Preparation of three-component covalent organic framework and application of three-component covalent organic framework in photosynthesis of hydrogen peroxide

Abstract

The invention relates to preparation and photocatalytic application of a three-component covalent organic framework photocatalyst. The invention aims to solve the problems of low visible light utilization rate, low efficiency of photocatalytic synthesis of hydrogen peroxide and complex synthesis process of a multi-component covalent organic framework material in the synthesis of a high-performance photocatalyst in the prior art. The method comprises the following steps: dispersing two reaction monomers into an organic solvent to form a mixed solution, adding a catalyst into the mixed solution, then adding the third monomer, carrying out ultrasonic dispersion, carrying out a heating reaction for a period of time, cooling to room temperature, and carrying out solid-liquid separation to obtain a solid; and carrying out solid separation, collecting the solid, washing and drying to obtain the three-component covalent organic framework material. The prepared TTBTP-1 three-component covalent organic framework photocatalytic material is high in crystallinity and good in catalytic effect and is superior to a two-component photocatalyst, the preparation method is simple, through the design thought that p-phenylenediamine is adopted as a linker to connect two monomers with different structures, the thought is broadened for the design of a novel COF structure and function, and the application prospect is broad. The method has important research significance.

Description

Technical Field

[0001] The present invention relates to the preparation of a three-component covalent organic framework and photocatalytic synthesis of hydrogen peroxide. Background Art

[0002] With the continuous growth of industry and population, the development of human society is increasingly dependent on chemical products. The synthesis of many chemical products relies on traditional synthesis methods with high energy consumption and high pollution, as well as environmentally unfriendly chemical raw materials. As an important oxidant, hydrogen peroxide is an environmentally friendly and widely used chemical raw material. It can be applied in fields such as pulp bleaching, sewage treatment, food and medicine, and metallurgy. According to statistical data, the production capacity of H2O2 in China shows an increasing trend year by year. In 2027, the global production capacity is expected to reach 5.7 million tons. Currently, the mature industrial production method is the anthraquinone method. However, there are still the following problems in large-scale production of high-concentration products, such as cumbersome production processes, high energy consumption, many by-products, and difficult treatment.

[0003] In contrast, photocatalytic technology has the advantages of environmental friendliness, energy conservation and sustainability, and high catalytic performance, which is conducive to the green production of H2O2. However, most reported photocatalysts still have problems such as a narrow light absorption range, low absorption utilization rate, and easy and rapid recombination of photo-generated electrons and holes.

[0004] Covalent organic frameworks (COFs), as a new type of photocatalyst, have the characteristics of regular and ordered structures, narrow pore size distributions, high surface areas, and π-conjugated structures. The tunable structure of COFs enables targeted design of photocatalysis. The high specific surface area and porosity can introduce and expose more catalytic sites. Therefore, more and more COF materials have been successfully applied in the field of photocatalysis. Summary of the Invention

[0005] In order to solve the problems of low visible light utilization rate of the existing photocatalytic materials, low efficiency of photocatalytic synthesis of hydrogen peroxide, and complex synthesis process of multi-component covalent organic framework materials, the present invention provides a simple method for synthesizing a three-component covalent organic framework photocatalytic material, which can effectively improve the efficiency of photocatalytic synthesis of hydrogen peroxide.

[0006] The object of the present invention is achieved as follows:

[0007] The preparation of a three-component covalent organic framework material includes the following steps:

[0008] (1) Preparation of TP-1-COF: Phloroglucinol trialdehyde and p-phenylenediamine were successively added into a Schlenk glass tube. o-Dichlorobenzene and n-butanol solvents were added to the Schlenk glass tube to form a mixed solution. The mixed solution was ultrasonically treated to obtain a uniform dispersion, and then an aqueous acetic acid solution was added. The Schlenk tube was quickly frozen in a liquid nitrogen bath and degassed by three freeze-thaw cycles. Finally, the tube was heated under vacuum-sealed conditions for several hours. The reaction product was collected by filtration, washed successively with DMF and ethanol, and finally vacuum-dried at 60 °C for 24 hours to obtain the TP-1-COF material with a yield of about 85%;

[0009] (2) Preparation of TTBPDA-COF: 5,5,5-(benzene-1,3,5-triyl)tris(thiophene-2-carbaldehyde) and p-phenylenediamine were successively added into a Schlenk glass tube. o-Dichlorobenzene and n-butanol solvents were added to the Schlenk glass tube to form a mixed solution. The mixed solution was ultrasonically treated to obtain a uniform dispersion, and then an aqueous acetic acid solution was added. The Schlenk tube was quickly frozen in a liquid nitrogen bath and degassed by three freeze-thaw cycles. Finally, the tube was heated under vacuum-sealed conditions for several hours. The reaction product was collected by filtration, washed successively with DMF and ethanol, and finally vacuum-dried at 60 °C for 24 hours to obtain the TTBPDA-COF material with a yield of about 55%;

[0010] (3) Preparation of TTBTP-1-COF: 5,5,5-(benzene-1,3,5-triyl)tris(thiophene-2-carbaldehyde) and p-phenylenediamine were successively added into a Schlenk glass tube. Ethanol was added to the Schlenk glass tube to form a mixed solution. At the same time, phloroglucinol trialdehyde was added to a centrifuge tube and o-dichlorobenzene was added to it to form a mixed solution. The mixed solution was ultrasonically treated to obtain a uniform dispersion. Subsequently, an aqueous acetic acid solution was added to the Schlenk glass tube and ultrasonically treated for a period of time. Then, the phloroglucinol trialdehyde dispersion in the centrifuge tube was added to the Schlenk glass tube and ultrasonically dispersed evenly. The Schlenk tube was quickly frozen in a liquid nitrogen bath and degassed by three freeze-thaw cycles. Finally, the tube was heated under vacuum-sealed conditions for several hours. The reaction product was collected by filtration, washed successively with DMF and ethanol, and finally vacuum-dried at 60 °C for 24 hours to obtain the TTBTP-1-COF material with a yield of about 75%;

[0011] Preferably, in the synthesis of the above-mentioned TP-1-COF catalyst, in step (1), the molar ratio of phloroglucinol trialdehyde to p-phenylenediamine is 1:1.5;

[0012] Preferably, in the synthesis of the above-mentioned TP-1-COF catalyst, in step (1), the volume ratio of o-dichlorobenzene to n-butanol is 1:1;

[0013] Preferably, in the synthesis of the above-mentioned TP-1-COF catalyst, in step (1), the concentration of the acetic acid aqueous solution is 3 mol·L -1 ;

[0014] Preferably, in the synthesis of the above-mentioned TP-1-COF catalyst, in step (1), the heating reaction temperature is 100-140 °C and the heating time is 48-96 h.

[0015] Preferably, in the synthesis of the above-mentioned TTBPDA-COF catalyst, in step (2), the molar ratio of 5,5,5-(benzene-1,3,5-triyl)tris(thiophene-2-carbaldehyde) to p-phenylenediamine is 1:1.5;

[0016] Preferably, in the synthesis of the above-mentioned TTBPDA-COF catalyst, in step (2), the volume ratio of o-dichlorobenzene to n-butanol is 1:1;

[0017] Preferably, in the synthesis of the above-mentioned TTBPDA-COF catalyst, in step (2), the concentration of the acetic acid aqueous solution is 3 mol·L -1 ;

[0018] Preferably, in the synthesis of the above-mentioned TTBPDA-COF catalyst, in step (2), the heating reaction temperature is 100-140 °C and the heating time is 48-96 h.

[0019] Preferably, in the synthesis of the above-mentioned TTBTP-1-COF catalyst, in step (3), the molar ratio of phloroglucinol trialdehyde, 5,5,5-(benzene-1,3,5-triyl)tris(thiophene-2-carbaldehyde) to p-phenylenediamine is 1:1:3;

[0020] Preferably, in the synthesis of the above-mentioned TTBTP-1-COF catalyst, in step (3), the volume ratio of o-dichlorobenzene to ethanol is 1:3;

[0021] Preferably, in the synthesis of the above-mentioned TTBTP-1-COF catalyst, in step (3), the concentration of the acetic acid aqueous solution is 3 mol·L -1 ;

[0022] Preferably, in the synthesis of the above-mentioned TTBTP-1-COF catalyst, in step (3), the heating reaction temperature is 100-140 °C and the heating time is 48-96 h.

[0023] The method for preparing hydrogen peroxide by applying a photocatalyst is as follows: Mix the photocatalyst with deionized water, introduce oxygen, and irradiate under a xenon lamp to obtain hydrogen peroxide. Among them, the photocatalyst is the above-mentioned TP-1-COF, TTBPDA-COF, and TTBTP-1-COF.

[0024] Compared with the prior art, the present invention has the following characteristics:

[0025] The three-component TTBTP-1-COF photocatalyst prepared by the one-pot method in the present invention has a simple and easy-to-operate synthesis method and certain universality. The ability to photocatalytically synthesize hydrogen peroxide is significantly improved compared with TP-1-COF and TTBPDA-COF. Among them, the efficiency of photocatalytic synthesis of hydrogen peroxide by TP-1-COF is 0.6 - 0.7 mmol·g -1 ·h-1, the efficiency of photocatalytic synthesis of hydrogen peroxide by TTBPDA-COF is 0.3 - 0.4 mmol·g -1 ·h-1, and the efficiency of photocatalytic synthesis of hydrogen peroxide by TTBTP-1-COF is 1.0 - 1.2 mmol·g -1 ·h-1. The present invention effectively improves the problem of low efficiency of photocatalytic synthesis of hydrogen peroxide in such COFs materials. By adopting the idea of connecting two aldehyde monomers with different structures using p-phenylenediamine as a linker, the separation of photo-generated charges can be effectively improved, the photocatalytic ability of COFs materials can be enhanced, and the diversity of COFs structures and functions can be expanded, opening up a new way for the design of new COF structures and functions. Description of the Drawings

[0026] Figure 1 It is the XRD spectrum of the three-component TTBTP-1-COF, TP-1-COF, and TTBPDA-COF synthesized in the present invention.

[0027] Figure 2 It is the infrared spectrum of the three-component TTBTP-1-COF, TP-1-COF, and TTBPDA-COF synthesized in the present invention.

[0028] Figure 3 It is the performance diagram of photocatalytic synthesis of hydrogen peroxide by the three-component TTBTP-1-COF, TP-1-COF, and TTBPDA-COF synthesized in the present invention. Detailed Embodiments

[0029] The present invention will be further described below with examples. These examples only illustrate the method of the present invention and have no limitation on the scope of application of the present invention.

[0030] Example 1, Preparation steps of TP-1-COF:

[0031] 8.4 mg of trialdehyde phloroglucinol and 6.5 mg of p-phenylenediamine were successively added to a Schlenk glass tube. 1 mL of o-dichlorobenzene and 1 mL of n-butanol solvent were added to the Schlenk glass tube to form a mixed solution. The mixed solution was ultrasonically treated for 20 min to obtain a uniform dispersion. Subsequently, 0.2 mL of 3 mol·L -1 acetic acid aqueous solution was added. The Schlenk tube was quickly frozen in 77 K (liquid nitrogen bath) and degassed by three freeze-thaw cycles. Finally, the Schlenk tube was heated at 120 °C for 72 h in a vacuum-sealed state. The reaction product was collected by filtration, washed 5 times with DMF and ethanol in turn, and finally dried in vacuo at 60 °C for 24 h to obtain the TP-1-COF material with a yield of about 85%;

[0032] Example 2, Preparation steps of TTBPDA-COF:

[0033] 8.2 mg of 5,5,5-(benzene-1,3,5-triyl)tris(thiophene-2-carbaldehyde) and 3.2 mg of p-phenylenediamine were successively added to a Schlenk glass tube. 1 mL of o-dichlorobenzene and 1 mL of n-butanol solvent were added to the Schlenk glass tube to form a mixed solution. The mixed solution was ultrasonically treated for 20 min to obtain a uniform dispersion. Subsequently, 0.1 mL of 3 mol·L -1 acetic acid aqueous solution was added. The Schlenk tube was quickly frozen in 77 K (liquid nitrogen bath) and degassed by three freeze-thaw cycles. Finally, the Schlenk tube was heated at 120 °C for 72 h in a vacuum-sealed state. The reaction product was collected by filtration, washed 5 times with DMF and ethanol in turn, and finally dried in vacuo at 60 °C for 24 h to obtain the TTBPDA-COF material with a yield of about 55%;

[0034] Example 3, Preparation steps of TTBTP-1-COF:

[0035] 8.2 mg of 5,5,5-(benzene-1,3,5-triyl)tris(thiophene-2-carbaldehyde) and 6.5 mg of p-phenylenediamine were successively added to a Schlenk glass tube. 1.5 mL of ethanol was added to the Schlenk glass tube to form a mixed solution. At the same time, 4.2 mg of trialdehyde phloroglucinol was added to a 5 mL centrifuge tube and 0.5 mL of o-dichlorobenzene was added thereto to form a mixed solution. The mixed solution was ultrasonically treated for 20 min to obtain a uniform dispersion. Subsequently, 0.2 mL of 3 mol·L -1The acetic acid aqueous solution was ultrasonically treated for another 5 min. Subsequently, the tri-formylphloroglucinol dispersion in the centrifuge tube was added to a Schlenk tube and ultrasonically dispersed evenly. The Schlenk tube was quickly frozen in liquid nitrogen at 77 K and degassed by three freeze-thaw cycles. Finally, the tube was heated at 120 °C for 72 h in a vacuum-sealed state. The reaction product was collected by filtration, washed 5 times with DMF and ethanol in sequence, and finally dried in vacuo at 60 °C for 24 h to obtain the TTBTP-1-COF material with a yield of about 75%;

[0036] The method for photocatalytic application is as follows:

[0037] To investigate the photocatalytic hydrogen peroxide synthesis effect of the three-component TTBTP-1-COF material, its visible-light photocatalytic hydrogen peroxide synthesis performance was tested according to the following method. The test process is as follows: TP-1-COF, TTBPDA-COF, and TTBTP-1-COF (10 mg) were used as photocatalysts respectively, and deionized water was used as the reaction solution. The three COF materials were respectively dispersed in beakers and ultrasonically treated for 30 min to form a uniform suspension. After the suspension was poured into the reactor, oxygen was introduced for 20 min to exhaust the air in the reactor. Then, a xenon lamp was used as the light source. After illumination for 30 min, the suspension after the reaction was filtered through a 1 mL syringe with a filter tip to remove the catalyst, and the liquid was collected. 1 mL of the collected liquid to be tested was added to 1 mL of potassium iodide solution with a concentration of 6.5 mg·mL -1 and 0.5 mL of potassium hydrogen phthalate solution with a concentration of 20.4 mg·mL -1 and mixed well, and then left standing for 30 min, and analyzed with a UV-visible spectrophotometer. As Figure 3 shown, under visible light, the three-component TTBTP-1-COF has a significantly improved efficiency in photocatalytic hydrogen peroxide synthesis under visible light compared with TP-1-COF and TTBPDA-COF, showing good performance in photocatalytic hydrogen peroxide synthesis.

[0038] In summary, the three-component TTBTP-1-COF photocatalyst prepared by the one-pot method in this example can significantly improve the ability of photosynthetic hydrogen peroxide synthesis, and the synthesis method is simple and easy to operate. By adopting the design idea of connecting two aldehyde monomers with different structures using p-phenylenediamine as a linker, a new way is opened up for the design of new COF structures and functions.

Claims

1. Preparation of a three-component covalent organic framework and its application in photosynthetic production of hydrogen peroxide, characterized in that The method is carried out according to the following steps: (1) Preparation of TP-1-COF: 8.4 mg of trialdehyde phloroglucinol and 6.5 mg of p-phenylenediamine were successively added into a Schlenk glass tube. 1 mL of o-dichlorobenzene and 1 mL of n-butanol solvent were added into the Schlenk glass tube to form a mixed solution. The mixed solution was ultrasonically treated for 20 min to obtain a uniform dispersion. Subsequently, 0.2 mL of 3 mol·L -1 acetic acid aqueous solution was added. The Schlenk tube was quickly frozen in 77 K (liquid nitrogen bath) and degassed by three freeze-thaw cycles. Finally, the Schlenk tube was heated at 120 °C for 72 h in a vacuum-sealed state. The reaction product was collected by filtration, washed 5 times with DMF and ethanol successively, and finally dried in vacuum at 60 °C for 24 h to obtain the TP-1-COF material with a yield of about 85%; (2) Preparation of TTBPDA-COF: 8.2 mg of 5,5,5-(benzene-1,3,5-triyl)tris(thiophene-2-carbaldehyde) and 3.2 mg of p-phenylenediamine were successively added into a Schlenk glass tube. 1 mL of o-dichlorobenzene and 1 mL of n-butanol solvent were added into the Schlenk glass tube to form a mixed solution. The mixed solution was ultrasonically treated for 20 min to obtain a uniform dispersion. Subsequently, 0.1 mL of 3 mol·L -1 aqueous acetic acid solution was added. The Schlenk tube was quickly frozen in 77 K (liquid nitrogen bath) and degassed by three freeze-thaw cycles. Finally, the Schlenk tube was heated at 120 °C for 72 h in a vacuum-sealed state. The reaction product was collected by filtration, washed 5 times successively with DMF and ethanol, and finally dried in vacuo at 60 °C for 24 h to obtain the TTBPDA-COF material with a yield of about 55%; (3) Preparation of TTBTP-1-COF: 8.2 mg of 5,5,5-(benzene-1,3,5-triyl)tris(thiophene-2-carbaldehyde) and 6.5 mg of p-phenylenediamine were successively added to a Schlenk glass tube. 1.5 mL of ethanol was added to the Schlenk glass tube to form a mixed solution. At the same time, 4.2 mg of phloroglucinol trialdehyde was added to a 5 mL centrifuge tube and 0.5 mL of o-dichlorobenzene was added thereto to form a mixed solution. The mixed solution was ultrasonically treated for 20 min to obtain a uniform dispersion. Subsequently, 0.2 mL of 3 mol·L -1 aqueous acetic acid solution was added to the Schlenk glass tube and ultrasonically treated for another 5 min. Subsequently, the phloroglucinol trialdehyde dispersion in the centrifuge tube was added to the Schlenk glass tube and ultrasonically dispersed evenly. The Schlenk tube was quickly frozen in liquid nitrogen bath at 77 K and degassed by three freeze-thaw cycles. Finally, the tube was heated at 120 °C for 72 h in a vacuum-sealed state. The reaction product was collected by filtration, washed successively with DMF and ethanol 5 times, and finally dried in vacuo at 60 °C for 24 h to obtain the TTBTP-1-COF material with a yield of about 75%.

2. Preparation of a three-component TTBTP-1-COF photocatalyst according to claim 1, characterized in that, A three-component covalent organic framework photocatalyst is applied to the field of photocatalytic synthesis of hydrogen peroxide.

3. Preparation of a three-component TTBTP-1-COF photocatalyst according to claim 1, characterized in that, The molar ratio of the described phloroglucinol trialdehyde, 5,5,5-(benzene-1,3,5-triyl)tris(thiophene-2-carbaldehyde), and p-phenylenediamine is 1:1:

3.

4. The application according to claim 1, wherein The application method is as follows: Deionized water is used as the reaction solution. The three COF materials are respectively dispersed in beakers and ultrasonicated for 30 min to form a uniform suspension. After pouring the suspension into the reactor, oxygen is introduced for 20 min to exhaust the air in the reactor. Then, a xenon lamp is used as the light source. After 30 min of light irradiation, the reaction suspension is taken, and the catalyst is filtered off with a 1 mL syringe with a filter tip, and the liquid is collected. 1 mL of the collected liquid to be measured is added to 1 mL of potassium iodide solution with a concentration of 6.5 mg·mL -1 and 0.5 mL of potassium hydrogen phthalate solution with a concentration of 20.4 mg·mL -1 . After mixing well, it is left standing for 30 min and analyzed with a UV-visible spectrophotometer.

5. Preparation of a three-component covalent organic framework and its application in photosynthetic production of hydrogen peroxide, characterized in that Different from two-component covalent organic frameworks, the photocatalytic synthesis efficiency of hydrogen peroxide reaches 1.0-1.2 mmol·g -1 ·h-1, which is superior to two-component TP-1-COF and TTBPDA-COF materials.

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