Preparation of fluorine-containing triazine-based covalent organic framework material and application in hydrogen peroxide production

Abstract

The application relates to preparation of a fluorine-containing triazine group covalent organic framework material and application of hydrogen peroxide production. Three imine bond connected covalent organic framework materials are prepared to solve the problems of low photocatalytic performance and low solar energy conversion efficiency of existing covalent organic framework materials. The method is as follows: 1,3,5-tris(3-fluoro-4-formylphenyl)benzene and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine are prepared into TFBTAPT-COF by a solvent method. The preparation process is simple and effective, reagent consumption is low, and the yield is high; and the photocatalyst provided by the application can effectively improve the hydrogen peroxide production performance. The application is applied to photocatalytic preparation of hydrogen peroxide, and experiments show that the material TFBTAPT-COF has excellent photocatalytic hydrogen peroxide production performance, and the hydrogen peroxide performance can reach 8750mmol g ‑1 h ‑1 under visible light irradiation.

Description

Technical Field

[0001] This invention relates to the field of photocatalytic preparation of hydrogen peroxide. Background Technology

[0002] Since its first discovery in 1818 in the reaction of barium peroxide and nitric acid, hydrogen peroxide (H₂O₂) has attracted increasing attention worldwide due to its remarkable versatility. As a clean and mild oxidant, H₂O₂ boasts numerous advantages, including the highest content of reactive oxygen species, excellent treatment performance over a wide pH range, and non-toxic byproducts (producing only water / O₂). It has been widely applied in various industrial sectors. [3] Such as bleaching, mining and metal processing [4] H₂O₂ has recently been reported as an ideal energy carrier for single-component fuel cell power generation, with a significantly lower output potential (1.09V) compared to hydrogen fuel cells (1.23V) or methanol fuel cells (1.21V). More importantly, its perfect solubility in water provides an easier and safer method for storage and transportation. Currently, industrial production of H₂O₂ primarily employs the anthraquinone oxidation method. However, this process is not entirely green, exhibiting instability issues such as high energy input and pollution (e.g., wastewater, solid waste). Therefore, developing an environmentally friendly and cost-effective method for producing H₂O₂ is crucial. Another approach involves the direct reaction between H₂ and O₂ in the presence of noble metal catalysts (such as Pd, Pt, and PdAu). In this reaction, H₂ and O₂ gases enter an acidic methanol solvent and react to produce H₂O₂ at near-0°C with the aid of a catalyst. However, due to the high risk of explosion and the high cost of noble metal catalysts, this method remains less than optimal. Photocatalysis is a highly attractive and forward-looking solar-powered chemical conversion technology that could be a breakthrough in H2O2 chemistry. In contrast, this process is a completely green and safe method for producing H2O2. For example, hazardous hydrogen is replaced by abundant water on Earth; renewable sunlight provides all the energy input for the reaction; and no pollution is generated or emitted throughout the entire process.

[0003] Solar energy is clean and pollution-free. Calculations show that the energy reaching the Earth's surface annually is nearly ten thousand times the Earth's annual energy consumption, making it highly promising for solving the energy crisis and environmental problems. Therefore, utilizing solar energy to convert oxygen and pure water into hydrogen peroxide is a promising avenue for future development. Photocatalysis, a mild and environmentally friendly catalytic pathway, is of great significance in addressing energy shortages and the environmental crisis. From both energy and environmental perspectives, as well as economic considerations, developing solar-powered catalytic technologies is an inevitable trend in the development of green catalysis. Covalent organic frameworks (COFs) are porous crystalline materials composed of light elements such as C, B, O, N, and Si linked by covalent bonds. They possess advantages such as light weight, low density, high specific surface area, regular structure, uniform pores, relatively stable structure, and ease of functionalization modification. These advantages make COFs highly promising for applications in various fields such as gas storage and separation, catalysis, sensing, energy storage, and photoelectric conversion. The presence of triazine groups can not only reduce the recombination rate of photogenerated charges and holes but also enhance electron transport efficiency and provide catalytic sites. At the same time, the introduction of fluorine atoms can enhance the ability of COFs to adsorb oxygen and accelerate the forward catalytic reaction. Summary of the Invention

[0004] The purpose of this invention is to solve the problem of low performance in the photocatalytic preparation of hydrogen peroxide using existing covalent organic framework materials, and to provide a method for preparing covalent organic framework materials containing triazine groups and fluorine atoms, as well as their application in the photocatalytic preparation of hydrogen peroxide.

[0005] The preparation method of the covalent organic framework material of the present invention is carried out according to the following steps:

[0006] I. Preparation of TFBTAPT-COF: 1,3,5-tris(3-fluoro-4-formylphenyl)benzene and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine were added to a heat-resistant glass tube. 1,3,5-trimethylbenzene and DMA were then pipetted into the heat-resistant glass tube, and the mixture was sonicated for 30 min to ensure uniform dispersion. Subsequently, a 3 mol / L aqueous acetic acid solution was added to the system, and the mixture was immediately subjected to three freeze-thaw cycles in a liquid nitrogen bath for degassing. After sealing, the heat-resistant glass tube was placed in an oven and heated at 120°C for 72 h. After cooling to room temperature, the product was washed with a large amount of DMF and ethanol, and then dried to obtain TFBTAPT-COF.

[0007] II. Preparation of TBTAPT-COF: 1,3,5-tris(4-formylphenyl)benzene and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine were added to a heat-resistant glass tube. 1,3,5-trimethylbenzene and DMA were then pipetted into the heat-resistant glass tube, and the mixture was sonicated for 30 min to ensure uniform dispersion. Subsequently, a 3 mol / L aqueous acetic acid solution was added to the system, and the mixture was immediately subjected to three freeze-thaw cycles in a liquid nitrogen bath for degassing. After sealing, the heat-resistant glass tube was placed in an oven and heated at 120°C for 72 h. After cooling to room temperature, the product was washed with a large amount of DMF and ethanol, and then dried to obtain TBTAPT-COF.

[0008] III. Preparation of TBTAPB-COF: 1,3,5-tris(4-formylphenyl)benzene and 2,4,6-tris(4-aminophenyl)benzene were added to a heat-resistant glass tube. 1,3,5-trimethylbenzene and DMA were then pipetted into the heat-resistant glass tube, and the mixture was sonicated for 30 min to ensure uniform dispersion. Subsequently, a 3 mol / L aqueous acetic acid solution was added to the system, and the tube was immediately subjected to three freeze-thaw cycles in a liquid nitrogen bath for degassing. After sealing, the heat-resistant glass tube was placed in an oven at 120°C for 72 h. After cooling to room temperature, the product was washed with a large amount of DMF and ethanol, and then dried to obtain TBTAPB-COF.

[0009] The masses of 1,3,5-tris(3-fluoro-4-formylphenyl)benzene and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine mentioned in step one are 22 mg and 18.5 mg, respectively;

[0010] The molar ratio of 1,3,5-tris(3-fluoro-4-formylphenyl)benzene and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine mentioned in step one is 1:1;

[0011] The masses of 1,3,5-tris(4-formylphenyl)benzene and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine mentioned in step two are 22 mg and 18.5 mg, respectively;

[0012] The mass ratio of 1,3,5-tris(4-formylphenyl)benzene and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine in step two is 1:1;

[0013] The masses of 1,3,5-tris(4-formylphenyl)benzene and 2,4,6-tris(4-aminophenyl)benzene mentioned in step three are 22 mg and 18.5 mg, respectively;

[0014] In step three, the molar ratio of 1,3,5-tris(4-formylphenyl)benzene and 2,4,6-tris(4-aminophenyl)benzene is 1:1.

[0015] The volume ratio of 1,3,5-trimethylbenzene and DMA in step one is 1:1;

[0016] The concentration of acetic acid used in step one is 6 mol·L⁻¹. -1 ;

[0017] The volume ratio of 1,35-trimethylbenzene and DMA in step two is 1:1;

[0018] The concentration of acetic acid used in step two is 6 mol·L⁻¹. -1 ;

[0019] The volume ratio of 1,3,5-trimethylbenzene and DMA in step three is 1:1;

[0020] The concentration of acetic acid used in step three is 6 mol·L⁻¹. -1 ;

[0021] The beneficial effects of this invention: Of the three COFs prepared by the solvothermal method, the TFBTAPT-COF prepared from 1,3,5-tris(3-fluoro-4-formylphenyl)benzene and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine exhibits a photocatalytic hydrogen peroxide performance of 8750 mmol g. -1 h -1 This material possesses good visible light absorption capabilities, and its unique triazine group containing N sites can enhance the adsorption capacity of reactants, increase redox power, and effectively separate and transfer the charge carriers generated by light. The F atoms on the aryl group near the imine bond regulate the electronic structure, expand visible light absorption, and promote O2 adsorption. Therefore, its performance is 2.7 times higher than that of TBTAPT-COF, which contains only triazine groups and no F atoms, and 5.1 times higher than that of TBTAPB-COF, which contains neither triazine groups nor F atoms. Attached Figure Description

[0022] Figure 1 The XRD pattern and simulated XRD pattern of TFBTAPT-COF are shown.

[0023] Figure 2 The XRD pattern and simulated XRD pattern of TBTAPT-COF are shown.

[0024] Figure 3 The XRD pattern and simulated XRD pattern of TBTAPB-COF are shown.

[0025] Figure 4 This is a scanning electron microscope image of TFBTAPT-COF.

[0026] Figure 5 This is a scanning electron microscope image of TBTAPT-COF.

[0027] Figure 6 This is a scanning electron microscope image of TBTAPB-COF.

[0028] Figure 7 The FT-IR plots are for TFBTAPT-COF, TBTAPT-COF, and TBTAPB-COF.

[0029] Figure 8 The hydrogen peroxide performance spectra of TFBTAPT-COF, TBTAPT-COF, and TBTAPB-COF over time are shown. Detailed Implementation

[0030] The present invention will be further illustrated by the following examples. These examples are only for illustrating the method of the present invention and do not limit the scope of application of the present invention in any way.

[0031] Example 1: The preparation of the three COF materials in this embodiment is carried out according to the following steps:

[0032] Preparation of TFBTAPT-COF: 1,3,5-tris(3-fluoro-4-formylphenyl)benzene and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine were added to a heat-resistant glass tube. 1,3,5-trimethylbenzene and DMA were then pipetted into the heat-resistant glass tube, and the mixture was sonicated for 30 min to ensure uniform dispersion. Subsequently, a 3 mol / L aqueous acetic acid solution was added to the system, and the mixture was immediately subjected to three freeze-thaw cycles in a liquid nitrogen bath for degassing. After sealing, the heat-resistant glass tube was placed in an oven and heated at 120 °C for 72 h. After cooling to room temperature, the product was washed with a large amount of DMF and ethanol, and then dried to obtain TFBTAPT-COF.

[0033] Preparation of TBTAPT-COF: 1,3,5-tris(4-formylphenyl)benzene and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine were added to a heat-resistant glass tube. 1,3,5-trimethylbenzene and DMA were then pipetted into the heat-resistant glass tube, and the mixture was sonicated for 30 min to ensure uniform dispersion. Subsequently, a 3 mol / L aqueous acetic acid solution was added to the system, and the mixture was immediately subjected to three freeze-thaw cycles in a liquid nitrogen bath for degassing. After sealing, the heat-resistant glass tube was placed in an oven at 120 °C for 72 h. After cooling to room temperature, the product was washed with a large amount of DMF and ethanol, and then dried to obtain TBTAPT-COF.

[0034] Preparation of TBTAPB-COF: 1,3,5-tris(4-formylphenyl)benzene and 2,4,6-tris(4-aminophenyl)benzene were added to a heat-resistant glass tube. 1,3,5-trimethylbenzene and DMA were then pipetted into the heat-resistant glass tube, and the mixture was sonicated for 30 min to ensure uniform dispersion. Subsequently, a 3 mol / L aqueous acetic acid solution was added to the system, and the mixture was immediately subjected to three freeze-thaw cycles in a liquid nitrogen bath for degassing. After sealing, the heat-resistant glass tube was placed in an oven at 120 °C for 72 h. After cooling to room temperature, the product was washed with a large amount of DMF and ethanol, and then dried to obtain TBTAPB-COF.

[0035] To verify the beneficial effects of the present invention, the following experiments were conducted: To investigate the photocatalytic conversion ability of TFBTAPT-COF, TBTAPT-COF, and TBTAPB-COF materials to benzyl alcohol, their visible light photocatalytic performance was tested according to the following method. The test procedure is as follows: TFBTAPT-COF, TBTAPT-COF, and TBTAPB-COF (5mg) were used as photocatalysts, and 50ml of distilled water was used as the reaction solution. The mixture was sonicated for 30min to form a uniform suspension. The suspension was poured into a reactor, and oxygen was introduced for 20min to purge the air from the reactor. Then, a xenon lamp was used as the light source. 1ml of filtrate was collected every 10 minutes. 1ml of the collected test liquid was added to 1ml of potassium iodide solution (0.1M) and 0.5ml of potassium hydrogen phthalate solution (0.1M). After standing for half an hour, the absorbance of the solution was measured using a UV spectrophotometer. The hydrogen peroxide yield was obtained by substituting the absorbance into the hydrogen peroxide standard curve.

[0036] Figure 1 , Figure 2 , Figure 3 The XRD patterns of the three COFs prepared according to this invention are shown. X-ray diffraction (XRD) was used to characterize the phase structure of the COF materials. As shown in the figure, the peak positions of the three COFs are consistent with the peak positions of the COFs simulated using Material Studio, proving the successful preparation of the three materials.

[0037] Figure 4 , Figure 5 , Figure 6 SEM images of the three COFs prepared according to this invention are shown in the figure. Figure 4 The SEM image of TFBTAPT-COF shows a stacked columnar structure. Figure 5 , Figure 6 The SEM image of TBTAPT-COF is a collection of elongated, rod-like structures stacked together.

[0038] Figure 7The images show the FT-IR spectra of the three COFs. All three COFs exhibit strong absorption peaks around 1600 nm, indicating that the COFs underwent a Schiff base reaction to generate C=N, thus proving the successful preparation of the materials.

[0039] Figure 8 The graphs show the hydrogen peroxide performance of three COFs over time. The TBTAPT-COF performance is 3150 mmol g. - 1 h -1 The performance of TBTAPB-COF is 1742 mmol g. -1 h -1 The optimal performance of TFBTAPT-COF is 8750 mmol g. -1 h -1 .

[0040] In summary, this example demonstrates the use of a solvothermal method to prepare the TFBTAPT-COF photocatalyst, which exhibits excellent photocatalytic performance in the preparation of hydrogen peroxide.

Claims

1. Preparation and application of a fluorinated triazine-based covalent organic framework material for hydrogen peroxide production, characterized in that... This method is performed in the following steps: I. Preparation of TFBTAPT-COF: 1,3,5-tris(3-fluoro-4-formylphenyl)benzene and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine were added to a heat-resistant glass tube. 1,3,5-trimethylbenzene and DMF were then pipetted into the heat-resistant glass tube, and the mixture was sonicated for 30 min to ensure uniform dispersion. Subsequently, a 3 mol / L aqueous acetic acid solution was added to the system, and the mixture was immediately subjected to three freeze-thaw cycles in a liquid nitrogen bath for degassing. After sealing, the heat-resistant glass tube was placed in an oven at 120 °C for 72 h. After cooling to room temperature, the product was washed with a large amount of DMF and ethanol, and then dried to obtain TFBTAPT-COF.

2. The preparation of the TFBTAPT-COF material according to claim 1, characterized in that... The molar ratio of the substances in step one, 1,3,5-tris(3-fluoro-4-formylphenyl)benzene and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, is 1:

1.

3. The preparation of the TFBTAPT-COF material according to claim 1, characterized in that... The volume ratio of 1,3,5-trimethylbenzene and DMF in step one is 1:

1.

4. The preparation of the TFBTAPT-COF material according to claim 1, characterized in that... The volume of acetic acid mentioned in step one is 0.2 ml.

Images