A method for photocatalytic production of hydrogen peroxide without sacrificial agent based on naphthalimide / perylenimide polymer

Abstract

The application discloses a method for preparing hydrogen peroxide by photocatalysis without a sacrifice agent based on naphthalene imide / perylene imide polymer. The naphthalene imide / perylene imide polymer photocatalyst is synthesized by a hydrothermal method, and the catalyst can catalyze the reaction of oxygen and water to prepare hydrogen peroxide by photocatalysis without adding a sacrifice agent. The naphthalene imide / perylene imide polymer synthesized by the application is a photocatalyst with a donor / acceptor electron transport interface, and the structure greatly improves the electron-hole transport rate, thereby promoting the generation of hydrogen peroxide and inhibiting the decomposition of hydrogen peroxide. The application first applies the naphthalene imide / perylene imide polymer catalyst to the field of photocatalytic preparation of hydrogen peroxide. Compared with the industrial anthraquinone method and the method for preparing hydrogen peroxide by electric and thermal catalysis, the application is safe and environmentally friendly, simple to operate and low in cost.

Description

Technical Field

[0001] This invention relates to the field of green chemical technology, specifically to a method for the sacrificial agent-free photocatalytic production of hydrogen peroxide based on a naphthalimide / peryleneimide polymer. Background Technology

[0002] Hydrogen peroxide, also known as hydrogen peroxide 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 production volume, 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 violent decomposition of hydrogen peroxide, with very serious consequences. The thermocatalytic method mainly uses a H2 / O2 mixture for heating and catalytic direct preparation of hydrogen peroxide. Because the mixture is explosive over a wide concentration range, its safety hazards are even greater. Therefore, safe, efficient, energy-saving, and environmentally friendly production of hydrogen peroxide is extremely challenging.

[0003] Emerging photocatalytic technology uses H2O and O2 as raw materials and abundant solar energy as its energy source, avoiding the mixing of H2 and O2. Compared with thermal catalysis and electrocatalysis, photocatalytic preparation of hydrogen peroxide is a highly efficient, safe, environmentally friendly, and low-cost method. However, current photocatalytic preparation of hydrogen peroxide requires the addition of organic sacrificial agents as oxidizing hole acceptors, which not only reduces the theoretical quantum yield and increases economic and energy consumption but also makes it difficult to separate the hydrogen peroxide product from the organic sacrificial agent and its oxidation products. Among them, polyimide-based photocatalysts have advantages such as strong light absorption capacity (absorbing all visible wavelengths), a special structure that can promote the separation and transport of photogenerated charges, and being green and non-toxic, and have been widely studied as one of the potential high-efficiency photocatalysts. In addition, there are no reports on the application of naphthalimide / peryleneimide polymer photocatalysts alone in the efficient photocatalytic preparation of hydrogen peroxide using H2O and O2 as raw materials. Summary of the Invention

[0004] This invention uses naphthalimide / peryleneimide polymer as a photocatalyst to promote the photothermal catalytic preparation of hydrogen peroxide from H2O and O2, which meets the current needs of the chemical industry for compatibility with the ecological environment and sustainable development, and therefore has important industrial application value and social significance.

[0005] One of the objectives of this invention is to provide a sacrificial agent-free photocatalytic method for producing hydrogen peroxide based on naphthalimide / peryleneimide polymers, and to provide its application in the preparation of hydrogen peroxide.

[0006] The second objective of this invention is to develop a method for preparing a naphthalimide / peryleneimide polymer photocatalyst with a donor / acceptor electron transport interface;

[0007] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a naphthalimide / peryleneimide polymer according to the present invention includes the following steps:

[0008] (1) Preparation of N-AT precursor: 3,5-diamino-1,2,4-triazole was dispersed in N,N-dimethylacetamide and dissolved completely in an anaerobic ice bath. Then, 1,4,5,8-naphthalenetetracarboxylic anhydride was added and stirred to form a clear liquid. N,N-dimethylacetamide was then added and the above mixed solution was placed in a stainless steel autoclave. After sealing, a certain temperature was set for reaction. After the reaction was completed, the mixture was cooled to room temperature and washed with N,N-dimethylformamide, methanol and deionized water respectively. Finally, the precursor N-AT was obtained by freeze drying.

[0009] (2) Preparation of N-AT / PDI polymer: 3,4,9,10-perylenetetracarboxylic anhydride was dispersed in N-methylpyrrolidone and stirred at room temperature; the precursor in step (1) was dispersed in N-methylpyrrolidone and stirred evenly before being added to the above solution, and stirring was continued. The above mixed solution was placed in a stainless steel autoclave, sealed, and a certain temperature was set for reaction. After the reaction was completed, it was cooled to room temperature, washed with N-methylpyrrolidone, ethanol, and hot water respectively, and dried at 60°C to obtain the naphthaleneimide / peryleneimide polymer N-AT / PDI polymer.

[0010] Further, in step (1), the mass ratio of 3,5-diamino-1,2,4-triazole and 1,4,5,8-naphthalenetetracarboxylic anhydride is 0.05~0.10g:0.10~0.20g.

[0011] Furthermore, in step (1), the volume ratio of N,N-dimethylacetamide added sequentially is 10 mL: 25 mL; the sealed reaction conditions are 180 °C for 12 h.

[0012] Furthermore, in step (2), the mass ratio of the N-AT precursor to 3,4,9,10-perylenetetracarboxylic anhydride is 0.05~0.2g:0.1g; and the volume ratio of the N-methylpyrrolidone added sequentially is 15mL:20mL.

[0013] Furthermore, in step (2), the stirring time is 0.5~1.5h, and the stirring time continues for 0.5~1.5h.

[0014] Furthermore, in step (2), the sealing reaction conditions are 180°C for 24 hours.

[0015] The method for sacrificial-free photocatalytic preparation of hydrogen peroxide based on naphthalimide / peryleneimide polymer according to the present invention includes the following steps: continuously introducing O2 at a flow rate of 80 mL / min into the naphthalimide / peryleneimide polymer N-AT / PDI polymer dispersion while stirring, at a temperature of 25°C, and simultaneously using light with an intensity of 100 mW / cm². 2 Hydrogen peroxide is produced by reacting the visible light with the light for a period of time.

[0016] Furthermore, the visible light comes from a xenon lamp with an external 420 nm cutoff filter.

[0017] The application of the naphthaleneimide / peryleneimide polymer described in this invention in the photocatalytic preparation of hydrogen peroxide.

[0018] Beneficial Effects: This invention relates to a novel photocatalytic method for preparing hydrogen peroxide, which does not use organic solvents, making it green, environmentally friendly, and pollution-free. Using O2 as the oxygen source and visible light as the energy source, it features low energy consumption, high safety, simple operation, mild reaction conditions, and a high yield of hydrogen peroxide per unit time. The naphthalimide / peryleneimide polymer synthesized in this invention is a photocatalyst with a donor / acceptor electron transport interface. This structure greatly enhances the electron-hole transport rate, thereby promoting the production of hydrogen peroxide and inhibiting its decomposition.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] (1) The polymer photocatalyst provided by this invention has a donor / acceptor electron transport interface that can promote electron transport to improve the photocatalytic hydrogen peroxide production activity, thereby significantly increasing the hydrogen peroxide yield per unit time. This invention is the first to apply a naphthalimide / peryleneimide polymer catalyst to the field of photocatalytic hydrogen peroxide preparation.

[0021] (2) The method for producing hydrogen peroxide by photocatalysis without sacrificial agent based on naphthalimide / peryleneimide polymer 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.

[0022] (3) The method for producing hydrogen peroxide without sacrificial agent based on naphthalimide / peryleneimide polymer 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 in industry, the method of the present invention has lower energy consumption.

[0023] (3) Compared with the industrial anthraquinone method and the electro- and thermo-catalytic methods for preparing hydrogen peroxide, the present invention is safe, environmentally friendly, simple to operate, and low in cost. This method eliminates the problem of difficult separation of organic sacrificial agents and their oxidation products from the source. Therefore, the method of the present invention for preparing hydrogen peroxide has the advantages of high yield and efficient and stable catalytic performance, and has good application prospects. Attached Figure Description

[0024] Figure 1 The images show the XRD patterns of the samples prepared in this invention; they are PDI, N-AT, and N-AT / PDI, respectively.

[0025] Figure 2 These are TEM images of the samples prepared in this invention; a is PDI, with a size of 200 nm; b is N-AT, with a size of 100 nm; c is N-AT / PDI, with a size of 500 nm.

[0026] Figure 3 The graph shows the relationship between the concentration and time of the N-AT / PD sample prepared in this invention during photocatalytic preparation of hydrogen peroxide in 1 hour.

[0027] Figure 4 The graph shows the relationship between the concentration and time of the N-AT / PD sample prepared in this invention during photocatalytic preparation of hydrogen peroxide over 6 hours.

[0028] Figure 5 This is a graph showing the concentration of hydrogen peroxide produced by photocatalysis of the N-AT / PDI sample prepared in this invention at different pH values ​​over 1 hour. Detailed Implementation

[0029] The invention will be further explained below with reference to specific implementation examples.

[0030] The activity evaluation of the catalyst prepared in this invention for the photocatalytic production of hydrogen peroxide was performed as follows: 25 mg of the catalyst was ultrasonically dispersed in 25 mL of ultrapure water in a 50 mL borosilicate flask, and the flask was sealed with a reverse stopper. The mixture was magnetically stirred at 25 °C, with an O2 flow rate maintained at 80 mL / min, and irradiated using a xenon lamp (λ ≥ 420 nm). Every 20 min or 1 h, 3 mL of the reaction solution was collected, filtered through a 0.45 μm filter to remove the catalyst, and then 2 mL of potassium titanium oxalate solution (0.018 M) was added. The solution turned yellow, and the absorbance of this yellow solution was measured at 400 nm using a UV spectrophotometer to calculate the concentration of hydrogen peroxide.

[0031] Method for testing hydrogen peroxide concentration: The concentration of H2O2 produced by photocatalysis during the reaction process is determined: Prepare a 0.018M potassium titanium oxalate standard solution containing 5 vol% concentrated sulfuric acid and plot a standard curve. Take 3 mL and add it to the above 2 mL filtered reaction solution. Shake well and wait 10 min to allow the reaction solution to react completely with potassium titanium oxalate. Take an appropriate amount of solution and place it in a quartz cuvette. Use a UV-Vis spectrophotometer to detect the corresponding absorbance (Abs) at a wavelength of 400 nm. Calculate the H2O2 concentration by comparing it with the standard curve relationship y (mmol•L-1) = 1.83986*x (Abs).

[0032] Example 1

[0033] This invention discloses a sacrificial agent-free photocatalytic method for preparing hydrogen peroxide based on a naphthylimide / peryleneimide polymer, comprising the following steps: preparation of N-AT / PDI photocatalyst.

[0034] (1) Preparation of N-AT precursor: 0.0991 g of 3,5-diamino-1,2,4-triazole was dispersed in 10 mL of N,N-dimethylacetamide. After it was completely dissolved in an anaerobic ice bath, 0.134 g of 1,4,5,8-naphthalenetetracarboxylic anhydride was added and stirred. After forming a clear liquid, 25 mL of N,N-dimethylacetamide was added. The above mixed solution was placed in a stainless steel autoclave, sealed, and heated to 180 °C for 12 h. After the reaction was completed, it was cooled to room temperature and washed with N,N-dimethylformamide, methanol, and deionized water, respectively. Finally, it was freeze-dried to obtain the precursor N-AT.

[0035] (2) Preparation of N-AT / PDI polymer: 0.1 g of 3,4,9,10-perylenetetracarboxylic anhydride was dispersed in 15 mL of N-methylpyrrolidone and stirred at room temperature for 1 h; the precursor in step (1) was dispersed in 20 mL of N-methylpyrrolidone and stirred evenly before being added to the above solution and stirred for another 1 h. The above mixed solution was placed in a stainless steel autoclave, sealed, and heated to 180 °C for 24 h. After the reaction was completed, the mixture was cooled to room temperature, washed with N-methylpyrrolidone, ethanol, and hot water respectively, and dried at 60 °C to obtain N-AT / PDI polymer.

[0036] The prepared catalyst was subjected to X-ray diffraction (XRD) spectroscopy. Figure 1 As shown), transmission electron microscope (TEM) Figure 2 As shown in the TEM image, PDI appears as narrow nanosheets. Figure 2 a), the N-AT precursor exhibits a large, stacked lamellar structure ( Figure 2 (b) After polymerization, the PDI flakes are uniformly dispersed on the N-AT flakes.

[0037] Example 2

[0038] The present invention provides a method for the sacrificial-free photocatalytic preparation of hydrogen peroxide based on naphthalimide / peryleneimide polymer, comprising the following steps: (1) Preparation of N-AT precursor: Refer to step (1) in Example 1;

[0039] (2) Preparation of N-AT / PDI polymer: 0.1 g of 3,4,9,10-perylenetetracarboxylic anhydride was dispersed in 15 mL of N-methylpyrrolidone and stirred at room temperature for 1 h; 0.01 g, 0.03 g, 0.05 g, 0.07 g and 0.1 g of the precursor in step (1) were dispersed in 20 mL of N-methylpyrrolidone and stirred evenly before being added to the above solution. The mixture was stirred for another 1 h and then placed in a stainless steel autoclave. After sealing, the autoclave was heated to 180 °C for 24 h. After the reaction was completed, the autoclave was cooled to room temperature, washed with N-methylpyrrolidone, ethanol and hot water respectively, and then dried at 60 °C to obtain N-AT / PDI polymer.

[0040] The activity results show that adjusting the mass of N-AT added during the preparation process will affect the catalytic efficiency.

[0041] Experimental Example 1

[0042] The performance of the prepared photocatalyst in producing hydrogen peroxide

[0043] 25 mg of the N-AT / PDI polymer sample obtained in Example 1 was ultrasonically dispersed in 25 mL of ultrapure water and sealed with a reverse stopper. The mixture was magnetically stirred at 25 °C, with an O2 flow rate maintained at 80 mL / min, and irradiated with a xenon lamp (λ ≥ 420 nm) for 1 h. Every 20 min, 3 mL of the reaction solution was taken, filtered through a 0.45 μm filter to remove the catalyst, and then 2 mL of potassium titanium oxalate solution (0.018 M) was added. The solution turned yellow, and the absorbance of this yellow solution was measured at 400 nm using a UV spectrophotometer to calculate the hydrogen peroxide concentration. Figure 3 It can be seen that the concentration of hydrogen peroxide produced by the N-AT / PDI polymer after 1 hour is 8.72 mM / g.

[0044] 25 mg of the N-AT / PDI polymer sample obtained in Example 1 was ultrasonically dispersed in 25 mL of ultrapure water and sealed with a reverse stopper. The mixture was magnetically stirred at 25 °C, with an O2 flow rate maintained at 80 mL / min, and irradiated with a xenon lamp (λ ≥ 420 nm) for 6 h. Every 1 h, 3 mL of the reaction solution was taken, filtered through a 0.45 μm filter to remove the catalyst, and then 2 mL of potassium titanium oxalate solution (0.018 M) was added. The solution turned yellow, and the absorbance of this yellow solution was measured at 400 nm using a UV spectrophotometer to calculate the hydrogen peroxide concentration. Figure 4It can be seen that the concentration of hydrogen peroxide produced by the N-AT / PDI polymer after 1 hour is 8.72 mM / g. (From...) Figure 3 It can be seen that the concentration of hydrogen peroxide produced by the N-AT / PDI polymer after 6 hours is 12.8 mM / g.

[0045] 25 mg of the N-AT / PDI polymer sample obtained in Example 1 was ultrasonically dispersed in 25 mL of ultrapure water and sealed with a reverse stopper. The mixture was magnetically stirred at 25 °C, with an O2 flow rate maintained at 80 mL / min, and irradiated with a xenon lamp (λ ≥ 420 nm) for 1 h. Every 1 h, 3 mL of the reaction solution was taken, filtered through a 0.45 μm filter to remove the catalyst, and then 2 mL of potassium titanium oxalate solution (0.018 M) was added. The solution turned yellow, and the absorbance of this yellow solution was measured at 400 nm using a UV spectrophotometer to calculate the hydrogen peroxide concentration. Figure 5 It can be seen that when the pH is higher than that of the original solution environment, the reactivity gradually decreases, and decreases significantly when it is weakly alkaline; the concentration of hydrogen peroxide is the highest at pH 3, which is 10.92 mM / g.

[0046] 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 the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention. All technical solutions and improvements that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a naphthalimide / peryleneimide polymer, characterized in that... Includes the following steps: (1) Preparation of N-AT precursor: 3,5-diamino-1,2,4-triazole was dispersed in N,N-dimethylacetamide and dissolved completely in an anaerobic ice bath. Then, 1,4,5,8-naphthalenetetracarboxylic anhydride was added and stirred to form a clear liquid. N,N-dimethylacetamide was then added and the above mixed solution was placed in a stainless steel autoclave. After sealing, a certain temperature was set for reaction. After the reaction was completed, the mixture was cooled to room temperature and washed with N,N-dimethylformamide, methanol and deionized water respectively. Finally, the precursor N-AT was obtained by freeze drying. (2) Preparation of N-AT / PDI polymer: 3,4,9,10-perylenetetracarboxylic anhydride was dispersed in N-methylpyrrolidone and stirred at room temperature; the precursor in step (1) was dispersed in N-methylpyrrolidone and stirred evenly before being added to the above solution, and stirring was continued. The above mixed solution was placed in a stainless steel autoclave, sealed, and a certain temperature was set for reaction. After the reaction was completed, it was cooled to room temperature, washed with N-methylpyrrolidone, ethanol, and hot water respectively, and dried at 60°C to obtain the naphthaleneimide / peryleneimide polymer N-AT / PDI polymer.

2. The method for preparing the naphthalimide / peryleneimide polymer according to claim 1, characterized in that: In step (1), the mass ratio of 3,5-diamino-1,2,4-triazole and 1,4,5,8-naphthalenetetracarboxylic anhydride is 0.05~0.10g:0.10~0.20g.

3. The method for preparing the naphthalimide / peryleneimide polymer according to claim 2, characterized in that: In step (1), the volume ratio of N,N-dimethylacetamide added sequentially is 10 mL: 25 mL; the sealed reaction conditions are 180 °C for 12 h.

4. The method for preparing the naphthalimide / peryleneimide polymer according to claim 1, characterized in that: In step (2), the mass ratio of the N-AT precursor and 3,4,9,10-perylenetetracarboxylic anhydride is 0.05~0.2g:0.1g; the volume ratio of the N-methylpyrrolidone added sequentially is 15mL:20mL.

5. The method for preparing the naphthalimide / peryleneimide polymer according to claim 3, characterized in that: In step (2), the stirring time is 0.5~1.5h, and the stirring time continues for 0.5~1.5h.

6. The method for preparing the naphthalimide / peryleneimide polymer according to claim 5, characterized in that: In step (2), the sealing reaction conditions are 180°C for 24 hours.

7. A method for the photocatalytic preparation of hydrogen peroxide without sacrificial agents, characterized in that, The process includes the following steps: At a temperature of 25°C, continuously introducing O2 at a flow rate of 80 mL / min into the N-AT / PDI polymer dispersion of naphthalimide / peryleneimide polymer prepared by any one of claims 1-6 while stirring, and simultaneously using light with an intensity of 100 mW / cm². 2 Hydrogen peroxide is produced by reacting the visible light with the light for a period of time.

8. The method for preparing hydrogen peroxide by photocatalysis without sacrificial agents according to claim 7, characterized in that: The visible light is from a xenon lamp with an external 420 nm cutoff filter.

9. The application of the naphthaleneimide / peryleneimide polymer prepared by the method of claim 1 in the photocatalytic preparation of hydrogen peroxide.

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