Polyimide material for photocatalytic hydrogen peroxide synthesis and preparation method therefor

Abstract

Disclosed is a method for preparing a polyimide material for photocatalytic hydrogen peroxide synthesis, belonging to the fields of environmental chemistry, chemical engineering and materials science. The present invention prepares a polyimide catalytic material by means of thermal imidization of an aromatic triamine monomer and an aromatic dianhydride monomer, the aromatic triamine monomer being selected from TABPB, TAB and TBZ, and the aromatic dianhydride monomer being BDA. The present invention uses widely available raw materials and a simple synthesis method to obtain a polyimide material having excellent photocatalytic activity. This polyimide material, as a catalyst, is dispersed in an oxygen-containing aqueous solution for photocatalytic hydrogen peroxide production, and after irradiation with light for a period of time, hydrogen peroxide is obtained. The present method has the advantages of being green and environmentally friendly, safe and pollution-free, using water and oxygen as raw materials, using solar energy as an energy source, and having simple synthesis, mild reaction conditions, a stable and easily recyclable catalyst, and high hydrogen peroxide yield.

Description

Polyimide material and method for photocatalytic synthesis of hydrogen peroxide Technical Field

[0001] The invention belongs to the fields of environmental chemistry, chemical engineering and material science, and relates to a polyimide material for photocatalytic synthesis of hydrogen peroxide and a preparation method and a use method thereof. Background Art

[0002] With the development of society and the needs of human life, energy issues have attracted widespread attention, especially in response to the energy future of "carbon neutrality and carbon peak." Hydrogen peroxide is an important chemical reagent with extensive applications in medical environmental protection, environmental disinfection, wastewater treatment, and chemical synthesis. It is estimated that by 2027, the market demand for hydrogen peroxide may increase to 5.7 million tons. my country leads the world in hydrogen peroxide production capacity, output, and consumption, but supply exceeds demand. The global hydrogen peroxide market is expected to reach US$15.4 billion by 2030. Currently, over 95% of hydrogen peroxide on the market is produced primarily using the anthraquinone method, which involves precious metal catalysts, has a complex reaction process, high energy consumption, and produces a large number of toxic byproducts. The direct mixing of hydrogen and oxygen faces serious safety issues such as explosion, while the electrochemical method is expensive and energy-intensive. Therefore, there is a need to explore environmentally friendly, efficient, and stable methods for synthesizing hydrogen peroxide. Photocatalytic synthesis of hydrogen peroxide uses sunlight as the sole energy source, water and oxygen as raw materials, and semiconductor photocatalysts to synthesize hydrogen peroxide. This method is green, sustainable, safe, pollution-free, energy-efficient, and environmentally friendly, making it an ideal alternative to industrial anthraquinone in the context of a sustainable energy future. Artificial photosynthesis of hydrogen peroxide using organic semiconductor photocatalysts is a green, sustainable, and energy-efficient method that contributes to a carbon-neutral future.

[0003] Despite significant progress, catalytic efficiency still falls short of industrial-grade requirements. Consequently, numerous efficient modification methods have been explored to enhance photogenerated H₂O₂ production, including morphology manipulation, doping, composite material construction, surface modification, and nanoparticle deposition. However, significant limitations remain, necessitating the urgent development of advanced organic semiconductor materials for efficient photocatalytic synthesis of hydrogen peroxide in pure water. In particular, most hydrogen peroxide production experiments have been conducted in solution-powder photocatalyst systems, which hinders hydrogen peroxide extraction and photocatalyst recovery. Although some studies have been conducted in pure water, their photocatalytic efficiencies consistently fall short of those achieved with sacrificial agents. Therefore, the exploration of novel catalysts to achieve stable and efficient hydrogen peroxide production in sacrificial agent-free systems is urgently needed. Among the numerous organic photocatalysts, polyimides represent a novel class of conjugated polymer photocatalysts, characterized by their abundant availability, low production cost, high chemical and thermal stability, adjustable electronic structure, strong mechanical properties, and ease of processing. They represent a promising class of materials, often referred to as "engineering plastics." Polyimide-based materials have applications in membrane separation, coatings, aerospace, microelectronics and optoelectronics, lithium-ion batteries, and sensing. However, due to high photogenerated charge recombination rates, a lack of effective active sites, poor two-electron selectivity, and low adsorption capacity for oxygen and protons, they cannot be efficiently used for the photocatalytic synthesis of hydrogen peroxide. Therefore, there is an urgent need to develop effective strategies to improve polyimide materials and achieve efficient and stable hydrogen peroxide synthesis in pure water systems.

[0004] Summary of the Invention

[0005] This invention develops a polyimide material and method for the photocatalytic synthesis of hydrogen peroxide, achieving efficient and stable synthesis of hydrogen peroxide. This method is groundbreaking and meets the current needs of the chemical industry for compatibility with the ecological environment and sustainable development, thus possessing significant industrial application value and social significance.

[0006] The present invention provides a polyimide material and method for the photocatalytic synthesis of hydrogen peroxide, achieving efficient and stable synthesis of hydrogen peroxide. Furthermore, it provides a material capable of efficient photocatalytic production of hydrogen peroxide without sacrificial reagents. Photocatalytic production of hydrogen peroxide is a green, environmentally friendly, and pollution-free process. Using oxygen and water as raw materials and sunlight as the sole energy source, it offers advantages such as low energy consumption, high safety, simple operation, mild reaction conditions, high hydrogen peroxide concentration per unit time, efficient accumulation, and long-term stable circulation.

[0007] Specific plan:

[0008] The invention provides a polyimide catalytic material for photocatalytic synthesis of hydrogen peroxide. The polyimide catalytic material is prepared by thermal imidization of an aromatic triamine monomer and an aromatic dianhydride monomer. The aromatic triamine monomer is selected from any one or more of the following: 5"-(4'-amino-[1,1'-biphenyl]-4-yl)-[1,1':4',1":3",1"':4"',1""-pentaphenyl]-4,4""-diamine (TABPB), 1,3,5-triaminobenzene (TAB), and 1,3,5-tris(4-aminophenyl)benzene (TBZ). The aromatic dianhydride monomer is 3,3',4,4'-biphenyltetracarboxylic dianhydride (BDA).

[0009] In one embodiment of the present invention, the preparation method of the polyimide catalytic material includes the following process:

[0010] (1) dissolving an aromatic triamine monomer in solvent A to prepare an aromatic triamine monomer solution; dissolving an aromatic dianhydride monomer in solvent B to prepare an aromatic dianhydride monomer solution; mixing the two solutions, then adding isoquinoline, mixing and reacting to obtain a reaction solution;

[0011] (2) Pour the obtained reaction solution into a mold, first gel at 0-5°C for a period of time, and then continue heat treatment at 150-200°C for a period of time to obtain a primary product; the primary product is gradiently immersed in an N-methylpyrrolidone-ethanol solution, and then washed and dried.

[0012] In one embodiment of the present invention, in step (1), solvent A is mesitylene, N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), or N,N-dimethylacetamide (DMAc), preferably mesitylene.

[0013] In one embodiment of the present invention, in step (1), solvent B is NMP, DMF, DMAc, or mesitylene.

[0014] In one embodiment of the present invention, in step (1), preferably: solvent A is mesitylene and solvent B is NMP.

[0015] In one embodiment of the present invention, in step (1), the volume ratio of solvent A to solvent B is 1:1.

[0016] In one embodiment of the present invention, in step (1), the concentration of the aromatic triamine monomer solution is 0.1-0.5 mmol / mL; specifically, 0.3 mmol / mL.

[0017] In one embodiment of the present invention, in step (1), the concentration of the aromatic dianhydride monomer solution is 0.1-1.0 mmol / mL; 0.45 mmol / mL.

[0018] In one embodiment of the present invention, in step (1), the molar ratio of the aromatic triamine monomer to the aromatic dianhydride monomer is 1:(1-2); specifically, it can be 1:1.5.

[0019] In one embodiment of the present invention, in step (1), the amount of isoquinoline relative to the aromatic triamine monomer is 0.02-0.05 ml / mmol.

[0020] In one embodiment of the present invention, in step (2), the obtained reaction solution is poured into a mold, first gelled at 0°C for 60 minutes, and then further solvent thermally treated at 180°C for 48 hours.

[0021] In one embodiment of the present invention, in step (2), the gradient soaking refers to soaking in a 75% organic solvent-ethanol solution for 24 hours, then exchanging the solvent with a 25%-50% organic solvent-ethanol solution every 24 hours, and then exchanging the solvent with ethanol three times. The organic solvent is N-methylpyrrolidone, dimethylformamide, or dimethylacetamide.

[0022] In one embodiment of the present invention, in step (2), the drying is freeze-drying.

[0023] In one embodiment of the present invention, the preparation method of the polyimide catalytic material specifically includes:

[0024] (1) A polyimide photocatalyst was prepared by thermal imidization using aromatic triamine and aromatic dianhydride. Aromatic dianhydride is usually dissolved in a polar solvent solution such as N-methylpyrrolidone, dimethylformamide or dimethylacetamide, and then a certain proportion of aromatic triamine is dispersed in a mesitylene solution, and then a small amount of catalyst isoquinoline is added; after ultrasonication for 10-30 minutes, a transparent uniform solution is obtained; then it is poured into a suitable mold and gelled in an ice water bath at about 0-5°C for 30-60 minutes, and then placed in an oven at 120-180°C for heat treatment for 48-60 hours;

[0025] (2) soaking the product obtained by heat treatment in step (1) in a 75% N-methylpyrrolidone or dimethylformamide or dimethylacetamide-ethanol mixed solution for 24-48 hours; subsequently, performing solvent exchange with a 50% N-methylpyrrolidone or dimethylformamide or dimethylacetamide-ethanol mixed solvent and a 25% N-methylpyrrolidone or dimethylformamide or dimethylacetamide-ethanol mixed solvent every 24-48 hours, and then exchanging with an ethanol solution three times; finally, rinsing the product with deionized water and drying it to obtain a final product.

[0026] In one embodiment of the present invention, the method is specifically:

[0027] (1) Scheme 1: A polyimide BTABPB photocatalyst was prepared by thermal imidization of aromatic triamine 5”-(4’-amino-[1,1’-biphenyl]-4-yl)-[1,1’:4’,1’:3’,1’’:4’’,1’’-pentaphenyl]-4,4’’-diamine (TABPB) and aromatic dianhydride 3,3’,4,4’-biphenyltetracarboxylic dianhydride (BDA). BDA (0.9 mmol) was dissolved in 2 mL of N-methylpyrrolidone solution, and TABPB (0.6 mmol) was then added. Disperse in 2 mL of mesitylene solution, and finally add isoquinoline (0.02 mL). After ultrasonication at a power of 100 W for 10 minutes, a transparent colorless solution is quickly obtained. Then pour it into a mold and gel at 0°C for 60 minutes. The gel is further solvent-thermally treated at 180°C for 48 hours. The product is soaked in a 75% N-methylpyrrolidone-ethanol solution for 24 hours. Subsequently, the solvent is exchanged with 25% N-methylpyrrolidone-ethanol every 24 hours, and then exchanged with ethanol three times. Finally, rinse with deionized water and freeze-dry to obtain the final product BTABPB.

[0028] (2) Scheme 2: A polyimide BTAB photocatalyst was prepared by thermal imidization of aromatic triamine 1,3,5-triaminobenzene (TAB) and aromatic dianhydride 3,3',4,4'-biphenyltetracarboxylic dianhydride (BDA). BDA (0.9 mmol) was usually dissolved in 2 mL of N-methylpyrrolidone solution, then TAB (0.6 mmol) was dispersed in 2 mL of mesitylene solution, and finally isoquinoline (0.02 mL) was added. After ultrasonication at a power of 100 W for 10 min, a transparent colorless solution was quickly obtained. It was then poured into a mold and gelled at 0 ° C for 60 min. The gel was further solvent-thermally treated at 180 ° C for 48 h. The product was soaked in 75% N-methylpyrrolidone-ethanol solution for 24 h. Subsequently, the solvent was exchanged with 25% N-methylpyrrolidone-ethanol every 24 h, and then with ethanol three times. Finally, it was rinsed with deionized water and freeze-dried to obtain the final product BTAB.

[0029] (3) Scheme 3: A polyimide BTAB photocatalyst was prepared by thermal imidization of aromatic triamine 1,3,5-tris(4-aminophenyl)benzene (TBZ) and aromatic dianhydride 3,3',4,4'-biphenyltetracarboxylic dianhydride (BDA). BDA (0.9 mmol) was usually dissolved in 2 mL of N-methylpyrrolidone solution, then TAB (0.6 mmol) was dispersed in 2 mL of mesitylene solution, and finally isoquinoline (0.02 mL) was added. After ultrasonication at a power of 100 W for 10 min, a transparent colorless solution was quickly obtained. It was then poured into a mold and gelled at 0 ° C for 60 min. The gel was further solvent-thermally treated at 180 ° C for 48 h. The product was soaked in 75% N-methylpyrrolidone-ethanol solution for 24 h. Subsequently, the solvent was exchanged with 25% N-methylpyrrolidone-ethanol every 24 h, and then with ethanol three times. Finally, it was rinsed with deionized water and freeze-dried to obtain the final product BTBZ.

[0030] The present invention also provides application of the polyimide catalytic material in photocatalytic synthesis of hydrogen peroxide.

[0031] The present invention provides a method for photocatalytically synthesizing hydrogen peroxide, which utilizes the polyimide catalytic material as a photocatalyst.

[0032] In one embodiment of the present invention, the method comprises adding the polyimide catalytic material into water, introducing air or oxygen, and irradiating the water with light for a period of time.

[0033] In one embodiment of the present invention, the method uses water and oxygen as raw materials, uses the above-mentioned polyimide catalytic material as a photocatalyst, and photocatalytically synthesizes hydrogen peroxide under light.

[0034] In one embodiment of the present invention, a polyimide material for photocatalytically synthesizing hydrogen peroxide is prepared. The polyimide material can photocatalytically synthesize hydrogen peroxide efficiently and stably based on a photocatalytic method.

[0035] In one embodiment of the present invention, the photocatalyst refers to a substance that can absorb photon energy under the excitation of photons, and then electrons undergo transition or are excited to generate reducing photogenerated electrons.

[0036] In one embodiment of the present invention, the amount of the polyimide catalytic material relative to water is 1 mg / mL.

[0037] In one embodiment of the present invention, the wavelength of light is determined by the requirements of the photocatalyst. Specifically, the light is sunlight or an artificial light source; artificial light sources include xenon lamps, UV lamps, LED lamps, lasers, etc. The light source can be full-band light, simulated sunlight, visible light, single-wavelength light sources, and natural light.

[0038] In one embodiment of the present invention, the power of the illumination is 200-300 mM / cm 2 .

[0039] In one embodiment of the present invention, the oxygen-rich environment refers to bubbling oxygen into the water at a flow rate of 20-80 mL / min during the reaction, and the specific flow rate can be 50 mL / min.

[0040] In one embodiment of the present invention, during the photocatalytic synthesis of hydrogen peroxide, the photocatalyst can photocatalytically synthesize hydrogen peroxide in a pure water-oxygen, pure water-air, sacrificial reagent-oxygen, or sacrificial reagent-air environment. The sacrificial reagent is a C1-4 alkyl alcohol, specifically methanol, ethanol, isopropanol, or the like.

[0041] In one embodiment of the present invention, the photocatalytic synthesis of hydrogen peroxide can react continuously to accumulate high-concentration hydrogen peroxide.

[0042] In one embodiment of the present invention, the photocatalytic synthesis of hydrogen peroxide can be cyclically reacted for a long time.

[0043] In one embodiment of the present invention, the method is specifically:

[0044] Weigh 20 mg of the BTABPB, BTAB, or BTBZ photocatalyst prepared above and 20 mL of deionized water into a 100 mL quartz bottle. Inject oxygen into the suspension in the dark for 30 minutes. During the reaction, oxygen is continuously bubbled to maintain an oxygen-rich environment. A xenon lamp is used as the light source. The hydrogen peroxide concentration is determined using the potassium titanium oxalate method. At 20, 40, and 60 minutes, 2 mL of the reaction solution is taken and filtered through a 0.45 μm filter to remove the catalyst, ultimately obtaining a hydrogen peroxide solution.

[0045] In one embodiment of the present invention, the catalyst can efficiently photocatalytically produce hydrogen peroxide in a water-oxygen or water-air environment.

[0046] The present invention utilizes widely available raw materials and a simple synthesis method to produce a polyimide material with excellent photocatalytic activity. The polyimide photocatalyst prepared by the present invention exhibits excellent charge separation efficiency and well-defined redox sites, significantly promoting photocatalytic production of hydrogen peroxide. The photocatalytic production of hydrogen peroxide involves dispersing a predetermined concentration of the polyimide catalyst in an aqueous solution. A constant flow of oxygen is introduced with stirring, and the mixture is then irradiated under a xenon lamp for a period of time. The resulting reaction solution is then filtered to remove the catalyst, yielding a hydrogen peroxide solution of a predetermined concentration.

[0047] Beneficial effects of the present invention:

[0048] (1) The present invention prepares a polyimide photocatalyst capable of efficiently and stably photocatalytically synthesizing hydrogen peroxide via a sol-gel-thermal amidation route. The conjugated, cross-linked molecular structure contains electron donors and electron acceptors, which promotes the separation of photogenerated carriers and improves the inherent poor conductivity of polyimide materials.

[0049] (2) The polyimide photocatalyst prepared by the present invention has a clear oxygen reduction point, which promotes the adsorption and activation of oxygen, greatly improving the selectivity and activity of hydrogen peroxide generation. The material also synthesizes high concentrations of hydrogen peroxide per unit time and can be recycled stably for a long time.

[0050] (3) The polyimide photocatalytic material prepared by the present invention uses water and oxygen as raw materials at room temperature and pressure, and sunlight as the only energy source. It has the advantages of simple synthesis, mild reaction conditions, stable catalyst and easy circulation, and high hydrogen peroxide production. Compared with the industrial anthraquinone method for indirect synthesis of hydrogen peroxide, the method of the present invention has lower energy consumption and is green and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] FIG1 is a synthesis diagram of the catalyst BTABPB prepared in Example 1.

[0052] Figure 2 is a picture of the catalyst BTABPB prepared in Example 1.

[0053] FIG3 is a SEM image of the catalyst BTABPB prepared in Example 1.

[0054] FIG4 is an infrared spectrum of the catalyst BTABPB prepared in Example 1.

[0055] FIG5 is a diagram showing the photocatalytic H2O2 production rate of the catalyst BTABPB prepared in Example 1.

[0056] FIG6 is a cumulative graph of photocatalytic H2O2 production of the catalyst BTABPB prepared in Example 1.

[0057] FIG7 shows the photocatalytic H2O2 production cycle of the catalyst BTABPB prepared in Example 1.

[0058] FIG8 is a graph showing the photocatalytic H2O2 production rates of the catalysts BTAB and BTBZ prepared in Examples 2 and 3. DETAILED DESCRIPTION

[0059] The present invention will be further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0060] The photocatalytic activity of the catalyst prepared in the present invention was evaluated:

[0061] (1) Weigh 20 mg of the prepared BTABPB photocatalyst and place it in a quartz bottle containing 20 mL of deionized water. Inject oxygen into the suspension in the dark for 30 minutes. During the reaction, oxygen is continuously bubbled to maintain an oxygen-rich environment. A 300W xenon lamp is used as the light source. The concentration of hydrogen peroxide is determined using the potassium titanium oxalate method. At different time points of 20, 40, and 60 minutes, 2 mL of the reaction solution is taken and filtered through a 0.45 μm filter membrane to remove the catalyst, and finally a hydrogen peroxide solution is obtained.

[0062] (2) Weigh 20 mg of the prepared BTABPB photocatalyst and place it in a quartz bottle containing 20 mL of deionized water. Inject air into the suspension in the dark for 30 minutes. During the reaction, air is continuously bubbled. A 300W xenon lamp is used as the light source. The H2O2 concentration is determined using the potassium titanium oxalate method. At different time points, 2 mL of the reaction solution is taken and filtered through a 0.45 μm filter membrane to remove the catalyst, thereby obtaining a hydrogen peroxide solution.

[0063] (3) 20 mg of the prepared BTABPB photocatalyst and 20 mL of deionized water were placed in a quartz bottle (100 mL). Air was injected into the suspension in the dark for 30 minutes. During the reaction, air was continuously bubbled. Visible light was used as the light source. The concentration of hydrogen peroxide was determined using the potassium titanium oxalate method. At different time points, 2 mL of the reaction solution was taken and filtered through a 0.45 μm filter membrane to remove the catalyst, and finally a hydrogen peroxide solution was obtained.

[0064] Hydrogen peroxide concentration test method:

[0065] Hydrogen peroxide and potassium titanium oxalate form a yellow solution. Its absorbance at 400 nm is measured using a UV spectrophotometer, and the hydrogen peroxide concentration is calculated using the Lambert-Beer law. Specifically, every 20 minutes, 2 mL of the reaction solution is removed through a 0.45 μm filter to remove impurities, followed by the addition of 1 mL of potassium titanium oxalate. After the reaction is allowed to proceed for at least 30 minutes, the absorbance of the solution is measured using a UV spectrophotometer, and the hydrogen peroxide concentration is calculated.

[0066] Example 1: Preparation of polyimide aerogel photocatalyst BTABPB

[0067] Polyimide BTABPB photocatalyst was prepared by thermal imidization of aromatic triamine 5"-(4'-amino-[1,1'-biphenyl]-4-yl)-[1,1':4',1":3",1"':4"',1""-pentabiphenyl]-4,4""-diamine (TABPB) with aromatic dianhydride 3,3',4,4'-biphenyltetracarboxylic dianhydride (BDA).

[0068] Specific process: Usually 53mg BDA is dissolved in 2.5mL N-methylpyrrolidone solution, then 70mg TABPB is dispersed in 2.5mL mesitylene solution, the two are mixed, and finally isoquinoline (0.05mL) is added. After ultrasonication at a power of 100W for 20min, a transparent colorless solution is quickly obtained. Then it is poured into a mold and gelled at 0℃ for 60min. The gel is further solvent-thermally treated at 180℃ for 48h. The product is washed in 75% NMP ethanol solution for 24h. Subsequently, the solvent is exchanged with 25% NMP ethanol every 24h, and then exchanged with 100% ethanol three times. Finally, it is rinsed with deionized water and freeze-dried to obtain the final product BTABPB material.

[0069] The unit structure of the obtained BTABPB material is:

[0070] The prepared BTABPB material was subjected to scanning electron microscopy (SEM) (shown in FIG3 ) and Fourier transform infrared spectroscopy (FTIR) (shown in FIG4 ) to confirm the morphology and structure of the BTABPB.

[0071] Test Example 1: Rate of photocatalytic H2O2 production by polyimide aerogel photocatalyst BTABPB in pure water

[0072] 20 mg of the photocatalyst BTABPB of Example 1 was dispersed in 20 mL of aqueous solution, and oxygen was introduced at a flow rate of 50 mL / min and stirred for 30 min to reach oxygen saturation. Then, the mixture was stirred under simulated sunlight (light power 300 mM / cm 2 ) for 20, 40, and 60 min under illumination, 2 mL of the reaction solution was taken at different time points and filtered through a 0.45 μm filter to measure the concentration of hydrogen peroxide. The results are shown in Figure 5 (Full-arc O2).

[0073] Test Example 2: Photocatalytic H2O2 production rate of polyimide aerogel photocatalyst BTABPB in pure water

[0074] 20 mg of the photocatalyst BTABPB of Example 1 was dispersed in 20 mL of aqueous solution, and oxygen was introduced at a flow rate of 50 mL / min and stirred for 30 min to reach oxygen saturation. Then, visible light (optical power 245 mM / cm 2 ) for 20, 40, and 60 min, 2 mL of the reaction solution was taken at different time points and filtered through a 0.45 μm filter to measure the concentration of hydrogen peroxide. The results are shown in Figure 5 (Vis-light O2).

[0075] Test Example 3: Photocatalytic H2O2 production rate of polyimide aerogel photocatalyst BTABPB in pure water

[0076] 20 mg of the photocatalyst BTABPB from Example 1 was dispersed in 20 mL of aqueous solution, which was then exposed to air. The solution was then exposed to simulated sunlight for 20, 40, and 60 min. 2 mL of the reaction solution was then filtered through a 0.45 μm filter at different time points, and the hydrogen peroxide concentration was measured. The results are shown in FIG5 (Full-arcAir).

[0077] Test Example 4: Cumulative performance of polyimide aerogel photocatalyst BTABPB in photocatalytic H2O2 production in pure water

[0078] 20 mg of the photocatalyst BTABPB of Example 1 was dispersed in 20 mL of aqueous solution, and oxygen was introduced at a flow rate of 50 mL / min and stirred for 30 min to reach oxygen saturation. 2 ) At time points of 0.5, 1, 2, 3, 4, 6, 8, 10, and 12 h of illumination, 2 mL of the reaction solution was filtered through a 0.45 μm filter and the hydrogen peroxide concentration was measured. The results are shown in FIG6 .

[0079] Test Example 5: Cumulative performance of polyimide aerogel photocatalyst BTABPB in photocatalytic H2O2 production in pure water

[0080] 20 mg of the photocatalyst BTABPB of Example 1 was dispersed in 20 mL of aqueous solution and exposed to the air. Then, 2 mL of the reaction solution was taken at time points of 0.5, 1, 2, 3, 4, 6, 8, 10, and 12 h under simulated sunlight and filtered with a 0.45 μm filter. The hydrogen peroxide concentration was measured, and the results are shown in Figure 6.

[0081] Test Example 6: Cyclic Performance of Polyimide Aerogel Photocatalyst BTABPB for Photocatalytic H2O2 Production in Pure Water

[0082] 20 mg of the photocatalyst BTABPB of Example 1 was dispersed in 20 mL of aqueous solution, and oxygen was introduced at a flow rate of 50 mL / min and stirred for 30 min to reach oxygen saturation. Then, the mixture was stirred under simulated sunlight (light power 300 mM / cm 2 ) for 12 hours. 2 mL of the reaction solution was sampled at different time points and filtered through a 0.45 μm filter to determine the hydrogen peroxide concentration. Between each run, residual hydrogen peroxide and water on the catalyst surface were removed by evaporation. The remaining photocatalyst, BTABPB, was then dried in a vacuum oven at 60°C for 12 hours before the next 12-hour cycle. The results are shown in Figure 7.

[0083] Example 2: Preparation of polyimide aerogel photocatalyst BTAB

[0084] Polyimide BTAB photocatalyst was prepared by thermal imidization of aromatic triamine 1,3,5-triaminobenzene (TAB) and aromatic dianhydride 3,3',4,4'-biphenyltetracarboxylic dianhydride (BDA).

[0085] Specific process: BDA (0.9 mmol) was dissolved in 2 mL of N-methylpyrrolidone solution, and then TAB (0.6 mmol) was dispersed in 2 mL of mesitylene solution. The two were mixed and finally isoquinoline (0.02 mL) was added. After ultrasonication at a power of 100 W for 10 minutes, a transparent colorless solution was quickly obtained. Then it was poured into a mold and gelled at 0°C for 60 minutes. The gel was further solvent-thermally treated at 180°C for 48 hours. The product was soaked in 75% N-methylpyrrolidone-ethanol solution for 24 hours. Subsequently, the solvent was exchanged with 25% N-methylpyrrolidone-ethanol every 24 hours, and then exchanged with ethanol three times. Finally, it was rinsed with deionized water and freeze-dried to obtain the final product BTAB.

[0086] The unit structure of the obtained BTAB material is:

[0087] Test Example 7: Photocatalytic H2O2 production rate of polyimide aerogel photocatalyst BTAB in pure water

[0088] 20 mg of the photocatalyst BTAB of Example 2 was dispersed in 20 mL of aqueous solution, and oxygen was introduced at a flow rate of 50 mL / min and stirred for 30 min to reach oxygen saturation. Then, the photocatalyst BTAB was exposed to simulated sunlight (light power 300 mM / cm 2 ) for 10, 20, 30, 40, 50, and 60 min, respectively, 2 mL of the reaction solution was taken at different time points and filtered through a 0.45 μm filter to measure the concentration of hydrogen peroxide. The results are shown in FIG8 .

[0089] Example 3: Preparation of polyimide aerogel photocatalyst BTBZ

[0090] Polyimide BTAB photocatalyst was prepared by thermal imidization of aromatic triamine 1,3,5-tri(4-aminophenyl)benzene (TBZ) and aromatic dianhydride 3,3',4,4'-biphenyltetracarboxylic dianhydride (BDA).

[0091] Specific process: BDA (0.9 mmol) was dissolved in 2 mL of N-methylpyrrolidone solution, TAB (0.6 mmol) was then dispersed in 2 mL of mesitylene solution, the two were mixed, and finally isoquinoline (0.02 mL) was added. After ultrasonication at a power of 100 W for 10 minutes, a transparent colorless solution was quickly obtained. Then it was poured into a mold and gelled at 0°C for 60 minutes. The gel was further solvent-thermally treated at 180°C for 48 hours. The product was soaked in a 75% N-methylpyrrolidone-ethanol solution for 24 hours. Subsequently, the solvent was exchanged with 25% N-methylpyrrolidone-ethanol every 24 hours, and then exchanged with ethanol three times. Finally, it was rinsed with deionized water and freeze-dried to obtain the final product BTBZ.

[0092] The unit structure of the obtained BTBZ material is:

[0093] Test Example 8: Photocatalytic H2O2 production rate of polyimide aerogel photocatalyst BTBZ in pure water

[0094] 20 mg of the photocatalyst BTBZ of Example 3 was dispersed in 20 mL of aqueous solution, and oxygen was introduced at a flow rate of 50 mL / min and stirred for 30 min to reach oxygen saturation. Then, the photocatalyst BTBZ was dispersed in 20 mL of aqueous solution under simulated sunlight (light power 300 mM / cm 2 ) for 10, 20, 30, 40, 50, and 60 min under light, and 2 mL of the reaction solution was taken at different time points and filtered through a 0.45 μm filter to measure the concentration of hydrogen peroxide. The results are shown in Figure 8.

[0095] Comparative Example 1: Comparison of polyimide catalytic materials reported in existing literature

[0096] Sample: Polyamic acid monomer (diamine is 1,4-phenylenediamine, dianhydride is benzene-1,2,4,5-tetracarboxylic dianhydride) forms polyamic acid, and then closed-loop polycondensation forms polyimide. The structure of the polyimide catalyst material is as follows:

[0097] The photocatalytic H2O2 production performance of the material was measured according to the process of Test Example 1.

[0098] The test results of the above test cases 1, 7, and 8 are specifically shown in Table 1.

[0099] Table 1

[0100] Note: The above yield data are the average values ​​of three parallel experiments.

[0101] Comparative Example 2: Comparison of different polyimide monomers

[0102] Referring to Example 1, the aromatic triamine was replaced with other monomers shown in Table 2, and the other conditions remained unchanged to obtain the corresponding polyimide materials.

[0103] The corresponding photocatalytic H2O2 production performance was measured according to the process of Test Example 1. The results are shown in Table 2.

[0104] Table 2

[0105] Note: The above yield data are the average values ​​of three parallel experiments.

[0106] The corresponding unit structures of the above polymers 1-7 are shown below:

[0107] Comparative Example 3: Comparative Optimization of Preparation Methods

[0108] Referring to Example 1, only the solvent environment was adjusted: TABPB was dispersed in an equal volume of other organic solvents (as shown in Table 3) to prepare the corresponding catalytic materials.

[0109] The corresponding photocatalytic H2O2 production performance was measured according to the process of Test Example 1. The results are shown in Table 3.

[0110] Table 3

[0111] Note: The above yield data are the average values ​​of three parallel experiments.

[0112] Note: The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Therefore, although this specification has described the present invention in detail with reference to the above embodiments, it should be understood by those skilled in the art that the present invention may still be modified or replaced by equivalents. All technical solutions and improvements that do not depart from the spirit and scope of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A polyimide catalytic material for photocatalytic synthesis of hydrogen peroxide, characterized in that, The polyimide catalytic material is prepared by thermal imidization of an aromatic triamine monomer and an aromatic dianhydride monomer; the aromatic triamine monomer is selected from any one or more of the following: 5”-(4'-amino-[1,1'-biphenyl]-4-yl)-[1,1':4',1”:3”,1”':4”',1””-quaterphenyl]-4,4””-diamine, 1,3,5-triaminobenzene, 1,3,5-tris(4-aminophenyl)benzene; the aromatic dianhydride monomer is 3,3',4,4'-biphenyltetracarboxylic dianhydride.

2. The preparation method of a polyimide catalytic material for photocatalytic synthesis of hydrogen peroxide according to claim 1, characterized in that, It includes the following process: (1) Dissolve the aromatic triamine monomer in solvent A to prepare an aromatic triamine monomer solution; dissolve the aromatic dianhydride monomer in solvent B to prepare an aromatic dianhydride monomer solution; mix the two solutions, then add isoquinoline, mix well and react to obtain a reaction solution; (2) Pour the obtained reaction solution into a mold, first gel at 0-5 °C for a period of time, and then continue heat treatment at 150-200 °C for a period of time to obtain a preliminary product; soak the preliminary product in an N-methylpyrrolidone-ethanol solution in a gradient manner, and then wash and dry.

3. The method according to claim 2, wherein In step (1), solvents A and B are each independently selected from any one or more of the following: mesitylene, DMF, NMP, DMAc.

4. The method according to claim 2, wherein In step (1), solvent A is mesitylene and solvent B is NMP.

5. The method according to claim 2, wherein In step (1), the concentration of the aromatic triamine monomer solution is 0.1-0.5 mmol / mL.

6. The method according to claim 2, wherein In step (1), the concentration of the aromatic dianhydride monomer solution is 0.1-1.0 mmol / mL; 0.45 mmol / mL.

7. The method according to claim 2, characterized in that, In step (1), the molar ratio of the aromatic triamine monomer to the aromatic dianhydride monomer is 1:(1-2).

8. The method according to claim 2, wherein In step (1), the dosage of isoquinoline relative to the aromatic triamine monomer is 0.02-0.05 ml / mmol.

9. The method according to any one of claims 2-8, characterized in that, In step (2), pour the obtained reaction solution into a mold, first gel at 0 °C for 60 min, and then further perform solvent heat treatment at 180 °C for 48 h.

10. Use of the polyimide catalytic material according to claim 1 in the photocatalytic synthesis of hydrogen peroxide.

11. The application according to claim 10, wherein In the process of photocatalytic synthesis of hydrogen peroxide, the photocatalyst photocatalytically synthesizes hydrogen peroxide in an environment of pure water-oxygen or pure water-air or sacrificial reagent-oxygen or sacrificial reagent-air; the sacrificial reagent is a C1-4 alkyl alcohol.

12. A method for photocatalytic synthesis of hydrogen peroxide, characterized in that, Using water and oxygen as raw materials, and using the polyimide catalytic material according to claim 1 as a photocatalyst, photocatalytically synthesize hydrogen peroxide under illumination.

13. The method according to claim 12, wherein The dosage of the polyimide catalytic material relative to water is 1 mg / mL.

14. The method according to claim 12, wherein The light source is full-spectrum light, simulated sunlight, visible light, single-wavelength light source, or natural light.

15. The method according to any one of claims 12 - 14, characterized in that, The power of the light is 200 - 300 mM / cm 2 .

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