under the same experimental conditions.

[0097] Captured Air Bubble (CAB) Method This method measures the contact angle of an air bubble on a surface immersed in a liquid, in this case water. Because the determination is performed on an already wetted film, swelling and water absorption are suppressed. The instrument configuration used for the determination is described in WO 2021 / 12262S A1 (page 40 and Figure I). Air contact angle (ACA) measurements were performed at room temperature using a conditioned environmental chamber filled with deionized water (DI water). Prior to analysis, the wet sample was supported on a 15 x 5 mm glass substrate and fixed to the sample holder with double-sided tape. The sample was then immersed in DI water, and a 2 pL air bubble was dropped onto the sample surface using a J-shaped syringe. Contact angle measurements were performed using an optical tensiometer (Attension Theta Flex supplied by BIOLIN) equipped with a high-quality monochromatic low-temperature LED light and a high-resolution (1984 x 1264) digital camera. Image acquisition parameters were set at 5 frames per second (FPS) and a minimum acquisition time of 60 seconds. The instrument was calibrated using a calibration ball (CA = 143.15') with a tolerance of 0.03. The contact angle values ​​obtained are the average of five measurements performed on the same sample.

[0098] Preparation of precursor membrane (PQ) PEEK and sodium benzoate were blended using a ZSK-26 twin-screw extruder (Coperion GmbH, Stuttgart, Germany) equipped with 12 barrel zones and a heated exit die operating at a maximum temperature of 450°C. The barrel profile was as follows:

[0099] [Table 1]

[0100] To obtain the proper mass ratio of the components, the preblend was fed into the feed section of the extruder using a K-Tron T-35 gravimetric feeder (from Coperion GmbH, Stuttgart, Germany). The components were melted and mixed in a screw designed to obtain a homogeneous molten composition. The actual melt temperature at the exit die was measured with a small instrument and found to be between 390 and 400°C.

[0101] The melt stream was air-cooled and fed into a Maag Primo 60E pelletizer (from Maag Automatik GmbH, Stuttgart, Germany). The pellets were collected and used to make compounds containing the following (all amounts expressed as weight percent relative to the total weight of the composition): PEEK: 40.6% by weight PSU: 38.5% by weight Sodium benzoate: 20.9% by weight.

[0102] The pellets were collected and stored in sealed plastic buckets until use in melt film extrusion. The pellets were dried overnight at 130°C and then fed into a single-screw extruder and extruded into a film using a film die at a profile temperature of 360-390°C. The film was wound onto a cooled godet roll operating at a speed of 0.5-2 m / min and a temperature of 90-170°C.

[0103] The precursor layer obtained in the above step was leached overnight in DMSO at 120 °C, allowed to settle, and fresh DMSO was added with stirring for 2 h. The washing was repeated by adding clean DMSO with stirring at room temperature for 2 h, and then transferred to water for three water washes with stirring for 1 h each.

[0104] Example: Preparation and testing of membranes 1-3 A sample of the precursor film obtained in the previous step was pre-wetted with alcohol and then soaked in hydrogen peroxide and Fe(NH4)2(SO4)2 * 6H2O(9.1×10 -4 The samples were immersed in a Pyrex® glass pan containing 0.8 L of an aqueous solution containing 0.05 M HSO. The pH of the solution was set to 4.0 by adding 0.05 M HSO. The temperature was set to 75°C and the reaction was allowed to proceed for 30 minutes. Various concentrations of hydrogen peroxide were used. The results are summarized in Table 1.

[0105] [Table 2]

[0106] The static contact angle, its change over time, and the trapped bubble contact angle were determined and are summarized in Table 2.

[0107] [Table 3]

[0108] The contact angle results in Table 2 show an increase in hydrophilicity of films 1 to 3. The higher the hydrogen peroxide concentration during the film preparation process, the higher the hydrophilic properties of the film.

[0109] Membrane 3 exhibits the most hydrophilic properties: in the case of the static contact angle, a water droplet is adsorbed in less than 30 seconds. In the trapped air bubble test, air bubbles cannot even be deposited on the surface of the membrane due to its hydrophilicity. This is a particularly advantageous result, as this measurement mimics the real conditions of use of the membrane in an alkaline electrolyzer.

[0110] Determination of the presence of hydroxyl groups in membrane 3 Sample of membrane 3 (4 × 4 cm 2 The surface of the sample was treated overnight with a solution of trifluoroacetic anhydride (4 ml) in diethyl ether (60 ml), rinsed twice with acetonitrile, and then dried under reduced pressure at 40°C.

[0111] The samples thus obtained in the form of thin sheets were characterized by solid-state NMR spectroscopy. 19 F MAS NMR spectra were recorded on an Agilent DD2 400 MHz NB spectrometer using a 1.6 mm T3 MAS special HFXY probe at room temperature. 19 F one-pulse spectra were acquired at a spinning rate of 34 kHz using a 4.2 μs 90° pulse, a 20 s recycle delay, and 304 scans. F chemical shifts, δC, are reported relative to CFCl3 using PTFE (δC = −123 ppm) as the secondary standard.

[0112] The spectrum obtained for Film 3 after treatment with trifluoroacetic anhydride showed a contribution at −75 ppm that was clearly observable and absent in the NMR spectrum of Film 3. The peak at −75 ppm is assigned to the presence of —CF3 groups resulting from the conversion of —OH groups to —CF3 groups in the sample by trifluoroacetylation.

[0113] The H-Cell system is used to measure the through-plane conductivity of the membrane in alkaline electrolyte. The determination of membrane conductivity is based on measuring the slope of the cell polarization curve performed on a voltage sweep in a graph of voltage (V) versus current (I); the slope represents the resistance of the cell. The resistance of the cell without the membrane was subtracted from the resistance of the membrane, and this value was multiplied by the free area of ​​the sample to obtain the areal surface resistivity (ASR) of each membrane.

[0114] The cell consists of two glass compartments (or a single compartment if installed without a membrane) separated by a membrane. Each compartment contains a working electrode consisting of a platinum spiral filament and an Ag / AgCl reference electrode. The reference electrode is inserted into a glass tube (Luggin capillary) with both ends positioned close to the membrane; the voltage of the reference electrode is related to the voltage of the electrolyte near the tip of the glass tube. The measured resistance of the cell is therefore a function of the distance between the two tubes.

[0115] The ASR data are reported in Table 3. All membranes 1-3 had a thickness of 310 microns.

[0116]

Table 4

Claims

1. A porous membrane comprising at least one poly(aryl ether ketone) polymer, wherein the membrane has a contact angle of at least 155° as measured according to a trapped bubble contact angle test and / or a static contact angle that decreases over time as measured according to ASTM D5725-99, preferably a static contact angle that is at least 15° lower than the initial value when measured after 60 seconds, and the membrane comprises at least one surface comprising at least one functionalized poly(aryl ether ketone) polymer comprising a hydroxyl group bonded to the aromatic ring of the poly(aryl ether ketone) polymer backbone.

2. The poly(aryl ether ketone) polymer is, in this specification, the following formulas (J-A) to (J-O): 【Chemistry 1】 【Chemistry 2】 (In the formula, Each of R', which may be equal to or different from each other, is selected from the group consisting of halogens, alkyls, alkenyls, alkynyls, aryls, ethers, thioethers, carboxylic acids, esters, amides, imides, alkali or alkaline earth metal sulfonates, alkyl sulfonates, alkali or alkaline earth metal phosphonates, alkyl phosphonates, amines, and quaternary ammonium compounds; (j' is zero or an integer between 1 and 4) Repeating units (R) selected from the group consisting of the following ＰＡＥＫ The film according to claim 1, comprising at least 50 mol% of ).

3. Repeating unit (R ＰＡＥＫ ) is expressed in the following equations (J'-A) to (J'-D) and (J''-B): 【Transformation 3】 The membrane according to claim 2, selected from the group consisting of units.

4. The functionalized poly(aryl ether ketone) polymer is defined by the following formulas (K-A) to (K-D): 【Chemistry 4】 (In the formula, each of Q' is -OH, and independently, i is zero or an integer from 1 to 4, provided that in the repeating unit, the sum of all i is not zero.) Repeating units (R) selected from a group consisting of units ＰＡＥＫ－ＯＨ The film according to claim 1, comprising ).

5. The functionalized poly(aryl ether ketone) polymer is a repeating unit (R) selected from the group consisting of units of formulas (J'-A) to (J'-D) and (J''-B) as defined in claim 3. ＰＡＥＫ The film according to claim 4, further comprising ).

6. The functionalized poly(aryl ether ketone) polymer has a repeating unit (R) relative to the total number of repeating units in the functionalized poly(aryl ether ketone) polymer. ＰＡＥＫ－ＯＨ ) and repeating units (R ＰＡＥＫ The membrane according to claim 1, comprising at least 50 mol% of the total amount of ).

7. The functionalized poly(aryl ether ketone) polymer contains 0.001 mol% or more of repeating units (R) relative to the number of repeating units in the functionalized poly(aryl ether ketone) polymer. ＰＡＥＫ－ＯＨ The film according to claim 1, comprising ).

8. The film according to claim 1, wherein the functionalized poly(aryl ether ketone) polymer contains at least 60 mol%, 70 mol%, 80 mol%, 90 mol%, 95 mol%, 99 mol%, and 100 mol% of repeating units which are combinations of repeating units of formulas (K-A) and (J'-A) as defined in claims 3 and 4, wherein the amount of repeating units (K-A) is not zero.

9. The film according to claim 1, wherein the functionalized poly(aryl polymer) contains at least 60 mol%, 70 mol%, 80 mol%, 90 mol%, 95 mol%, 99 mol%, and 100 mol% of repeating units which are combinations of repeating units of formula (K-A) and / or (J'-A) and repeating units of formula (K-D) and / or (J'-D) as defined in claims 3 and 4, wherein the amount of repeating units (K-A) + (K-D) is not zero.

10. - To provide a precursor film which is a film containing a poly(aryl ether ketone) polymer having a contact angle of less than 155° and / or a static contact angle that does not decrease over time, as measured according to a trapped bubble contact angle test; - Chemically treat the precursor film to provide the film with at least one surface containing a hydroxyl group bonded to the aromatic ring of the poly(aryl ether ketone) polymer main chain, thereby obtaining a contact angle of at least 155° and / or a static contact angle that decreases over time, as measured according to a trapped bubble contact angle test. A method for producing the film described in claim 1, including the method described in claim 1.

11. The method according to claim 10, wherein the precursor film comprises at least one surface containing a poly(aryl ether ketone) polymer.

12. The method according to claim 10, wherein the step of chemically treating the precursor film includes contacting the precursor film with a peroxide in the presence of an oxidation catalyst containing iron(II) or iron(III) ions to obtain hydroxyl groups bonded to the aromatic rings of the poly(aryl ether ketone) polymer main chain in the precursor film.

13. The process of providing the precursor film is as follows: (I) To provide a composition comprising at least one poly(aryl ether ketone) polymer, at least one poly(aryl ether sulfone) polymer, and at least one compound comprising a sulfonate or carboxylate of a metal selected from the group consisting of alkali metals, alkaline earth metals, aluminum, iron, zinc, nickel, copper, palladium, and silver; (II) Processing the composition to obtain pellets; (III) The pellets obtained in step (II) are melt-extruded to obtain a precursor layer; (IV) Contacting the precursor layer with at least one organic solvent, or contacting it with water, and then contacting it with at least one organic solvent, thereby obtaining an intermediate porous layer; (V) The intermediate porous layer obtained in step (IV) is brought into contact with water, thereby obtaining a porous film. The method according to claim 10, including the method described in claim 10.

14. Alkaline water electrolysis device, - Anode; - Cathode; and - The film according to claim 1, which is disposed between the anode and the cathode. Alkaline water electrolysis device, including [specific component].

15. A method for generating hydrogen, comprising the step of electrolyzing alkaline water by applying a voltage to the alkaline water electrolysis apparatus described in claim 14, preferably using a power source derived from a renewable energy source.

16. A method for filtering at least one fluid, comprising contacting the fluid with at least one membrane as described in claim 1, wherein the at least one fluid is a gas or a liquid, preferably selected from the group consisting of a biological solution, a buffer solution, an oil / water emulsion, water, and hydrocarbons.

Images