Ion exchange membrane, method for producing the same, use thereof, and apparatus for organic electrosynthesis

Abstract

The embodiment of the application discloses an ion exchange membrane and a preparation method and application thereof, and an organic electrosynthesis device. The ion exchange membrane comprises a base film and a functional layer, the functional layer is loaded on the base film, and the material of the functional layer comprises two-dimensional nanomaterials covalently modified with organic molecular fragments, the organic molecular fragments are used for regulating the interlayer spacing of the two-dimensional nanomaterials, and the interlayer spacing of the two-dimensional nanomaterials covalently modified with the organic molecular fragments in the functional layer is 0.8 nm to 1.5 nm. The ion exchange membrane comprises the base film and the functional layer, and the material of the functional layer comprises the two-dimensional nanomaterials covalently modified with the organic molecular fragments. By covalently modifying the two-dimensional nanomaterials with the organic molecular fragments, strong interaction force is introduced between the nanosheet layers of the two-dimensional nanomaterials, the interlayer spacing of the nanosheet layers is effectively 'anchored', and when the ion exchange membrane is soaked in a solvent, the risk that a large amount of solvent enters the interlayer of the nanosheet layers and causes serious swelling of the ion exchange membrane can be reduced.

Description

Technical Field

[0001] This application relates to the field of organic electrosynthesis technology, specifically to an ion exchange membrane, its preparation method, application, and organic electrosynthesis apparatus. Background Technology

[0002] Organic electrosynthesis utilizes electrons to directly drive chemical reactions, effectively replacing highly polluting redox reagents in traditional synthesis, significantly reducing toxic byproducts and improving atom economy. However, this technology still faces many challenges in transitioning from laboratory to industrial applications. The most critical bottleneck lies in the cross-permeability phenomenon in the reaction system—the unintended migration of reactants, intermediates, or products between the electrodes. This cross-permeability not only reduces energy efficiency and product yield but also significantly increases subsequent separation costs.

[0003] Traditional organic electrosynthesis systems typically employ polymer ion-exchange membranes (such as Nafion) to isolate the electrodes and regulate ion transport. However, these membrane materials are highly susceptible to swelling in organic solvents, leading to increased pore size and microstructural deformation, ultimately resulting in a loss of ion selectivity. For example, excessive swelling of Nafion membranes in alcohol or ether solvents can drastically increase the cross-permeability between protons and organic molecules; furthermore, their mechanical strength tends to degrade over long-term operation, making them unsuitable for large-scale organic electrosynthesis. Summary of the Invention

[0004] This application provides an ion exchange membrane, its preparation method, application, and an organic electrosynthesis apparatus, aiming to solve the problem of easy swelling of ion exchange membranes.

[0005] This application provides an ion exchange membrane for organic electrosynthesis, the ion exchange membrane comprising:

[0006] Base film; and

[0007] A functional layer is loaded on the base film. The material of the functional layer includes two-dimensional nanomaterials covalently modified with organic molecular fragments. The two-dimensional nanomaterials include at least one of graphene oxide, transition metal dichalcogenides, and transition metal carbonitrides. The organic molecular fragments have at least one of amide, alkyl, hydroxyl, and carboxyl groups. The organic molecular fragments are used to regulate the interlayer spacing of the two-dimensional nanomaterials. The interlayer spacing of the two-dimensional nanomaterials covalently modified with organic molecular fragments in the functional layer is 0.8 nm to 1.5 nm.

[0008] Optionally, in some embodiments of this application, the transition metal disulfide includes molybdenum disulfide.

[0009] Optionally, in some embodiments of this application, the thickness of the functional layer is 0.5 μm to 5 μm.

[0010] Optionally, in some embodiments of this application, the relative molecular mass of the organic molecular fragment is 10 g / mol to 200 g / mol.

[0011] Optionally, in some embodiments of this application, the material of the base film includes at least one of nylon, polyethersulfone, polyvinylidene fluoride, and polytetrafluoroethylene.

[0012] Optionally, the base membrane is a porous membrane.

[0013] Accordingly, this application also provides a method for preparing an ion exchange membrane, comprising:

[0014] A first dispersion is provided, the first dispersion comprising two-dimensional nanomaterials;

[0015] An organic molecule is added to the first dispersion, and the organic molecule reacts with the two-dimensional nanomaterial to covalently modify the organic molecule fragment on the two-dimensional nanomaterial to obtain a second dispersion.

[0016] The two-dimensional nanomaterial modified with organic molecular fragments in the second dispersion is loaded onto a base membrane to obtain an ion exchange membrane.

[0017] Optionally, in some embodiments of this application, the two-dimensional nanomaterial includes molybdenum disulfide, and the preparation process of the first dispersion includes:

[0018] Molybdenum disulfide powder was intercalated using a lithium n-butyl solution with a concentration of 1 mol / L to 3 mol / L and the molybdenum disulfide powder had an average particle size of 1 μm to 10 μm to obtain an intercalated compound.

[0019] The intercalation compound is added to water and subjected to ultrasonic exfoliation for 1 to 3 hours to obtain a first dispersion. The first dispersion is a molybdenum disulfide dispersion with a molybdenum disulfide concentration of 0.5 mg / mL to 5 mg / mL.

[0020] Optionally, in some embodiments of this application, the reaction time between the organic molecules and the two-dimensional nanomaterial is 0.5 h to 10 h.

[0021] Optionally, in some embodiments of this application, the organic molecule is a halogenated compound, which includes at least one of 2-iodoacetamide, 2-bromoacetamide, and 2-chloroacetamide.

[0022] Optionally, in some embodiments of this application, loading the two-dimensional nanomaterial modified with organic molecular fragments in the second dispersion onto a base membrane to obtain an ion exchange membrane includes: depositing the two-dimensional nanomaterial modified with organic molecular fragments in the second dispersion onto a base membrane using a vacuum filtration method to obtain an ion exchange membrane, wherein the vacuum filtration time is 1h to 3h.

[0023] Accordingly, this application also provides an organic electrosynthesis apparatus, including a cathode, an anode, and an ion exchange membrane disposed between the cathode and the anode, wherein the ion exchange membrane is the ion exchange membrane described above or an ion exchange membrane prepared by the method described above.

[0024] Furthermore, this application also provides an application of ion exchange membranes in organic electrosynthesis, wherein the ion exchange membrane is the aforementioned ion exchange membrane or an ion exchange membrane prepared by the aforementioned ion exchange membrane preparation method.

[0025] Optionally, in some embodiments of this application, the organic electrosynthesis includes at least one of the following: electroreduction of acetone to prepare isopropanol, electroreduction of nitromethane to prepare N-methylhydroxylamine, and electrooxidation of vinyl sulfite to prepare vinyl sulfate.

[0026] The ion exchange membrane provided in this application includes a base membrane and a functional layer. The material of the functional layer includes two-dimensional nanomaterials covalently modified with organic molecular fragments. By covalently modifying the two-dimensional nanomaterials with organic molecular fragments, strong interaction forces are introduced between the nanosheets of the two-dimensional nanomaterials, effectively "anchoring" the interlayer spacing of the nanosheets. When the ion exchange membrane is immersed in a solvent, the risk of a large amount of solvent entering the interlayer of the nanosheets and causing severe swelling of the ion exchange membrane can be reduced. Attached Figure Description

[0027] Figure 1 This is a SEM image of the acetamide-modified MoS2 membrane in the ion exchange membrane prepared in Example 1 of this application;

[0028] Figure 2 The images show the XRD patterns of the acetamide-modified MoS2 membrane prepared in Example 1 of this application and the unmodified MoS2 membrane prepared in Comparative Example 1, respectively, in dry membrane, in deionized water, and in 1 M methanol solution. Detailed Implementation

[0029] The technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0030] This application provides an ion exchange membrane, its preparation method, application, and an organic electrosynthesis apparatus. These are described in detail below. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc., are used merely as illustrative and do not impose numerical requirements or establish an order. Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single digits within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0031] This application provides an ion exchange membrane for organic electrosynthesis. The ion exchange membrane includes a base membrane and a functional layer. The functional layer is loaded on the base membrane, and the material of the functional layer includes two-dimensional nanomaterials covalently modified with organic molecular fragments.

[0032] Ion exchange membranes exhibit selective permeability. The ion exchange membrane provided in this application embodiment is used for organic electrosynthesis; the ion exchange membrane can be either a cation exchange membrane or an anion exchange membrane.

[0033] Ion exchange membranes include a base membrane. The base membrane is typically made of organic polymer materials, thus possessing electrical insulation properties. Optionally, the base membrane material includes at least one of nylon, polyethersulfone, polyvinylidene fluoride, and polytetrafluoroethylene.

[0034] The ion exchange membrane also includes a functional layer. The functional layer is loaded on the base membrane, and the base membrane supports the functional layer. Specifically, the functional layer is attached to at least one surface of the base membrane. As an example, functional layers are attached to both opposite surfaces of the base membrane.

[0035] The functional layer materials include two-dimensional nanomaterials. Two-dimensional nanomaterials refer to materials that have atomic or nanometer-scale dimensions in the thickness direction and extend to micrometer or even macroscopic scales in the planar direction. For example, the thickness of two-dimensional nanomaterials is 1 nm to 100 nm. Due to their atomic or nanometer-scale thickness and precisely controllable nanochannel structure, two-dimensional nanomaterials exhibit excellent ion selectivity, high proton conductivity, and superior resistance to organic solvents. Optionally, two-dimensional nanomaterials include at least one of graphene oxide, transition metal disulfides (TMDCs), and transition metal carbonitrides. For example, transition metal disulfides include at least one of molybdenum disulfide (MoS2) and tungsten disulfide (WS2); transition metal carbonitrides include MXenes.

[0036] Furthermore, the two-dimensional nanomaterials in the functional layer are also modified with organic molecular fragments. Specifically, the organic molecular fragments are covalently bonded to the two-dimensional nanomaterials. This can be achieved by reacting the organic molecules with the two-dimensional nanomaterials, for example, through a substitution reaction, thereby converting the organic molecules into organic molecular fragments that are then covalently bonded to the two-dimensional nanomaterials. This process modifies the two-dimensional nanomaterials with organic molecular fragments, resulting in two-dimensional nanomaterials modified with organic molecular fragments. Optionally, the organic molecular fragments have at least one of amide, alkyl, hydroxyl, and carboxyl groups. As examples, the organic molecular fragments include at least one of -CH2CH3, -CH2CH2CH3, -CH2CONH2, -CH2CH2CH2OH, -CH2COOCH2CH3, -C6H4Br, and -CH2CH2C6H5.

[0037] In the embodiments of this application, organic molecular fragments are used to regulate the interlayer spacing of the two-dimensional nanomaterials. The interlayer spacing of the two-dimensional nanomaterials covalently modified with organic molecular fragments in the functional layer is 0.8 nm to 1.5 nm. The interlayer spacing of the two-dimensional nanomaterials covalently modified with organic molecular fragments in the functional layer refers to the spacing between the nanosheets of the two-dimensional nanomaterials covalently modified with organic molecular fragments in the functional layer. As an example, when the two-dimensional nanomaterial is MoS2 and the organic molecular fragment is -CH2CH3, the interlayer spacing of MoS2 covalently modified with this organic molecular fragment is 10.2 Å, which is the distance between Mo atoms in two layers of MoS2 nanosheets; when the organic molecular fragment is -CH2CH2CH3, the interlayer spacing of MoS2 covalently modified with this organic molecular fragment is 11.4 Å; when the organic molecular fragment is -CH2COOCH2CH3, the interlayer spacing of MoS2 covalently modified with this organic molecular fragment is 12.1 Å; when the organic molecular fragment is -C6H4Br, the interlayer spacing of MoS2 covalently modified with this organic molecular fragment is 13.1 Å; when the organic molecular fragment is -CH2CH2C6H5, the interlayer spacing of MoS2 covalently modified with this organic molecular fragment is 13.3 Å; and when the organic molecular fragment is -CH2CH2CH2OH, the interlayer spacing of MoS2 covalently modified with this organic molecular fragment is 14.2 Å. When the interlayer spacing of two-dimensional nanomaterials with covalently modified organic molecular fragments in the functional layers is 0.8 nm to 1.5 nm, this interlayer spacing can effectively block water and most organic solvents from entering the interlayer space of the nanosheets, thereby reducing the risk of swelling of the ion exchange membrane. As an example, the interlayer spacing of two-dimensional nanomaterials with covalently modified organic molecular fragments in the functional layers can be 0.8 nm, 0.9 nm, 1.0 nm, 1.1 nm, 1.2 nm, 1.3 nm, 1.4 nm, or 1.5 nm.

[0038] The ion exchange membrane provided in this application includes a base membrane and a functional layer. The material of the functional layer includes two-dimensional nanomaterials covalently modified with organic molecular fragments. By covalently modifying the two-dimensional nanomaterials with organic molecular fragments, strong interaction forces are introduced between the nanosheets of the two-dimensional nanomaterials, effectively "anchoring" the interlayer spacing of the nanosheets. When the ion exchange membrane is immersed in a solvent (organic solvent or water), the risk of a large amount of solvent entering the interlayer of the nanosheets and causing severe swelling of the ion exchange membrane can be reduced.

[0039] In some embodiments of this application, the transition metal disulfide includes molybdenum disulfide. The layered structure and high hydrophilicity of molybdenum disulfide provide rapid channels for water molecules. Its hexagonal channel structure is similar to biological aquaporins, enabling highly selective separation of water molecules and ions. Furthermore, the permeability of molybdenum disulfide increases linearly with increasing pressure, and it is not easily deformed, ensuring long-term operational stability. Optionally, the organic molecular fragment is -CH2CONH2, and the interlayer spacing of the modified molybdenum disulfide is 8 Å to 12 Å. The modified molybdenum disulfide exhibits excellent anti-swelling properties and precisely controllable interlayer channels.

[0040] In some embodiments of this application, the thickness of the functional layer is 0.5 μm to 5 μm. The ion exchange membrane includes a base membrane and a functional layer. The base membrane is mainly made of organic materials, while the functional layer is mainly made of inorganic materials. The functional layer has a significant impact on improving the mechanical strength of the ion exchange membrane. Increasing the thickness of the functional layer can improve the mechanical strength of the ion exchange membrane, but excessive thickness of the functional layer will lead to an excessively thick ion exchange membrane, which will significantly increase the resistance to ion passage. By controlling the thickness of the functional layer, the mechanical strength and ion conductivity of the ion exchange membrane can be effectively balanced. As an example, the thickness of the functional layer is 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, or 5 μm.

[0041] In some embodiments of this application, the relative molecular mass of the organic molecular fragments is 10 g / mol to 200 g / mol. The relative molecular mass of the organic molecular fragments affects the chain length of the organic molecular fragments, which in turn affects the interlayer spacing of the two-dimensional nanomaterials covalently modified with organic molecular fragments in the functional layers. By controlling the relative molecular mass of the organic molecular fragments to be 10 g / mol to 200 g / mol, the interlayer spacing of the two-dimensional nanomaterials covalently modified with organic molecular fragments in the functional layers can be kept at the nanoscale, thereby effectively inhibiting the entry of organic solvents or water into the interlayer of the two-dimensional nanomaterials and reducing the risk of swelling of the ion exchange membrane when immersed in solvent. As an example, the relative molecular masses of the organic molecular fragments are 10 g / mol, 20 g / mol, 40 g / mol, 60 g / mol, 80 g / mol, 100 g / mol, 120 g / mol, 140 g / mol, 160 g / mol, 180 g / mol, or 200 g / mol.

[0042] In some embodiments of this application, the base membrane is a porous membrane. The porous base membrane provides physical support as a framework, reducing the risk of the functional layers rupturing under pressure or fluid action. The porous membrane has pores that can be filled with electrolyte solution, forming permeation channels that allow ions to flow freely within the porous membrane, significantly reducing the overall ion conduction resistance of the ion exchange membrane. In other embodiments, the base membrane may also be a dense membrane.

[0043] This application also provides a method for preparing an ion exchange membrane, which includes:

[0044] A first dispersion is provided, the first dispersion comprising two-dimensional nanomaterials;

[0045] Organic molecules are added to the first dispersion, and the organic molecules react with the two-dimensional nanomaterials to covalently modify the organic molecular fragments on the two-dimensional nanomaterials to obtain the second dispersion.

[0046] Two-dimensional nanomaterials modified with organic molecular fragments in the second dispersion are loaded onto the base membrane to obtain an ion exchange membrane.

[0047] The method for preparing ion exchange membranes provided in this application is simple to operate, has mild conditions, and is easy to scale up, thus having broad market application prospects.

[0048] In some embodiments of this application, a lithium-ion intercalation and exfoliation method is used to prepare the first dispersion. The two-dimensional nanomaterial contained in the first dispersion is a single-layer nanosheet or a few-layer nanosheet (2 to 10 layers).

[0049] As an example, the two-dimensional nanomaterial includes molybdenum disulfide, and the preparation process of the first dispersion includes: intercalating molybdenum disulfide powder with a n-butyllithium solution to obtain an intercalated compound; adding the intercalated compound to water and performing ultrasonic exfoliation to obtain the first dispersion, wherein the first dispersion is a molybdenum disulfide dispersion.

[0050] n-Butyllithium, as an intercalating agent, transfers lithium ions (Li) through a strong reduction reaction. + Intercalation into the interlayer space of MoS2 induces interlayer distance expansion, yielding the intercalation compound Li. x MoS2 is used to ultrasonically exfoliate intercalated compounds, ultimately separating them into monolayers or few-layer nanosheets under the mechanical shearing force of ultrasound.

[0051] When preparing the first dispersion using lithium-ion intercalation and exfoliation, the molybdenum disulfide powder used is in bulk form, wherein the average particle size of the molybdenum disulfide powder is 1 μm to 10 μm. For example, the average particle size of the molybdenum disulfide powder is 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm.

[0052] n-Butyllithium is a highly reactive organolithium reagent, typically stored and used only in solution form. It is primarily soluble in hydrocarbons (such as cyclohexane, hexane, and n-hexane) and ethers (such as diethyl ether). The concentration of the n-butyllithium solution used in intercalation treatment ranges from 1 mol / L to 3 mol / L. For example, concentrations of n-butyllithium solutions are 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, or 3 mol / L.

[0053] After intercalating an intercalating agent expands the interlayer spacing of a layered material to obtain an intercalating compound, the intercalating compound is dispersed in water. High-energy shock waves generated by ultrasonic cavitation break the interlayer van der Waals forces, causing the atomic-layer material to peel off from the bulk material, forming a nanosheet suspension, i.e., the first dispersion. The ultrasonic exfoliation time affects the number of layers in the final nanosheets. Generally, the longer the ultrasonic exfoliation time, the fewer the layers. Due to the relatively strong interlayer adhesion of MoS2, the ultrasonic exfoliation time is relatively long. When the ultrasonic exfoliation treatment time is 1h to 3h, MoS2 nanosheets with fewer layers, or even single-layer MoS2 nanosheets, can be obtained. As examples, the ultrasonic exfoliation treatment times are 1h, 1.5h, 2h, 2.5h, or 3h.

[0054] The first dispersion obtained after ultrasonic exfoliation is a molybdenum disulfide dispersion, and the concentration of molybdenum disulfide in the molybdenum disulfide dispersion is 0.5 mg / mL to 5 mg / mL. As an example, the concentration of molybdenum disulfide in the first dispersion is 0.5 mg / mL, 1 mg / mL, 2 mg / mL, 3 mg / mL, 4 mg / mL, or 5 mg / mL.

[0055] In some embodiments of this application, the organic molecules are halogenated compounds. Halogenated compounds can undergo nucleophilic substitution reactions with two-dimensional nanomaterials. The portion of the halogenated compound that has lost a halogen atom acts as an organic molecular fragment and covalently binds to the two-dimensional nanomaterial, thereby obtaining two-dimensional nanomaterials modified with organic molecular fragments.

[0056] As an example, the halogenated compounds include at least one of 2-iodoacetamide, 2-bromoacetamide, and 2-chloroacetamide. These halogenated compounds can undergo a nucleophilic substitution reaction with molybdenum disulfide to yield acetamide-modified molybdenum disulfide.

[0057] In some embodiments of this application, the reaction time between the organic molecules and the two-dimensional nanomaterials is 0.5 h to 10 h. As examples, the reaction time is 0.5 h, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, or 10 h.

[0058] In some embodiments of this application, a two-dimensional nanomaterial modified with organic molecular fragments in a second dispersion is loaded onto a base membrane using a vacuum filtration method to obtain an ion exchange membrane. Specifically, the two-dimensional nanomaterial modified with organic molecular fragments in the second dispersion is deposited onto a base membrane using a vacuum filtration method to obtain an ion exchange membrane. Optionally, the vacuum filtration time is 1 h to 3 h. As an example, the vacuum filtration time is 1 h, 1.5 h, 2 h, 2.5 h, or 3 h.

[0059] This application also provides an organic electrosynthesis apparatus, which includes a cathode, an anode, and an ion exchange membrane disposed between the cathode and the anode. The ion exchange membrane is the ion exchange membrane described above or an ion exchange membrane prepared by the method described above.

[0060] Organic electrosynthesis is a technique that uses electrochemical reactions to construct or modify organic molecules. In an organic electrosynthesis device, the cathode is where reduction reactions occur, and the anode is where oxidation reactions occur; the ion exchange membrane acts like a one-way door, ensuring that specific ions (cations or anions) can pass through under the drive of an electric field, thereby achieving the separation, purification, or safe conduct of chemical reactions. An organic electrosynthesis device is an electrolytic device. By passing current through the electrodes, the transfer of electrons is directly controlled, thereby achieving the breaking or formation of chemical bonds.

[0061] As an example, the organic electrosynthesis apparatus is an apparatus for the electroreduction of acetone to prepare isopropanol, wherein the cathode of the apparatus is carbon paper coated with ruthenium oxide and the anode is titanium felt coated with iridium oxide.

[0062] As another example, the organic electrosynthesis apparatus is an apparatus for the electroreduction of nitromethane to prepare N-methylhydroxylamine, wherein the cathode of the apparatus is carbon paper and the anode is titanium felt coated with iridium oxide.

[0063] As another example, the organic electrosynthesis apparatus is an apparatus for the electro-oxidation of vinyl sulfite to prepare vinyl sulfate, wherein the cathode of the apparatus is a platinum-plated titanium felt and the anode is a titanium felt coated with antimony-doped tin oxide.

[0064] This application also provides an application of ion exchange membranes in organic electrosynthesis, wherein the ion exchange membrane is the ion exchange membrane described above or prepared by the above-described method.

[0065] Thanks to the anti-swelling properties and precisely controllable interlayer channels brought about by two-dimensional nanomaterials covalently modified with organic molecular fragments, this ion exchange membrane can effectively block the permeation of organic molecules in complex organic electrosynthesis systems, thus improving and solving the problems of reduced yield and soaring separation costs caused by unexpected migration of substances in traditional electrolyzers.

[0066] In some embodiments of this application, organic electrosynthesis includes at least one of the following: electroreduction of acetone to prepare isopropanol, electroreduction of nitromethane to prepare N-methylhydroxylamine, and electrooxidation of vinyl sulfite to prepare vinyl sulfate.

[0067] The following description is based on specific embodiments.

[0068] Example 1

[0069] This embodiment provides an ion exchange membrane, the preparation process of which is as follows:

[0070] In a glove box, 1 g of MoS2 powder was weighed and placed in a glass bottle, and 10 mL of n-butyllithium solution (1.6 M) was added. The mixture was stirred at room temperature for 48 h. After washing the mixture three times with n-hexane by centrifugation, 200 mL of deionized water was added to the resulting solid and the mixture was ultrasonically exfoliated for 2 h. The dispersion obtained by ultrasonication was centrifuged to remove the lower layer of unexfoliated multilayer MoS2, retaining the upper liquid layer to obtain a monolayer MoS2 dispersion. Subsequently, 10 mL of this dispersion was taken and 0.2 g of 2-iodoacetamide was added. The mixture was stirred at room temperature for 30 min to obtain an acetamide-modified MoS2 dispersion. Finally, the modified dispersion was deposited on a nylon substrate (47 mm in diameter) using vacuum filtration to obtain an acetamide-modified MoS2 membrane (referred to as MoS2-Acet membrane). The thickness of the MoS2-Acet membrane was 2 μm, thus obtaining an ion exchange membrane.

[0071] Example 2

[0072] A monolayer graphene oxide dispersion was prepared using the Hummers method. Then, 10 mL of this dispersion was taken, and 0.2 g of 2-iodoacetamide was added. The mixture was stirred at room temperature for 30 min to obtain an acetamide-modified graphene oxide dispersion. Finally, this modified dispersion was deposited on a nylon substrate (47 mm in diameter) using vacuum filtration to form an acetamide-modified graphene oxide membrane with a thickness of 2 μm, thus obtaining an ion exchange membrane.

[0073] Example 3

[0074] This embodiment provides an ion exchange membrane. The preparation process of this ion exchange membrane is described in Example 1, except that 2-iodoethane is used instead of 2-iodoacetamide as the modifying molecule. Everything else is the same as in Example 1.

[0075] Comparative Example 1

[0076] This comparative example provides an ion exchange membrane. The preparation process of this ion exchange membrane is described in Example 1, except that the MoS2 dispersion is not modified with acetamide and the MoS2 membrane is obtained directly by vacuum filtration. Everything else is the same as in Example 1.

[0077] Application Example 1 (Electroreduction of acetone to prepare isopropanol)

[0078] (1) Construction of the electrosynthesis system: The electrolytic cell is assembled from a cathode, an anode, and an ion exchange membrane separating the two electrodes. The cathode is carbon paper coated with ruthenium oxide, the anode is titanium felt coated with iridium oxide, and the ion exchange membrane is the ion exchange membrane containing MoS2-Acet membrane prepared in Example 1.

[0079] (2) Electrosynthesis conditions: 5 mL of 0.5 M H2SO4 containing 1 M acetone was added to the cathode chamber as the cathode electrolyte; 5 mL of 0.5 M H2SO4 was added to the anode chamber as the anode electrolyte. A constant voltage of 1.8 V was applied between the cathode and anode, and electrolysis was stopped when the charge on the system reached 1200 C.

[0080] Application Example 2 (Preparation of N-methylhydroxylamine by electroreduction of nitromethane)

[0081] (1) Construction of the electrosynthesis system: The electrolytic cell is assembled from a cathode, an anode, and an ion exchange membrane separating the two electrodes. The cathode is carbon paper, the anode is titanium felt coated with iridium oxide, and the ion exchange membrane is the ion exchange membrane containing MoS2-Acet membrane prepared in Example 1.

[0082] (2) Electrosynthesis conditions: 5 mL of 0.5 M H2SO4 containing 0.5 M nitromethane was added to the cathode chamber as the cathode electrolyte; 5 mL of 0.5 M H2SO4 was added to the anode chamber as the anode electrolyte. A constant voltage of 2.3 V was applied between the cathode and anode, and electrolysis was stopped when the charge on the system reached 1000 C.

[0083] Application Example 3 (Electrooxidation of vinyl sulfite to vinyl sulfate)

[0084] (1) Construction of the electrosynthesis system: The electrolytic cell is assembled from a cathode, an anode, and an ion exchange membrane separating the two electrodes. The cathode is a platinum-plated titanium felt, the anode is a titanium felt coated with antimony-doped tin oxide, and the ion exchange membrane is the ion exchange membrane containing MoS2-Acet membrane prepared in Example 1.

[0085] (2) Electrosynthesis conditions: 5 mL of 0.5 M H2SO4 solution was added to the cathode chamber as the cathode electrolyte; 5 mL of a mixture containing 1 M vinyl sulfite (prepared by mixing 0.5 M H2SO4 and CH3CN at a volume ratio of 1:1) was added to the anode chamber as the anolyte. A constant voltage of 2.2 V was applied between the cathode and anode, and electrolysis was stopped when the charge on the system reached 1200 C.

[0086] Application Example 4

[0087] The difference from Application Example 1 is that the ion exchange membrane used is the ion exchange membrane prepared in Example 2.

[0088] Application Example 5

[0089] The difference from Application Example 1 is that the ion exchange membrane used is the ion exchange membrane prepared in Example 3.

[0090] Compare with Example 1

[0091] The difference between Comparative Example 1 and Application Example 1 is that the ion exchange membrane used is a commercially available Nafion 117 membrane. Everything else is the same as in Application Example 1.

[0092] Compare with Example 2

[0093] The difference between Comparative Example 2 and Application Example 2 is that the ion exchange membrane used is a commercially available Nafion 117 membrane. Everything else is the same as in Application Example 2.

[0094] Compare with Example 3

[0095] The difference between Comparative Example 3 and Application Example 3 is that the ion exchange membrane used is a commercially available Nafion 117 membrane. Everything else is the same as in Application Example 3.

[0096] Compare with Example 4

[0097] The difference from Application Example 1 is that the ion exchange membrane used is the same as the one prepared in Comparative Example 1.

[0098] Performance testing:

[0099] 1. Scanning Electron Microscopy (SEM): The cross-section of the acetamide-modified MoS2 membrane in the ion exchange membrane provided in Example 1 was characterized using SEM. The results are as follows: Figure 1 As shown, from Figure 1 As can be seen from the SEM image shown, the thickness of the acetamide-modified MoS2 film is 2 μm.

[0100] 2. X-ray diffraction (XRD): The interlayer spacing changes of the MoS2-Acet film in Example 1 and the unmodified MoS2 film in Comparative Example 1 were measured using XRD in deionized water and 1 M methanol solution, respectively. The results are shown in [link to XRD section]. Figure 2 .from Figure 2 It can be seen that the interlayer spacing of the unmodified dry MoS2 film increased dramatically from 11.4 Å to 19.6 Å after immersion; while the interlayer spacing of the MoS2-Acet film only increased slightly from 9.6 Å to 10.7 Å before and after immersion. This characterization data directly confirms that the modification effect of acetamide molecules can effectively inhibit solvent-induced interlayer swelling.

[0101] 3. Nuclear magnetic resonance hydrogen spectrum (NMR) 1 H NMR: After the electrosynthesis reaction is completed, through 1 ¹H NMR is used for quantitative analysis of substances in the cathode electrolyte and anolyte.

[0102] Cross-penetration rate (X) and product yield (Y) are calculated using the following formulas (taking application example 1 as an example):

[0103]

[0104]

[0105] in, n anolyte Indicates the number of moles of organic matter in the anode chamber. n total This represents the sum of the molar numbers of organic compounds at the anode and cathode. n catholyte , indicating the number of moles of organic matter in the cathode chamber. n initial , indicates the initial molar number of reactants.

[0106] Please refer to Table 1 for the test results of each application example and control example:

[0107] Table 1

[0108]

[0109] As can be seen from Table 1:

[0110] Application Examples 1, 4, and 5 all involve the application of ion exchange membranes in the organic electrosynthesis system for the electroreduction of acetone to prepare isopropanol. The difference lies in that the ion exchange membrane used in Application Example 1 is an acetamide-modified MoS2 membrane, the ion exchange membrane used in Application Example 4 is an acetamide-modified graphene oxide membrane, and the ion exchange membrane used in Application Example 5 is an ethane-modified MoS2 membrane. The results showed that the cross-permeability of Application Examples 1, 4, and 5 was 0.7%–5.2%, and the yield of the target product (isopropanol) was 90.2%–95.9%.

[0111] Comparing Application Example 1 with Control Example 1 and Control Example 4: Application Example 1 uses an ion exchange membrane with a MoS2-Acet membrane, and its electrosynthesis reaction system has a cross-permeability of only 0.7% and a yield of the target product (isopropanol) as high as 95.9%. In contrast, under the same conditions, Control Example 1 uses a commercial Nafion 117 membrane, and its electrosynthesis reaction system has a cross-permeability that surges to 22.7% and a yield of only 67.2%. Under the same conditions, Control Example 4 uses an ion exchange membrane with an unmodified MoS2 membrane, and its electrosynthesis reaction system has a cross-permeability as high as 19.7% and a yield of only 70.2%.

[0112] Comparing Application Example 2 with Control Example 2: The ion exchange membrane used in Application Example 2 is a MoS2-Acet membrane, and its electrosynthesis reaction system has a cross-permeability of only 2%, with a yield of the target product (N-methylhydroxylamine) as high as 97.6%; in contrast, under the same conditions, Control Example 2 uses a commercial Nafion 117 membrane, and its electrosynthesis reaction system has a cross-permeability that surges to 50.6%, with a yield of only 45.5%.

[0113] Comparing Application Example 3 with Control Example 3: Application Example 3 uses an ion exchange membrane with a MoS2-Acet membrane, and its electrosynthesis reaction system has a cross-permeability of only 3.8% and a yield of the target product (ethylene sulfate) as high as 86.4%; in contrast, under the same conditions, Control Example 3 uses a commercial Nafion 117 membrane, and its electrosynthesis reaction system has a cross-permeability that surges to 33.8% and a yield of only 58.3%.

[0114] The above demonstrates that ion exchange membranes made of two-dimensional nanomaterials covalently modified with organic molecular fragments can effectively inhibit cross-permeation of organic substances and significantly improve the yield of electrosynthesized products. This is because covalent modification of two-dimensional nanomaterials with organic molecular fragments can introduce strong interaction forces between the nanosheets of the two-dimensional nanomaterials, effectively "anchoring" the interlayer spacing of the nanosheets. When the ion exchange membrane is immersed in a solvent, it can reduce the risk of a large amount of solvent entering the interlayer of the nanosheets and causing severe swelling of the ion exchange membrane, thereby reducing the risk of cross-permeation of organic substances during organic electrosynthesis and improving the product yield.

[0115] The foregoing has provided a detailed description of an ion exchange membrane, its preparation method, its application, and an organic electrosynthesis apparatus provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An ion exchange membrane used for organic electrosynthesis, characterized in that, The ion exchange membrane comprises: Base film; and A functional layer is loaded on the base film. The material of the functional layer includes two-dimensional nanomaterials covalently modified with organic molecular fragments. The two-dimensional nanomaterials include at least one of graphene oxide, transition metal dichalcogenides, and transition metal carbonitrides. The organic molecular fragments have at least one of amide, alkyl, hydroxyl, and carboxyl groups. The organic molecular fragments are used to regulate the interlayer spacing of the two-dimensional nanomaterials. The interlayer spacing of the two-dimensional nanomaterials covalently modified with organic molecular fragments in the functional layer is 0.8 nm to 1.5 nm.

2. The ion exchange membrane according to claim 1, characterized in that, The transition metal disulfides include molybdenum disulfide.

3. The ion exchange membrane according to claim 1, characterized in that, The thickness of the functional layer is 0.5μm to 5μm.

4. The ion exchange membrane according to claim 1, characterized in that, The relative molecular mass of the organic molecular fragment is 10 g / mol to 200 g / mol.

5. The ion exchange membrane according to any one of claims 1 to 4, characterized in that, The base film is made of at least one of nylon, polyethersulfone, polyvinylidene fluoride, and polytetrafluoroethylene; and / or, The base membrane is a porous membrane.

6. A method for preparing an ion exchange membrane, used to prepare the ion exchange membrane according to any one of claims 1 to 5, characterized in that, include: A first dispersion is provided, the first dispersion comprising two-dimensional nanomaterials; An organic molecule is added to the first dispersion, and the organic molecule reacts with the two-dimensional nanomaterial to covalently modify the organic molecule fragment on the two-dimensional nanomaterial to obtain a second dispersion. The two-dimensional nanomaterial modified with organic molecular fragments in the second dispersion is loaded onto a base membrane to obtain an ion exchange membrane.

7. The method for preparing the ion exchange membrane according to claim 6, characterized in that, The two-dimensional nanomaterial includes molybdenum disulfide, and the preparation process of the first dispersion includes: Molybdenum disulfide powder was intercalated using a lithium n-butyl solution with a concentration of 1 mol / L to 3 mol / L and the molybdenum disulfide powder had an average particle size of 1 μm to 10 μm to obtain an intercalated compound. The intercalation compound is added to water and subjected to ultrasonic exfoliation for 1-3 hours to obtain a first dispersion, which is a molybdenum disulfide dispersion with a molybdenum disulfide concentration of 0.5 mg / mL-5 mg / mL; and / or, The reaction time between the organic molecules and the two-dimensional nanomaterial is 0.5 h to 10 h; and / or, The organic molecule is a halogenated compound, which includes at least one of 2-iodoacetamide, 2-bromoacetamide, and 2-chloroacetamide; and / or, Loading the two-dimensional nanomaterial modified with organic molecular fragments in the second dispersion onto a base membrane to obtain an ion exchange membrane includes: depositing the two-dimensional nanomaterial modified with organic molecular fragments in the second dispersion onto a base membrane using a vacuum filtration method to obtain an ion exchange membrane, wherein the vacuum filtration time is 1h to 3h.

8. An organic electrosynthesis apparatus, characterized in that, It includes a cathode, an anode, and an ion exchange membrane disposed between the cathode and the anode, wherein the ion exchange membrane is the ion exchange membrane according to any one of claims 1 to 5 or the ion exchange membrane prepared by the method according to claim 6 or 7.

9. An application characterized in that, The application is the use of ion exchange membranes in organic electrosynthesis, wherein the ion exchange membrane is the ion exchange membrane according to any one of claims 1 to 5 or the ion exchange membrane prepared by the method according to claim 6 or 7.

10. The application according to claim 9, characterized in that, The organic electrosynthesis includes at least one of the following: electroreduction of acetone to prepare isopropanol, electroreduction of nitromethane to prepare N-methylhydroxylamine, and electrooxidation of vinyl sulfite to prepare vinyl sulfate.

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