Preparation of size-controllable resin ball for porous carbon-based catalyst template
The nanoscale resin sphere with controllable size is prepared by the ionic micelle assisted method. As a hard template, the problems of complex catalyst preparation process and large particle size in the prior art are solved, and efficient and economical porous carbon-based catalyst preparation is achieved, which improves the performance and application range of the catalyst.
Patent Information
- Application Number
- CN202311562369.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-22
- Publication Date
- 2025-05-23
AI Technical Summary
In the prior art, when silica nanoparticles and polystyrene spheres are used as hard templates to prepare porous carbon-based catalysts, there are problems such as complex preparation process, large particle size and difficult to disperse, which limits the performance and application range of the catalyst.
The ionic micelle assisted method is used to regulate the polymerization of melamine formaldehyde resin to prepare nanoscale resin balls with controllable sizes as hard templates for the preparation of porous carbon-based catalysts. The method includes reacting melamine and formaldehyde in an alkali solution, adding polystyrene-b-polyacrylic micelle solution, followed by hydrothermal reaction and drying to obtain a resin ball template.
The preparation of nanoscale controllable melamine formaldehyde resin spheres is realized. As an ideal template, the preparation process of the catalyst is simplified, the cost is reduced, and the electrochemical oxygen reduction catalytic performance of the catalyst is improved. It is suitable for zinc air batteries and fuel cells and other fields.
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Figure CN120025508A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the preparation of size-controllable resin balls for porous carbon-based catalyst templates, and belongs to the field of polymer synthesis and electrocatalysis. Background Art
[0002] Energy transformation is an important strategy for the country's social and economic development. In recent years, the energy crisis has become increasingly serious, and research on sustainable green energy storage and conversion devices has made important progress. Electrocatalytic oxygen reduction reaction, oxygen evolution reaction, hydrogen evolution reaction, etc. are key reactions in various energy storage and conversion devices. The development of efficient electrocatalysts is of great significance.
[0003] Carbon-based materials are ideal photoelectrocatalytic materials due to their large specific surface area, good stability, and high structural designability. Non-metal-doped carbon-based catalysts and transition metal-nitrogen-carbon catalysts are new-generation catalytic materials. Increasing the dispersion of active sites and improving the intrinsic activity of active sites are the main strategies for catalyst development. High specific surface area and interconnected multi-level pore structure provide favorable conditions for electrolyte penetration and oxygen transport in electrocatalytic reactions, which can ensure that the active sites play their role to the greatest extent. At present, the hard template method is an important method for constructing porous carbon-based catalysts. Silica nanoparticles and polystyrene spheres are the most commonly used hard templates. As hard templates, silica nanoparticles need to be etched with corrosive acids and alkalis, and the preparation process is complicated; although polystyrene spheres can be easily removed by high-temperature pyrolysis, the particle size is generally large, and they are not polar, making it difficult to stably disperse in the precursor. Therefore, small-sized polymer hard templates are ideal for preparing carbon-based catalysts. Melamine formaldehyde resin has poor thermal stability and is a potentially ideal hard template for preparing porous materials, but its size is often large. For example, Greulich-Weber used formic acid as a catalyst to synthesize 1.6μm melamine formaldehyde resin spheres of uniform size. JungHyun Kim studied the effects of surfactants and pH on the reaction and successfully prepared 0.7-4μm resin microspheres. The larger size limits the use of melamine formaldehyde resin as a template to prepare porous carbon-based catalysts. Summary of the invention
[0004] In order to solve the above technical problems, the present invention proposes an ionic micelle-assisted method, which can prepare nano-scale size-controllable melamine formaldehyde resin, prepare size-controllable and uniformly distributed resin balls, and the minimum particle size of melamine formaldehyde resin balls that can be prepared is 15nm. The specific operation steps are as follows:
[0005] (1) Melamine and formaldehyde aqueous solution are added to a 0.1-1 M alkaline solution, and the mixture is reacted under heating conditions for 0.5-2 h. Then, a polystyrene-b-polyacrylic acid (PS-b-PAA) micelle solution is added and reacted for 4-48 h to obtain a solution having an opalescent luster.
[0006] (2) The solution obtained in step (1) is transferred to a tetrafluoroethylene reactor and subjected to a hydrothermal reaction in a forced air oven for 8 to 48 hours. The product is then filtered, washed alternately with ethanol and distilled water, and dried to obtain a resin ball solid powder.
[0007] The alkaline solution in the above step (1) is one of sodium hydroxide, calcium hydroxide, sodium carbonate, sodium bicarbonate or potassium hydroxide.
[0008] The concentration of the formaldehyde aqueous solution in the above step (1) is 37%, and the molar ratio of melamine to formaldehyde is 1:1 to 1:12, preferably 1:3, 1:6, or 1:9.
[0009] In the above step (1), the mixing ratio of polystyrene-b-polyacrylic acid: melamine formaldehyde resin is 1:1 to 1:50 by mass, preferably 1:2 to 1:40, and the preferred ratios are 1:4, 1:5, 1:8, 1:25, and 1:40.
[0010] The heating temperature condition in the above step (1) is 30-90°C.
[0011] The polystyrene-b-polyacrylic acid (PS-b-PAA) described in step (1) is specifically PS x -b-PAA y , micelle component x=60-200, y=8-30, preferably x=80-155, y=10-20, and preferred (x, y) are (150, 10), (150, 20), (100, 10), (90, 8), (90, 15) or (90, 20).
[0012] The hydrothermal reaction temperature in the blast oven described in the above step (2) is 90-180°C.
[0013] A porous carbon-based catalyst is prepared by using the resin spheres as a hard template.
[0014] A method for preparing a porous carbon-based catalyst using size-controlled melamine formaldehyde resin balls, the specific steps are as follows:
[0015] a) Take the solid powder of resin balls and disperse it in distilled water by ultrasonic. Then add sugars to it and hydrothermally react it in an oven at 140-200°C for 2-12 hours. After the reaction is completed, wash the sample with distilled water and dry it.
[0016] b) The sample obtained in step a) is heated to a high temperature for pyrolysis for 2 hours under an inert gas atmosphere to finally obtain a porous carbon-based catalyst.
[0017] The mass ratio of the resin ball solid powder to the polysaccharide substance in the above step a) is 1:1-1:8, preferably 1:1.5-1:4, such as 1:2, 1:3.
[0018] The sugar substance described in step a) above is one or a combination of sucrose, lactose, maltose, fructose and glucose.
[0019] The inert gas atmosphere described in step b) is N 2 Or one of Ar.
[0020] The heating rate in step b) is 2-5°C min -1 , the temperature rise range is 700~1000℃.
[0021] A zinc-air battery or fuel cell is prepared using a porous carbon-based catalyst prepared from melamine-formaldehyde resin balls with controllable sizes.
[0022] Compared with the prior art, the present invention has the following beneficial effects:
[0023] 1. The present invention proposes a method for regulating the polymerization of melamine formaldehyde resin by regulating the block copolymer polystyrene-b-polyacrylic acid, and applying resin balls to prepare hard templates for carbon-based catalysts. Compared with silica nanoparticles and polystyrene ball templates, the raw materials are easily available and the preparation process is simple, which effectively reduces the cost of catalyst preparation.
[0024] 2. The present invention uses a micelle-assisted method to synthesize nano-scale melamine formaldehyde resin balls, the particle size of which can be as small as 15 nm, and is an ideal template for preparing carbon-based catalysts.
[0025] 3. The size of the melamine formaldehyde resin balls prepared by the present invention is controllable, and the particle size of the carbon-based catalyst can be controlled by adjusting the size of the resin balls, thereby achieving the effect of controlling the catalytic activity. In addition, because the particle size is controllable, the application scope is not limited to the preparation of catalysts.
[0026] 4. The melamine formaldehyde resin ball template prepared by the present invention contains a large amount of nitrogen element, and can prepare a carbon material with high nitrogen content and uniform distribution after pyrolysis. This series of nitrogen-rich carbon-based catalysts has excellent electrocatalytic performance.
[0027] 5. The carbon-based catalyst material prepared by the melamine formaldehyde resin ball template of the present invention has good electrochemical oxygen reduction catalytic performance and can be applied to zinc-air batteries, fuel cells and other fields. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 The transmission electron microscope image (a) and particle size distribution diagram (b) of the resin ball template of Example 1;
[0029] Figure 2 The transmission electron microscope image (a) and particle size distribution diagram (b) of the resin ball template of Example 2;
[0030] Figure 3 The transmission electron microscope image (a) and particle size distribution diagram (b) of the resin ball template of Example 3;
[0031] Figure 4 The transmission electron microscope image (a) and particle size distribution diagram (b) of the resin ball template of Example 4;
[0032] Figure 5 TEM morphology of carbon-based catalysts prepared using templates with different particle sizes (a) Example 5, (b) Example 6, (c) Example 7, (d) Example 8;
[0033] Figure 6 The adsorption-desorption curve (a) and pore size distribution curve (b) of the carbon-based catalyst of Example 6;
[0034] Figure 7 The oxygen reduction performance curves of Example 6 and Example 7 under alkaline conditions. DETAILED DESCRIPTION
[0035] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail by way of embodiments below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.
[0036] Embodiment 1:
[0037] (1) Add 50 mL of 0.2 M NaOH solution to a three-necked flask, then add 2 g of melamine and 14.4 mL of 37% formaldehyde solution, heat at 70 °C, and then add 200 mL of 2 mg / mL -1 PS 90 -b-PAA 20 The micellar solution was heated and reacted for 24 h.
[0038] (2) The solution was then transferred to a tetrafluoroethylene reactor, and the reactor was placed in a 110° C. forced air oven for reaction for 24 h, and then filtered and dried to obtain resin nanospheres.
[0039] See also Figure 1 , are the transmission electron microscopy image (a) and particle size distribution diagram (b) of the resin ball template prepared in step (2). It can be seen from the transmission electron microscopy image (a) that the particle size distribution of the synthesized beads is uniform, and from the particle size distribution trend (b), the average particle size of the obtained beads is 15nm, which has an ultra-small particle size.
[0040] Embodiment 2:
[0041] (1) Add 30 mL of 0.1 M NaOH solution to a three-necked flask, then sequentially add 1 g of melamine and 0.9 mL of 37% aqueous formaldehyde solution, heat at 60 °C, and then add 80 mL of a PS -1 -b-PAA 90 micelle solution with a concentration of 0.5 mg·mL 15 and continue heating and reacting for 24 h.
[0042] (2) Then transfer the solution to a polytetrafluoroethylene reaction kettle, place the reaction kettle in a forced-air oven at 120 °C and react for 24 h, filter with suction and dry to obtain resin nanospheres.
[0043] Refer to Figure 2 for the transmission electron micrograph (a) and particle size distribution curve (b) of the resin sphere template prepared in step (2). It can be seen from the transmission electron micrograph (a) that the synthesized small spheres have a uniform particle size distribution, and from the particle size distribution trend (b), the average particle size of the obtained small spheres is 47 nm.
[0044] Example 3:
[0045] (1) Add 30 mL of 0.1 M KOH solution to a three-necked flask, then sequentially add 2 g of melamine and 7.2 mL of 37% aqueous formaldehyde solution, heat at 80 °C, and then add 50 mL of a PS -1 -b-PAA 100 micelle solution with a concentration of 5 mg·mL 10 and continue heating and reacting for 24 h.
[0046] (2) Then transfer the solution to a polytetrafluoroethylene reaction kettle, place the reaction kettle in a forced-air oven at 150 °C and react for 24 h, filter with suction and dry to obtain resin nanospheres.
[0047] Refer to Figure 3 for the transmission electron micrograph (a) and particle size distribution curve (b) of the resin sphere template prepared in step (2). It can be seen from the transmission electron micrograph (a) that the synthesized small spheres have a uniform particle size distribution, and from the particle size distribution trend (b), the average particle size of the obtained small spheres is 80 nm.
[0048] Example 4:
[0049] (1) Add 30 mL of 0.2 M NaOH solution to a three-necked flask, then sequentially add 2 g of melamine and 3.6 mL of 37% aqueous formaldehyde solution, heat at 70 °C, and then add 50 mL of a PS -1 -b-PAA 150 micelle solution with a concentration of 1 mg·mL 10 and continue heating and reacting for 24 h.
[0050] (2) The solution was then transferred to a tetrafluoroethylene reactor, and the reactor was placed in a 150° C. forced air oven for reaction for 24 h, and then filtered and dried to obtain resin nanospheres.
[0051] See also Figure 4 , are the transmission electron microscopy image (a) and particle size distribution curve (b) of the resin ball template prepared in step (2). It can be seen from the transmission electron microscopy image (a) that the particle size distribution of the synthesized beads is relatively uniform, and from the particle size distribution trend (b), the average particle size of the obtained beads is 130nm.
[0052] Embodiment 5:
[0053] (1) Take 0.5 g of the synthesized resin sphere template in Example 1 and disperse it in 50 mL of distilled water by ultrasonic dispersion to obtain a milky white solution, which is evenly dispersed. Add 1.5 g of sucrose dissolved in 15 mL of deionized water, stir for 2 h, and then hydrothermally react in an oven at 140° C. for 12 h. After the reaction is completed, wash the sample with water three times and dry it in a vacuum drying oven.
[0054] (2) Finally, in N 2 At 2℃·min -1 The carbonized catalyst was pyrolyzed at 800 °C for 2 h to obtain a carbon-based catalyst.
[0055] See also Figure 5 (a) is the TEM morphology of the carbon-based catalyst prepared by resin ball template. It can be seen from the transmission electron microscopy image that the material has an obvious mesoporous structure.
[0056] Embodiment 6:
[0057] (1) Take 1 g of the synthesized resin sphere template in Example 2 and disperse it in 100 mL of distilled water by ultrasonic dispersion to obtain a milky white solution, which is evenly dispersed. Add 4 g of fructose dissolved in 15 mL of deionized water, stir for 2 h, and then hydrothermally react in an oven at 180° C. for 4 h. After the reaction is completed, wash the sample with water three times and dry it in a vacuum drying oven.
[0058] (2) Finally, in N 2 At 5℃·min -1 The carbonized catalyst was pyrolyzed at 900 °C for 2 h to obtain a carbon-based catalyst.
[0059] See also Figure 5 (b) is the TEM morphology of the carbon-based catalyst prepared by the resin ball template. It can be seen from the transmission electron microscopy image that the carbon material after pyrolysis has a uniform pore structure.
[0060] Depend on Figure 6From the adsorption-desorption curve (a), we can see an obvious hysteresis loop, indicating that the material has a mesoporous structure. From the pore size distribution curve (b), we can see that there is a wide peak near 30nm, indicating that the pore size is about 30nm.
[0061] Embodiment 7:
[0062] (1) Take 1 g of the synthesized resin sphere template in Example 3 and disperse it in 100 mL of distilled water by ultrasonic dispersion to obtain a milky white solution, which is evenly dispersed. Add 2 g of fructose dissolved in 15 mL of deionized water, stir for 2 h, and then hydrothermally react in an oven at 160° C. for 8 h. After the reaction is completed, wash the sample with water three times and dry it in a vacuum drying oven.
[0063] (2) Finally, in N 2 At 2℃·min -1 The carbonized catalyst was pyrolyzed at 900 °C for 2 h to obtain a carbon-based catalyst.
[0064] See also Figure 5 (c) is the TEM morphology of the carbon-based catalyst prepared by the resin ball template. It can be seen from the transmission electron microscopy image that the material has a relatively uniform porous structure and a large pore size.
[0065] Embodiment 8:
[0066] (1) Take 1 g of the synthesized resin sphere template in Example 4 and disperse it in 100 mL of distilled water by ultrasonic dispersion to obtain a milky white solution, which is uniformly dispersed. Add 1.5 g of sucrose dissolved in 15 mL of deionized water, stir for 2 h, and then hydrothermally react in an oven at 140° C. for 12 h. After the reaction is completed, wash the sample with water three times and dry it in a vacuum drying oven.
[0067] (2) Finally, in N 2 At 3℃·min -1 The carbonized catalyst was pyrolyzed at 1000 °C for 2 h to obtain a carbon-based catalyst.
[0068] See also Figure 5 (d) is the TEM morphology of the carbon-based catalyst prepared by the resin ball template. It can be seen from the transmission electron microscopy image that the material has a porous structure with a large pore size.
[0069] Embodiment 9:
[0070] The oxygen reduction performance of the carbon-based catalyst materials prepared in Example 6 and Example 7 was tested under alkaline conditions. In 0.1M KOH solution, a three-electrode system was used to test the linear voltammetric curve, where the working electrode, counter electrode, and reference electrode were glassy carbon electrode, Ag / AgCl, and platinum sheet, respectively, and the oxygen reduction catalytic performance was evaluated by calculating its half-wave potential.
[0071] See also Figure 7 It can be seen that the carbon-based catalyst material prepared in Example 6 has a higher half-wave potential than that in Example 7. This is because the particle size of the resin ball template in Example 2 is smaller, and the mesopore size of the carbon-based catalyst material in Example 6 is also smaller. This shows that the carbon-based catalyst prepared using the small-size resin ball template of the present invention has good oxygen reduction performance, and also illustrates the advantage of controllable catalyst template size.
[0072] The above-described embodiments only represent the embodiments of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. The present invention can also be implemented in other specific ways or other specific forms without departing from the gist or essential features of the present invention. Therefore, the described embodiments should be regarded as illustrative rather than restrictive in any respect. The scope of the present invention should be described by the attached claims, and any changes equivalent to the intention and scope of the claims should also be included in the scope of the present invention.
Claims
1. A method for preparing size-controlled melamine formaldehyde resin balls, It is characterized in that The specific steps are as follows: (1) adding melamine and formaldehyde aqueous solution to an alkaline solution with a concentration of 0.1 to 1 M, reacting under heating conditions for 0.5 to 2 hours, and then adding polystyrene-b-polyacrylic acid (PS-b-PAA) micelle solution to react for 4 to 48 hours to obtain a solution with opalescence; (2) The solution obtained in step (1) is transferred to a tetrafluoroethylene reactor and subjected to a hydrothermal reaction in a forced air oven for 8 to 48 hours. The product is then filtered, washed alternately with ethanol and distilled water, and dried to obtain a resin ball solid powder.
2. A method for preparing size-controlled melamine formaldehyde resin balls according to claim 1, Features: The alkaline solution in step (1) is one of sodium hydroxide, calcium hydroxide, sodium carbonate, sodium bicarbonate or potassium hydroxide solution.
3. The method for preparing a size-controlled melamine formaldehyde resin ball according to claim 1, Features: The polystyrene-b-polyacrylic acid (PS-b-PAA) used in step (1) is specifically PS x -b-PAA y , micelle component x=60-200, y=8-30, preferably x=80-155, y=10-20, and preferred (x, y) are (150, 10), (150, 20), (100, 10), (90, 8), (90, 15) or (90, 20).
4. The method for preparing size-controlled melamine formaldehyde resin balls according to claim 1, Features: The concentration of the formaldehyde aqueous solution in step (1) is 37%, the molar ratio of melamine to formaldehyde is 1:1-1:12, preferably 1:3, 1:6, 1:9; the mass ratio of polystyrene-b-polyacrylic acid: melamine formaldehyde resin is 1:1-1:50, preferably 1:2-1:40, and the preferred ratio is 1:4, 1:5, 1:8, 1:25, 1:
40.
5. The method for preparing size-controlled melamine formaldehyde resin balls according to claim 1, Features: The heating temperature condition in step (1) is 30-90°C; the hydrothermal reaction temperature in the blast oven in step (2) is 90-180°C.
6. A porous carbon-based catalyst, It is characterized in that The method is prepared by using the resin spheres described in any one of claims 1 to 5 as hard templates.
7. A method for preparing a porous carbon-based catalyst using the resin ball according to any one of claims 1 to 5, It is characterized in that The porous carbon-based catalyst was prepared using size-controlled melamine formaldehyde resin spheres as hard templates. The specific steps are as follows: a) taking solid powder of melamine formaldehyde resin balls, dispersing it in distilled water by ultrasonic, then adding sugar substances thereto, and hydrothermally reacting it in an oven at 140-200° C. for 2-12 hours; after the reaction is completed, washing the sample with distilled water and drying it; b) The sample obtained in step a) is heated to a high temperature for pyrolysis for 2 hours under an inert gas atmosphere to finally obtain a porous carbon-based catalyst.
8. The method according to claim 7, Features: The mass ratio of the resin ball solid powder to the sugar substance in step a) is 1:1 to 1:8, preferably 1:1.5 to 1:4, such as 1:2 or 1:
3.
9. The method according to claim 7, Features: The sugar substance in step a) is one or a combination of sucrose, lactose, maltose, fructose and glucose.
10. The method according to claim 7, Features: The inert gas atmosphere in step b) is N 2 Or one of Ar.
11. The method according to claim 7, Features: The heating rate in step b) is 2-5°C·min -1 , the temperature rise range is 700~1000℃.
12. A zinc-air battery or fuel cell, prepared using the catalyst according to claim 6 or the catalyst prepared by the method according to claim 7.