WO2016095237A1

WO2016095237A1 - N1-substituted imidazole compound, and alkaline anion exchange membrane and preparation

Info

Publication number: WO2016095237A1
Application number: PCT/CN2014/094471
Authority: WO
Inventors: 孙公权; 杨丛荣; 王素力
Original assignee: 中国科学院大连化学物理研究所
Priority date: 2014-12-16
Filing date: 2014-12-22
Publication date: 2016-06-23
Also published as: CN105777642A

Abstract

An N1-substituted imidazole compound, R1 being C₁-C₁₀ straight-chain alkane, and R₂ being a C₁-C₉ chain alkane, C₃-C₆ cycloalkane, phenyl or biphenyl. An alkaline anion exchange membrane and a preparation method therefor. The alkaline anion exchange membrane comprises a halomethylated high molecular polymer main chain and an N1 alkyl-substituted imidazole branched chain with a molecular formula, the high molecular polymer main chain being one of polyether sulfone, polyether ketone, polyphenylene sulfone, polystyrene, poly(phthalazinone ether sulfone ketone) and polypheylene ether. The N1 alkyl-substituted imidazole can be used in an alkaline fuel cell.

Description

N1-substituted imidazole compound and basic anion exchange membrane and preparation thereof

Technical field

The invention belongs to the field of polymer compounds and basic anion exchange membranes, and in particular relates to an alkyl substituted imidazole at the N1 position and a substituted imidazole type basic anion exchange membrane at the N1 position and a preparation method thereof.

Background technique

Compared with the traditional proton exchange membrane fuel cell, the alkaline anion exchange membrane fuel cell has the advantages of fast electrode reaction kinetics and weak corrosive environment, so the electrode of the alkaline anion exchange membrane fuel cell can use non-precious metal as a catalyst. The cost is greatly reduced; compared with the alkaline fuel cell, the basic anion exchange membrane fuel cell can avoid the problems of electrolyte loss and carbonation caused by the liquid electrolyte. Therefore, at present, researchers in various fields of research on basic anion exchange membrane fuel cells have devoted a lot of work. However, the basic anion exchange membrane fuel cell is not widely available for production and application. The limiting factor is that the performance of the basic anion exchange membrane (especially the conductivity and stability) is far from meeting the requirements of the basic anion exchange membrane fuel cell. Therefore, the development of research on basic anion exchange membranes for fuel cells has become a hot spot and focus of researchers.

At present, the functional groups used in the basic anion exchange membrane are studied more in the quaternary ammonium salt structure, and are also more in-depth. Through the in-depth study and improvement of the quaternary ammonium salt type basic anion exchange membrane (including increasing the IEC value and changing the phase separation structure of the membrane), the conductivity of the membrane has been greatly improved. 10 ^-2 Scm ^{-1 is} increased to 10 ^-1 Scm ^-1 or above (see: Energy Environ. Sci., 2014, 7, 354-360; ChemSusChem 2013, 6, 1376 - 1383). However, there are still some problems with the chemical stability of quaternary ammonium groups in alkalis. Researchers believe that the quaternary ammonium salt type functional groups at high temperatures, a high concentration of the alkali conditions chemically unstable, readily OH ^- ions attack, such degradation, degradation is generally considered a quaternary ammonium group into three categories. The first type is OH ^- attacking α-C, which causes quaternary ammonium group degradation by nucleophilic substitution reaction; the second type is OH ^- ion attacking β-H, Hofmann elimination reaction occurs, resulting in functional group degradation; the third type is OH ^- The ions attack α-H and then rearrange through Stevens and Sommelet-Hauser to cause the quaternary ammonium group to lose its ability to conduct ions. Recently, some groups have been proposed which can replace quaternary ammonium functional groups, such as sulfhydryl groups (see: Chem. Commun. 2010, 46, 7495-7497), piperazine (see: J. Mater. Chem., 2011, 21, 6158–6160), metal cation type (see: J. Am. Chem. Soc. 2012, 134, 4493-4496), quaternary phosphine type (see: J. Am. Chem. Soc. 2012, 134, 18161-18164) , imidazole type (see: Macromolecules 2014, 47, 208-216) and the like. Among them, the imidazole type is the most studied. Moreover, the current research results show that the modified imidazole (especially 2-methylimidazole) is a basic anion exchange membrane that conducts OH ^- ion functional groups, which can maintain certain chemical stability in alkali, and other properties of the membrane are better. (J. Mater. Chem., 2011, 21, 12744-12724; Chem. Mater. 2013, 25, 1858-1867), showing that such membranes have certain application prospects in alkaline fuel cells. However, there has not been a related study of imidazole-type basic anion exchange membranes with different alkyl substitutions at the N1 position.

Summary of the invention

In view of the problems existing in the prior art, an object of the present invention is to provide an imidazole-type basic anion exchange membrane substituted with an alkyl group at the N1 position and a preparation method thereof.

An imidazole compound substituted at the N1 position R ₁ is a C ₁ -C ₁₀ linear alkane; R ₂ is a C ₁ -C ₉ chain alkane, or a C ₃ -C ₆ cycloalkane, or a phenyl group or a biphenyl group.

The N1 substituted imidazole compound

Preparation method for adding in solvent

Strong base reagent and R ₁ -X, after reacting for a period of time, extracting and drying the reaction solution to obtain an imidazole compound substituted at the N1 position

Wherein R1 is a C ₁ -C ₁₀ linear alkane; R ₂ is a C ₁ -C ₉ chain alkane, or a C ₃ -C ₆ cycloalkane, or a phenyl group or a biphenyl group; It is one or two of Cl and Br.

The solvent is one or more selected from the group consisting of acetonitrile, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone.

The strong base reagent is one or more selected from the group consisting of NaOH, KOH, NaH, KH, LiH, potassium t-butoxide, and butyl lithium.

Said

The concentration in the solvent is 0.05-0.33 g/mL;

The mass ratio to the strong base reagent is 1:1 to 1:4;

The ratio of the mass of the substance to R ₁ -X is 1:1 to 1:3; the reaction temperature is 0 ° C to 75 ° C; and the reaction time is not less than 12 h.

The extraction process is carried out using one of ethyl acetate, diethyl ether, n-hexane, and n-pentane.

A basic anion exchange membrane comprising a halomethylated polymer backbone and a molecular formula

An alkyl substituted alkyl imidazole branch at the N1 position;

The polymer main chain is one of polyether sulfone, polyether ketone, polyphenylene sulfone, polystyrene, polyaryl ether sulfone ketone, polyphenylene ether; the alkyl group substituted imidazole at the N1 position Wherein R ₁ is a C ₁ -C ₁₀ linear alkane; R ₂ is a C ₁ -C ₉ chain alkane, or a C ₃ -C ₆ cycloalkane, either a phenyl group or a biphenyl group.

In the basic anion exchange membrane,

The N3 position is linked to the methylene group of the halomethylated polyethersulfone, polyether ketone, polyphenylene sulfone, polyaryl ether sulfone ketone, polyphenylene ether, and the methylene group after removal of the halogen element; or

The methylene group after removal of the halogen element in the N3 position and the para-halomethylated polystyrene is bonded by a CN chemical bond.

A preparation method of the basic anion exchange membrane, comprising the following steps,

(1) Synthesis of alkyl substituted imidazole at the N1 position: added to the first solvent

The strong base reagent and R ₁ -X are reacted for a period of time to obtain an alkyl group substituted imidazole solution at the N1 position;

Wherein R ₁ is a C ₁ -C ₁₀ linear alkane; R ₂ is a C ₁ -C ₉ chain alkane, or a C ₃ -C ₆ cycloalkane, or a phenyl group or a biphenyl group; X is one or two of Cl, Br;

(2) Preparation of halomethylated polymer backbone: a high molecular polymer, a halomethylating agent and a catalyst are added to a second solvent and reacted at a temperature below 20 ° C for a period of time and then mixed with a third solvent to precipitate a polymerization. a substance, that is, a halomethylated high molecular polymer;

(3) Preparation of N1-position alkyl-substituted imidazole-type anion exchange membrane: adding the halomethylated high molecular polymer obtained in the step (2) and the N1-position alkyl-substituted imidazole obtained in the step (1) to the fourth solvent, stirring and After the reaction for a while, the mixture was filtered, and the obtained transparent solution was cast by a solvent evaporation method to obtain an N1-position alkyl-substituted imidazole-type basic anion exchange membrane.

The method further comprises the step of subjecting the obtained N1-position alkyl-substituted imidazole-type basic anion exchange membrane to a potassium hydroxide or sodium hydroxide solution for a period of time for ion exchange. The total concentration of the potassium hydroxide and/or sodium hydroxide is from 0.1 to 3 mol/L; and the solution temperature is from room temperature to 40 °C.

The step (1) further comprises the steps of extracting and drying the obtained N1-position alkyl substituted imidazole solution;

The step (2) further includes a step of obtaining a halomethylated polymer and then washing it with one or more of water, methanol, ethanol, isopropanol, and acetone.

The first solvent in the step (1) is acetonitrile, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, One or more of N-methylpyrrolidone; the strong base reagent is one or more selected from the group consisting of NaOH, KOH, KH, NaH, LiH, potassium t-butoxide, and butyl lithium;

Said in step (1)

The concentration in the first solvent is 0.05-0.33 g/mL;

The mass ratio to the strong base reagent is 1:1 to 1:4;

The ratio of the mass to the mass of R ₁ -X is 1:1 to 1:3.

The catalyst in the step (2) is one or more of anhydrous tin tetrachloride, zinc chloride, trifluoroacetic acid and concentrated sulfuric acid; the halogen methylation reagent is chloromethyl ether and chloromethylbutyl One or more of ether, chloromethyl hexyl ether, 1,4-dichloromethoxybutane, and N-bromosuccinimide;

The second solvent in the step (2) is concentrated sulfuric acid, carbon tetrachloride, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, dichloromethane, chloroform, dichloro One or more of ethane; the third solvent is one or more of water, methanol, ethanol, isopropanol, acetone;

The mass of the high molecular polymer added to the second solvent in the step (2) is 0.017-0.067 g/mL; the mass ratio of the polymer to the catalyst added is 200:1 to 1:5; The volume ratio of the mass of the polymer to be added to the halomethylating agent is from 1:1 to 1:10.

The fourth solvent in the step (3) is one or more of dimethylformamide, dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone; and the fourth solvent is added. The mass of the halomethylated polymer is 0.02-0.067 g/mL; the mass ratio of the halomethylated polymer to the alkyl substituted imidazole at the N1 position in the step (3) is 10:1 to 1:2.

The organic reagent used in the extraction process is one of ethyl acetate, diethyl ether, n-hexane, and n-pentane.

The reaction temperature in the step (1) is from 0 ° C to 75 ° C; and the reaction time is not less than 12 h.

The reaction time described in the step (2) is not less than 0.5 h.

The reaction temperature in the step (3) ranges from room temperature to 90 ° C; the reaction time is not less than 12 h; the casting film temperature is 40-70 ° C, and the casting time is not less than 4 h.

The N1-position alkyl-substituted imidazole, the N1-position alkyl-substituted imidazole-type basic anion exchange membrane and the preparation method thereof have the following advantages:

1) The preparation method is environmentally friendly and the process is simple;

2) The prepared N1-position alkyl-substituted imidazole compound has good stability, non-toxicity, moderate molecular weight, and easy OH ^- conduction;

2) The prepared N1-position alkyl-substituted imidazole-type basic anion exchange membrane has a uniform, smooth and compact surface, and the conductivity of the N1-position alkyl-substituted imidazole-type anion exchange membrane film in deionized water is >15 mS/cm at 60 ° C, It shows that such membranes have good ability to conduct ions;

3) The prepared N1-position alkyl-substituted imidazole-type basic anion exchange membrane has good thermodynamic stability, and its glass transition temperature is above 150 ° C, which can satisfy the operating temperature of the battery;

4) The prepared N1-position alkyl-substituted imidazole-type basic anion exchange membrane has good mechanical strength, and the tensile strength is above 40 MPa, which is higher than the tensile strength of the commercial Nafion-117 membrane;

5) The prepared N1-position alkyl-substituted imidazole-type basic anion exchange membrane is assembled into a single cell for testing, and the maximum power density in the alkaline direct methanol fuel cell can reach 40 mWcm ^-2 , indicating that such basic anion exchange The membrane has good application value in alkaline fuel cells.

DRAWINGS

Figure 1 is a dynamic thermodynamic analysis curve (DMA) of the chloromethylated polyether ketone obtained in Examples 1 and 2;

2 is a chemical structural formula of an imidazole-type basic anion exchange membrane substituted with a halogenated methylated polyether ketone as a main chain at the N1 position;

3 is a N1-methyl-2-methylimidazole type polyether ketone basic anion exchange membrane obtained in Example 1 in deionized water. The conductivity of the curve as a function of temperature;

4 is a dynamic thermodynamic analysis curve (DMA) of the N1-methyl-2-methylimidazole type polyether ketone basic anion exchange membrane obtained in Example 1;

Figure 5 is a graph showing the conductivity versus temperature of a N1-mercapto-2-isopropylimidazole type polyetherketone basic anion exchange membrane in deionized water of Example 2;

Figure 6 is a schematic diagram showing the chemical structure of N1-hexyl-2-butylimidazole type polystyrene;

Figure 7 is a graph showing the conductivity versus temperature of the N1-hexyl-2-butylimidazole type polystyrene basic anion exchange membrane of Example 3;

Figure 8 is a graph showing the conductivity versus temperature of the N1-octyl-2-methylimidazole type basic anion exchange membrane of Example 4;

Figure 9 is a graph showing changes in conductivity, size, and ion exchange capacity (IEC) values of the N1-octyl-2-methylimidazole-type basic anion exchange membrane of Example 4 before and after immersion in 1 M KOH at 60 °C;

Figure 10 is a discharge curve of the assembly of a single cell using an N1-octyl-2-methylimidazole type basic anion exchange membrane in Example 4;

Figure 11 is a chemical structural formula of an imidazole-type basic anion exchange membrane substituted with a halogenated methylated polyphenylene ether as a main chain at the N1 position;

Figure 12 is a chemical structural formula of an imidazole-type basic anion exchange membrane substituted with a halogenated methylated polyethersulfone as a main chain at the N1 position;

Figure 13 is a chemical structural formula of an imidazole-type basic anion exchange membrane substituted with a halogenated methylated polyphenylenesulfone as a main chain at the N1 position;

Fig. 14 is a chemical structural formula of an imidazole-type basic anion exchange membrane substituted with a halogenated methylated polyaryl ether sulfone ketone as a main chain at the N1 position.

detailed description

Example 1

2 g of polyether ketone polymer was added to 50 mL of CCl ₄ and dissolved by magnetic stirring at 40 ° C in a condensation cycle. Under ice-water bath conditions, 0.5 g of trifluoroacetic acid was added, and after stirring for 10 min, 10 mL of chloromethyl ether was slowly added dropwise, and the mixture was stirred at 15 to 17 ° C for 4 hours. The reactant was poured into absolute ethanol to precipitate a solid to obtain a chloromethylated polyether ketone polymer, which was then washed thoroughly with ethanol, washed several times with deionized water, and vacuum dried at 40 ° C until use. 0.5 g of chloromethylated polyether ketone polymer was added to 10 mL of dimethylacetamide, and the mixture was dissolved by magnetic stirring at 70 ° C, and then 0.096 g of 1,2-dimethylimidazole was added, and the mixture was magnetically stirred at 70 ° C for 24 hours. The reaction solution was returned to room temperature for filtration, and a film was cast by a volatile solvent in a 50 ° C blast oven. The prepared membrane was thoroughly washed with deionized water and stored in sealed deionized water.

The mechanical strength test of the 1,2-dimethylimidazole type polyether ketone as the main chain film was carried out by TA Corporation's Q800. The stretch mode was chosen using a linear stretch rate of 5%. Thermodynamic dynamic analysis was performed using TA's DMA test. The heating rate is 3 ° C min ^-1 and the temperature range is from room temperature to 350 ° C. The frequency is 1 Hz and the amplitude used is 20 μm. It can be seen from the data structure analysis of Fig. 4 and Table 5 that the mechanical strength and thermodynamic properties of such films are good.

The conductivity of the basic anion exchange membrane of the 1,2-dimethylimidazole type polyether ketone as the main chain was tested by an alternating current impedance method. The formula for calculating the conductivity is:

Where б is the conductivity (S/cm) of the film, L is the distance between the two electrodes (cm), W is the width (cm) of the film, T is the thickness (cm) of the film, and R is the resistance of the film ( Ω).

Prior to testing Cl ^- form a basic anion-exchange membrane cut rectangle (1 * 4cm ²⁾ intermediate film sample was sandwiched with polytetrafluoroethylene mold silver, the balance of the AC impedance measurements after which into deionized water. The experimental instrument used a Solartron AC1260 impedance analyzer and a 1287 electrochemical workstation with a scanning frequency range of 1-10 ⁶ Hz. The conductivity of the film was measured multiple times to average. In deionized water, when the temperature is raised from 25 ° C to 60 ° C, the conductivity of the basic anion exchange membrane changes significantly (from 5.7 mScm ^-1 to 13.5 mScm ^-1 ), probably because the temperature changes the membrane The microstructure, which changes the ion transport pathway, leads to an increase in conductivity.

Table 1 Comparison of mechanical strength between N1-methyl-2-methylimidazole type polyetherketone basic anion exchange membrane and commercial Nafion-117 membrane

Fig. 2 is a schematic view showing the chemical structure of a polymer of the N1-methyl-2-methylimidazole type polyether ketone obtained in Example 1 as a main chain.

Fig. 3 is a graph showing the electrical conductivity of a film cast from a polymer of the N1-methyl-2-methylimidazole type polyether ketone obtained in Example 1 as a main chain in deionized water as a function of temperature. In Fig. 3, the abscissa is the temperature (°C), and the ordinate is the conductivity (mScm ^-1 ); as shown in Fig. 3, the conductance of the film of the N1-methyl-2-methylimidazole type polyether ketone as the main chain The rate varies significantly with temperature.

4 is a dynamic thermodynamic analysis curve (DMA) of a film of the N1-methyl-2-methylimidazole type polyether ketone obtained in Example 1 as a main chain. In Fig. 4, the abscissa is the temperature (°C), the ordinate on the left side is the storage modulus (MPa), and the ordinate on the right side is the loss modulus (MPa). Wherein, the temperature corresponding to the peak in the loss modulus curve is the glass transition temperature of the film. From the results of dynamic thermodynamic analysis, the initial storage modulus of this type of film can reach 1950MPa, and the glass transition temperature is above 200 °C, indicating that its thermodynamic performance is better, which can meet the requirements of fuel cell working conditions.

Table 1 is a comparison of the mechanical strength of the film of the N1-methyl-2-methylimidazole type polyether ketone obtained in Example 1 as a main chain with the commercial Nafion-117 film. It can be found from the table that although the elongation at break of the film is much lower than the value of the commercial Nafion film, the tensile strength and elastic modulus are greater than those of the commercial Nafion film, indicating that the film has poor elasticity, but mechanical The strength is better.

Example 2

2 g of polyether ketone polymer was added to 80 mL of CCl ₄ and dissolved by magnetic stirring at 60 ° C in a condensation cycle. Under ice water bath conditions, 10 g of tin tetrachloride was added, and then 10 mL of 1,4-dichloromethoxybutane was slowly added dropwise thereto, and reacted at 15 ° C for 7 hours. The reactant was poured into deionized water to precipitate a solid to obtain a chloromethylated polyether ketone polymer, which was then thoroughly washed with deionized water and dried at 45 ° C in vacuo. 4 g (about 40 mmol) of 2-isopropylimidazole was added to 10 mL of acetonitrile and dissolved by magnetic stirring. Under ice water bath, 4 g of 60% NaH/kerosene solid (100 mmol) was added, and after stirring for 10 min, 17.2 mL (about 72 mmol) of bromo-n-decane was added and stirred at room temperature overnight. The reaction solution was poured into water, and then extracted with ethyl acetate. The organic layer was dried over anhydrous MgSO ₄ and then purified by column chromatography to give 1-mercapto 2-isopropyl imidazole. It is placed in a normal temperature nitrogen tank for use. Add 0.5g of chloromethylated polyether ketone polymer to 10mL of dimethylacetamide, dissolve it by magnetic stirring at 70 ° C, then add 0.28g (1mmol) of 1-mercapto-2-isopropyl imidazole, 70 ° C magnetic force The reaction was stirred for 24 h. The reaction solution was returned to room temperature for filtration, dried in a blast oven at 40 ° C for 4 h, and dried at 70 ° C overnight to cast a film. The prepared membrane was thoroughly washed with deionized water and stored in sealed deionized water for testing.

The conductivity of the basic anion exchange membrane having the 1-mercapto-2-isopropyl imidazole type polyether ketone as the main chain was also tested by the alternating current impedance method. It can be seen from the test results that the conductivity of such a film changes with temperature similarly to the change of the conductivity of the film in Example 1, and the change in conductivity is relatively large when the temperature is raised from 25 ° C to 60 ° C. Moreover, the conductivity of such a film is smaller than that of the film of Example 1, and the reason is that the addition of a long substituent increases the molecular weight of the polymer and lowers the ion exchange capacity (i.e., IEC value) of the film, while the film The ion exchange capacity is closely related to the conductivity of the membrane. Off, so the ionic conductivity of the membrane is lowered.

Figure 1 is a dynamic thermodynamic analysis curve (DMA) of the chloromethylated polyether ketone obtained in Examples 1 and 2. In Fig. 1, the abscissa is the temperature (°C), the ordinate on the left side is the storage modulus (MPa), and the ordinate on the right side is the loss modulus (MPa). In Figure 1, the temperature corresponding to the peak in the loss modulus curve is the glass transition temperature of the polymer. From the results of dynamic thermodynamic analysis, the glass transition temperature of chloromethylated polyether ketone is above 150 °C, indicating that its thermodynamic properties are good and can meet the requirements of fuel cell operating conditions.

Figure 5 is a graph showing the conductivity versus temperature of a film of N1-mercapto-2-isopropylimidazole type polyether ketone as the main chain in Example 2 in deionized water. In Fig. 5, the abscissa is the temperature (°C), and the ordinate is the conductivity (mScm ^-1 ); as can be seen from Fig. 5, the conductivity of such a film changes with temperature, but the change trend does not have a N1 position as a methyl group. The trend of change is obvious, indicating that its conductivity is not affected by temperature, probably because its mechanism of conducting ions is different from that of N1.

Example 3

2 g of polystyrene was added to 50 mL of CCl ₄ and dissolved by magnetic stirring at 40 ° C in a condensation cycle. Under ice water bath conditions (17 ° C), 2.23 g of tin tetrachloride was added, and then 10 mL of 1,4-dichloromethoxybutane was slowly added dropwise thereto, and reacted at room temperature for 4 hours. The reactant was poured into deionized water to precipitate a solid to obtain a chloromethylated polystyrene, which was then thoroughly washed with deionized water and dried at 45 ° C under vacuum. 4 g (about 29 mmol) of 2-butylimidazole was added to 10 mL of dimethylformamide, and dissolved by magnetic stirring. Under ice-water bath, 6.7 g of potassium t-butoxide (60 mmol) was added, and after stirring for 10 min, 10.0 mL (about 72 mmol) of bromo-n-hexane was added and stirred at room temperature overnight. The reaction solution was poured into water, and then extracted with ethyl acetate to give an organic layer. The organic layer was dried with anhydrous MgSO ₄ and then purified by column chromatography to give 1-hexyl 2- butyl imidazole. It is used in a normal temperature nitrogen tank. 0.5 g of chloromethylated polystyrene was added to 10 mL of dimethyl sulfoxide, dissolved by magnetic stirring at 80 ° C, and then 0.22 g of 1-hexyl-2-butylimidazole was added, and the mixture was magnetically stirred at 80 ° C for 15 h. The reaction solution was returned to room temperature for filtration, and dried in a blast oven at 50 ° C overnight to cast a film. The prepared membrane was thoroughly washed with deionized water and stored in sealed deionized water.

The conductivity of the basic anion exchange membrane of the 1-hexyl-2-butylimidazolium type polystyrene as the main chain was tested. At room temperature, the conductivity of the exchange membrane in deionized water is 8.7 mScm ^-1 , probably due to the lower degree of chloromethylation of polystyrene, resulting in less functional grouping and lower conductivity. However, such films have a conductivity of 10 ^-2 Scm ^-1 or more at temperatures above 40 ° C, which can meet the requirements of fuel cells.

Fig. 6 is a schematic diagram showing the chemical structure of a polymer of N1-hexyl-2-butylimidazole type polystyrene as a main chain in Example 3.

Fig. 7 is a graph showing the electrical conductivity versus temperature of a film cast from a polymer of N1-hexyl-2-butylimidazole type polystyrene as a main chain in Example 3. In Fig. 7, the abscissa is the temperature (°C), and the ordinate is the conductivity (mScm ^-1 ); as can be seen from Fig. 8, when the temperature is raised from 40 ° C to 60 ° C, the conductivity of the film changes significantly, possibly It is the increase in temperature that causes the internal phase structure of the membrane to change, so that the way in which ions are conducted changes, and the conductivity changes accordingly.

Example 4

2 g of polystyrene was added to 60 mL of CCl ₄ and dissolved by magnetic stirring at 30 ° C in a condensation cycle. Under ice water bath conditions (about 7-17 ° C), 4 g of tin tetrachloride was added, and then 20 mL of 1,4-dichloromethoxybutane was slowly added dropwise, and reacted at 15 ° C for 7 h. The reactant was poured into deionized water to precipitate a solid to obtain a chloromethylated polystyrene, which was then thoroughly washed with deionized water and dried at 45 ° C under vacuum. Then, N1-octyl-2-methylimidazole was synthesized. 4 g (about 29 mmol) of 2-methylimidazole was added to 10 mL of dimethylformamide, and dissolved by magnetic stirring. Under ice-water bath, 7.2 g of potassium t-butoxide (61 mmol) was added, and after stirring for 10 min, 12.6 mL (about 72 mmol) of bromo- n-octane was added, and the reaction was stirred at room temperature for 24 h. The reaction solution was poured into water, and then extracted with ethyl acetate to give an organic layer. The organic layer was dried over anhydrous MgSO ₄ and then purified by column chromatography to give 1-octyl 2-methylimidazole, vacuum at 60 ° C Dry for 12h. The synthesis process of 1-octyl-2-methylimidazole type polymer is as follows: adding 0.5 g of chloromethylated polystyrene to 10 mL of dimethyl sulfoxide, dissolving it at 60 ° C and adding 0.3 g of 1-octine Base-2-methylimidazole, magnetically stirred at 80 ° C for 24 h. The reaction solution was returned to room temperature for filtration, dried in a blast oven at 50 ° C for 2 h, and dried at 70 ° C overnight to cast a film. The prepared membrane was thoroughly washed with deionized water and stored in sealed deionized water for testing.

The basic anion exchange membrane of the 1-octyl-2-methylimidazole type polystyrene as a main chain was subjected to conductivity test. At room temperature, the conductivity of such membranes in deionized water is 11.1 mScm ^-1 , which can meet the requirements of fuel cells.

The basic anion exchange membrane of the 1-octyl-2-methylimidazole type polystyrene as a main chain was subjected to a thermal alkali stability test. The chemical stability of the membrane was examined by measuring the change in conductivity, size and ion exchange capacity of the membrane before and after alkali treatment. It can be seen from the data analysis that the conductivity, size and ion exchange capacity of these membranes remain basically unchanged before and after alkali treatment, indicating that the stability of such membranes in hot alkali is good.

The prepared basic anion exchange membrane of 1-octyl-2-methylimidazole type polystyrene as a main chain was assembled into a single cell for testing. The anode used was a PtRu/C catalyst having a metal loading of 2.6 mg cm-2, and the cathode was a Pt/C catalyst having a metal loading of 2 mg cm-2. The ionomers used in the anode and the anode are Nafion and 1-octyl-2-methylimidazole type polystyrene as the main chain polymer, and the mass fraction is 20%. The instrument used for the test was Arbin's fuel cell test system. The test temperature was 60 ° C, the anode feed was 1 M MeOH + 1 M KOH, the flow rate was ¹ mL min ^-1 ; the cathode was oxygen and the flow rate was 80 sccm. The single cell discharge data shows that the single cell assembled with such a membrane as a solid electrolyte has better performance (power density up to 44 mWcm ^-2 ).

Figure 8 is a graph showing the electrical conductivity as a function of temperature for the N1-octyl-2-methylimidazole-type basic anion exchange membrane of Example 4. In Fig. 8, the abscissa is the temperature (°C), and the ordinate is the conductivity (mScm ^-1 ); as can be seen from Fig. 8, the conductivity of the film at room temperature is >10 mScm ^-1 , which can satisfy the alkaline fuel cell. Test requirements.

Figure 9 is a graph showing the changes in conductivity, size, and ion exchange capacity (IEC) values of the N1-octyl-2-methylimidazole-type basic anion exchange membrane of Example 4 before and after immersion in 1 M KOH at 60 °C. It can be seen from Fig. 9 that the conductivity, size and IEC value of the film have no obvious change before and after the hot alkali treatment, indicating that the film has good stability in the hot alkali and can satisfy the basic anion exchange with the alkaline fuel cell. The requirements for chemical stability of the membrane indicate that such membranes have certain application prospects in alkaline fuel cells.

Figure 10 is a graph showing the discharge of a single cell in which a N1-octyl-2-methylimidazole type basic anion exchange membrane was assembled in Example 4. In Fig. 10, the abscissa is the current density (mAcm ^-2 ), the left ordinate is the potential (V), and the right ordinate is the power density (mWcm ^-2 ). It can be seen from Fig. 10 that the N1-octyl-2-methylimidazole basic anion exchange membrane is a solid electrolyte assembled single cell with a high open circuit voltage >0.8V, indicating that the noble metal is used as a catalyst, N1-octyl-2 - The methylimidazole type basic anion exchange membrane has a small polarization of the single cell assembled by the solid electrolyte; at the same time, the maximum power density of the single cell is close to 44 mWcm ^-2 , and the corresponding current density is 121 mAcm ^-2 . The field of alkaline direct methanol is relatively high, indicating that such membranes have good application value in alkaline fuel cells.

Claims

[Correct according to Rule 26 01.06.2015]
An imidazole compound substituted at the N1 position, characterized in that the structural formula is
R 1 is a C 1 -C 10 linear alkane; R 2 is a C 1 -C 9 chain alkane, or a C 3 -C 6 cycloalkane, or a phenyl group or a biphenyl group.
[Correct according to Rule 26 01.06.2015]
The N1-substituted imidazole compound according to claim 1
Preparation method, characterized in that: adding in a solvent
, a strong base reagent and R 1 -X, after the reaction, the reaction solution is extracted and dried to obtain an imidazole compound substituted at the N1 position.

Wherein R 1 is a C 1 -C 10 linear alkane; R 2 is a C 1 -C 9 chain alkane, or a C 3 -C 6 cycloalkane, or a phenyl group or a biphenyl group; X is one or two of Cl and Br.
The method according to claim 2, wherein the solvent is one or more of acetonitrile, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone. .
The method according to claim 2, wherein the strong base reagent is one or more selected from the group consisting of NaOH, KOH, KH, NaH, LiH, potassium t-butoxide, and butyl lithium.
[Correct according to Rule 26 01.06.2015]
The preparation method according to claim 2, wherein:
The concentration in the solvent is 0.05-0.33 g/mL;
The mass ratio to the strong base reagent is 1:1 to 1:4;
The ratio of the mass of the substance to R 1 -X is 1:1 to 1:3; the reaction temperature is 0 ° C to 75 ° C; and the reaction time is not less than 12 h.
The process according to claim 2, wherein the extraction process is carried out using one of ethyl acetate, diethyl ether, n-hexane and n-pentane.
[Correct according to Rule 26 01.06.2015]
A basic anion exchange membrane characterized by comprising a halomethylated polymer backbone and a molecular formula
An alkyl substituted alkyl imidazole branch at the N1 position;
The polymer main chain is one of polyether sulfone, polyether ketone, polyphenylene sulfone, polystyrene, polyaryl ether sulfone ketone, polyphenylene ether; the alkyl group substituted imidazole at the N1 position Wherein R 1 is a C 1 -C 10 linear alkane; R 2 is a C 1 -C 9 chain alkane, or a C 3 -C 6 cycloalkane, or a phenyl group or a biphenyl group.
[Correct according to Rule 26 01.06.2015]
The basic anion exchange membrane according to claim 7, wherein:
The methylene group after the removal of the halogen element from the halogenated methylated polyethersulfone, polyether ketone, polyphenylene sulfone, polyaryl ether sulfone ketone or polyphenylene ether is chemically bonded by CN; or
The methylene group after the removal of the halogen element in the N3 position and the parahalomethylated polystyrene is bonded by a CN chemical bond.
[Correct according to Rule 26 01.06.2015]
A method for preparing a basic anion exchange membrane according to claim 7 or 8, comprising the steps of
(1) Synthesis of alkyl substituted imidazole at the N1 position: added to the first solvent
The strong base reagent and R 1 -X are reacted for a period of time to obtain an alkyl group substituted imidazole solution at the N1 position;
Wherein, Rl is a linear alkane of C1-C10; R 2 is a C1-C9 alkane or cycloalkane is a C 3 -C 6 or a phenyl group, or a biphenyl group; X is Cl, Br One or two of them;
(2) Preparation of a halomethylated polymer backbone: a polymer, a halomethylating agent and a catalyst are added to a second solvent, and the polymer is mixed with a third solvent after reacting at 20 ° C or lower. That is, a halomethylated high molecular polymer;
(3) Preparation of N1-position alkyl-substituted imidazole-type anion exchange membrane: adding the halomethylated high molecular polymer obtained in the step (2) and the N1-position alkyl-substituted imidazole obtained in the step (1) to the fourth solvent, stirring and After the reaction for a while, the mixture was filtered, and the obtained transparent solution was cast by a solvent evaporation method to obtain an N1-position alkyl-substituted imidazole-type basic anion exchange membrane.
The method for preparing a basic anion exchange membrane according to claim 9, further comprising: immersing the obtained N1-position alkyl-substituted imidazole-type basic anion exchange membrane in a potassium hydroxide or sodium hydroxide solution for a period of time. The step of ion exchange.
A method of preparing a basic anion exchange membrane according to claim 9, wherein:

The step (1) further comprises the steps of extracting and drying the obtained N1-position alkyl substituted imidazole solution;

The step (2) further includes a step of obtaining a halomethylated polymer and then washing it with one or more of water, methanol, ethanol, isopropanol, and acetone.
[Correct according to Rule 26 01.06.2015]
A method of preparing a basic anion exchange membrane according to claim 9, wherein:
The first solvent in the step (1) is one or more selected from the group consisting of acetonitrile, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone; Is one or more of NaOH, KOH, KH, NaH, LiH, potassium t-butoxide, butyl lithium;
Said in step (1)
The concentration in the first solvent is 0.05-0.33 g/mL;
The mass ratio to the strong base reagent is 1:1 to 1:4;
The ratio of the mass to the mass of R 1 -X is 1:1 to 1:3.
A method of preparing a basic anion exchange membrane according to claim 9, wherein:

The catalyst in the step (2) is one or more of anhydrous tin tetrachloride, zinc chloride, trifluoroacetic acid and concentrated sulfuric acid; the halogen methylation reagent is chloromethyl ether and chloromethylbutyl One or more of ether, chloromethyl hexyl ether, 1,4-dichloromethoxybutane, and N-bromosuccinimide;

The second solvent in the step (2) is concentrated sulfuric acid, carbon tetrachloride, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, dichloromethane, chloroform, dichloro One or more of ethane; the third solvent is one or more of water, methanol, ethanol, isopropanol, acetone;

The mass of the high molecular polymer added to the second solvent in the step (2) is 0.017-0.067 g/mL; the mass ratio of the polymer to the catalyst added is 200:1 to 1:5; The volume ratio of the mass of the polymer to be added to the halomethylating agent is from 1:1 to 1:10.
A method of preparing a basic anion exchange membrane according to claim 9, wherein:

The fourth solvent in the step (3) is one or more of dimethylformamide, dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone; and the fourth solvent is added. The mass of the halomethylated polymer is 0.02-0.067 g/mL; the mass ratio of the halomethylated polymer to the alkyl substituted imidazole at the N1 position in the step (3) is 10:1 to 1:2.
The method for preparing a basic anion exchange membrane according to claim 11, wherein the organic reagent used in the extraction process is one of ethyl acetate, diethyl ether, n-hexane and n-pentane.
The method for preparing a basic anion exchange membrane according to claim 9, wherein the reaction temperature in the step (1) is from 0 ° C to 75 ° C; and the reaction time is not less than 12 h.
The method for preparing a basic anion exchange membrane according to claim 9, wherein the reaction time in the step (2) is not less than 0.5 h.
The method for preparing a basic anion exchange membrane according to claim 9, wherein the reaction temperature in the step (3) ranges from room temperature to 90 ° C; the reaction time is not less than 12 h; The temperature is 40-70 ° C, and the casting time is not less than 4 h.
The method for preparing a basic anion exchange membrane according to claim 10, wherein the total concentration of the potassium hydroxide and/or sodium hydroxide is 0.1 to 3 mol/L; and the temperature of the solution is room temperature to 40 °C. .