CN116574371A - Conjugated branched anion exchange membrane, preparation method and application - Google Patents

Abstract

The application relates to the technical field of alkaline water electrolytic baths, and particularly discloses a preparation method and application of a conjugated branched anion exchange membrane. The synthesis strategy of the application is simple, convenient and effective, low in preparation cost, excellent in performance, strong in universality, convenient for industrial production and has great application potential.

Description

A kind of conjugated branched anion exchange membrane, preparation method and application

technical field

The invention belongs to the technical field of alkaline water electrolyzers, and in particular relates to a conjugated branched anion exchange membrane, a preparation method and an application.

Background technique

The development of green hydrogen energy is crucial to optimize the current energy structure and achieve sustainable growth of mankind. The electrolysis of water hydrogen production technology combined with renewable energy will be the main way to produce green hydrogen energy, and it will also occupy most of the hydrogen energy production market in the future. Alkaline water hydrogen production electrolyzer does not use precious metal resources in the manufacturing process, the cost is low, and it also has the advantage of long working life. As a key component in the alkaline electrolyzed water device, the diaphragm plays the role of isolating hydrogen and oxygen and transferring ions in the electrolytic cell. An ideal separator should have high air tightness, high electrical conductivity, and excellent dimensional stability and alkali resistance. The separators on the market at this stage are mainly the Zirfon series membranes developed by Agfa in Belgium and the PPS cloth of Toray. However, these two membranes have high surface resistance, which makes the energy consumption of hydrogen production by electrolysis of water too high, resulting in the high cost of hydrogen production, which limits the further promotion of alkaline electrolysis of water technology.

Anion-exchange membrane electrolyzer (AEMWE) is an emerging water electrolysis technology. Wherein, the used anion exchange membrane (AEM) is a kind of high molecular polymer membrane containing basic active groups and having selective permeability to anions. The dense homogeneous membrane can effectively prevent the cross-channeling of hydrogen and oxygen at the two poles, and the excellent ion conductivity gives AEMWE a higher current density. For example, AEMWE based on polyarylpiperidine-based AEM has a current density of up to 1600mA cm ^-2 under the conditions of 1M KOH solution, 80°C, and nickel-based catalyst (Lee, YMEnergy Environ.Sci., 2021, 14, 6338-6348 ), showing good application prospects. After years of hard work, researchers have gradually developed a series of AEMs with excellent comprehensive properties, but most of the AEMs reported in the literature often require the use of expensive transitions during the preparation of polymerized monomers, polymerization reactions, or post-polymer functionalization. Metal catalysts or high-cost and highly corrosive superacid catalysts inevitably lead to an increase in the cost of anion exchange membrane preparation, which largely limits the further promotion and application of AEMWE. Therefore, the development of simple and effective synthetic strategies to prepare anion exchange membrane materials with low cost and excellent performance is still the focus and difficulty of current research.

Contents of the invention

Aiming at the deficiencies of the prior art, the object of the present invention is to propose a conjugated branched anion exchange membrane, its preparation method and application, and the electrolyzer constructed by this type of membrane exhibits excellent performance in electrolyzing water.

To achieve this goal, the present invention adopts the following technical solutions:

A kind of conjugated branched polymer, general structural formula is as follows:

Wherein x is the degree of branching (%), and the scope of x is 1-20; R is one or more in the following structures:

The M structure is one or more of the following:

Q=F, Cl, Br, I

A kind of preparation method of conjugated branched anion exchange membrane is characterized in that, comprises the following steps:

(1) Polymer preparation: in an inert gas atmosphere at -10-20°C, place the catalyst in the organic solvent a and stir for 10-120 minutes, then add the polymerized monomer mixture dropwise to start the reaction. After reacting for 24-144h, it was quenched with an alkaline solution, and then extracted to obtain a polymer precursor. Dissolve the polymer precursor in the organic solvent b, add the amine solution under an inert atmosphere, react at 20-80°C for 24-72 hours, the organic solvent sinks out of the polymer, wash it with water for 2-8 times, and dry it in vacuum to obtain a pure polymer product.

(2) Dissolving the polymer obtained in step (1) in the organic solvent b. After filtering and defoaming, casting to form a membrane, the conjugated branched anion exchange membrane is obtained.

The inert atmosphere is nitrogen or argon;

The catalyst is one or more of subgroup metals and their corresponding oxides and halides; more preferably copper, zinc, copper-zinc alloy, magnesium, zinc-silver alloy, titanium trichloride, titanium tetrachloride, etc.

The polymerized monomer mixture is selected from a mixture of difunctional and trifunctional acid chloride monomers, wherein the difunctional acyl chloride monomers include but not limited to terephthaloyl dichloride and biphthaloyl dichloride, and the trifunctional acyl chloride monomers include But not limited to trimesoyl chloride, 1,3,5-tris(p-formyl chloride)benzene, 3,4',5-triacyl chloride-1,1-biphenyl, tris(4-formyl chloride phenyl) phosphine. The addition of the trifunctional acid chloride monomer significantly improved the electrochemical performance of the membrane material.

The molar ratio of the polymerized monomer mixture to the entire system is 0.1-15%; if the molar ratio is too high, it will lead to gelation and cannot obtain a soluble polymer.

The alkaline solution described in step (1) is one or more aqueous solutions in potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate;

The organic solvent a described in step (1) is methanol, ethanol, N,N'-dimethylformamide, dimethyl sulfoxide, ether, acetone, tetrahydrofuran, ethyl acetate, dichloromethane, chloroform, tetrachloro One or more mixtures of carbon dioxide and petroleum ether.

The amine solution in step (1) includes but not limited to trimethylamine aqueous solution.

The organic solvent b described in step (1), (2) is N-methylpyrrolidone, N,N'-dimethylformamide, N,N'-dimethylacetamide, dimethyl sulfoxide One or more solvents are mixed in any ratio.

The present invention also proposes the application of the anion exchange membrane in the alkaline electrolyzed water device, comprising the following steps:

(1) Membrane electrode preparation: dissolving the conjugated branched anion exchange membrane in a polar organic solvent to obtain an ionomer solution; uniformly dispersing the catalyst Pt/C and _IrO in a dispersant to prepare a catalyst solution; The ionomer solution and the catalyst solution are evenly mixed, and then evenly sprayed on both sides of the conjugated branched anion exchange membrane to form a membrane electrode; then ion exchange is performed in an alkaline solution;

(2) Assemble the electrolyzed water device: sandwich the membrane electrode between the anode and cathode to assemble the electrolyzed water device.

Polar organic solvents include NMP, DMF, DMSO, DMAc, and the like.

Preferably, the application of the anion exchange membrane in the alkaline electrolyzed water device comprises the following steps:

(1) Membrane electrode preparation: the above-mentioned anion exchange membrane was dissolved in DMSO (4wt%) as an ionomer solution. After that, a certain amount of Pt/C and IrO ₂ catalysts (2 mg cm ^-2 ) were weighed, and water and isopropanol solution were added as dispersants to prepare a catalyst solution, which was uniformly dispersed by magnetic stirring and ultrasonic crushing. Finally, the ionomer solution is added and ultrasonically treated again to make it uniform, and it is evenly sprayed on both sides of the conjugated branched anion exchange membrane to form a membrane electrode. After the solvent evaporates, immerse it in 1M KOH solution for ion exchange for 48 hours;

(2) Assemble the electrolyzed water device: sandwich the membrane electrode between the cathode and anode to assemble the electrolyzed water device;

(3) Electrolyzed water performance test: The electrochemical test was carried out in 1M KOH solution soaked in the anode and cathode, and the temperature was kept at 80°C. Polarization curves were obtained by measuring the cell voltage at different current densities.

Beneficial result of the present invention is:

(1) In the conjugated branched polymer-based anion exchange membrane of the present invention, the reactant of trifunctionality has been added in the polymerized monomer, which significantly improves the electrochemical performance of the membrane, and has a good relationship with the industrial alkaline electrolyzer It also has good dimensional stability; the polymer prepared by the present invention has good solubility and can be dissolved in polar organic solvents at room temperature, such as NMP, DMF, DMSO, DMAc, etc.

(2) The present invention has the characteristics of strong universality, and can realize the preparation of high-performance conjugated branched polymers under the condition of rationally controlling the types and proportions of difunctional and trifunctional reaction precursors.

(3) The invention reduces the preparation cost of the anion exchange membrane, and the synthesis strategy is simple and effective, which is more conducive to industrial promotion and use.

Description of drawings

Fig. 1 carries the polarization curve on the alkaline electrolyzed water device of example 1-5 and comparative example 1 polymer film.

Detailed ways

The present invention will be further described in combination with examples and accompanying drawings. The examples are only used to explain the present invention, and the present invention is not limited to be used only for this. Therefore, with reference to the requirements of the present invention, simple modifications and changes made to examples or related types of conjugated branched polymers all belong to the scope of the technical solution of the present invention.

Example 1

A method for preparing a conjugated branched anion exchange membrane, comprising the following steps:

(1) Disperse 24g of zinc-copper alloy in 140mL of tetrahydrofuran at 0°C, slowly add 15mL of titanium tetrachloride dropwise, and after mixing evenly, add terephthaloyl chloride (5g) and trimesoyl chloride (0.3 g) After reacting for 120 h, the reaction was quenched with 10% potassium carbonate aqueous solution, filtered and extracted, and the solvent was distilled off to obtain a polymer precursor. Dissolve the polymer precursor in NMP (10wt%), add 2M THF solution of trimethylamine under nitrogen atmosphere, react at room temperature for 72h, precipitate the polymer with ethyl acetate, wash 8 times with water and dry in vacuum to obtain the conjugated Branched anionic polymers.

(2) Dissolve the oven-dried polymer in DMAc solution (solid content: 6%) to form a membrane-building liquid, which is filtered and defoamed and then poured on a glass plate and scraped off with a scraper. After drying at 80° C. for 6 hours, the membrane was removed to obtain a conjugated branched anion exchange membrane with a thickness of about 60 μm.

Example 2

A method for preparing a conjugated branched anion exchange membrane, comprising the following steps:

(1) Disperse 24g of zinc in 120mL of tetrahydrofuran at -10°C, slowly add 15mL of titanium tetrachloride dropwise, and after mixing evenly, add terephthaloyl chloride (5g) and tris(4-formyl chloride benzene Base) phosphine (0.5 g) was reacted for 100 h, and the reaction was quenched with 10% potassium carbonate aqueous solution, filtered and extracted, and the solvent was distilled off to obtain a polymer precursor. Dissolve the polymer precursor in NMP (10wt%), add trimethylamine under nitrogen atmosphere, react at room temperature for 72 hours, precipitate the polymer with ethyl acetate, wash it with water for 8 times, and dry it in vacuum to obtain a conjugated branched anionic polymer. things.

(2) Dissolve the oven-dried polymer in DMAc solution (solid content: 4%) to form a membrane-building liquid, which is filtered and defoamed, poured on a glass plate, and scraped off with a scraper. After drying at 60° C. for 6 hours, vacuum drying at 80° C. for 3 hours, the membrane was removed to obtain a conjugated branched anion exchange membrane with a thickness of about 63 μm.

Example 3

A method for preparing a conjugated branched anion exchange membrane, comprising the following steps:

(1) Disperse 18g of magnesium in 100mL of tetrahydrofuran at 0°C, slowly add 18g of titanium trichloride dropwise, and after mixing evenly, add terephthaloyl dichloride (5g) and tris(4-formyl chloride phenyl ) phosphine (0.3 g) was reacted for 100 h and then quenched with 10% potassium carbonate aqueous solution, filtered and extracted, and the solvent was distilled off to obtain a polymer precursor. Dissolve the polymer precursor in NMP (10wt%), add trimethylamine under nitrogen atmosphere, react at room temperature for 72 hours, precipitate the polymer with ethyl acetate, wash it with water for 8 times, and dry it in vacuum to obtain a conjugated branched anionic polymer. thing.

(2) Dissolve the oven-dried polymer in DMAc solution (solid content: 8%) to form a membrane-building liquid, which is filtered and defoamed and then poured on a glass plate and scraped off with a scraper. After drying at 60° C. for 3 hours, vacuum drying at 80° C. for 3 hours, the membrane was removed to obtain a conjugated branched anion exchange membrane with a thickness of about 67 μm.

Example 4

A method for preparing a conjugated branched anion exchange membrane, comprising the following steps:

(1) Disperse 10g of zinc in 90mL of tetrahydrofuran at 20°C, slowly add 18g of titanium trichloride dropwise, after mixing evenly, add biphenyl dicarboxylic acid chloride (8g) and 3,4',5-tri Acyl chloride-1,1-biphenyl (1 g) was reacted for 100 h, and the reaction was quenched with 10% potassium carbonate aqueous solution, filtered and extracted, and the solvent was distilled off to obtain a polymer precursor. Dissolve the polymer precursor in NMP (10wt%), add trimethylamine under nitrogen atmosphere, react at room temperature for 48 hours, precipitate the polymer with ethyl acetate, wash it with water for 8 times, and dry it in vacuum to obtain a conjugated branched anionic polymer. things.

(2) Dissolve the oven-dried polymer in DMAc solution (solid content: 4%) to form a membrane-building liquid, which is filtered and defoamed, poured on a glass plate, and scraped off with a scraper. After drying at 60° C. for 6 hours, vacuum drying at 80° C. for 6 hours, the membrane was removed to obtain a conjugated branched anion exchange membrane with a thickness of about 58 μm.

Example 5

A method for preparing a conjugated branched anion exchange membrane, comprising the following steps:

(1) Disperse 15g of zinc-silver alloy in 150mL of tetrahydrofuran at 0°C, slowly add 15mL of titanium tetrachloride dropwise, and after mixing evenly, add biphenyl dicarboxylic acid chloride (8g) and 1,3,5- After reacting tris(p-formyl chloride)benzene (0.8 g) for 240 h, the reaction was quenched with 10% potassium carbonate aqueous solution, filtered and extracted, and the solvent was distilled off to obtain a polymer precursor. Dissolve the polymer precursor in NMP (10wt%), add trimethylamine under nitrogen atmosphere, react at room temperature for 48 hours, precipitate the polymer with ethyl acetate, wash it with water for 8 times, and dry it in vacuum to obtain a conjugated branched anionic polymer. thing.

(2) Dissolve the oven-dried polymer in DMAc solution (solid content: 6%) to form a membrane-building liquid, which is filtered and defoamed and then poured on a glass plate and scraped off with a scraper. After drying at 60° C. for 6 hours, vacuum drying at 80° C. for 6 hours, the membrane was removed to obtain a conjugated branched anion exchange membrane with a thickness of about 57 μm.

Comparative examples 1 and 2 are commercially purchased FuMA-Tech anion exchange membranes FAA-3-PK-75 and FAM.

Example 6

Carry out ion exchange capacity (IEC), swelling rate, water absorption to the obtained conjugated branched anion exchange membrane prepared in the present embodiment 1-5 and the FuMA-Tech anion exchange membrane FAA-3-PK-75 and FAM of comparative examples 1 and 2 rate and ionic conductivity tests. The ion exchange capacity (IEC) is calculated by the precipitation titration method to calculate the anion content in a certain mass of anionic polymer membrane, so as to obtain the IEC of the anionic polymer membrane. Water absorption and swelling are measured by soaking the film in water for 24 hours, and testing the percentage difference between its mass and size and the initial state. The ionic conductivity was measured by Shanghai Chenhua electrochemical testing system, and the ionic conductivity of the fully wet anionic polymer membrane was measured by the two-electrode AC impedance method. The specific results are shown in Table 1.

Table 1. IEC, conductivity, water absorption and swelling rate of Examples 1-5, Comparative Examples 1 and 2 (all measured at 80°C)

IEC(mmol/g) Swelling rate (%) Water absorption (%) Conductivity (mS cm ^-1 ) Example 1 2.05 7 39 125 Example 2 2.08 7 43 130 Example 3 2.08 8 42 128 Example 4 2.1 11 45 131 Example 5 2.03 6 38 119 Comparative example 1 1.24 16.7 33 93 Comparative example 2 1.37 twenty one 37 109

Table 1 shows that the conjugated branched anion exchange membrane prepared by the present invention has better dimensional stability and higher conductivity than commercially available ones, and meets the needs of alkaline electrolyzed water.

Example 7

The obtained conjugated branched anion-exchange membrane of embodiment 1-5 and the FuMA-Tech anion-exchange membrane FAA-3-PK-75 of comparative example 1 are used in alkaline electrolytic water tank device, and concrete steps are as follows:

(1) Prepare the membrane electrode assembly of the electrolyzed water device:

Take the anion exchange membrane dissolved in DMSO (4wt%) as the ionomer solution. After that, a certain amount of Pt/C and IrO ₂ catalysts (2 mg cm ^-2 ) were weighed, and water and isopropanol solution were added as dispersants to prepare catalyst inks, which were dispersed uniformly by magnetic stirring and ultrasonic crushing. Finally, the ionomer solution is added and ultrasonically treated again to make it uniform, and it is evenly sprayed on both sides of the conjugated branched anion exchange membrane to form a membrane electrode. After the solvent evaporated, it was immersed in 1M KOH solution for ion exchange for 48h.

(2) Electrolyzed water performance test: The electrolyzed water device was assembled by sandwiching the membrane electrode between the cathode and anode. Electrochemical tests were carried out in a 1M KOH solution immersed in the anode and cathode at a temperature of 80°C. Polarization curves were obtained by measuring the cell voltage at different current densities.

Accompanying drawing 1 is the polarization curve of the conjugated branched anion exchange membrane prepared based on Examples 1-5 and the FuMA-Tech anion exchange membrane FAA-3-PK-75 of Comparative Example 1 on an alkaline electrolysis device. It can be seen that the membrane-assembled electrolyzer prepared in Examples 1-5 has significantly improved water electrolysis performance, and the lowest voltage at 500mA/cm ^-2 is 1.53V, which is obviously better than the commercially available level.

Although the content of the present invention can be partially demonstrated through the above examples, the present invention is not limited to the monomers described in the examples, that is, the description of the above examples does not limit the present invention. Those skilled in the art should understand that the improvement of the present invention, the equivalent replacement of the raw materials of the product of the present invention and the addition of auxiliary components, or direct or indirect application in other related technical fields, should be included in the protection scope of the patent of the present invention.

Claims (10)

1. a conjugated branched anion exchange membrane is characterized in that the anion exchange membrane is a conjugated branched polymer, and the structural formula is as follows: Wherein x represents the degree of branching%, and the range of x is 1-20; R is one or more of the following: M is one or more of the following: Q=F, Cl, Br, I 2. a preparation method of conjugated branched anion exchange membrane according to claim 1, is characterized in that, comprises the following steps: In an inert atmosphere, at -10-20°C, place the catalyst in an organic solvent a and stir for 10-120 minutes, then add the polymerized monomer mixture dropwise to start the reaction; After reacting for 24-144h, it is quenched with an alkaline solution, and then extracted to obtain a polymer precursor; Dissolve the polymer precursor in an organic solvent b, add an amine solution under an inert atmosphere, react at 20-80°C for 24-72 hours, sink the polymer in the organic solvent, wash it with water for 2-8 times, and dry it in vacuum to obtain a polymer thing; The polymer is dissolved in the organic solvent b, filtered, defoamed, and cast to form a membrane to obtain the conjugated branched anion exchange membrane. 3. The preparation method of conjugated branched anion exchange membrane according to claim 2, characterized in that, the inert atmosphere is nitrogen or argon. 4. The method for preparing a conjugated branched anion exchange membrane according to claim 2, wherein the catalyst is one or more of subgroup metals and their corresponding oxides and halides. 5. the preparation method of conjugated branched anion exchange membrane according to claim 2 is characterized in that, described organic solvent a is methanol, ethanol, N,N'-dimethylformamide, dimethylmethylene One or more mixtures of sulfone, ether, acetone, tetrahydrofuran, ethyl acetate, methylene chloride, chloroform, carbon tetrachloride, and petroleum ether; the organic solvent b is N-methylpyrrolidone, N,N' One or more solvents in dimethylformamide, N,N'-dimethylacetamide, and dimethyl sulfoxide are mixed in any ratio. 6. the preparation method of conjugated branched anion exchange membrane according to claim 2, is characterized in that, described polymerized monomer mixed solution is the mixed solution of two, trifunctional acid chloride monomer, and described polymerized monomer The molar ratio of the mixed liquid to the whole system is 0.1-15%. 7. the preparation method of conjugated branched anion exchange membrane according to claim 6 is characterized in that, described difunctionality acid chloride monomer is selected from terephthaloyl dichloride, biphenyl dicarboxylic acid chloride; Trifunctionality Acyl chloride monomers are selected from trimesoyl chloride, 1,3,5-tri(p-formyl chloride)benzene, 3,4',5-triacyl chloride-1,1-biphenyl, tris(4-formyl chloride)benzene base) phosphine. 8. the preparation method of conjugated branched anion exchange membrane according to claim 2 is characterized in that, described alkaline solution is one or more in potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate An aqueous solution; the amine solution is trimethylamine aqueous solution. 9. An application of a conjugated branched anion exchange membrane, characterized in that, the conjugated branched anion exchange membrane is the conjugated branched anion exchange membrane of claim 1, or in claims 2-8 The conjugated branched anion exchange membrane prepared by any one of the preparation methods, the conjugated branched anion exchange membrane is used for hydrogen production by alkaline electrolysis of water. 10. The application of the anion-exchange membrane according to claim 9, characterized in that the application of the conjugated branched anion-exchange membrane in the production of hydrogen from alkaline electrolyzed water comprises the following steps: (1) Membrane electrode preparation: dissolving the conjugated branched anion exchange membrane in a polar organic solvent to obtain an ionomer solution; uniformly dispersing the catalyst Pt/C and _IrO in a dispersant to prepare a catalyst solution; The ionomer solution and the catalyst solution are evenly mixed, and then evenly sprayed on both sides of the conjugated branched anion exchange membrane to form a membrane electrode; then ion exchange is performed in an alkaline solution; (2) Assemble the electrolyzed water device: sandwich the membrane electrode between the anode and cathode to assemble the electrolyzed water device.