Method for preparing hydrogen peroxide based on amorphous porphyrin supermolecular photocatalyst

Abstract

This invention provides a method for preparing an amorphous porphyrin supramolecular photocatalyst. The method involves synthesizing amorphous porphyrin supramolecular molecules at room temperature using porphyrin monomers as raw materials, and then using these amorphous porphyrin supramolecular molecules as a photocatalyst to prepare hydrogen peroxide. This invention utilizes amorphous porphyrin supramolecular molecules as a photocatalyst, which is convenient and rapid to synthesize. In the hydrogen peroxide preparation process, O2 is used as the oxygen source and visible light as the energy source, resulting in low energy consumption and high safety. The method is green and pollution-free, with mild reaction conditions, and a high yield of hydrogen peroxide per unit time. The yield of hydrogen peroxide prepared by amorphous porphyrin supramolecular molecules as a photocatalyst is approximately twice that of crystalline porphyrin supramolecular molecules. Among these, amorphous TCPP supramolecular molecules exhibit the highest yield of hydrogen peroxide, reaching up to 300 mM / g.

Description

Technical Field

[0001] This invention relates to a method for preparing hydrogen peroxide based on an amorphous porphyrin supramolecular photocatalyst, belonging to the field of energy chemistry. Background Technology

[0002] Hydrogen peroxide, also known as hydrogen peroxide solution in aqueous solution, is a green and efficient oxidant widely used in pulp and textile bleaching, chemical synthesis, medical disinfection, and rocket propellant. Currently, commercial production of hydrogen peroxide both domestically and internationally mainly employs two methods: the anthraquinone (AO) method or the thermocatalytic method. While both methods offer advantages in terms of low cost and high yield, they also have their drawbacks. The AO method uses flammable and explosive H2 and highly toxic heavy aromatic hydrocarbons as raw materials. If the flow rate is too high, static electricity within the pipeline can cause combustion and explosion. Furthermore, the AO method requires a palladium catalyst; if it leaks into the oxidation or extraction system, it will cause severe decomposition of the hydrogen peroxide, with potentially serious consequences. Chinese patent CN103496674A proposes a method for preparing hydrogen peroxide using an anthraquinone method with a fully acidic working fluid system, improving upon the original alternating acid and alkaline working fluid system. However, it remains essentially a high-energy-consuming synthesis method, and the fully acidic reaction conditions may reduce the lifespan of the equipment. Thermocatalysis uses a mixture of H2 / O2 gas to directly produce hydrogen peroxide. However, this method poses significant safety risks due to the explosiveness of the mixture over a wide concentration range. For example, patent CN108144605A discloses a method for preparing a supported alloy catalyst and its application in the synthesis of hydrogen peroxide from H2 / O2; patent US7364718B2 discloses a method for promoting the production of hydrogen peroxide from H2 / O2 using a noble metal catalyst. Both patents utilize precious metals such as gold, palladium, or platinum, resulting in high production costs. Furthermore, both use a mixture of H2 / O2 gas as a raw material, posing considerable danger. Therefore, safe, efficient, energy-saving, and environmentally friendly production of hydrogen peroxide presents a significant challenge.

[0003] Emerging photocatalytic technologies, using H2O and O2 as raw materials and leveraging the inexhaustible energy of sunlight, avoid the mixing of H2 and O2, making them safe and environmentally friendly, and have attracted much attention in recent years. Porphyrin supramolecular photocatalysts are the main components of chlorophyll photoactivity, possessing advantages such as strong light absorption capacity (absorbing all visible wavelengths), a special structure that promotes photogenerated charge separation and transport, and being green and non-toxic, making them a widely studied potential high-efficiency photocatalyst. Keiko et al. reported the photocatalytic production of hydrogen peroxide from porphyrin aggregate solutions under tungsten lamp irradiation. However, the photocatalyst studied in this report was a porphyrin solution, which is not conducive to the separation from the generated hydrogen peroxide, making the obtained product difficult to utilize, and the catalyst difficult to recover and reuse. Powdered porphyrin photocatalysts have been reported for the direct photocatalytic production of hydrogen peroxide using H2O and O2 as raw materials (Zhang, Y., Pan, C., Bian, G. et al. Nat Energy 8, 361–371 (2023).). In this method, porphyrin molecules need to be self-assembled under heating conditions, and the resulting porphyrin supramolecular molecules are highly crystalline. Electron transport is restricted by the anisotropy of the crystal lattice, and their photocatalytic activity for producing hydrogen peroxide is limited by their exposed crystal faces. Compared with crystalline catalysts, amorphous catalysts, due to their high specific surface area, can provide more active sites, thereby increasing the contact area between the reactants and the catalyst and promoting the reaction. Secondly, amorphous catalysts have abundant defects and structural deficiencies, which give them better catalytic activity and selectivity. Furthermore, compared to crystalline catalysts, amorphous photocatalysts have a shorter electron diffusion path, which is not limited by their exposed crystal faces, thus facilitating electron diffusion to the catalyst surface to participate in the reaction (Wu, G., Zheng, X., Cui, P. et al. ANat Commun 10, 4855 (2019); Yang, H., Li, C., Liu, T. et al. Nat. Nanotechnol. 18, 307–315 (2023).). Therefore, the preparation of an efficient amorphous photocatalyst for hydrogen peroxide production and the study of its catalytic ability to produce hydrogen peroxide have become research priorities. Summary of the Invention

[0004] To address the aforementioned problems, this invention aims to provide a method for preparing an amorphous porphyrin supramolecular photocatalyst, and to use this photocatalyst, water, and O2 as raw materials to prepare hydrogen peroxide via photothermal catalysis. The preparation of the amorphous porphyrin supramolecular photocatalyst does not require further heating, making it convenient and rapid. In the process of synthesizing hydrogen peroxide, O2 is used as the oxygen source and visible light as the energy source, resulting in low energy consumption and high safety. It is green and pollution-free, with mild reaction conditions and a high yield of hydrogen peroxide per unit time.

[0005] To achieve the above objectives, the present invention first provides a method for preparing an amorphous porphyrin supramolecular photocatalyst, comprising the following steps: dissolving porphyrin molecules in solvent A to obtain a porphyrin solution; slowly adding solvent B dropwise into the porphyrin solution; stirring; centrifuging to collect the precipitate; washing and drying to obtain the amorphous porphyrin supramolecular photocatalyst; wherein, solvent A is at least one of tetrahydrofuran, ethylene glycol, and KOH solution, and solvent B is at least one of methanol, anhydrous ethanol, and HCl solvent.

[0006] In one embodiment of the present invention, the porphyrin molecule includes at least one selected from 5,10,15,20-tetrakis(3,5-dicarboxyphenyl)porphyrin, 5-(4-carboxyphenyl)-10,15,20-triphenylporphyrin, 5,10-(4-carboxyphenyl)-15,20-diphenylporphyrin, 5,10,15-(4-carboxyphenyl)-20-phenylporphyrin, and tetrakis(4-carboxyphenyl)porphyrin.

[0007] In one embodiment of the present invention, the mass-to-volume ratio of the porphyrin molecule to solvent A is (2-40) mg:(1-4) mL, and the mass-to-volume ratio of the porphyrin molecule to solvent B is (1-20) mg:(3-10) mL.

[0008] In one embodiment of the present invention, the stirring time is 5 to 10 hours.

[0009] The present invention also provides an amorphous porphyrin supramolecular photocatalyst prepared by the above method.

[0010] The present invention also provides an application of the above-mentioned amorphous porphyrin supramolecular photocatalyst in the field of photocatalysis.

[0011] This invention also discloses a method for preparing hydrogen peroxide using the above-mentioned amorphous porphyrin supramolecular photocatalyst, comprising the following steps:

[0012] a. Preparation of amorphous porphyrin supramolecular dispersion: Amorphous porphyrin supramolecular photocatalyst was ultrasonically dispersed in water to obtain an amorphous porphyrin supramolecular dispersion;

[0013] b. Preparation of hydrogen peroxide from amorphous porphyrin supramolecular photocatalyst: O2 is continuously introduced into the porphyrin supramolecular catalyst dispersion obtained in step a and stirred, while the reaction is carried out by visible light irradiation. The resulting reaction product is filtered to obtain an aqueous solution of hydrogen peroxide.

[0014] In one embodiment of the present invention, in step a, the concentration of the amorphous porphyrin supramolecular dispersion is 0.3-1.5 g / L, the ultrasonic dispersion power is 2000-4500 Hz, and the time is 5-60 min.

[0015] In one embodiment of the present invention, in step b, the oxygen flow rate is maintained at 50-150 mL / min.

[0016] In one embodiment of the present invention, in step b, the reaction temperature is maintained at 20-80°C and the irradiation time is 2-24h.

[0017] In one embodiment of the present invention, in step b, the visible light comes from a xenon lamp with an external 420nm cutoff filter, and the light intensity of the xenon lamp is 20-200mW / cm2.

[0018] Beneficial effects of the present invention

[0019] (1) This invention provides methods for preparing amorphous 5,10,15,20-tetra(3,5-dicarboxyphenyl)porphyrin supramolecular photocatalysts (AM-TDCPP), (AM-CATPP), (AM-DiCPP), (AM-TriCPP), and (AM-TCPP), and their photocatalytic performance in producing hydrogen peroxide is measured. Compared with crystalline catalysts, amorphous catalysts, due to their high specific surface area, can provide more active sites, thereby increasing the contact area between the reactants and the catalyst and promoting the reaction. Secondly, amorphous catalysts possess abundant defects and structural deficiencies, which enhance their catalytic activity and selectivity. Furthermore, compared to crystalline catalysts, amorphous photocatalysts have shorter electron diffusion free paths, unrestricted by exposed crystal faces, facilitating electron diffusion to the catalyst surface for reaction participation. The amorphous catalysts of this invention are prepared under relatively mild reaction conditions, eliminating the need for continuous high-temperature heating, thus reducing production costs and facilitating large-scale production. The sacrificial agent-free catalytic hydrogen peroxide production method based on five amorphous porphyrin supramolecular photocatalysts provided in this invention significantly improves the hydrogen peroxide yield per unit time compared to the same method using crystalline porphyrin supramolecular photocatalysts.

[0020] (2) The method for producing hydrogen peroxide by photothermal catalysis without sacrificial agent based on amorphous porphyrin supramolecular catalyst provided by the present invention does not use organic solvents (ethanol, isopropanol, benzyl alcohol, etc.) as sacrificial agents, and is green, environmentally friendly and pollution-free.

[0021] (3) The method for producing hydrogen peroxide without sacrificial agent based on amorphous porphyrin supramolecular catalyst provided by the present invention uses O2 as oxygen source and sunlight (visible light) as energy source under normal pressure. Compared with the indirect synthesis of hydrogen peroxide by anthraquinone method in industry, the method of the present invention has lower energy consumption and higher safety.

[0022] (4) The method for producing hydrogen peroxide without sacrificial agent based on amorphous porphyrin supramolecular catalyst provided by the present invention is safer than the method for preparing hydrogen peroxide directly by mixing oxygen and hydrogen.

[0023] (5) Compared with the traditional photocatalytic preparation of hydrogen peroxide, this method eliminates the problem of difficult separation of organic sacrificial agents and their oxidation products from the source;

[0024] (6) The method for preparing hydrogen peroxide according to this invention has mild reaction conditions and simple operation. It only requires mixing the porphyrin supramolecular photocatalyst with ultrapure water, irradiating it with visible light for a period of time at a temperature of 20–80℃ and an O2 flow rate of 50–150 mL / min with stirring, and then filtering the reaction solution to obtain hydrogen peroxide of a relatively high concentration. Further concentration by vacuum distillation yields commercially available hydrogen peroxide (approximately 3.00 wt%). The method for preparing hydrogen peroxide using this invention has the advantages of high yield and efficient and stable catalytic performance, and has good application prospects.

[0025] (7) The hydrogen peroxide prepared by the method of the present invention has a high yield. The yield of hydrogen peroxide prepared by amorphous porphyrin supramolecular as photocatalyst is about twice that of crystalline porphyrin supramolecular. Among them, the yield of hydrogen peroxide prepared by amorphous TCPP supramolecular as photocatalyst is the highest, which can reach 300mM / g. Attached Figure Description

[0026] Figure 1 The XRD patterns are of the five amorphous porphyrin supramolecular photocatalysts in Examples 1 to 5.

[0027] Figure 2 XRD patterns of five crystalline porphyrin supramolecular photocatalysts from Comparative Examples 1 to 5;

[0028] Figure 3 TEM (a) and AFM (b) images of the amorphous tetra(4-carboxyphenyl)porphyrin supramolecular structure of Example 5;

[0029] Figure 4 This is a comparison diagram of the photocatalytic activity of different amorphous porphyrin supramolecular molecules in Examples 6 to 10 and different crystalline porphyrin supramolecular molecules in Comparative Examples 6 to 10 in generating hydrogen peroxide. Detailed Implementation

[0030] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0031] Methods for testing hydrogen peroxide concentration:

[0032] Hydrogen peroxide and potassium titanium oxalate form a yellow complex solution. The absorbance at 400 nm is measured using a UV spectrophotometer, and the concentration of hydrogen peroxide is calculated using Beer-Lambert's law. Specifically, 1 mL of the sample (the reaction solution in the examples or comparative examples) is taken every 1 hour. After filtering out catalyst particles through a 0.45 μm filter membrane, 1 mL of potassium titanium oxalate solution (0.02 M) and 3 mL of ultrapure water are added. Finally, the absorbance of the solution at 400 nm is measured using a UV spectrophotometer, and the concentration of hydrogen peroxide is calculated.

[0033] The raw material source for the porphyrin supramolecular catalyst prepared in this invention is as follows:

[0034] 5,10,15,20-Tetra(3,5-dicarboxyphenyl)porphyrin (TDCPP): Purchased from Beijing Innocare Technology Co., Ltd., with a purity of 97%.

[0035] 5-(4-Carboxyphenyl)-10,15,20-Triphenylporphyrin (CATPP): Prepared in the laboratory. The preparation method is as follows:

[0036] Under argon protection, methyl paraformylbenzoate (2.1 g, 0.013 mol) and benzaldehyde (4.0 mL, 0.039 mol) were dissolved in 100 mL of propionic acid in a 250 mL three-necked flask. Pyrrole (3.5 mL, 0.051 mol) was then added dropwise using a constant-pressure dropping funnel. The solution was refluxed in the dark for 3 hours. Propionic acid was removed by vacuum distillation to obtain a deep purple solid. Subsequently, the solid was purified by column chromatography using a mobile phase of V:V dichloromethane = 4:1 to obtain a purple 5-(4-esterophenyl)-10,15,20-triphenylporphyrin. The obtained purple solid was stirred in a mixture of 25 mL THF and 25 mL MeOH, and then 25 mL of KOH aqueous solution (3.0 g, 0.053 mol) was added. The mixture was refluxed overnight at 66 °C. After cooling to room temperature, 100 mL of water was added to the resulting aqueous phase, and the mixture was heated until the solid was completely dissolved. The mixture was then acidified with 1 mol·L⁻¹ HCl until no precipitate was detected. The mixture was collected by filtration, washed with water, and dried under vacuum. MS(+): m / z = 673.

[0037] 5,10-(4-Carboxyphenyl)-15,20-Diphenylporphyrin (DiCPP): Prepared in the laboratory. The preparation method is as follows:

[0038] Under argon protection, methyl paraformylbenzoate (4.2 g, 0.026 mol) and benzaldehyde (2.5 mL, 0.026 mol) were dissolved in 100 mL of propionic acid in a 250 mL three-necked flask. Pyrrole (7 mL, 0.102 mol) was then added dropwise using a constant-pressure dropping funnel. The solution was refluxed in the dark for 3 hours. Propionic acid was removed by vacuum distillation to obtain a deep purple solid. Subsequently, the solid was purified by column chromatography using a mobile phase of V:V petroleum ether = 4:1 to obtain a purple 5,10(4-esterophenyl)-15,20-diphenylporphyrin. The obtained purple solid was stirred in a mixture of 25 mL THF and 25 mL MeOH, and then 25 mL of KOH aqueous solution (6.0 g, 0.102 mol) was added. The mixture was refluxed overnight at 66 °C. After cooling to room temperature, 100 mL of water was added to the resulting aqueous phase, and the mixture was heated until the solid was completely dissolved. The mixture was then acidified with 1 mol·L⁻¹ HCl until no precipitate was detected. The mixture was collected by filtration, washed with water, and dried under vacuum. MS(+): m / z = 704.

[0039] 5,10,15-(4-Carboxyphenyl)-20-phenylporphyrin (TriCPP): Prepared in the laboratory. The preparation method is as follows:

[0040] Under argon protection, methyl paraformylbenzoate (9.7 g, 0.06 mol) and benzaldehyde (2.0 mL, 0.02 mol) were dissolved in 100 mL of propionic acid in a 250 mL three-necked flask. Pyrrole (5.5 mL, 0.08 mol) was then added dropwise using a constant-pressure dropping funnel. The solution was refluxed in the dark for 3 hours. Propionic acid was removed by vacuum distillation to obtain a deep purple solid. Subsequently, the solid was purified by column chromatography using a mobile phase of V:V dichloromethane:V petroleum ether = 4:1 to obtain a purple 5,10,15-(4-esterophenyl)-20-phenylporphyrin. The obtained purple solid was stirred in a mixture of 25 mL THF and 25 mL MeOH, and then 25 mL of KOH aqueous solution (4.5 g, 0.08 mol) was added. The mixture was refluxed overnight at 66 °C. After cooling to room temperature, 100 mL of water was added to the resulting aqueous phase, and the mixture was heated until the solid was completely dissolved. The mixture was then acidified with 1 mol·L⁻¹ HCl until no precipitate was detected. The mixture was collected by filtration, washed with water, and dried under vacuum. MS(-): m / z = 745.

[0041] Tetra(4-carboxyphenyl)porphyrin (TCPP): Prepared in the laboratory. The preparation method is as follows:

[0042] Under argon protection, methyl paraformylbenzoate (6.9 g, 0.042 mol) was dissolved in 100 mL of propionic acid in a 250 mL three-necked flask. Pyrrole (3.0 mL, 0.043 mol) was then added dropwise using a constant-pressure dropping funnel. The solution was refluxed in the dark for 3 hours. Propionic acid was removed by vacuum distillation to obtain a deep purple solid. The solid was then purified by column chromatography with a mobile phase of Vdichloromethane:Vpetroleum ether = 4:1. The purple crystals were collected by filtration, washed with water, and dried under vacuum. MS(-): m / z = 789.

[0043] Example 1

[0044] The preparation of an amorphous porphyrin supramolecular photocatalyst includes the following steps: 500 mg of TDCPP molecules are dissolved in 10 ml of 0.5 M KOH aqueous solution, and 0.1 M HCl aqueous solution is added dropwise through a constant pressure dropping funnel until pH = 4. The mixture is stirred for 5 hours, centrifuged, collected, filtered, and dried.

[0045] Example 2

[0046] Example 2 differs from Example 1 only in that the type of porphyrin molecule is changed; specifically, TDCPP is replaced with CATPP.

[0047] Example 3

[0048] Example 3 differs from Example 1 only in that the type of porphyrin molecule is changed; specifically, TDCPP is replaced with DiCPP.

[0049] Example 4

[0050] Example 4 differs from Example 1 only in that the type of porphyrin molecule is changed; specifically, TDCPP is replaced with TriCPP.

[0051] Example 5

[0052] Example 5 differs from Example 1 only in that the type of porphyrin molecule is changed; specifically, TDCPP is replaced with TCPP.

[0053] Comparative Example 1

[0054] The preparation of a crystalline porphyrin supramolecular photocatalyst includes the following steps: 500 mg of TDCPP molecules are dissolved in 10 mL of 0.5 M KOH aqueous solution at 80 °C. 0.1 M HCl aqueous solution is added dropwise through a constant pressure dropping funnel until pH = 4. The mixture is stirred at 80 °C for 72 hours. After cooling, the mixture is centrifuged and washed several times until pH = 7. The mixture is collected by filtration and dried under vacuum at 60 °C.

[0055] Comparative Example 2

[0056] The only difference between Comparative Example 2 and Comparative Example 1 is that the type of porphyrin molecule is changed; specifically, TDCPP is replaced with CATPP.

[0057] Comparative Example 3

[0058] The only difference between Comparative Example 3 and Comparative Example 1 is that the type of porphyrin molecule is changed; specifically, TDCPP is replaced with DiCPP.

[0059] Comparative Example 4

[0060] The only difference between Comparative Example 4 and Comparative Example 1 is that the type of porphyrin molecule is changed; specifically, TDCPP is replaced with TriCPP.

[0061] Comparative Example 5

[0062] The only difference between Comparative Example 5 and Comparative Example 1 is that the type of porphyrin molecule is changed; specifically, TDCPP is replaced with TCPP.

[0063] Example 6

[0064] A method for sacrificial agent-free photothermal catalytic production of hydrogen peroxide based on an amorphous porphyrin supramolecular photocatalyst includes the following steps:

[0065] In a 100 mL borosilicate flask, 25 mg of catalyst (AM-TDCPP) was ultrasonically dispersed in 50 mL of ultrapure water and sealed with a reverse stopper. Heating (60 °C) and magnetic stirring were performed in an oil bath, with the O2 flow rate maintained at 80 mL / min, and irradiation was carried out for 4 h using a xenon lamp (λ≥420 nm) with a light intensity of 90 mW / cm². The preparation method of AM-TDCPP was the same as in Example 1.

[0066] Every 1 hour, 1 mL of the reaction solution was taken, filtered through a 0.45 μm filter membrane to remove the catalyst, and then 1 mL of potassium titanium oxalate solution (0.02 M) and 3 mL of ultrapure water were added. The absorbance at 400 nm was measured using a UV spectrophotometer, and the concentration of hydrogen peroxide was calculated using Beer-Lambert's law.

[0067] Example 7

[0068] The only difference between Example 7 and Example 6 is that the type of porphyrin supramolecular catalyst is changed. Specifically, AM-TDCPP is replaced with AM-CATPP, and the preparation method of AM-CATPP is the same as that in Example 2.

[0069] Example 8

[0070] The only difference between Example 8 and Example 6 is that the type of porphyrin supramolecular catalyst is changed. Specifically, AM-TDCPP is replaced with AM-DiCPP, and the preparation method of AM-DiCPP is the same as that in Example 3.

[0071] Example 9

[0072] The only difference between Example 9 and Example 6 is that the type of porphyrin supramolecular catalyst is changed. Specifically, AM-TDCPP is replaced with AM-TriCPP, and the preparation method of AM-TriCPP is the same as that in Example 4.

[0073] Example 10

[0074] The only difference between Example 9 and Example 6 is that the type of porphyrin supramolecular catalyst is changed, and AM-TDCPP is replaced with AM-TCPP. The preparation method of AM-TCPP is the same as that of Example 5.

[0075] Comparative Example 6

[0076] A method for sacrificial agent-free photothermal catalytic production of hydrogen peroxide based on a crystalline porphyrin supramolecular photocatalyst includes the following steps:

[0077] In a 100 mL borosilicate flask, 25 mg of catalyst (CRY-TDCPP) was ultrasonically dispersed in 50 mL of ultrapure water and sealed with a reverse stopper. The mixture was heated (60 °C) and magnetically stirred in an oil bath, with an O2 flow rate maintained at 80 mL / min, and irradiated for 4 h using a xenon lamp (λ≥420 nm) with a light intensity of 90 mW / cm². The preparation method of CRY-TDCPP was the same as that of Comparative Example 1.

[0078] Every 1 hour, 1 mL of the reaction solution was taken, filtered through a 0.45 μm filter membrane to remove the catalyst, and then 1 mL of potassium titanium oxalate solution (0.02 M) and 3 mL of ultrapure water were added. The absorbance at 400 nm was measured using a UV spectrophotometer, and the concentration of hydrogen peroxide was calculated using Beer-Lambert's law.

[0079] Comparative Example 7

[0080] The only difference between Comparative Example 7 and Comparative Example 6 is that the type of porphyrin supramolecular catalyst is changed. Specifically, CRY-TDCPP is replaced with CRY-CATPP, and the preparation method of CRY-CATPP is the same as that of Comparative Example 2.

[0081] Comparative Example 8

[0082] The only difference between Comparative Example 8 and Comparative Example 6 is that the type of porphyrin supramolecular catalyst is changed. Specifically, CRY-TDCPP is replaced with CRY-DiCPP, and the preparation method of CRY-DiCPP is the same as that of Comparative Example 3.

[0083] Comparative Example 9

[0084] The only difference between Comparative Example 9 and Comparative Example 6 is that the type of porphyrin supramolecular catalyst is changed. Specifically, CRY-TDCPP is replaced with CRY-TriCPP, and the preparation method of CRY-TriCPP is the same as that of Comparative Example 4.

[0085] Comparative Example 10

[0086] The only difference between Comparative Example 10 and Comparative Example 6 is that the type of porphyrin supramolecular catalyst is changed, and CRY-TDCPP is replaced with CRY-TCPP. The preparation method of CRY-TCPP is the same as that of Comparative Example 5.

[0087] I. XRD patterns of amorphous porphyrin supramolecular photocatalysts (Examples 1-5) and crystalline porphyrin supramolecular photocatalysts (Comparative Examples 1-5)

[0088] Figure 1 The XRD patterns of five amorphous porphyrin supramolecular photocatalysts are shown. Their XRD spectra reveal a peak around 20°, with no other sharp peaks, indicating the amorphous structure of these five photocatalysts. For comparison, the XRD patterns of five crystalline porphyrin supramolecular photocatalysts are shown below. Figure 2 The figure shows a distinct peak, indicating its good crystallinity. The higher catalytic activity of the amorphous porphyrin supramolecular photocatalyst compared to the crystalline porphyrin supramolecular photocatalyst may be due to the fact that the amorphous form exposes more active sites for photothermal catalytic hydrogen peroxide production.

[0089] II. Comparison of the photothermal catalytic performance of different amorphous porphyrin supramolecular catalysts (Examples 6-10) and crystalline porphyrin supramolecular photocatalysts (Comparative Examples 6-10) in producing hydrogen peroxide.

[0090] Figure 4 This is a comparison of the hydrogen peroxide production performance of different amorphous porphyrin supramolecular photocatalysts from Examples 6-10 and different crystalline porphyrin supramolecular photocatalysts from Comparative Examples 6-10. The irradiation time was 4 hours. Figure 4 It can be seen that if the cumulative hydrogen peroxide yield after a 4-hour photothermal reaction at 60℃ is used as an indicator to evaluate the photothermal catalytic hydrogen peroxide production capability of several porphyrin supramolecular catalysts, from... Figure 4It can be seen that the photothermal catalytic production of hydrogen peroxide by several porphyrin supramolecular catalysts, from high to low, is AM-TCPP>AM-TDCPP>AM-TriCPP>AM-DiCPP>AM-CATPP. Figure 4 As shown in Figure 5, the activities of amorphous porphyrin supramolecular photocatalysts are all higher than those of crystalline porphyrin supramolecular photocatalysts.

[0091] III. Morphological Characterization of the AM-TCPP Photothermal Catalyst in Example 5

[0092] The morphology of the AM-TCPP photothermal catalyst with the best photothermal catalytic performance for hydrogen peroxide production was characterized. Figure 3 (a) is a TEM image of the AM-TCPP photothermal catalyst. The TEM image shows that AM-TCPP has a morphology of approximately 4 μm × 5 μm sheet-like structures. This large-size sheet-like structure provides more active sites for AM-TCPP to produce hydrogen peroxide. Figure 3 (b) shows the AFM image of AM-TCPP. The AFM image reveals that AM-TCPP exhibits a nanosheet structure with a thickness of approximately 9.5 nm. This nanoscale thickness facilitates the rapid migration of photogenerated carriers from the catalyst interior to the surface, thereby improving the separation and mobility of photogenerated electron-hole pairs and thus enhancing the photothermal catalytic efficiency. Therefore, the higher catalytic activity of amorphous TCPP supramolecular catalysts compared to other amorphous porphyrin supramolecular catalysts may be due to its larger and thinner nanosheet morphology and its amorphous structure. These conditions are conducive to exposing more active sites in the amorphous TCPP supramolecular catalyst for photothermal catalytic hydrogen peroxide production.

[0093] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. The application of an amorphous porphyrin supramolecular photocatalyst in improving the yield of hydrogen peroxide in the photocatalytic preparation of hydrogen peroxide, characterized in that, The method for photocatalytic preparation of hydrogen peroxide includes the following steps: ultrasonically dispersing an amorphous porphyrin supramolecular photocatalyst in water to obtain an amorphous porphyrin supramolecular dispersion; continuously introducing O2 into the obtained porphyrin supramolecular catalyst dispersion and stirring, while simultaneously irradiating the reaction with visible light; filtering the obtained reaction product to obtain an aqueous solution of hydrogen peroxide. The preparation method of the amorphous porphyrin supramolecular photocatalyst includes the following steps: dissolving porphyrin molecules in solvent A to obtain a porphyrin solution; slowly adding solvent B dropwise to the porphyrin solution; stirring; centrifuging to collect the precipitate; washing and drying to obtain the amorphous porphyrin supramolecular photocatalyst; wherein, solvent A is KOH solution, solvent B is HCl solution, and the pH of the porphyrin solution is 4 after slowly adding solvent B dropwise.

2. The application according to claim 1, characterized in that, The porphyrin molecule includes at least one selected from 5,10,15,20-tetrakis(3,5-dicarboxyphenyl)porphyrin, 5-(4-carboxyphenyl)-10,15,20-triphenylporphyrin, 5,10-(4-carboxyphenyl)-15,20-diphenylporphyrin, 5,10,15-(4-carboxyphenyl)-20-phenylporphyrin, and tetrakis(4-carboxyphenyl)porphyrin.

3. The application according to claim 1, characterized in that, The mass-to-volume ratio of the porphyrin molecule to solvent A is (2-40) mg:(1-4) mL, the mass-to-volume ratio of the porphyrin molecule to solvent B is (1-20) mg:(3-10) mL, and the stirring time is 5-10 h.

4. The method according to claim 1, characterized in that, The concentration of the amorphous porphyrin supramolecular dispersion is 0.3-1.5 g / L, the ultrasonic dispersion power is 2000-4500 Hz, and the time is 5-60 min.

5. The method according to claim 1, characterized in that, The flow rate of O2 was maintained at 50-150 mL / min, the temperature of the visible light irradiation reaction was maintained at 20-80℃, and the irradiation time was 2-24 h.

6. The method according to claim 1, characterized in that, The visible light comes from a xenon lamp with an external 420 nm cutoff filter, and the light intensity of the xenon lamp is 20-200 mW / cm². 2 .

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