Preparation method and application of pyrenyl conjugated organic polymer containing dinitrogen heterocyclic coupling proton transmission site

Abstract

The invention belongs to the field of photocatalytic preparation of hydrogen peroxide, and provides a preparation method and application of a pyrenyl conjugated organic polymer catalyst which is applied to photocatalytic preparation of hydrogen peroxide and contains a dinitrogen heterocyclic coupling proton transport site. The pyrenyl structure and the dinitrogen heterocyclic ring are combined in a covalent bond mode, a stable D-A structure is formed, and a proton transmission channel is constructed. Furthermore, carboxyl functional groups can be introduced, the hydrophilic performance of the catalyst is directionally modified, photo-induced electrons and holes are efficiently utilized, the utilization rate of photocatalytic energy is increased, the photocatalytic performance of the obtained material is further improved, and the highest yield can reach 7.32 mmol g <-1 > h <-1 >.

Description

[0001] The present invention belongs to the field of photocatalytic production of hydrogen peroxide, and specifically relates to a preparation method and application of a photocatalyst for producing hydrogen peroxide. Background Art

[0002] As a multifunctional green catalyst, hydrogen peroxide (H2O2) has been widely used in fields such as medical disinfection, environmental remediation, chemical synthesis, and automotive batteries. Traditional hydrogen peroxide is produced by the anthraquinone method (AQ), which has limitations such as environmental pollution, high energy consumption, and low economic efficiency. Therefore, photocatalytic generation of hydrogen peroxide has received extensive attention as a green and sustainable production route. Photocatalytic generation of hydrogen peroxide mainly utilizes electrons and holes generated by the excitation of photocatalysts under light irradiation to react with oxygen and water to produce hydrogen peroxide. Currently reported photocatalysts include metal oxides such as TiO and ZnO, graphitic carbon nitride (g-C3N4), covalent organic frameworks (COFs), etc. Among them, constructing donor-acceptor type porous conjugated organic polymers through strong electron donor groups and weak electron acceptor groups is an effective strategy for developing highly efficient photocatalysts.

[0003] Conjugated polymer materials are constructed with organic molecules as building blocks. The wide sources and diverse types of various organic molecules make the building blocks diverse, facilitating the regulation of the structure and function of target materials by modifying different functional groups. At the same time, the spatial network structure formed by covalent bonds has good thermal stability and chemical stability. Therefore, based on this, it is crucial to construct a photocatalytic material with high specific surface area, porous structure, light response performance, and high activity by introducing catalytic active sites on its surface. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method and application of a pyrene-based conjugated organic polymer catalyst containing a double nitrogen heterocycle coupled with a proton transfer site for photocatalytic production of hydrogen peroxide, so as to solve the problems proposed in the above background art.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] The present invention provides a donor-acceptor (D-A) type pyrene-based conjugated organic polymer material containing a double nitrogen heterocycle coupled with a proton transfer site, and the D-A type pyrene-based conjugated organic polymer material is a D-A type pyrene-based conjugated organic polymer material containing a pyrene group and a double nitrogen heterocycle.

[0007] The pyrene group structure is covalently bonded to the double nitrogen heterocycle.

[0008] The D-A type pyrene-based conjugated organic polymer material containing a pyrene group structure and a double nitrogen heterocycle is a catalyst for photocatalytic reactions.

[0009] The present invention provides a preparation method of a D-A type pyrene-based conjugated organic polymer material, which specifically includes three different catalysts, namely PY-DQ, PY-MD, and DQ-COOH31.

[0010] The present invention provides a preparation method of the PY-DQ catalyst, which specifically includes the following steps:

[0011] Step 1.1: Take a 100 mL round-bottom flask, add 60 mL of a mixed solvent of N,N-dimethylformamide / water, and perform nitrogen bubbling degassing for 30 min.

[0012] Step 1.2: Sequentially add 1,3,6,8-tetrakis(pinacolato)pyrene, 3,6-dibromopyridazine, tetrakis(triphenylphosphine)palladium, and anhydrous potassium carbonate into the flask, then stir at 150 °C for 48 h under a nitrogen atmosphere. After cooling to room temperature, filter to collect the precipitate.

[0013] Step 1.3: Soxhlet extract the solid collected in the previous step with methanol and dichloromethane for 72 h, and dry the final product at 80 °C for 12 h to obtain the PY-DQ material.

[0014] The present invention provides a preparation method of the PY-MD catalyst, which specifically includes the following steps:

[0015] Step 2.1: Take a 100 mL round-bottom flask, add 60 mL of a mixed solvent of N,N-dimethylformamide / water, and perform nitrogen bubbling degassing for 30 min.

[0016] Step 2.2: Sequentially add 1,3,6,8-tetrakis(pinacolato)pyrene, 2,5-dibromopyrimidine, tetrakis(triphenylphosphine)palladium, and anhydrous potassium carbonate into the flask, then stir at 150 °C for 48 h under a nitrogen atmosphere. After cooling to room temperature, filter to collect the precipitate.

[0017] Step 2.3: Soxhlet extract the solid collected in the previous step with methanol and dichloromethane for 72 h, and dry the final product at 80 °C for 12 h to obtain the PY-MD material.

[0018] The present invention provides a preparation method of the DQ-COOH31 catalyst, which specifically includes the following steps:

[0019] Step 3.1: Take a 100 mL round-bottom flask, add 60 mL of a mixed solvent of N,N-dimethylformamide / water, and perform nitrogen bubbling degassing for 30 min.

[0020] Step 3.2: Sequentially add 1,3,6,8-tetrakis(pinacolato)pyrene, 3,6-dibromopyridazine, 2,5-dibromoterephthalic acid, tetrakis(triphenylphosphine)palladium, and anhydrous potassium carbonate into the flask, then stir at 150 °C for 48 h under a nitrogen atmosphere. After cooling to room temperature, filter to collect the precipitate.

[0021] Step 3.3, Soxhlet extract the solid collected in the previous step with methanol and dichloromethane for 72 h, and dry the final product at 80 °C for 12 h to obtain the DQ-COOH31 material.

[0022] In the preparation method of DQ-COOH31, the addition ratio of 2,5-dibromoterephthalic acid to 3,6-dibromopyridazine is 1:3;

[0023] In Steps 1.1, 2.1, and 3.1, the mixed solvent is a mixed solution of water and N,N-dimethylformamide with a volume ratio of 1:5;

[0024] In Steps 1.1, 2.1, and 3.1, the air in the solvent needs to be removed before the reaction of the mixed solvent, and N2 protection is required throughout the reaction;

[0025] Furthermore, as described in Step 1.2 for the synthesis of PY-DQ, it is characterized in that pyrene and pyridazine structures are polymerized through a long-time high-temperature reaction to form a pyrene-based conjugated organic polymer containing a double nitrogen heterocycle-coupled proton transport site.

[0026] Furthermore, as described in Step 2.2 for the synthesis of PY-MD, it is characterized in that pyrene and pyrimidine structures are polymerized through a long-time high-temperature reaction to form a pyrene-based conjugated organic polymer containing a double nitrogen heterocycle-coupled proton transport site.

[0027] Furthermore, as described in Step 3.2 for the synthesis of DQ-COOH31, it is characterized in that through a long-time high-temperature reaction, a pyrene-based conjugated organic polymer containing a double nitrogen heterocycle-coupled proton transport site is formed.

[0028] Furthermore, as described in Step 3.2 for the synthesis of DQ-COOH31, it is characterized in that by introducing a carboxyl functional group, the material performance is optimized from multiple key aspects such as electron extraction, proton transfer, charge separation, and reactant adsorption, providing a more potential catalyst for photocatalytic synthesis of hydrogen peroxide.

[0029] The present invention provides the application of the D-A type pyrene-based conjugated organic polymer catalyst described in any one of the above technical solutions or the D-A type pyrene-based conjugated organic polymer catalyst prepared by the preparation method described in any one of the above technical solutions in the photocatalytic preparation of hydrogen peroxide.

[0030] The present invention also provides a method for photocatalytic preparation of hydrogen peroxide, including the following steps:

[0031] Step 1, after mixing the D-A type pyrene-based conjugated organic polymer catalyst photocatalyst with an aqueous solution, carry out a photocatalytic reaction under the irradiation of a xenon lamp to obtain hydrogen peroxide;

[0032] The addition amount of the D-A type porous conjugated organic polymer catalyst is 0.05 - 1 g / L;

[0033] The light intensity of the xenon lamp is 60 - 450 mW / cm 2 ;

[0034] The light wavelength irradiated by the xenon lamp is greater than 400 nm;

[0035] The temperature of the photocatalytic reaction is 20 - 30 °C;

[0036] The time of the photocatalytic reaction is 0.5 - 1 h.

[0037] The present invention provides a catalyst for photocatalytic production of hydrogen peroxide: namely a pyrene-based conjugated organic polymer catalyst containing a double nitrogen heterocycle coupled proton transport site, which is characterized in that the pyrene-based structure is used as an electron donor, and the double nitrogen heterocycle composed of pyridazine or pyrimidine groups is used as an electron acceptor to form a novel D-A structure, thereby constructing a stable proton transport channel. Further, the performance of the catalyst itself is improved by introducing functional groups. It is characterized in that by regulating the types of reactants and changing the reactant ratio, groups with an optimization effect on the structure are introduced.

[0038] Compared with the prior art, the present invention can obtain the following technical effects:

[0039] 1) Compared with the traditional covalent organic framework photocatalytic material, the pyrene-based conjugated covalent organic polymer catalyst of the present invention forms a stable D-A structure by introducing a double nitrogen heterocycle and combining it with the pyrene-based structure in a covalent bond form, promoting the intramolecular electron transfer of photo-generated carriers, inhibiting the recombination of photo-generated carriers, and thus improving the yield of the obtained material for photocatalytic production of hydrogen peroxide;

[0040] 2) On the basis of PY-DQ, a carboxyl functional group is introduced to further optimize the catalytic performance of the catalyst.

[0041] 3) The structure of the traditional semiconductor material is relatively simple, the synthesis method is limited, and there will be a situation where the active sites are unevenly distributed. The active sites constructed by the porous conjugated covalent organic polymer catalyst proposed by the present invention are evenly distributed, the synthesis is relatively simple, and it has a porous structure by itself, which can promote the reaction mass transfer and thus promote the reaction process of photocatalytic production of hydrogen peroxide. Brief Description of the Drawings

[0042] Figure 1 It is the molecular formula of a catalyst for catalyzing water oxidation to produce hydrogen peroxide according to the present invention, which are PY-DQ, PY-MD, and DQ-COOH31 in sequence;

[0043] Figure 2 It is the infrared spectrum diagram of a specific embodiment of the catalyst of the present invention for catalytic water oxidation to produce hydrogen peroxide;

[0044] Figure 3 It is a comparison diagram of the hydrogen peroxide yields of different catalysts of the catalyst of the present invention for catalytic water oxidation to produce hydrogen peroxide;

[0045] Figure 4 It is the SEM diagram of the catalyst of the present invention for catalytic water oxidation to produce hydrogen peroxide, which are PY-DQ, PY-MD, and DQ-COOH31 in sequence; Specific Embodiments

[0046] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. Unless otherwise specified, all commodities or reagents in the present invention are purchased through market channels.

[0047] Example 1: Preparation of catalyst PY-DQ

[0048] The specific preparation process of catalyst PY-DQ is as follows:

[0049] Take a 100 mL round-bottom flask, add 60 mL of a mixed solvent of N,N-dimethylformamide / water, and perform nitrogen bubbling degassing for 30 min. Add 1,3,6,8-tetrakis(pinacolato)pyrene (0.2 mmol, 141.2 mg), 3,6-dibromopyridazine (0.3 mmol, 71.4 mg), tetrakis(triphenylphosphine)palladium (0.01 mmol, 11.5 mg), and anhydrous potassium carbonate (1 mmol, 138.2 mg) into the flask in sequence, and then stir at 150 °C for 48 h under a nitrogen atmosphere. After cooling to room temperature, filter and collect the precipitate. Soxhlet extract the solid collected in the previous step with methanol and dichloromethane for 72 h, and finally dry the product at 80 °C for 12 h to obtain the PY-DQ material.

[0050] Example 2: Preparation of catalyst PY-MD

[0051] The specific preparation process of catalyst PY-MD is as follows:

[0052] Take a 100 mL round-bottom flask, add 60 mL of a mixed solvent of N,N-dimethylformamide / water, and conduct nitrogen bubbling degassing for 30 min. Sequentially add 1,3,6,8-tetrakis(pinacolato)pyrene (0.2 mmol, 141.2 mg), 2,5-dibromopyrimidine (0.3 mmol, 71.4 mg), tetrakis(triphenylphosphine)palladium (0.01 mmol, 11.5 mg), and anhydrous potassium carbonate (1 mmol, 138.2 mg) into the flask, then stir at 150 °C for 48 h under a nitrogen atmosphere. After cooling to room temperature, filter to collect the precipitate. Soxhlet extract the solid collected in the previous step with methanol and dichloromethane for 72 h, and dry the final product at 80 °C for 12 h to obtain the PY-MD material.

[0053] Example 3: Preparation of catalyst DQ-COOH31

[0054] The specific preparation process of catalyst DQ-COOH31 is as follows:

[0055] Take a 100 mL round-bottom flask, add 60 mL of a mixed solvent of N,N-dimethylformamide / water, and conduct nitrogen bubbling degassing for 30 min. Sequentially add 1,3,6,8-tetrakis(pinacolato)pyrene (0.2 mmol, 141.2 mg), 3,6-dibromopyridazine (0.3 mmol, 71.4 mg), 2,5-dibromoterephthalic acid (0.1 mmol, 32.3 mg), tetrakis(triphenylphosphine)palladium (0.01 mmol, 11.5 mg), and anhydrous potassium carbonate (1 mmol, 138.2 mg) into the flask, then stir at 150 °C for 48 h under a nitrogen atmosphere. After cooling to room temperature, filter to collect the precipitate. Soxhlet extract the solid collected in the previous step with methanol and dichloromethane for 72 h, and dry the final product at 80 °C for 12 h to obtain the DQ-COOH31 material.

[0056] It should be noted that in Examples 1 to 3 of the present invention, the inert gas used is nitrogen in order to better illustrate the technical solution of the present invention. Those skilled in the art can also select other inert gases as the protective gas.

[0057] Test Example 1

[0058] In a reaction kettle, add 30 mL of water and 1 mg of different types of catalysts, 0.1 MPa O2, and react for 1 hour at room temperature (20 - 30 °C), and then use ultraviolet to detect the yield of hydrogen peroxide.

[0059] From Figure 3As can be seen, a catalyst of the present invention for preparing hydrogen peroxide can better realize the catalytic oxidation of water to prepare hydrogen peroxide. By horizontal comparison, it can be found that the performance of PY-DQ is better than that of PY-MD. And the catalytic performance of the catalyst DQ-COOH31 with a carboxyl group introduced has been significantly improved compared with PY-DQ, thus reflecting the feasibility of this preparation method.

[0060] The best-performing catalyst in the test example is DQ-COOH31, and the hydrogen peroxide yield is 7320 μmol·g after 1 h of reaction. -1 ·h -1 .

[0061] The present invention uses the above embodiments to illustrate the technical concept of the present invention, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, the equivalent replacement of individual raw materials of the products of the present invention, the addition of auxiliary components, and the selection of specific methods, etc., all fall within the protection scope and the disclosure scope of the present invention.

[0062] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claims involved.

Claims

1. The present invention provides a preparation method of a D-A type pyrene-based conjugated organic polymer material, which specifically includes three different catalysts, namely PY-DQ, PY-MD, and DQ-COOH31.

2. The present invention provides a preparation method of the PY-DQ catalyst, which specifically includes the following steps: Step 1.1, Take a 100 mL round-bottom flask, add 60 mL of a mixed solvent of N,N-dimethylformamide / water, and perform nitrogen bubbling degassing for 30 min. Step 1.2, Sequentially add 1,3,6,8-tetrakis(pinacolato)pyrene, 3,6-dibromopyridazine, tetrakis(triphenylphosphine)palladium, and anhydrous potassium carbonate into the flask, and then stir at 150 °C for 48 h under a nitrogen atmosphere. After cooling to room temperature, filter and collect the precipitate. Step 1.3, Soxhlet extract the solid collected in the previous step with methanol and dichloromethane for 72 h, and dry the final product at 80 °C for 12 h to obtain the PY-DQ material.

3. The present invention provides a preparation method of the PY-MD catalyst, which specifically includes the following steps: Step 2.1, Take a 100 mL round-bottom flask, add 60 mL of a mixed solvent of N,N-dimethylformamide / water, and perform nitrogen bubbling degassing for 30 min. Step 2.2, Sequentially add 1,3,6,8-tetrakis(pinacolato)pyrene, 2,5-dibromopyrimidine, tetrakis(triphenylphosphine)palladium, and anhydrous potassium carbonate into the flask, and then stir at 150 °C for 48 h under a nitrogen atmosphere. After cooling to room temperature, filter and collect the precipitate. Step 2.3, Soxhlet extract the solid collected in the previous step with methanol and dichloromethane for 72 h, and dry the final product at 80 °C for 12 h to obtain the PY-MD material.

4. The present invention provides a preparation method of the DQ-COOH31 catalyst, which specifically includes the following steps: Step 3.1, Take a 100 mL round-bottom flask, add 60 mL of a mixed solvent of N,N-dimethylformamide / water, and perform nitrogen bubbling degassing for 30 min. Step 3.2, Sequentially add 1,3,6,8-tetrakis(pinacolato)pyrene, 3,6-dibromopyridazine, 2,5-dibromoterephthalic acid, tetrakis(triphenylphosphine)palladium, and anhydrous potassium carbonate into the flask, and then stir at 150 °C for 48 h under a nitrogen atmosphere. After cooling to room temperature, filter and collect the precipitate. Step 3.3, Soxhlet extract the solid collected in the previous step with methanol and dichloromethane for 72 h, and dry the final product at 80 °C for 12 h to obtain the DQ-COOH31 material.

5. In the preparation method of the DQ-COOH31, the addition ratio of 2,5-dibromoterephthalic acid to 3,6-dibromopyridazine is 1:

3.

6. Further, in the synthesis step of PY-DQ as described in step 1.2, it is characterized in that By polymerizing pyrene and pyridazine structures through a long-time high-temperature reaction, a pyrene-based conjugated organic polymer containing a double nitrogen heterocycle-coupled proton transport site is formed.

7. Further, as for the synthesis step of PY-MD described in step 2.2, it is characterized in that By polymerizing pyrene and pyrimidine structures through a long-time high-temperature reaction, a pyrene-based conjugated organic polymer containing a double nitrogen heterocycle-coupled proton transport site is formed.

8. Further, the synthesis step of DQ-COOH31 as described in step 3.2 is characterized in that, By a long-time high-temperature reaction, a pyrene-based conjugated organic polymer containing a double nitrogen heterocycle-coupled proton transport site is formed.

9. Further, the synthesis steps of DQ-COOH31 as described in step 3.2 are characterized in that, By introducing carboxyl functional groups, the material properties are optimized at multiple key levels, including electron extraction, proton transfer, charge separation, and reactant adsorption, providing a more promising catalyst for photocatalytic synthesis of hydrogen peroxide.

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