A polystyrene-divinylbenzenesulfonate foam material, its preparation method and application

Abstract

This invention provides a polystyrene-divinylbenzene sulfonate foam material, its preparation method, and its applications, belonging to the field of electrocatalysis technology. This invention employs a microemulsion method, using styrene and divinylbenzene as raw materials, with an oil phase as the continuous phase and an aqueous phase as the dispersed phase, to obtain a sponge-like porous plate-shaped polystyrene-divinylbenzene sulfonate foam material. The plate-shaped solid electrolyte synthesized by this invention possesses high ion exchange capacity, high porosity, and high mechanical strength, and can be used in the electrochemical synthesis of bulk chemicals such as hydrogen peroxide, methanol, and formic acid. Simultaneously, the integrated plate-shaped design facilitates automated assembly during fuel cell stack production. Furthermore, unlike traditional preparation processes that involve polymerization followed by sulfonation, this invention allows for simultaneous polymerization and sulfonation reactions under mild conditions, eliminating the need for highly corrosive sulfonating reagents, thus facilitating large-scale production.

Description

Technical Field

[0001] This invention relates to the field of electrocatalysis technology, and in particular to a polystyrene-divinylbenzenesulfonate foam material, its preparation method, and its application. Background Technology

[0002] Hydrogen peroxide (H2O2) is widely used in industries such as papermaking, pulp production, disinfection, and wastewater treatment, and is one of the important inorganic chemicals. Currently, the main method for large-scale industrial production of H2O2 is the anthraquinone cycle process. This traditional process not only consumes large amounts of hydrogen and energy but also generates organic waste and requires complex separation processes to obtain high-purity H2O2. Furthermore, it poses safety concerns regarding the transportation and storage of high-concentration hazardous H2O2. Therefore, there is an urgent need for an alternative synthesis method that can reduce energy consumption, waste and costs, and address safety hazards. In recent years, the electrocatalytic two-electron oxygen reduction reaction for the synthesis of H2O2 has attracted widespread attention. Compared with the traditional anthraquinone method, electrochemical synthesis has advantages such as mild reaction conditions, no pollution, no carbon emissions, and low energy consumption, and can also achieve on-site production and use of hydrogen peroxide.

[0003] Currently, the technology for the industrial electrosynthesis of alkaline hydrogen peroxide is relatively mature and applicable to industries such as bleaching and textiles. However, the technology for the industrial electrosynthesis of neutral pure hydrogen peroxide still faces significant challenges. The main difficulties lie in developing high-performance acidic two-electron oxygen reduction catalysts and solving the problem of hydrogen peroxide discharge from the electrolyzer. Recently, some scholars have proposed that a dual-membrane system with a solid electrolyte can effectively solve the above problems (Xia, C.; Xia, Y.; Zhu, P.; Fan, L.; Wang, H. Direct electrosynthesis of pure aqueous H2O2 solutions up to 20% by weight using a solid electrolyte. Science 2019, 366 (6462), 226-231. DOI:doi:10.1126 / science.aay1844.): Hydrogen ions generated by the oxygen evolution reaction at the anode are conducted to the intermediate chamber of the solid electrolyte through the cation exchange membrane; hydroxide and hydrogen peroxide ions generated by the oxygen reduction reaction at the cathode are also conducted to the intermediate chamber of the solid electrolyte through the anion exchange membrane; in the solid electrolyte, hydrogen peroxide and hydrogen ions combine to form hydrogen peroxide. The solid electrolyte used in the intermediate chamber is polystyrene-divinylbenzenesulfonate sodium ion exchange resin particles (…). Figure 1However, these ion exchange resin particles exert strong compressive and shearing forces on the membrane, easily leading to membrane damage during installation and a rapid decrease in the efficiency of hydrogen peroxide electrosynthesis. Furthermore, the assembly process of these resin particles is complex, making large-scale automated assembly difficult. Summary of the Invention

[0004] The purpose of this invention is to provide a polystyrene-divinylbenzenesulfonate foam material, its preparation method, and its application. The polystyrene-divinylbenzenesulfonate foam material has high ion exchange capacity, high porosity, and high mechanical strength, and presents a porous plate-like structure. This avoids the problem of damage to the anion / cation membrane caused by the compression of granular ion exchange resin, and also effectively solves the problem of difficult automated assembly of ion exchange resin.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] This invention provides a method for preparing polystyrene-divinylbenzene sulfonate foam material, comprising the following steps:

[0007] Styrene, divinylbenzene, surfactant, and oil phase initiator are mixed to obtain the oil phase;

[0008] Sodium styrene sulfonate, an aqueous initiator, a stabilizer, and water are mixed to obtain an aqueous phase;

[0009] The oil phase and the aqueous phase are emulsified to obtain a water-in-oil emulsion;

[0010] The water-in-oil emulsion was subjected to a polymerization-sulfonation reaction to obtain polystyrene-divinylbenzene sulfonate sodium foam material.

[0011] Preferably, the surfactant includes one or more of polyoxyethylene ether surfactants and polysorbate surfactants; the oil phase initiator includes one or more of azobisisobutyronitrile, benzoyl peroxide, and cumene peroxide.

[0012] The volume ratio of styrene to divinylbenzene is 0.5~10:1;

[0013] The total mass ratio of styrene and divinylbenzene to surfactant is 3~6:1;

[0014] The total mass ratio of styrene and divinylbenzene to the mass ratio of the oil phase initiator is 10~50:1.

[0015] Preferably, the aqueous initiator includes one or more of potassium persulfate and methyl ethyl ketone peroxide; the auxiliary stabilizer includes one or more of polyvinyl alcohol, methyl cellulose, ethyl cellulose, and polyacryl alcohol; the mass ratio of the total mass of styrene and divinylbenzene to sodium styrene sulfonate is 1~10:1, the mass ratio of sodium styrene sulfonate to the aqueous initiator is 5~20:1, the mass ratio of sodium styrene sulfonate to the auxiliary stabilizer is 1~10:1, and the mass ratio of sodium styrene sulfonate to water is 1:5~300.

[0016] Preferably, the volume ratio of the oil phase to the water phase is 1:5 to 50.

[0017] Preferably, the emulsification conditions include: an air temperature of 10~50℃, a dropping rate of the aqueous phase into the oil phase of 0.2~5mL / min, and a stirring speed of 100~2000 rpm for the overhead stirrer used.

[0018] Preferably, the polymerization-sulfonation reaction is carried out at a temperature of 60~100℃ and the holding time is 8~16 h.

[0019] Preferably, the polystyrene-divinylbenzenesulfonate foam material has a porous plate-like structure.

[0020] This invention provides a polystyrene-divinylbenzenesulfonate foam material prepared by the method described above, wherein the density of the polystyrene-divinylbenzenesulfonate foam material is 10~100 mg·cm³. -3 It has a porosity of 60-100%, an ion exchange capacity of 1-5 mmol / g, and a compressive strength of 10-100 kPa.

[0021] This invention provides the application of the polystyrene-divinylbenzenesulfonate foam material described above as a solid electrolyte in the field of electrocatalytic synthesis.

[0022] Preferably, the target substance for the electrocatalytic synthesis includes hydrogen peroxide, methanol, or formic acid.

[0023] This invention provides a method for preparing polystyrene-divinylbenzene sulfonate foam material. The invention uses a microemulsion method to prepare porous plate-shaped polystyrene-divinylbenzene sulfonate foam material in one step. Styrene and divinylbenzene are used as raw materials, with an oil phase as the continuous phase and an aqueous phase as the dispersed phase. After the continuous oil phase has completed polymerization and solidification, the dispersed aqueous phase is removed by drying treatment to obtain a sponge-like structure of polystyrene-divinylbenzene sulfonate porous plate-shaped foam material.

[0024] Unlike the traditional suspension copolymerization method for preparing polystyrene-divinylbenzene sulfonate resin particles, the plate-shaped foam material synthesized in this invention has high ion exchange capacity, high porosity, and high mechanical strength. It can be used as a solid electrolyte in the electrochemical synthesis of bulk chemicals such as hydrogen peroxide, methanol, and formic acid. In particular, it is beneficial in the electrosynthesis of hydrogen peroxide to reduce the electrosynthesis cell pressure, improve the efficiency of hydrogen peroxide electrosynthesis, reduce energy consumption, and accelerate the removal of hydrogen peroxide products.

[0025] The polystyrene-divinylbenzenesulfonate foam material of this invention can be shaped into continuous sheet-like forms using molds. This overcomes the problem that commercially available solid electrolytes are all made of granular resin (spherical resin stacked together to form a solid electrolyte layer), which is inconvenient for assembly.

[0026] The integrated porous plate-like design structure prepared by the microemulsion method in this invention can avoid the problem of damage to the anion / cation membrane caused by the compression of particulate ion exchange resin. At the same time, the integrated plate-like structure facilitates the automatic assembly during the production of fuel cell stacks, solving the problem of difficult automated assembly of ion exchange resins.

[0027] Furthermore, unlike the traditional preparation process of polymerization followed by sulfonation, this invention adopts a one-step method, which can realize the polymerization and sulfonation reactions simultaneously, greatly simplifying the preparation process, reducing costs, and improving production efficiency. It achieves efficient and low-cost preparation of polystyrene-divinylbenzenesulfonate sodium solid electrolyte, which is of great significance to the industrial development of electrosynthesis technology. Moreover, the reaction conditions are mild, avoiding the use of highly corrosive sulfonating agents, which facilitates large-scale production.

[0028] Furthermore, this polystyrene-divinylbenzenesulfonate foam material, as a solid electrolyte, is not only suitable for the electrosynthesis of hydrogen peroxide, but can also be widely used in other electrochemical conversion processes. For example, in the fields of carbon dioxide reduction, electrocatalytic synthesis of methanol and formic acid, this material can provide stable ion conduction channels, improving reaction selectivity and efficiency. At the same time, its excellent chemical stability and mechanical strength make it a potential application in electrochemical energy storage systems.

[0029] The polystyrene-divinylbenzenesulfonate foam material of this invention has a uniform microstructure and a density of 10~100 mg·cm³. -3 It has a porosity of 60-100%, an ion exchange capacity of 1-5 mmol / g, and a compressive strength of 10-100 kPa. Attached Figure Description

[0030] Figure 1 A schematic diagram of an electrolyzer with a dual-membrane and solid electrolyte system;

[0031] Figure 2Scanning electron microscope images and photographs of the polystyrene-divinylbenzenesulfonate sodium prepared in Example 3 at different scales, where a is 2 μm, b is 5 μm, c is 20 μm, d is 100 μm, and the inset in d is a photograph of the appearance.

[0032] Figure 3 Fourier transform infrared spectrum of sodium polystyrene-divinylbenzenesulfonate prepared in Example 3;

[0033] Figure 4 The chronovoltage curves of sodium polystyrene-divinylbenzenesulfonate prepared in Examples 1 and 3 with particulate solid electrolyte in a neutral two-electron oxygen reduction hydrogen peroxide electrolyzer are shown.

[0034] Figure 5 The concentration change curves of hydrogen peroxide produced by the polystyrene-divinylbenzenesulfonate sodium prepared in Examples 1 and 3 and particulate solid electrolyte in a neutral two-electron oxygen reduction hydrogen peroxide electrolyzer are shown.

[0035] Figure 6 The Faraday efficiency curves of the polystyrene-divinylbenzenesulfonate sodium prepared in Examples 1 and 3 and the particulate solid electrolyte in a neutral two-electron oxygen reduction hydrogen peroxide electrolyzer are shown. Detailed Implementation

[0036] In this invention, unless otherwise specified, the raw materials or reagents required for preparation are all commercially available products well known to those skilled in the art.

[0037] This invention provides a method for preparing polystyrene-divinylbenzene sulfonate foam material, comprising the following steps:

[0038] Styrene, divinylbenzene, surfactant, and oil phase initiator are mixed to obtain the oil phase;

[0039] Sodium styrene sulfonate, an aqueous initiator, a stabilizer, and water are mixed to obtain an aqueous phase;

[0040] The oil phase and the aqueous phase are emulsified to obtain a water-in-oil emulsion;

[0041] The water-in-oil emulsion was subjected to a polymerization-sulfonation reaction to obtain polystyrene-divinylbenzene sulfonate sodium foam material.

[0042] This invention involves mixing styrene, divinylbenzene, a surfactant, and an oil phase initiator to obtain an oil phase.

[0043] In this invention, the surfactant preferably includes one or more of polyoxyethylene ether surfactants and polysorbate surfactants; the polyoxyethylene ether surfactant is preferably Tween 80 or Tween 60, and the polysorbate surfactant is preferably Span 80; the oil phase initiator preferably includes one or more of azobisisobutyronitrile, benzoyl peroxide, and cumene peroxide; when the surfactant or oil phase initiator is two or more of the above, this invention does not have a special limitation on the ratio of different types of reagents, and any ratio is acceptable.

[0044] In this invention, the volume ratio of styrene to divinylbenzene is preferably 0.5 to 10:1, more preferably 1 to 5:1; the mass ratio of the total mass of styrene and divinylbenzene to the surfactant is preferably 3 to 6:1, more preferably 3.75 to 5:1; and the mass ratio of the total mass of styrene and divinylbenzene to the oil phase initiator is preferably 10 to 50:1, more preferably 22.68 to 35:1.

[0045] In this invention, styrene and divinylbenzene are mixed, followed by the addition of a surfactant and an oil-phase initiator, and then ultrasonically mixed to obtain an oil phase. This invention does not impose any particular limitation on the ultrasonic mixing; mixing under ultrasonic conditions well-known in the art is acceptable.

[0046] This invention involves mixing sodium styrene sulfonate, an aqueous initiator, a stabilizer, and water to obtain an aqueous phase.

[0047] In this invention, the aqueous initiator preferably includes one or more of potassium persulfate and methyl ethyl ketone peroxide; the auxiliary stabilizer preferably includes one or more of polyvinyl alcohol, methyl cellulose, ethyl cellulose and polyacryl alcohol; when the aqueous initiator or auxiliary stabilizer is two or more of the above, this invention does not have a special limitation on the ratio of different types of reagents, and any ratio is acceptable.

[0048] In this invention, the mass ratio of the total mass of styrene and divinylbenzene to sodium styrene sulfonate is 1~10:1, more preferably 3~4.5:1; the mass ratio of sodium styrene sulfonate to aqueous initiator is preferably 5~20:1, more preferably 10:1; the mass ratio of sodium styrene sulfonate to stabilizer is preferably 1~10:1, more preferably 2~3:1, and even more preferably 2.5:1; the mass ratio of sodium styrene sulfonate to water is preferably 1:5~300, more preferably 1:90~210, and even more preferably 1:120~150.

[0049] The present invention does not impose any special limitations on the mixing conditions of the components in the aqueous phase; the components can be dissolved in water according to a process known in the art.

[0050] The present invention emulsifies the oil phase and the water phase to obtain a water-in-oil emulsion.

[0051] In this invention, the volume ratio of the oil phase to the water phase is preferably 1:5~50, more preferably 1:18~36, and even more preferably 1:24~30.

[0052] In this invention, the aqueous phase is preferably added dropwise to the oil phase and emulsified using a paddle mixer until a stable water-in-oil emulsion is formed.

[0053] In this invention, the emulsification conditions preferably include: an air temperature of 10~50℃, a dropping rate of the aqueous phase into the oil phase of 0.2~5 mL / min, and a stirring speed of 100~2000 rpm using a top-mounted stirrer. More preferably, the emulsification conditions are an air temperature of 25℃, a dropping rate of 1~1.5 mL / min, and a stirring speed of 400 rpm.

[0054] After obtaining the water-in-oil emulsion, the present invention performs a polymerization-sulfonation reaction on the water-in-oil emulsion to obtain polystyrene-sodium divinylbenzenesulfonate foam material.

[0055] In this invention, the water-in-oil emulsion is uniformly poured into a pre-prepared mold, ensuring that it is fully filled, and then placed in a vacuum drying oven. The mold is heated and kept warm at a set temperature to carry out a polymerization-sulfonation reaction. After the reaction is completed, the mold is cooled to room temperature, and after demolding, the product is washed with deionized water and ethanol in sequence to remove unreacted monomers and surface residues. The product is then dried in a forced-air drying oven to obtain polystyrene-divinylbenzene sulfonate foam material.

[0056] Unlike existing granular resin solid electrolytes, the polystyrene-divinylbenzenesulfonate foam material of this invention can be molded into any shape, and then subjected to heating polymerization and curing to form a specific shape. For application as a solid electrolyte in electrolytic cells, this invention uses the solid electrolyte chamber of a common electrolytic cell as a mold to synthesize a sheet-like foam material. A limiting cover plate is used to flatten and secure the uniform emulsion without applying additional pressure. Subsequently, heating polymerization and curing are performed to shape it into a sheet-like foam material resembling the solid electrolyte chamber of an electrolytic cell.

[0057] In this invention, the temperature of the polymerization-sulfonation reaction is preferably 60~100℃, more preferably 70~80℃, and the holding time is preferably 8~16 h, more preferably 14 h.

[0058] After the polymerization-sulfonation reaction is completed, the product is preferably cooled to room temperature, demolded, and then washed with deionized water and ethanol in sequence. It is then dried in a 60°C forced-air drying oven to obtain polystyrene-divinylbenzene sulfonate foam material.

[0059] In this invention, the polystyrene-divinylbenzenesulfonate foam material is preferably a porous plate structure.

[0060] This invention provides a polystyrene-divinylbenzenesulfonate foam material prepared by the method described above, wherein the density of the polystyrene-divinylbenzenesulfonate foam material is 10~100 mg·cm³. -3 It has a porosity of 60-100%, an ion exchange capacity of 1-5 mmol / g, and a compressive strength of 10-100 kPa.

[0061] This invention provides the application of the polystyrene-divinylbenzenesulfonate foam material described above as a solid electrolyte in the field of electrocatalytic synthesis.

[0062] In this invention, the target substance for electrocatalytic synthesis preferably includes hydrogen peroxide, methanol, or formic acid.

[0063] The principle of this invention: This invention achieves one-step preparation of a porous plate-like solid electrolyte of sodium styrene-divinylbenzenesulfonate via a microemulsion method. The core principle lies in utilizing a water-in-oil emulsion system as a reaction platform, with the oil phase as the continuous phase and the aqueous phase as the dispersed phase. A surfactant is added as a stabilizer at the oil / water interface, along with a co-stabilizer. High-speed stirring forms a stable emulsion structure, and polymerization and sulfonation reactions occur simultaneously within this system. The added co-stabilizer forms hydrogen bonds with water molecules through its hydroxyl groups, increasing the viscosity of the aqueous phase and the stability of the system, preventing the breakage or coalescence of water-in-oil emulsion droplets. It also forms a protective layer at the oil-water interface, preventing phase separation and promoting the formation of uniform polymer particles. Tween 80, as a nonionic surfactant, significantly reduces the interfacial tension between the aqueous and oil phases, helping to form a stable water-in-oil emulsion. After adsorption at the interface, it further inhibits droplet coalescence and, under high-speed conditions, promotes the uniform dispersion of hydrophobic monomers (such as divinylbenzene), providing a uniform microenvironment for the subsequent polymerization reaction. Styrene and divinylbenzene in the oil phase undergo free radical polymerization under the action of an oil-phase initiator. Simultaneously, sodium styrene sulfonate in the aqueous phase not only serves as a precursor for the introduced sulfonic acid groups but also synergistically reacts with the aqueous initiator to undergo polymerization in the aqueous phase, thus achieving an integrated polymerization and sulfonation process. This method avoids the cumbersome steps of polymerization followed by sulfonation required in traditional processes. Utilizing the continuous phase characteristics of the emulsion system, the resulting polymer exhibits a continuous, sponge-like porous structure, significantly improving ionic conductivity and mechanical strength. Furthermore, by optimizing the proportions of each component in the emulsion system and controlling the emulsification conditions, precise control over the polymer's microstructure is achieved, ensuring the consistency and repeatability of material properties. This provides an efficient, low-cost, and high-performance solid-state electrolyte solution for electrochemical devices.

[0064] The polystyrene-divinylbenzene sulfonate foam material prepared in this invention plays a crucial role as a solid electrolyte in electrochemical devices, with its performance advantages mainly reflected in proton conductivity, mechanical stability, and chemical stability. The material's molecular structure contains sulfonic acid groups (-SO3H), which can combine with water molecules to form proton conduction channels, effectively achieving efficient proton transfer in devices such as electrolytic cells for the production of organic matter through electroreduction, thus ensuring the smooth progress of electrochemical reactions. Simultaneously, the styrene and divinylbenzene monomers form a highly cross-linked three-dimensional network structure during the polymerization reaction. This porous solid electrolyte improves ionic conductivity, enhances battery performance, promotes ion migration, and improves mechanical properties, reducing electrolyte embrittlement, thereby improving battery efficiency, cycle life, and reliability. Furthermore, styrene-divinylbenzene sulfonate itself possesses excellent chemical stability, can withstand acidic or oxidizing environments, and is not easily degraded or degraded, extending the electrolyte's lifespan. The porous structure prepared by the microemulsion method further enhances the continuity and uniformity of the ion conduction channels, making the overall performance of the material superior and providing a reliable guarantee for the efficient operation of devices such as fuel cells and electrolytic cells.

[0065] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Unless otherwise specified, the experimental methods described in the embodiments of the present invention are conventional methods.

[0066] Unless otherwise specified, the experimental and testing methods described below are conventional methods; unless otherwise specified, the reagents and raw materials described below are commercially available.

[0067] Example 1

[0068] (1) Take 0.25 mL of divinylbenzene and 0.25 mL of styrene, the total mass of divinylbenzene and styrene is 0.45 g, add 0.12 g of surfactant Tween 80 and 0.02 g of initiator azobisisobutyronitrile, mix evenly by ultrasonication to obtain the oil phase;

[0069] (2) Dissolve 0.1 g sodium styrene sulfonate, 0.01 g potassium persulfate and 0.04 g polyvinyl alcohol in 9 mL of deionized water to obtain an aqueous phase;

[0070] (3) Add 9 mL of the aqueous phase to 0.5 mL of the oil phase at a dropping rate of 1.5 mL / min, and emulsify using a paddle mixer at a stirring speed of 400 rpm at 25°C until a stable water-in-oil emulsion is formed.

[0071] (4) Pour the emulsion evenly into the prepared mold (e.g., Figure 1 The solid electrolyte chamber of the electrolytic cell (shown) is filled to ensure that it is fully filled. Then, it is placed in a vacuum drying oven and heated to 70°C and kept at that temperature for 14 hours to carry out a polymerization-sulfonation reaction. After the reaction is completed, it is cooled to room temperature, demolded, and then washed with deionized water and ethanol in sequence. It is then dried in a 60°C forced-air drying oven to obtain polystyrene-divinylbenzene sulfonate foam material.

[0072] Example 2

[0073] The only difference from Example 1 is that in step (2), it is dissolved in 12 mL of deionized water to obtain an aqueous phase, and in step (3), 12 mL of the aqueous phase is added dropwise to 0.5 mL of the oil phase.

[0074] Example 3

[0075] The only difference from Example 1 is that in step (2), it is dissolved in 15 mL of deionized water to obtain an aqueous phase, and in step (3), 15 mL of the aqueous phase is added dropwise to 0.5 mL of the oil phase.

[0076] Example 4

[0077] The only difference from Example 1 is that in step (2), it is dissolved in 18 mL of deionized water to obtain an aqueous phase, and in step (3), 18 mL of the aqueous phase is added dropwise to 0.5 mL of the oil phase.

[0078] Example 5

[0079] The only difference from Example 1 is that in step (2), it is dissolved in 21 mL of deionized water to obtain an aqueous phase, and in step (3), 21 mL of the aqueous phase is added dropwise to 0.5 mL of the oil phase.

[0080] Example 6

[0081] The only difference from Example 3 is that in step (1), 0.2 mL of divinylbenzene and 0.3 mL of styrene are taken, and the total mass of styrene and divinylbenzene is 0.45 g. The rest is the same as in Example 3.

[0082] Example 7

[0083] The only difference from Example 6 is that in step (1), 0.3 mL of divinylbenzene and 0.2 mL of styrene are taken, and the total mass of styrene and divinylbenzene is 0.46 g.

[0084] Example 8

[0085] The only difference from Example 3 is that 0.15 g of surfactant Tween 80 is added in step (1), otherwise it is the same as Example 3.

[0086] Example 9

[0087] The only difference from Example 8 is that 0.09 g of surfactant Tween 80 is added in step (1).

[0088] Example 10

[0089] The only difference from Example 3 is that 0.15 g of sodium styrene sulfonate is used in step (2), and the rest is the same as in Example 3.

[0090] Example 11

[0091] The only difference from Example 10 is that 0.05 g of sodium styrene sulfonate is used in step (2).

[0092] Example 12

[0093] The only difference from Example 3 is that 0.12 g of surfactant Span 80 is added in step (1), otherwise it is the same as Example 3.

[0094] Example 13

[0095] The only difference from Example 12 is the addition of 0.12 g of surfactant Tween 60.

[0096] Structural characterization

[0097] Figure 2 Scanning electron microscope images and photographs of the polystyrene-divinylbenzenesulfonate sodium prepared in Example 3 at different scales are shown, where a is 2 μm, b is 5 μm, c is 20 μm, and d is 100 μm. The inset in d is a photograph of the appearance. In the microemulsion method, a porous polymer is synthesized through a water-in-oil system, where the proportion of added aqueous phase adjusts the amount of pores. Under the action of Tween 80, the organic phase and aqueous phase are successfully emulsified to form an oil-in-water emulsion. With the polymerization of the organic phase monomers and the subsequent drying process, the positions of the aqueous phase are replaced by countless tiny pores, thus forming a micron-scale rough structure on the framework of the polystyrene sponge material. After removing the aqueous phase and surfactant, "pits" are left on the pore wall surface, further increasing the roughness of the pore walls (e.g., ...). Figure 2 As shown). The synthesized material has a pale yellow appearance (as shown). Figure 2 (d) also provides a macroscopic and intuitive demonstration of the successful introduction of the sulfonic acid group.

[0098] Figure 3 Fourier transform infrared spectrum of sodium polystyrene-divinylbenzenesulfonate prepared in Example 3; as Figure 3 As shown, 3441 cm -1 The broad peak at 2922 cm⁻¹ is due to the stretching vibrations of water molecules in the polymer and the OH bonds in the sulfonic acid groups of the sulfonated polymer. -1 The peak is the -CH2- vibration peak, at 1603 cm⁻¹. -1 The peak observed at 1447 cm⁻¹ corresponds to the planar stretching vibration of the C-C bonds in the styrene benzene ring framework. - The vibrational band at position ¹ is due to the weaker effect of the benzene ring and the higher proportion of the sulfonated portion compared to the polystyrene portion in the crosslinking core. (1200~1100 cm) -1 The strong antisymmetric / symmetric stretching vibration absorption peak of the S=O group in Example 3 indicates the presence of a sulfonic acid group, consistent with the standard spectrum. Therefore, the Fourier transform infrared spectrum of sodium styrene-divinylbenzenesulfonate in Example 3 clearly demonstrates the successful one-step synthesis of the sulfonated polymer.

[0099] Performance testing

[0100] 1) Porosity: Polystyrene-divinylbenzenesulfonate foam materials prepared in different cases were dried to constant weight as solid electrolyte samples, and their geometric volume was measured. V 几何 Helium gas was introduced into the sample using a helium hydrometer to determine the sample's skeletal volume. V 骨架 Porosity is calculated using the following formula:

[0101]

[0102] in, V 几何 The geometric volume of the sample is in cm. 3 ; V 骨架 To determine the skeletal volume of a sample using a helium hydrometer, in cm³ 3 .

[0103] 2) Ion exchange capacity (IEC): Weigh a certain mass of a dry solid electrolyte sample and record the mass. m 样品 The sample was immersed in 0.1 M HCl solution, sealed, and allowed to stand for a certain period of time to allow the exchangeable cations in the sample to be completely replaced by hydrogen ions. Subsequently, the sample was removed from the acid solution and thoroughly rinsed with deionized water to remove residual acid.

[0104] The washed sample was placed in 0.1 M NaOH solution, and the mixture was shaken thoroughly to allow the hydrogen ions in the sample to neutralize the alkali in the solution. After the reaction was complete, the sample was removed, and the remaining alkali in the solution was titrated with 0.1 M HCl solution. The volume of acid solution consumed was recorded. V 酸

[0105] The ion exchange capacity (IEC) is calculated using the following formula.

[0106]

[0107] in C 酸 The acid concentration is 0.1 M; V 酸 The volume of the acid titration is in cm. 3 ; m 样品 The mass is the sample mass, expressed in grams (g).

[0108] 3) Compressive Strength: Prepare solid electrolyte samples to standard dimensions, ensuring a smooth surface free of cracks or defects. Use a materials testing machine to test the sample on a loading platform, ensuring the force direction is perpendicular to the loading surface. Set the loading speed and gradually apply pressure until the sample is crushed or shows significant damage. Record the maximum load at sample failure according to the formula. F max.

[0109]

[0110] Where σ is the compressive strength, in kPa; F max is the maximum load, in N; A The cross-sectional area of ​​the sample under pressure is in cm². 2 .

[0111] 4) Test the performance of the solid electrolyte in the electrolytic cell. Install the solid electrolyte material in the electrolytic cell, ensuring good contact between the electrolyte and the electrode. The electrode configuration uses an iridium-titanium electrode as the anode for the OER reaction and Cabot carbon as the cathode catalyst for the 2e reaction. -ORR reaction. Deionized water was added as the electrolyte to both the cathode and anode of the electrolyzer. The cathode electrolyte volume was 500 mL and recycled. High-purity oxygen was introduced into the cathode, and a 5 A constant current source was applied to control the current. During the test, the voltage of the electrolyzer was recorded, and the hydrogen peroxide concentration in the electrolyte was monitored. The performance of the solid electrolyte in practical applications was evaluated by analyzing the cell voltage, product formation rate, and efficiency.

[0112] Test results

[0113] 1. The test results of Examples 1 to 5 are shown in Table 1. The water phase ratio is calculated as water phase volume × 100% / (water phase + oil phase) total volume. Tween or Span, as surfactants, are not included in the oil phase volume. This water phase ratio is used to illustrate the degree of material expansion.

[0114] Table 1. Test results of sodium polystyrene-divinylbenzenesulfonate in Examples 1-5

[0115]

[0116] As shown in Table 1, compared with samples with different amounts of aqueous phase added, Example 3 exhibits superior performance across multiple indicators, demonstrating outstanding overall performance. Firstly, the ion exchange capacity of Example 3 reaches 3.56 mmol / g, close to the experimental peak value, second only to Examples 4 and 5, indicating high functionality and the ability to effectively meet the requirements of high-efficiency ion exchange. The porosity of Example 3 is 95.7%, which not only avoids the decrease in mechanical strength caused by excessive porosity but also ensures good ion transport channels, thus maintaining structural stability. Meanwhile, the compressive strength of Example 3 is 31 kPa, lower than Examples 1 and 2, but significantly better than Examples 4 and 5, fully demonstrating its high mechanical stability and ability to withstand greater external pressure in practical applications. Finally, the density of Example 3 is 24.5 mg / cm³, an optimized mass density that effectively achieves lightweighting while maintaining mechanical properties, making it more widely applicable in practical applications.

[0117] In addition, the solid electrolyte products prepared in Examples 1 and 3 were assembled into an electrolytic cell, and their electrochemical performance was compared with that of 732 strong acid styrene cation exchange resin (denoted as granular solid electrolyte) purchased from Aladdin Company. The results are shown in […]. Figures 4-6 . Figures 4-6The results show that the foamed styrene-divinylbenzenesulfonate prepared by this invention has significant advantages in terms of cell pressure, electrolytic hydrogen peroxide production capacity, and efficiency. Furthermore, Example 3 demonstrates superior performance compared to Example 1, indicating that optimizing the aqueous phase ratio can effectively optimize the ion conduction of the solid electrolyte in the electrolytic cell and prevent side reactions. In summary, the polystyrene-divinylbenzenesulfonate prepared in Example 3 exhibits balanced performance in terms of ion exchange capacity, porosity, and compressive strength, demonstrating ideal comprehensive performance and making it a preferred option for high-efficiency solid electrolytes.

[0118] 2. The test results of Examples 3 and 6-7 are shown in Table 2.

[0119] Table 2 Comparison of test results of sodium polystyrene-divinylbenzenesulfonate in Examples 6-7 and Example 3

[0120]

[0121] To investigate the effect of crosslinking agents on the properties of sulfonated polymers, the addition ratio of divinylbenzene to styrene was adjusted in Examples 6 and 7 (Table 2). Example 6 exhibited insufficient mechanical strength and stability due to the decrease in the amount of divinylbenzene added as a crosslinking agent. In Example 7, the volume ratio of divinylbenzene to styrene was increased from 1:1 to 1.5:1, thus increasing the proportion of the crosslinking agent. This directly affected the degree of crosslinking of the polymer, as divinylbenzene, as a crosslinking monomer, can form a three-dimensional network structure through its double bonds during polymerization. As the amount of crosslinking agent increases, the number of crosslinking points between molecules increases, resulting in a more compact and stable polymer chain, and a corresponding increase in the degree of crosslinking. The advantage of a high degree of crosslinking is enhanced polymer mechanical properties, manifested as higher compressive strength and greater durability. Simultaneously, a decrease in the proportion of the aqueous phase also optimizes compressive strength. However, a high degree of crosslinking also negatively impacts porosity and ion exchange capacity. With increasing crosslinking, the microporous structure of the polymer becomes more compact, and the porosity decreases. This high degree of crosslinking also limits the number and size of ion transport pathways, thereby inhibiting ion exchange capacity. Furthermore, the decrease in ion exchange capacity is also due to the reduced effective accessibility of sulfonated groups caused by excessive crosslinking. This is because excessive crosslinking structurally limits the exposed area of ​​sulfonated groups, preventing some active sites from effectively participating in the ion exchange reaction. Therefore, Example 7 showed a decrease in porosity and ion exchange capacity. This difference highlights the significant impact of controlling the amount of crosslinking agent on the final material properties.

[0122] 3. The test results of Examples 3 and 8-9 are shown in Table 3.

[0123] Table 3 Comparison of test results between Examples 8-9 and Example 3

[0124]

[0125] To investigate the effect of surfactant dosage on emulsions, the amount of Tween 80 was adjusted in Examples 8 and 9 (Table 3). Increasing the amount of surfactant improved emulsification, making the emulsion more stable and with a more uniform particle size distribution, which helped to form a finer and more uniform pore structure. The final polymer had higher porosity and finer pore size, thereby improving ion exchange capacity. However, excessive surfactant inhibited the efficiency of crosslinking reactions, leading to a decrease in the degree of crosslinking, which affected the mechanical strength of the polymer. Therefore, although the polymer of Example 9 showed improvements in ion exchange capacity and pore structure, its mechanical properties were inferior to those of Examples 8 and 3. A higher amount of surfactant in the emulsion provides certain advantages in porosity and ion exchange capacity, but its mechanical stability is lower.

[0126] 4. The test results of Examples 3 and 10-11 are shown in Table 4.

[0127] Table 4 Comparison of test results between Examples 10-11 and Example 3

[0128]

[0129] To investigate the effect of sulfonic acid group content on the polymer's performance as a solid electrolyte, the amount of sodium styrene sulfonate was adjusted in Examples 10 and 11 to control its content (Table 4). Example 10 added more sodium styrene sulfonate; however, the excessively high sulfonic acid group content increased both the polymer's brittleness and hardness, ultimately resulting in low mechanical strength unsuitable for assembly. In Example 11, the sample with a lower amount of sodium styrene sulfonate did not achieve the optimal ion exchange capacity; therefore, the amount of sodium styrene sulfonate added in Example 3 was superior.

[0130] 5. The test results of Examples 3 and 12-13 are shown in Table 5.

[0131] Table 5 Comparison of test results of sulfonated polymers in Examples 12-13 with those in Example 3

[0132]

[0133] Further experiments investigated the effect of surfactants on the emulsion interface, with the type of surfactant changed in Examples 12 and 13 (Table 5). Tween 60 was used in Example 12, while Span 80 was used in Example 13. The results showed that the emulsions in the Tween 80 group exhibited higher porosity and ion exchange capacity. Specifically, Tween 80 effectively improved the pore structure of the emulsion, forming a more uniform oil-water distribution, thereby enhancing the stability of the emulsion. Furthermore, Tween 80 also increased the ion exchange capacity, possibly related to its strong hydrophilicity and optimized interfacial stability. In contrast, the emulsions in the Tween 60 and Span 80 groups had lower porosity and ion exchange capacity, indicating weaker emulsification effects, resulting in a more compact emulsion structure and decreased ion exchange performance. Therefore, Tween 80 can be considered a preferred surfactant in this one-step synthesis of styrene-divinylbenzene sulfonate systems.

[0134] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An application of a polystyrene-divinylbenzenesulfonate foam material as a solid electrolyte in the field of electrocatalytic synthesis, characterized in that... The preparation method of the polystyrene-divinylbenzenesulfonate foam material includes the following steps: Styrene, divinylbenzene, surfactant, and oil phase initiator are mixed to obtain the oil phase; Sodium styrene sulfonate, an aqueous initiator, a stabilizer, and water are mixed to obtain an aqueous phase; The oil phase and the aqueous phase are emulsified to obtain a water-in-oil emulsion; The water-in-oil emulsion was subjected to a polymerization-sulfonation reaction to obtain polystyrene-sodium divinylbenzenesulfonate foam material. The polymerization-sulfonation reaction is carried out at a temperature of 60~100℃ for 8~16 h. The polystyrene-divinylbenzenesulfonate foam material has a porous plate-like structure.

2. The application according to claim 1, characterized in that, The surfactant includes one or more of polyoxyethylene ether surfactants and polysorbate surfactants; the oil phase initiator includes one or more of azobisisobutyronitrile, benzoyl peroxide, and cumene peroxide. The volume ratio of styrene to divinylbenzene is 0.5~10:1; The total mass ratio of styrene and divinylbenzene to surfactant is 3~6:1; The total mass ratio of styrene and divinylbenzene to the mass ratio of the oil phase initiator is 10~50:

1.

3. The application according to claim 1, characterized in that, The aqueous initiator includes one or more of potassium persulfate and methyl ethyl ketone peroxide; the auxiliary stabilizer includes one or more of polyvinyl alcohol, methyl cellulose, ethyl cellulose, and polyacryl alcohol; the mass ratio of the total mass of styrene and divinylbenzene to sodium styrene sulfonate is 1~10:1, the mass ratio of sodium styrene sulfonate to the aqueous initiator is 5~20:1, the mass ratio of sodium styrene sulfonate to the auxiliary stabilizer is 1~10:1, and the mass ratio of sodium styrene sulfonate to water is 1:5~300.

4. The application according to claim 1, 2, or 3, characterized in that, The volume ratio of the oil phase to the water phase is 1:5~50.

5. The application according to claim 4, characterized in that, The emulsification conditions include: an air temperature of 10~50℃, a dropping rate of 0.2~5 mL / min from the aqueous phase to the oil phase, and a stirring speed of 100~2000 rpm for the overhead stirrer.

6. The application according to claim 5, characterized in that, The density of the polystyrene-divinylbenzenesulfonate foam material is 10~100 mg·cm³. -3 It has a porosity of 60-100%, an ion exchange capacity of 1-5 mmol / g, and a compressive strength of 10-100 kPa.

7. The application according to claim 1, characterized in that, The target substances for the electrocatalytic synthesis include hydrogen peroxide, methanol, or formic acid.

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