Method for improving photocatalytic synthesis efficiency of hydrogen peroxide
By loading photocatalysts on PP cotton and setting height difference, the problem of low hydrogen peroxide concentration in traditional photocatalytic synthesis is solved, and efficient photocatalytic H2O2 synthesis is achieved, with good stability and reusability, and is suitable for water treatment, air purification and energy conversion.
Patent Information
- Application Number
- CN202510527561.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-25
- Publication Date
- 2025-07-18
AI Technical Summary
The concentration of traditional photocatalytic hydrogen peroxide is low and the reaction efficiency is not high, making it difficult to separate and recover the catalyst in practical applications.
PP cotton is used as a support to support the photocatalyst, and it is immersed in an aqueous isopropanol solution by a specific method, and the height difference is set to achieve the synthesis of photocatalytic hydrogen peroxide, with the catalyst loading amount of 5.0-6.0 mg/cm2.
It significantly improves the synthesis concentration of photocatalytic H2O2 per unit time, improves the stability and reusability of the catalyst, and is suitable for water treatment, air purification and energy conversion.
Smart Images
Figure CN120325322A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of photocatalysis, and particularly relates to a method for improving the efficiency of photocatalytic synthesis of hydrogen peroxide. Background Art
[0002] Photocatalytic synthesis of hydrogen peroxide (H2O2) has received extensive attention in recent years as a green and environmentally friendly chemical synthesis route. However, in the traditional beaker reaction system, not only is the generated concentration of photocatalytic synthesis of H2O2 usually low and the reaction efficiency is not high, but also the separation, recovery, and reuse of photocatalytic powders are difficult in practical applications. To increase the concentration of photocatalytic synthesis of H2O2, researchers have made a great deal of efforts, mainly focusing on the optimization and modification of catalysts. Although the photocatalytic activity of the catalysts has been enhanced, the improvement of the yield during the synthesis of H2O2 is still limited. In response to these challenges, recent research has begun to explore loading the catalyst onto a support material in order to solve the recyclability of the catalyst and increase the concentration of photocatalytic synthesis of H2O2. Researchers have proposed to improve the catalytic effect by immobilizing the photocatalyst on different types of support carriers (such as glass, ceramics, and fabrics, etc.). This immobilization method can not only improve the contact efficiency between the catalyst and the reactants and increase the contact area with oxygen, but also effectively improve the stability and recyclability of the catalyst, thus overcoming some defects in the traditional beaker system. Among these support materials, non-woven fabric has become an ideal photocatalyst carrier due to its non-toxicity, low cost, excellent mechanical properties, and easy recyclability. Summary of the Invention
[0003] The present invention addresses the problems existing in the above-mentioned prior art and provides a method for improving the efficiency of photocatalytic synthesis of hydrogen peroxide. The method of the present invention can significantly increase the synthesis concentration of photocatalytic H2O2 per unit time.
[0004] The method for improving the efficiency of photocatalytic synthesis of hydrogen peroxide according to the present invention uses PP cotton as a carrier and loads a photocatalyst. One end of the PP cotton loaded with the photocatalyst is immersed in an isopropanol aqueous solution, and the other end hangs down and a collection device is arranged below it. Xenon lamp irradiation (the irradiation wavelength is the full band) is maintained, thereby realizing the synthesis of photocatalytic hydrogen peroxide.
[0005] There is a height difference between the two ends of the PP cotton loaded with the photocatalyst, and the end immersed in the isopropanol aqueous solution is kept higher than the hanging end.
[0006] In the isopropanol aqueous solution, the volume ratio of deionized water to isopropanol is 9:1.
[0007] The loading of the photocatalyst with PP cotton as a carrier includes the following steps:
[0008] Add the photocatalyst and sodium alginate to deionized water, stir in a water bath at 30 - 40 °C for 1 - 3 hours, and finally perform ultrasonic treatment to obtain a catalyst mixture for later use. Cut the PP cotton into appropriate sizes and lay it flat. Drop the catalyst mixture onto the surface of the PP cotton in small amounts multiple times, and then dry it at 30 - 40 °C. Finally, soak the obtained material in a 2 - 4 mg / mL calcium chloride solution for 15 - 20 min, take it out and dry it at room temperature to obtain the PP cotton-supported photocatalyst, where the loading amount of the photocatalyst is 2.5 - 7.0 mg / cm 2 。
[0009] Furthermore, the mass ratio of the photocatalyst to sodium alginate is 7 - 18:1, and more preferably 15:1.
[0010] Furthermore, it is preferred that the loading amount of the photocatalyst in the PP cotton-supported photocatalyst is 5.0 - 6.0 mg / cm 2 。
[0011] Furthermore, the water bath condition is 30 °C, the stirring time is 2 h, and the concentration of the calcium chloride solution is 3 mg / mL.
[0012] The photocatalyst is prepared by a method including the following steps:
[0013] Photocatalyst one: Grind 1.5 g of melamine and 1 g of sodium tripolyphosphate in a mortar, transfer the mixture to a boat-shaped ceramic crucible, place it in a tube furnace, and calcine it at 500 - 550 °C for 2 h. Continuously introduce nitrogen during the calcination process. After the calcination is completed, grind the obtained solid product into powder, wash it with deionized water and ethanol, and dry it to obtain the photocatalyst Na-P-CN1.0(N2).
[0014] Photocatalyst two: Mix 5.0 g of melamine, 10 mmol of KCl, and 10 mmol of KI by grinding, then put them into a covered crucible and calcine at 550 °C at a heating rate of 2 °C / min for 4 hours. Thoroughly grind, wash, and filter the obtained product, and dry it at 60 °C. The product is denoted as CN-KCl / KI.
[0015] Photocatalyst three: Heat 5 g of melamine in an air atmosphere at a heating rate of 5 °C per minute to 550 °C and keep it for 4 hours. The obtained yellow product is labeled as PCN. Then grind and mix 500 mg of PCN with 0.9 g of LiCl and 1.1 g of KI in a mortar, and then calcine at 550 °C at a heating rate of 5 °C / min in an air atmosphere for 4 hours. After cooling to room temperature, wash the powder with boiling water multiple times, and then dry it under vacuum at 60 °C. The obtained product is denoted as O / K-CN.
[0016] The beneficial effects of the present invention are as follows:
[0017] Due to the three-dimensional network structure of the PP cotton, the reactants can quickly penetrate and contact the surface of the catalyst, and the catalytic products can also diffuse smoothly, avoiding the accumulation of products or concentration inhibition. Therefore, the method of the present invention has a good rate of photocatalytic synthesis of hydrogen peroxide. In addition, the method of the present invention is simple, has a wide range of raw material sources, is safe and environmentally friendly, and has low requirements for equipment.
[0018] In the reaction system of the present invention, the optimal catalyst loading is 5.56 mg / cm 2 , under this condition, the concentration of H2O2 synthesized by photocatalysis reaches 20.3 mmol / L within 1 h, and the H2O2 concentration within 2 h even reaches 25.2 mmol / L, and a balanced state is maintained for 3 h. Compared with the traditional beaker system, within the same reaction time, the concentration of H2O2 synthesized by photocatalysis is significantly increased, indicating that the catalyst loaded on the PP cotton effectively improves the reaction efficiency.
[0019] In addition, after four cyclic tests, the PP cotton system loaded with the catalyst shows excellent stability, and the concentration of H2O2 generated per unit time hardly decreases significantly. This result shows that the PP cotton as a photocatalyst carrier can not only improve the efficiency of the photocatalytic reaction, but also has the advantages of good reusability and long-term stability. This makes the photocatalytic system have higher practical value in practical applications, especially in fields that require efficient and sustainable catalysis, such as water treatment, air purification and energy conversion. Through these optimization measures, the performance of photocatalytic synthesis of H2O2 is significantly improved, and a certain foundation is laid for future further research and industrial application. Description of the Drawings
[0020] Figure 1 It is a photocatalytic H2O2 synthesis performance diagram of different catalyst concentrations in the beaker system.
[0021] Figure 2 It is a physical diagram and scanning electron microscope diagram of pure PP cotton (a) and PP cotton (b) after loading the catalyst.
[0022] Figure 3 It is the concentration of H2O2 synthesized in 1 h under light (left); the concentration of H2O2 synthesized in 2 h under light (right).
[0023] Figure 4 It is a cyclic test of photocatalytic synthesis of H2O2: 1 hour (a) and 2 hours (b).
[0024] Figure 5 It is the experimental result of the CN-KCl / KI system in the process of photocatalytic synthesis of H2O2.
[0025] Figure 6 Experimental results of the O / K-CN system in the photocatalytic synthesis of H2O2.
[0026] Figure 7 Comparison of the photocatalytic synthesis of H2O2 concentrations under different systems.
[0027] Figure 8 Schematic diagram of a simple device for the photocatalytic synthesis of hydrogen peroxide in the PP cotton / photocatalyst system.
[0028] Figure 9 Volume of H2O2 dropped during each cycle test within 2 h (a); corresponding production rate (b).
[0029] Figure 10 Performance comparison of CN-KCl / KI, O / K-CN and Na-P-CN1.0 (N2) systems in the photocatalytic synthesis of H2O2. Specific implementation mode
[0030] In order to make the technical objectives, technical solutions and beneficial effects of the present invention clearer, the following further describes the technical solutions of the present invention in combination with specific embodiments, but the protection scope of the present invention is not limited thereto.
[0031] Put 1.5 g of melamine and 1.0 g of sodium tripolyphosphate into a mortar and grind for 20 minutes. After mixing evenly, transfer to a boat-shaped ceramic crucible and place it in a tubular furnace. Under a N2 atmosphere, heat it to 520 °C at a heating rate of 5 °C / min and keep it for 2 h; after the reaction is completed, transfer the calcined material to a mortar and grind it into powder, transfer it to a 250 mL beaker, add 100 mL of water and stir for 5 h. After completion, centrifuge, take the precipitate, wash it repeatedly with water, and finally place the solid precipitate in an oven at 60 °C and dry it for 24 h. The required catalyst is obtained. Take 50 mg of the catalyst, 5 mL of isopropanol and 45 mL of water, stir at 25 °C for 20 min, and irradiate with light. The catalyst is loaded onto the PP cotton and irradiated with light.
[0032] Broad-spectrum test
[0033] Example 1:
[0034] Mix 5.0 g of melamine, 10 mmol of KCl and 10 mmol of KI, grind them and put them into a covered crucible, and calcine at 550 °C at a heating rate of 2 °C / min for 4 hours. Thoroughly grind, wash, filter the obtained product, and dry it at 60 °C. The product is designated as CN-KCl / KI.
[0035] Example 2:
[0036] 5 g of melamine was heated to 550° C. in air at a heating rate of 5° C. per minute for 4 hours. The resulting yellow product was labeled PCN.
[0037] 500 mg PCN was ground and mixed with 0.9 g LiCl and 1.1 g KCl in a mortar and then calcined at 550 °C for 4 h at a heating rate of 5 °C / min in an air atmosphere. After cooling to room temperature, the powder was washed with boiling water several times and then dried at 60 °C under vacuum. The obtained product was recorded as O / K-CN.
[0038] Figure 1 The photocatalytic H2O2 synthesis performance diagram of different catalyst concentrations in the beaker system. Figure 1 The effect of different catalyst concentrations on the H2O2 synthesis performance in the beaker system is shown. As can be seen from the figure, with the increase of catalyst concentration, the concentration of H2O2 generated per unit time increases significantly. However, when the catalyst concentration reaches a certain critical value, the H2O2 concentration no longer increases further. This may be due to the fact that the catalyst concentration has reached saturation in the beaker system, and the reaction rate is no longer limited by the catalyst concentration. Further increasing the catalyst has limited effect on improving the reaction efficiency.
[0039] Figure 2 The actual picture and scanning electron microscope picture of pure PP cotton (a) and PP cotton loaded with catalyst (b). Figure 2 The actual pictures and scanning electron microscope (SEM) pictures of pure PP cotton and its catalyst loading are displayed, which intuitively presents the changes in the structure before and after the catalyst loading. From the SEM picture of pure PP cotton, it can be seen that its structure presents a complex long and flat strip shape and forms an intricate three-dimensional network. Such a structure not only provides a large specific surface area, but also provides a stable support for the loading of the catalyst, so that the catalyst can be evenly distributed on the surface of the PP cotton and give full play to its effectiveness. In the SEM picture of the PP cotton loaded with catalyst, the catalyst particles are tightly attached to the fiber surface and form a stable binding structure. This uniform and firm loading form makes full use of the supporting role of PP cotton and effectively avoids the phenomenon of agglomeration of catalyst particles during the reaction, thereby ensuring the full exposure of the active sites of the catalyst. This is crucial to improving the efficiency of the catalytic reaction, because the exposed active sites can better contact with the reactants and promote the photocatalytic reaction.
[0040] Figure 3 The concentration of H2O2 synthesized under light for 1 h (left); the concentration of H2O2 synthesized under light for 2 h (right). The results show that as the catalyst loading increases from 2.59 mg / cm 2 Increased to 5.56 mg / cm 2 (PP cotton area is 27cm2 ), the generated concentration of H2O2 gradually increases, and the catalytic performance is the best under the loading of 5.56 mg / cm 2 .
[0041] Figure 4 are the cyclic tests for photocatalytic synthesis of H2O2: 1 hour (a) and 2 hours (b). Figure 4 shows the results of the cyclic test under the optimal loading (150 mg). The experiment shows that after four cycles, the concentration of photocatalytically synthesized H2O2 per unit time does not decrease significantly, indicating that the system has good stability and reusability. Compared with the traditional beaker system, this method significantly increases the concentration synthesized per unit time and has advantages in experimental operation. In addition, since the traditional system requires complex filtration and centrifugation steps to separate the catalyst, it is easy to cause catalyst loss or performance degradation. However, the catalyst loaded on the PP cotton can be firmly attached to the fiber surface, avoiding the separation operation, reducing catalyst loss, and improving the cyclic stability of the system.
[0042] Figure 5 are the experimental results of the CN-KCl / KI system in the process of photocatalytic synthesis of H2O2.
[0043] Figure 5 (a) shows the effect of different catalyst concentrations on the H2O2 generation efficiency in the beaker system. With the increase of the catalyst concentration, the concentration of H2O2 per unit time increases significantly. However, when the concentration reaches a certain critical value, the generated concentration tends to saturate, and further increasing the catalyst concentration does not bring a significant increase, which is consistent with most photocatalytic systems. Figure 6 (b), (c), and (d) show the results of immobilizing the catalyst on the PP cotton by the calcium alginate loading method and evaluate the H2O2 generation performance of the immobilized catalyst system. The experiment shows that in the PP cotton system, the H2O2 generation efficiency is significantly improved: reaching 13.1 mM within 1 hour, 16.3 mM within 2 hours, and 17.1 mM within 3 hours. Compared with the traditional beaker system, the yield of H2O2 per unit time in the PP cotton system is significantly increased, which may be attributed to the efficient mass transfer environment provided by the PP cotton, the stable dispersion of the catalyst, and the optimization of the reaction interface, thus improving the photocatalytic efficiency.
[0044] Figure 6 are the H2O2 synthesis performance diagrams of different catalyst concentrations in the beaker system; the 1-hour, 2-hour, and 3-hour cyclic test results of the photocatalytic synthesis of H2O2 concentration in the PP cotton system. Figure 6 shows the experimental research results of the O / K-CN system in the process of photocatalytic synthesis of H2O2. Among them, Figure 6(a) shows the effect of different catalyst concentrations on the generation efficiency of H2O2 in a traditional beaker reaction system. The experimental results indicate that the change in catalyst concentration significantly affects the yield of H2O2, suggesting that the optimized design of the catalyst is crucial for enhancing photocatalytic performance. At the same time, Figure 6 (b)-(d) show that the generation efficiency of H2O2 is further improved in the polypropylene (PP) cotton-supported catalyst system compared to the traditional system, indicating that the immobilized catalyst strategy can effectively enhance the performance and stability of the photocatalytic reaction.
[0045] Figure 7 It is a comparison of the photocatalytic synthesis of H2O2 concentrations under different systems. Figure 7 The differences in the photocatalytic synthesis of H2O2 by the catalyst in the traditional beaker system and the PP cotton-supported system were compared, and both were tested under their respective optimal conditions. The results show that in the beaker system, the generation rate of H2O2 is relatively slow, while the PP cotton-supported catalyst system shows significant advantages. The PP cotton support not only optimizes the distribution of the catalyst, improves the light transmittance, but also enhances the contact efficiency between the reactants and the catalyst, thus greatly improving the photocatalytic performance. The experimental data show that within the same time, the H2O2 concentration in the PP cotton-supported catalyst system is about five times that of the beaker system. This result indicates that the PP cotton support strategy can effectively improve the utilization rate and photocatalytic efficiency of the catalyst, providing a simple and efficient method for the photocatalytic synthesis of H2O2.
[0046] Figure 8 It is a simple device diagram for the photocatalytic synthesis of hydrogen peroxide by the PP cotton photocatalyst system. As Figure 8 shown, the pretreated PP cotton is placed at the designated position of the experimental device. The beaker on the left lifting platform contains an isopropyl alcohol aqueous solution, and the empty beaker on the right is used to collect the H2O2 solution dripping from the PP cotton. During the experiment, one end of the PP cotton is immersed in the isopropyl alcohol solution, and the other end hangs above the empty beaker. By adjusting the height of the lifting platform to change the height difference between the two ends of the PP cotton, the volume of the liquid dripping from the PP cotton per unit time is measured.
[0047] Figure 9 It is the volume of H2O2 dripping during each cycle test within 2 h (a); the corresponding generation rate (b). Figure 9 (a) records the volume of the H2O2 solution dripping from the PP cotton within 2 hours during the cycle test to evaluate the influence of the dripping process on the photocatalytic reaction and ensure the controllability of the test conditions. By maintaining the consistency of the dripping volume per unit time, the interference of the dripping process on the generated concentration of H2O2 is effectively avoided, thus improving the reliability and comparability of the experiment. Figure 9(b) Further shows the distribution of the average dripping volume per minute in each cycle test. The results show that the dripping rate remains stable in each cycle, indicating that the PP cotton loading system has good liquid regulation ability during the reaction process, reducing the influence of the randomness of the dripping process on the experimental results.
[0048] In summary, by controlling the dripping volume and rate, the reaction conditions are optimized, ensuring the comparability of the experiments on photocatalytic synthesis of H2O2 and providing a solid foundation for the evaluation of catalyst performance.
[0049] Figure 10 For the performance comparison of the CN-KCl / KI, O / K-CN, and Na-P-CN1.0(N2) systems in photocatalytic synthesis of H2O2. It can be seen from the figure that after 3 hours of light irradiation, the photocatalytic synthesis efficiency of hydrogen peroxide in all three systems has increased, and the hydrogen peroxide concentration of the photocatalytic system mainly discussed in the present invention exceeds 25 mmol / L after 3 hours, which is significantly better than the other two systems.
[0050] The above are only the preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be regarded as limitations on the present invention, and the protection scope of the present invention should be subject to the scope defined by the claims. For those of ordinary skill in the art, without departing from the spirit and scope of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as within the protection scope of the present invention.
Claims
1. A method for improving the efficiency of photocatalytic synthesis of hydrogen peroxide, characterized in that: Using PP cotton as a carrier and loading a photocatalyst, dipping one end of the PP cotton loaded with the photocatalyst into an isopropyl alcohol aqueous solution, with the other end hanging down and a collection device being provided below it, and maintaining the irradiation of a xenon lamp, thereby realizing the synthesis of photocatalytic hydrogen peroxide; There is a height difference between the two ends of the PP cotton loaded with the photocatalyst, and the end dipped into the isopropyl alcohol aqueous solution is kept higher than the hanging end.
2. The method according to claim 1, characterized in that: In the isopropyl alcohol aqueous solution, the volume ratio of deionized water to isopropyl alcohol is 9:
1.
3. The method according to claim 1, wherein The loading of the photocatalyst with PP cotton as the carrier includes the following steps: Adding the photocatalyst and sodium alginate into deionized water, stirring in a water bath at 30 - 40 °C for 1 - 3 hours, and finally performing ultrasonic treatment to obtain a catalyst mixture for standby; cutting the PP cotton into appropriate sizes, laying it flat, dripping the catalyst mixture onto the surface of the PP cotton in small amounts and multiple times, and then drying it at 30 - 40 °C; finally, soaking the obtained material in a 2 - 4 mg / mL calcium chloride solution for 15 - 20 min, taking it out and drying it at room temperature to obtain the PP cotton loaded with the photocatalyst.
4. The method according to claim 3, characterized in that: The loading amount of the photocatalyst in the PP cotton supported photocatalyst is 2.5 - 7.0 mg / cm 2 .
5. The method according to claim 4, characterized in that: The loading amount of the photocatalyst in the PP cotton supported photocatalyst is 5.0 - 6.0 mg / cm 2 .
6. The method according to claim 3, characterized in that: The mass ratio of the photocatalyst to sodium alginate is 7 - 18:
1.
7. The method according to claim 6, characterized in that: The mass ratio of the photocatalyst to sodium alginate is 15:
1.
8. The method according to claim 3, wherein The photocatalyst is prepared by a method including the following steps: Grinding 1.5 g of melamine and 1 g of sodium tripolyphosphate in a mortar, transferring the mixture evenly to a boat-shaped ceramic crucible, putting it into a tubular furnace, and calcining it at 500 - 550 °C for 2 h; continuously introducing nitrogen during the calcination process, and after the calcination is completed, grinding the obtained solid product into powder, washing it with deionized water and ethanol, and drying it to obtain the photocatalyst Na - P - CN1.0(N2).
9. The method according to claim 3, characterized in that The photocatalyst is prepared by a method including the following steps: Mixing 5.0 g of melamine, 10 mmol of KCl, and 10 mmol of KI by grinding, putting them into a covered crucible, and calcining them at 550 °C for 4 hours, grinding, washing, filtering, and drying the obtained product, and recording the obtained product as the photocatalyst CN - KCl / KI.
10. The method according to claim 3, characterized in that The photocatalyst is prepared by a method including the following steps: Heating 5 g of melamine in an air atmosphere to 550 °C and maintaining it for 4 hours, and recording the obtained yellow product as PCN; then grinding and mixing 500 mg of PCN with 0.9 g of LiCl and 1.1 g of KI in a mortar, and then calcining it in an air atmosphere at a heating rate of 5 °C / min at 550 °C for 4 hours, cooling to room temperature, washing the powder with boiling water, and then drying it under vacuum conditions, and recording the obtained product as the photocatalyst O / K - CN.