Branched polyarylpiperidine anion exchange membrane and preparation method thereof

Abstract

The invention relates to the technical field of anion exchange membranes, in particular to a branched polyarylpiperidine anion exchange membrane and a preparation method thereof. The preparation method of the anion exchange membrane comprises the following steps: S1, by taking p-terphenyl, benzenetricarboxaldehyde and N-methyl-piperidine-4-ketone as raw materials, synthesizing a branched polymer through an acid catalytic polymerization reaction; s2, introducing a cationic group with iodomethane through a Menxu reaction, so as to obtain functionalized branched polyarylpiperidine; s3, obtaining the branched polyarylpiperidine anion exchange membrane through a flat plate tape casting method and an anion exchange reaction. The preparation method is simple and suitable for large-scale production; the prepared anion exchange membrane has high ionic conductivity, excellent chemical stability and mechanical strength, has good machinability and application potential, and has a good application prospect in a water electrolysis hydrogen production technology.

Description

Technical Field

[0001] The invention relates to the technical field of anion exchange membranes, and in particular to a branched polyarylpiperidine anion exchange membrane and a preparation method thereof. Background Art

[0002] As a clean and efficient renewable energy, hydrogen energy plays an important role in the future energy structure transformation. Alkaline water electrolysis and anion exchange membrane water electrolysis (AEMWE) technology have attracted widespread attention because they can achieve efficient and low-cost hydrogen production under mild conditions. Compared with traditional alkaline water electrolysis systems, AEMWE combines the economy of non-precious metal catalysts in alkaline environments and the high energy efficiency of proton exchange membrane water electrolysis systems, and has become a hot topic of research in recent years. Anion exchange membrane (AEM) is the core component of the AEMWE system. Its main function is to selectively transmit OH- ions while blocking gases and reducing water migration, thereby improving electrolysis efficiency and system stability. However, the chemical stability, ionic conductivity and mechanical strength of existing AEM materials in alkaline environments still have certain challenges. Therefore, the development of new AEM materials with high ionic conductivity, excellent chemical stability and good mechanical properties is crucial to enhance the practical application value of AEMWE technology.

[0003] At present, common AEM materials are mainly based on quaternized polymers, such as polyetheretherketone, polyethersulfone, etc. However, these traditional AEM materials often have problems such as insufficient stability and limited ion conductivity in alkaline environments, which limits their performance in long-term operation. In recent years, polyaryl anion exchange membranes have attracted widespread attention due to their excellent chemical stability and good mechanical properties. Although traditional linear polyaryl AEMs have good ion conductivity, they often have problems such as excessive swelling and decreased mechanical strength, which affect the long-term performance of the membrane. Therefore, through structural design optimization, such as introducing a branched structure, the alkali resistance stability and mechanical strength of the membrane can be significantly improved while maintaining high ion conductivity. Summary of the invention

[0004] In view of the deficiencies of the above-mentioned technologies, the present invention provides a branched poly(arylpiperidine) anion exchange membrane to solve the performance deficiencies of the existing anion exchange membranes in terms of stability, mechanical strength and ion conductivity.

[0005] In order to improve the above shortcomings, the inventors of the present application conceived to improve the dimensional stability, mechanical properties and ion conductivity of the anion exchange membrane by designing a branched structure; and to improve the chemical stability of the anion exchange membrane by designing a main chain without an ether bond. At the same time, the branched polyarylpiperidine anion exchange membrane is prepared by acid-catalyzed polymerization, Menxiujin reaction, flat plate casting, ion exchange and other steps. The preparation method is simple, suitable for large-scale production, and can meet the practical application needs of water electrolysis hydrogen production technology.

[0006] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0007] A branched polyarylpiperidine anion exchange membrane, the chemical structural formula of the anion exchange membrane is: n is a natural number.

[0008] Another aspect of the present invention is to provide a method for preparing the branched polyarylpiperidine anion exchange membrane as described above, the preparation method comprising the following steps:

[0009] S1: terphenyl, trimesic acid, N-methyl-piperidin-4-one and dichloromethane are mixed, and then a certain amount of trifluoromethanesulfonic acid is added dropwise to carry out an acid-catalyzed polymerization reaction, the product is poured into a precipitant for precipitation, and the product is filtered, washed and dried to obtain a branched polymer, the structural formula of which is shown in the figure below; n is a natural number;

[0010] S2: dissolving the branched polymer obtained in step S1 in an organic solvent, adding methyl iodide to carry out a Menxiu gold reaction, pouring the reaction solution into ether or petroleum ether for precipitation, filtering, washing and drying the product to obtain a branched polyaryl piperidine;

[0011] S3: dissolving the branched poly(aryl piperidine) obtained in step S2 in an organic solvent, and then coating the casting solution on a glass plate by a flat plate casting method and drying to form a film; immersing the membrane in a sodium hydroxide solution at room temperature for 48 hours to perform an ion exchange reaction to convert anions into hydroxides, thereby obtaining a branched poly(aryl piperidine) anion exchange membrane.

[0012] As a preferred technical solution, the molar ratio of the terphenyl, trimesaldehyde and N-methyl-piperidin-4-one is 1: (0.01-0.2): (0.4-0.97).

[0013] As a preferred technical solution, the mass ratio of dichloromethane to trifluoromethanesulfonic acid is 1:(0.1-0.5).

[0014] As a preferred technical solution, the precipitant is at least one of water, ethanol, methanol, propanol, and sodium hydroxide aqueous solution.

[0015] As a preferred technical solution, the organic solvent is at least one of N-methylpyrrolidone, N,N-dimethylformamide, and dimethyl sulfoxide.

[0016] As a preferred technical solution, the mass ratio of the branched polymer to methyl iodide is 1:(0.1-10).

[0017] As a preferred technical solution, the reaction temperature of the acid-catalyzed polymerization reaction is 0 to 50° C., and the reaction time is 5 to 36 hours.

[0018] As a preferred technical solution, the reaction temperature of the Menxiu gold reaction is room temperature to 80° C., and the reaction time is 1 to 72 hours.

[0019] As a preferred technical solution, in step S3, the drying film forming temperature is 40 to 100° C., and the drying time is 4 to 48 hours.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The branched polyarylpiperidine anion exchange membrane provided by the present invention has a branched structure that can effectively inhibit the dimensional stability of the membrane material and reduce the swelling rate (≤16%, 80°C). It can also promote polymer self-assembly to form a microphase separation structure, thereby obtaining a higher ion conductivity (≥132mS / cm, 80°C). The anion exchange membrane is assembled into an electrolytic cell and has a conductivity of ≥2.6A / cm at 80°C and 1.8V. 2 High current density performance.

[0022] The branched polyarylpiperidine anion exchange membrane provided by the present invention is prepared by acid-catalyzed polymerization, Menxiu gold reaction, flat plate casting, ion exchange and the like, and has a simple preparation process, is suitable for large-scale production, and can meet the practical application requirements of water electrolysis hydrogen production technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a physical picture of the branched poly(arylpiperidine) anion exchange membrane prepared in Example 1 of the present invention.

[0024] Figure 2 This is a schematic diagram of the relationship between ion conductivity and temperature of the branched poly(arylpiperidine) anion exchange membrane prepared in Example 1 of the present invention.

[0025] Figure 3 This is a schematic diagram of the mechanical properties of the branched poly(arylpiperidine) anion exchange membrane prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0026] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may think of other obvious variations.

[0027] Example 1

[0028] The method for preparing the branched poly(arylpiperidine) anion exchange membrane of this embodiment comprises the following steps:

[0029] S1: terphenyl (2.30 g), trimesic acid (0.032 g), N-methyl-piperidin-4-one (1.06 g) and dichloromethane (20 mL) were mixed, and then 8 mL of trifluoromethanesulfonic acid was added dropwise, and the mixture was reacted at 30° C. for 6 hours. The product was poured into a potassium hydroxide aqueous solution for precipitation, and the product was filtered, washed and dried to obtain a branched polymer;

[0030] S2: dissolving the branched polymer (1.0 g) obtained in step S1 in dimethyl sulfoxide, adding 1.0 mL of iodomethane, stirring at 30° C. in the dark for 24 hours, pouring the reaction solution into ether for precipitation, filtering, washing and drying the product to obtain a branched polyarylpiperidine;

[0031] S3: The branched poly(arylpiperidine) obtained in step S2 (0.5 g) was dissolved in dimethylformamide (15 mL), and then the casting solution was coated on a glass plate by a flat plate casting method, and dried at 60° C. for 5 hours to form a film; the film was immersed in a 1 M sodium hydroxide solution at room temperature for 48 hours to convert anions into hydroxides, thereby obtaining a branched poly(arylpiperidine) anion exchange membrane, such as Figure 1 shown.

[0032] The test results show that the ionic conductivity of the anion exchange membrane of this embodiment at 80°C is 136mS / cm ( Figure 2 The anion exchange membrane of this embodiment was immersed in 80℃, 1MNaOH solution for 1000 hours, and the ion conductivity only decreased by 5.6%. The anion exchange membrane of this embodiment was assembled into an alkaline membrane electrolyzer, and the current density at 80℃, 1.8V reached 2.8A / cm 2 .

[0033] Example 2

[0034] The method for preparing the branched poly(arylpiperidine) anion exchange membrane of this embodiment comprises the following steps:

[0035] S1: terphenyl (3.0 g), trimesic acid (0.063 g), N-methyl-piperidin-4-one (1.34 g) and dichloromethane (25 mL) were mixed, and then 10 mL of trifluoromethanesulfonic acid was added dropwise, and the mixture was reacted at 40° C. for 12 hours. The product was poured into a sodium hydroxide aqueous solution for precipitation, and the product was filtered, washed and dried to obtain a branched polymer;

[0036] S2: dissolving the branched polymer (2.0 g) obtained in step S1 in dimethyl sulfoxide, adding 2.5 mL of methyl iodide, stirring at 20° C. in the dark for 24 hours, pouring the reaction solution into petroleum ether for precipitation, filtering, washing and drying the product to obtain a branched polyaryl piperidine;

[0037] S3: The branched polyarylpiperidine (2.0 g) obtained in step S2 was dissolved in dimethylformamide (40 mL), and then the casting solution was coated on a glass plate by a flat plate casting method, and dried at 80°C for 6 hours to form a film; the membrane was immersed in a 1M sodium hydroxide solution at room temperature for 48 hours to convert anions into hydroxides, thereby obtaining a branched polyarylpiperidine anion exchange membrane.

[0038] The test results show that the ionic conductivity of the anion exchange membrane of this embodiment at 80°C is 132mS / cm, the swelling rate is 14%, and the tensile stress is 48.7MPa (such as Figure 3 When the anion exchange membrane of this embodiment is immersed in 1M NaOH solution at 80°C for 1000 hours, the ion conductivity only decreases by 5.3%. When the anion exchange membrane of this embodiment is assembled into an alkaline membrane electrolyzer, the current density at 80°C and 1.8V reaches 2.6A / cm 2 .

[0039] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention, and these changes and improvements fall within the scope of the present invention claimed.

Claims

1. A branched polyarylpiperidine anion exchange membrane, characterized in that: The chemical structural formula of the anion exchange membrane is: n is a natural number.

2. A method for preparing a branched polyarylpiperidine anion exchange membrane as claimed in claim 1, characterized in that: The preparation method comprises the following steps: S1: terphenyl, trimesic acid, N-methyl-piperidin-4-one and dichloromethane are mixed, and then a certain amount of trifluoromethanesulfonic acid is added dropwise to carry out an acid-catalyzed polymerization reaction, the product is poured into a precipitant for precipitation, and the product is filtered, washed and dried to obtain a branched polymer; S2: dissolving the branched polymer obtained in step S1 in an organic solvent, adding methyl iodide to carry out a Menxiu gold reaction, pouring the reaction solution into ether or petroleum ether for precipitation, filtering, washing and drying the product to obtain a branched polyaryl piperidine; S3: dissolving the branched poly(aryl piperidine) obtained in step S2 in an organic solvent, and then coating the casting solution on a glass plate by a flat plate casting method and drying to form a film; immersing the membrane in a sodium hydroxide solution at room temperature for 48 hours to perform an ion exchange reaction to convert anions into hydroxides, thereby obtaining a branched poly(aryl piperidine) anion exchange membrane.

3. The method for preparing a branched polyarylepiperidine anion exchange membrane according to claim 2, characterized in that: The molar ratio of the terphenyl, trimesaldehyde and N-methyl-piperidin-4-one is 1:(0.01-0.2):(0.4-0.97).

4. The method for preparing a branched polyaryleperidine anion exchange membrane according to claim 2, wherein: The mass ratio of the dichloromethane to trifluoromethanesulfonic acid is 1:(0.1-0.5).

5. The method for preparing a branched polyarylepiperidine anion exchange membrane according to claim 2, characterized in that: The precipitant is at least one of water, ethanol, methanol, propanol and sodium hydroxide aqueous solution.

6. The method for preparing a branched polyarylepiperidine anion exchange membrane according to claim 2, characterized in that: The organic solvent is at least one of N-methylpyrrolidone, N,N-dimethylformamide and dimethyl sulfoxide.

7. The method for preparing a branched polyarylepiperidine anion exchange membrane according to claim 2, characterized in that: The mass ratio of the branched polymer to methyl iodide is 1:(0.1-10).

8. The method for preparing a branched polyarylepiperidine anion exchange membrane according to claim 2, characterized in that: The reaction temperature of the acid-catalyzed polymerization reaction is 0 to 50° C., and the reaction time is 5 to 36 hours.

9. The method for preparing a branched polyarylepiperidine anion exchange membrane according to claim 2, characterized in that: The reaction temperature of the Menxiu gold reaction is room temperature to 80° C., and the reaction time is 1 to 72 hours.

10. The method for preparing a branched polyarylepiperidine anion exchange membrane according to claim 2, characterized in that: In step S3, the drying film forming temperature is 40 to 100° C., and the drying time is 4 to 48 hours.

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