Preparation method and application of imine-linked covalent organic framework material

Abstract

The invention discloses a preparation method and application of an imine-linked covalent organic framework material, and belongs to the technical field of photocatalysis. The invention aims to solve the problems that the conventional H2O2 preparation method is high in energy consumption, complex in process, high in cost and not suitable for large-scale production, and the conventional imine-linked COF synthesis method is complex in step, time-consuming in synthesis and single in synthesis method. On the basis of adopting an aldehyde monomer acid pre-activation strategy for the first time, all reactants are directly added into a reaction kettle to be mixed, the imine-linked covalent organic framework material is rapidly synthesized through a solvothermal method, compared with a conventional method, the reaction conditions are simple and convenient to operate, time is saved, and the cost is reduced. The obtained material has the advantages of wide visible light absorption range, narrow band gap, high crystallinity, high photocatalytic activity, high yield and the like; and the obtained imine-linked covalent organic framework material photocatalytic material has good H2O2 production capacity under all light, and has very high practical value.

Description

Technical Field

[0001] This invention belongs to the field of photocatalysis technology, specifically relating to a method for preparing and applying an imine-linked covalent organic framework material. Background Technology

[0002] Hydrogen peroxide (H2O2) is an important oxidant that produces only harmless water during oxidation, thus having wide applications in environmental remediation and organic synthesis. Traditional methods for H2O2 preparation mainly include electrolysis and the anthraquinone method. Electrolysis is unsuitable for large-scale production due to its high energy consumption and cost; while the anthraquinone method consumes large amounts of organic solvents and has a complex and cumbersome production process, limiting the widespread application of H2O2. Due to its low cost and environmental friendliness, photocatalysis has attracted considerable interest from researchers in recent years for the production of H2O2.

[0003] Covalent organic frameworks (COFs) are a revolutionary type of crystalline organic material, unique in their ability to efficiently utilize light energy to drive chemical reactions. These materials are composed of non-metallic elements such as carbon, hydrogen, oxygen, and nitrogen, cleverly bound to organic building blocks through strong covalent bonds, and possess the significant advantage of a modular structure. This structural characteristic allows for precise control of their photoelectric properties, enabling their application in various metal-free photocatalytic processes.

[0004] In recent years, researchers have developed various methods for preparing COFs, including solvothermal, sonochemical, microwave, and mechanochemical synthesis. Solvothermal synthesis is the most commonly used method, but it typically involves harsh experimental conditions (e.g., toxic organic solvents, high reaction temperatures, long reaction times, and appropriate pressures) and complex steps (e.g., freeze-pump-thaw cycles, flame-sealed tubes, and heating for several days). In particular, the toxic organic solvents used in the synthesis process result in significant economic and environmental costs. Furthermore, the complex steps greatly limit the large-scale synthesis of COFs. Therefore, there is great interest in exploring simple, scalable, and environmentally friendly methods for synthesizing COFs. The principle of imine bond formation through the Schiff base condensation reaction between amines and aldehydes has been widely used to construct porous organic materials, such as imine-linked COFs. Moreover, imine-linked COFs can be synthesized in aqueous or organic solvents (even via solid-state synthesis), meaning that the Schiff base reaction overcomes the drawbacks of using toxic organic solvents in solvothermal synthesis, making it suitable for environmentally friendly COF synthesis. However, most current synthesis methods still suffer from problems such as complex steps and time-consuming synthesis. Therefore, it is necessary to find a rapid and environmentally friendly method for synthesizing imine-linked COFs by dissolution heat, which is of great significance for the efficient and convenient synthesis of imine-linked COFs. Summary of the Invention

[0005] The purpose of this invention is to address the problems of high energy consumption, complex processes, high costs, and unsuitability for large-scale production in existing traditional methods for preparing H2O2, as well as the complex steps, time-consuming synthesis, and limited synthesis methods in existing imine-linked COF synthesis methods. Instead, this invention provides a method for preparing and applying imine-linked covalent organic framework materials.

[0006] This invention provides a simple, short-time solvothermal method for synthesizing an imine-linked covalent organic framework material with high crystallinity, high photocatalytic activity, and high yield, and applies it to the synthesis of H2O2.

[0007] A method for preparing an imine-linked covalent organic framework material, specifically comprising the following steps:

[0008] 1. Mix 1,3,5-tris(formylphenyl)benzene with an aqueous solution of acetic acid, disperse the mixture ultrasonically for a period of time, and then stir it magnetically to obtain an activated aldehyde monomer solution;

[0009] 2. Add 4,4',4''-(1,3,5-triazine-2,4,6-triyl)triphenylamine to 1,4-dioxane, disperse by ultrasonication, then add an activated aldehyde monomer solution, mix well to obtain a precursor solution;

[0010] 3. The precursor solution is transferred to a reaction vessel and then subjected to a hydrothermal reaction at 110℃~130℃ to obtain the reaction product;

[0011] 4. Centrifuge the reaction product, collect the solid material, wash the obtained solid material, and vacuum dry it to obtain an imine-linked covalent organic framework material.

[0012] Application of the imine-linked covalent organic framework material in the synthesis of hydrogen peroxide.

[0013] Compared with existing technologies, this invention proposes a method for preparing imine-linked covalent organic framework materials and demonstrates their application value in the field of H2O2 production. This invention, for the first time, utilizes a strategy of pre-activation with an aldehyde monomer acid to directly add all reactants to a reaction vessel for rapid synthesis of COF-2 via a solvothermal method. Compared with conventional methods, this method is simpler, saves time, and yields materials with advantages such as a wide visible light absorption range, narrow band gap, high crystallinity, high photocatalytic activity, and high yield. Furthermore, the COF-2 photocatalytic material obtained by this method exhibits good H2O2 production capability under full light, demonstrating high practical value. Attached Figure Description

[0014] Figure 1 This is a synthetic route diagram for the imine-linked covalent organic framework material prepared in Example 1;

[0015] Figure 2The Fourier transform infrared spectrum of the imine-linked covalent organic framework material prepared in Example 1 is shown below.

[0016] Figure 3 This is a scanning electron microscope image of the imine-linked covalent organic framework material prepared in Example 1;

[0017] Figure 4 The powder X-ray diffraction pattern of the imine-linked covalent organic framework material prepared in Example 1 is shown below.

[0018] Figure 5 The image shows the photocatalytic H2O2 production effect of the imine-linked covalent organic framework material prepared in Example 1. Detailed Implementation

[0019] Specific Implementation Method 1: This implementation method describes a method for preparing an imine-linked covalent organic framework material, which is specifically completed according to the following steps:

[0020] 1. Mix 1,3,5-tris(formylphenyl)benzene with an aqueous solution of acetic acid, disperse the mixture ultrasonically for a period of time, and then stir it magnetically to obtain an activated aldehyde monomer solution;

[0021] 2. Add 4,4',4''-(1,3,5-triazine-2,4,6-triyl)triphenylamine to 1,4-dioxane, disperse by ultrasonication, then add an activated aldehyde monomer solution, mix well to obtain a precursor solution;

[0022] 3. The precursor solution is transferred to a reaction vessel and then subjected to a hydrothermal reaction at 110℃~130℃ to obtain the reaction product;

[0023] 4. Centrifuge the reaction product, collect the solid material, wash the obtained solid material, and vacuum dry it to obtain an imine-linked covalent organic framework material.

[0024] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the concentration of the acetic acid aqueous solution in step one is 6 mol / L to 8 mol / L; the mass ratio of 1,3,5-tris(formylphenyl)benzene to the volume ratio of the acetic acid aqueous solution in step one is (25 mg to 75 mg):(2 mL to 6 mL). The other steps are the same as in Specific Implementation Method One.

[0025] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that: the ultrasonic dispersion time in step one is 10-15 minutes, and the ultrasonic dispersion power is 70W-80W; the magnetic stirring speed in step one is 600-700 r / min, and the magnetic stirring time is 30-40 minutes. Other steps are the same as in Specific Implementation Method One or Two.

[0026] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the molar ratio of 4,4',4''-(1,3,5-triazine-2,4,6-triyl)triphenylamine in step two to 1,3,5-tris(formylphenyl)benzene in step one is 1:1. The other steps are the same as in Specific Implementation Methods One to Three.

[0027] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the volume ratio of 1,4-dioxane in step two to the aqueous acetic acid solution in step one is (1~2):1. The other steps are the same as in Specific Implementation Methods One to Four.

[0028] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the ultrasonic dispersion time in step two is 10-15 minutes, and the ultrasonic dispersion power is 70W-80W. The other steps are the same as in Specific Implementation Methods One to Five.

[0029] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that: the hydrothermal reaction time in step three is 12h to 24h; the centrifugation speed in step four is 10000rpm to 12000rpm, and the centrifugation time is 5min to 10min. Other steps are the same as in Specific Implementation Methods One to Six.

[0030] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that: in step four, the obtained solid material is alternately washed with anhydrous ethanol and deionized water, each time 3 to 6 times; the vacuum drying temperature in step four is 70℃ to 80℃, and the vacuum drying time is 12h to 24h. Other steps are the same as in Specific Implementation Methods One to Seven.

[0031] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that it involves the application of the imine-linked covalent organic framework material in the synthesis of hydrogen peroxide. The other steps are the same as in Specific Implementation Methods One to Eight.

[0032] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that the application of the imine-linked covalent organic framework material in the synthesis of hydrogen peroxide is specifically carried out according to the following steps:

[0033] Under ultrasonic conditions, an imine-linked covalent organic framework material is uniformly dispersed in deionized water, and then subjected to a photocatalytic reaction under light source irradiation to obtain hydrogen peroxide; the mass ratio of the imine-linked covalent organic framework material to the volume ratio of deionized water is (3mg~9mg):(10mL~30mL); the light source is a 300W xenon lamp. Other steps are the same as in specific embodiments one to nine.

[0034] The beneficial effects of the present invention are verified using the following embodiments:

[0035] Example 1: A method for preparing an imine-linked covalent organic framework material, specifically carried out according to the following steps:

[0036] 1. Mix 50 mg of 1,3,5-tris(formylphenyl)benzene with 4 mL of 8 mol / L acetic acid aqueous solution, disperse by ultrasonication for a period of time, and then stir magnetically to obtain an activated aldehyde monomer solution.

[0037] The ultrasonic dispersion time mentioned in step one is 10 minutes, and the ultrasonic dispersion power is 70W.

[0038] The magnetic stirring speed mentioned in step one is 600 r / min, and the magnetic stirring time is 30 min;

[0039] 2. Add 46 mg of 4,4',4''-(1,3,5-triazine-2,4,6-triyl)triphenylamine to 4 mL of 1,4-dioxane, disperse by ultrasonication, then add the activated aldehyde monomer solution obtained in step 1, mix well, and obtain the precursor solution.

[0040] The ultrasonic dispersion time in step two is 10 minutes, and the ultrasonic dispersion power is 70W.

[0041] 3. The precursor solution is transferred to a reaction vessel and subjected to a hydrothermal reaction at 120°C for 24 hours to obtain the reaction product.

[0042] 4. Centrifuge the reaction product, collect the solid material, wash the obtained solid material, and vacuum dry it to obtain the imine-linked covalent organic framework material (COF-2).

[0043] The centrifugation speed in step four is 10,000 rpm, and the centrifugation time is 10 min;

[0044] In step four, the obtained solid substance is washed alternately with anhydrous ethanol and deionized water, three times each.

[0045] The vacuum drying temperature in step four is 80°C, and the vacuum drying time is 24 hours.

[0046] Figure 1 This is a synthetic route diagram for the imine-linked covalent organic framework material prepared in Example 1;

[0047] Figure 2 The Fourier transform infrared spectrum of the imine-linked covalent organic framework material prepared in Example 1 is shown below.

[0048] from Figure 2 It can be seen that imine-linked covalent organic frameworks were successfully and rapidly synthesized from aldehyde monomer (1,3,5-tris(formylphenyl)benzene) and amine monomer (4,4',4''-(1,3,5-triazine-2,4,6-triyl)triphenylamine) via solvent method.

[0049] Figure 3 This is a scanning electron microscope image of the imine-linked covalent organic framework material prepared in Example 1;

[0050] from Figure 3 It can be seen that COF-2 has a well-crystallized and uniformly shaped nanosphere morphology, indicating that it has a rich specific surface area, which is beneficial to fully exert its photocatalytic performance.

[0051] Figure 4 The powder X-ray diffraction pattern of the imine-linked covalent organic framework material prepared in Example 1 is shown below.

[0052] from Figure 4 It can be seen that strong reflection is observed in the low-angle region of 2θ = 4.0°, indicating that COF-2 has a large pore size; the low peak after 2θ = 20.0° indicates that the interplanar spacing of COF-2 is small, proving that the material has a good interlayer π-conjugated structure.

[0053] Example 2: The difference between this example and Example 1 is that in step two, 46 ​​mg of 4,4',4''-(1,3,5-triazine-2,4,6-triyl)triphenylamine was added to 6 mL of 1,4-dioxane. All other steps and parameters were the same as in Example 1.

[0054] Example 3: The difference between this example and Example 1 is that in step two, 46 ​​mg of 4,4',4''-(1,3,5-triazine-2,4,6-triyl)triphenylamine was added to 8 mL of 1,4-dioxane. All other steps and parameters are the same as in Example 1.

[0055] Example 4: The difference between this example and Example 1 is that in step three, the precursor solution is transferred to a reaction vessel and then subjected to a hydrothermal reaction at 120°C for 12 hours to obtain the reaction product. All other steps and parameters are the same as in Example 1.

[0056] Application Example 1: The application of imine-linked covalent organic framework materials in the synthesis of hydrogen peroxide is specifically carried out according to the following steps:

[0057] Under ultrasonic conditions, 6 mg of the imine-linked covalent organic framework material prepared in Example 1 was uniformly dispersed in 20 mL of deionized water. The mixture was then placed under a 300 W xenon lamp (approximately 5 cm from the center of the lamp) with open stirring for 0-60 hours at room temperature to obtain H2O2. (See attached image.) Figure 5 As shown;

[0058] The filtered sample was subjected to color development with cerium sulfate for 10 min, and the H2O2 content was determined at 316 nm using a UV spectrophotometer.

[0059] Figure 5 The image shows the photocatalytic H2O2 production effect of the imine-linked covalent organic framework material prepared in Example 1.

[0060] from Figure 5 As can be seen, the imine-linked covalent organic framework material (COF-2) prepared in Example 1 exhibits high visible light photocatalytic activity, with an H2O2 yield of 735.54 μmol·g in 1 h. -1 The resulting imine-linked covalent organic framework photocatalytic material exhibits good H2O2 production capability under full light.

[0061] After testing, the H2O2 yield of the imine-linked covalent organic framework materials prepared in Examples 2-4 was basically the same as that in Example 1, proving that the imine-linked covalent organic framework materials can be stably synthesized and applied in a shorter time by solvothermal method.

Claims

1. A method for preparing an imine-linked covalent organic framework material, characterized in that... The preparation method is specifically carried out according to the following steps:

1. Mix 1,3,5-tris(formylphenyl)benzene with an aqueous solution of acetic acid, disperse the mixture by ultrasonication for a period of time, and then stir it magnetically to obtain an activated aldehyde monomer solution; 2. Add 4,4',4''-(1,3,5-triazine-2,4,6-triyl)triphenylamine to 1,4-dioxane, disperse by ultrasonication, then add an activated aldehyde monomer solution, mix well to obtain a precursor solution; 3. The precursor solution is transferred to a reaction vessel and then subjected to a hydrothermal reaction at 110℃~130℃ to obtain the reaction product; 4. Centrifuge the reaction product, collect the solid material, wash the obtained solid material, and vacuum dry it to obtain an imine-linked covalent organic framework material.

2. The method for preparing an imine-linked covalent organic framework material according to claim 1, characterized in that... The concentration of the acetic acid aqueous solution mentioned in step one is 6 mol / L to 8 mol / L; the mass ratio of 1,3,5-tris(formylphenyl)benzene to the volume ratio of the acetic acid aqueous solution mentioned in step one is (25 mg to 75 mg): (2 mL to 6 mL).

3. The method for preparing an imine-linked covalent organic framework material according to claim 1, characterized in that... The ultrasonic dispersion time in step one is 10 min to 15 min, and the ultrasonic dispersion power is 70 W to 80 W; the magnetic stirring speed in step one is 600 r / min to 700 r / min, and the magnetic stirring time is 30 min to 40 min.

4. The method for preparing an imine-linked covalent organic framework material according to claim 1, characterized in that... The molar ratio of 4,4',4''-(1,3,5-triazine-2,4,6-triyl)triphenylamine mentioned in step two to 1,3,5-tris(formylphenyl)benzene mentioned in step one is 1:

1.

5. The method for preparing an imine-linked covalent organic framework material according to claim 1, characterized in that... The volume ratio of 1,4-dioxane in step two to the aqueous acetic acid solution in step one is (1~2):

1.

6. The method for preparing an imine-linked covalent organic framework material according to claim 1, characterized in that... The ultrasonic dispersion time in step two is 10 min to 15 min, and the ultrasonic dispersion power is 70 W to 80 W.

7. The method for preparing an imine-linked covalent organic framework material according to claim 1, characterized in that... The hydrothermal reaction time in step three is 12h~24h; the centrifugation speed in step four is 10000rpm~12000rpm, and the centrifugation time is 5min~10min.

8. The method for preparing an imine-linked covalent organic framework material according to claim 1, characterized in that... In step four, the obtained solid material is washed alternately with anhydrous ethanol and deionized water, each time 3 to 6 times; the vacuum drying temperature in step four is 70℃ to 80℃, and the vacuum drying time is 12h to 24h.

9. The application of the imine-linked covalent organic framework material prepared by the preparation method according to claim 1, characterized in that... Application of the imine-linked covalent organic framework material in the synthesis of hydrogen peroxide.

10. The method for preparing an imine-linked covalent organic framework material according to claim 1, characterized in that... The application of the imine-linked covalent organic framework material in the synthesis of hydrogen peroxide is specifically accomplished through the following steps: Under ultrasonic conditions, an imine-linked covalent organic framework material is uniformly dispersed in deionized water, and then subjected to a photocatalytic reaction under light source irradiation to obtain hydrogen peroxide; the mass ratio of the imine-linked covalent organic framework material to the volume ratio of deionized water is (3mg~9mg):(10mL~30mL); the light source is a 300W xenon lamp.

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