A nitrogen-doped spherical activated carbon, its preparation method and application

Abstract

This application discloses a nitrogen-doped spherical activated carbon, its preparation method, and its application. The method involves mixing raw materials containing epoxy resin, a curing agent, and an organic solvent to obtain a mixture. This mixture is then dropped into a hot oil column, and after cross-linking, curing, sphericalization, and drying, thermosetting epoxy resin spheres are obtained. Further high-temperature carbonization yields the nitrogen-doped spherical activated carbon. The preparation method described in this application is simple and can be operated continuously. The obtained spherical activated carbon has a uniform size.

Description

Technical Field

[0001] This application relates to a nitrogen-doped spherical activated carbon, its preparation method, and its application, belonging to the field of activated carbon materials. Background Technology

[0002] Spherical activated carbon is a novel type of high-performance activated carbon with a smooth surface, possessing unique properties such as high purity, low ash content, high strength, high abrasion resistance, high flowability, and narrow particle size distribution. Therefore, it has broad application prospects in solvent recovery, gas purification, and water treatment. For example, spherical activated carbon has been adopted as an adsorption material in cleanroom filters in the semiconductor industry and in gas treatment for electronic devices. Furthermore, due to its good physiological solubility, spherical activated carbon also has important applications in medical and health fields such as blood purification.

[0003] Spherical activated carbon can be classified into three types according to raw materials: pitch-based spherical activated carbon, coal-based spherical activated carbon, and polymer-based spherical activated carbon. Among them, polymer resins have advantages such as controllable raw material structure and low impurity content. In particular, thermosetting resins such as epoxy resins can be directly carbonized, greatly simplifying the operation process and making them ideal raw materials for the preparation of spherical activated carbon.

[0004] Compared to carbon atoms, nitrogen atoms have a slightly smaller atomic radius and a greater electronegativity (N has an electronegativity of 3.04, while C has an electronegativity of 2.55). Incorporating nitrogen into the structure of carbon materials alters the atomic and electronic structure of the matrix, increases its conductivity, and forms a delocalized conjugated system of sp2 hybrid C. This, in turn, leads to changes in the material's reactivity, mechanical properties, and other macroscopic properties, resulting in significant alterations to its adsorption and catalytic performance.

[0005] Currently, the main method of nitrogen doping is post-doping, which involves infiltrating nitrogen atoms into carbon materials (graphene, carbon nanotubes, carbon black, etc.) through post-treatment processes such as oxidation, pyrolysis, and substitution. Because the graphite layer has already formed in these carbon materials, nitrogen atoms cannot penetrate, so NC catalysts prepared by this method generally have low nitrogen content and slightly insufficient catalytic activity. In particular, research on nitrogen doping of spherical activated carbon is relatively limited, and the preparation process of nitrogen-doped spherical activated carbon is quite complex. Summary of the Invention

[0006] According to one aspect of this application, a method for preparing nitrogen-doped spherical activated carbon is provided. The method involves mixing raw materials containing epoxy resin, a curing agent, and an organic solvent to obtain a mixture, dripping the mixture into a hot oil column, and then subjecting it to crosslinking, curing, spherical formation, and drying to obtain thermosetting epoxy resin spheres. Further high-temperature carbonization yields the nitrogen-doped spherical activated carbon, thus solving the problem of low nitrogen content and slightly insufficient catalytic activity in existing NC catalysts.

[0007] The technical solution adopted in this application is as follows:

[0008] A method for preparing nitrogen-doped spherical activated carbon includes the following steps:

[0009] S1. A mixture containing epoxy resin, curing agent and organic solvent is dropped into a hot oil column, and the mixture droplets are cured into balls in the hot oil column. After being removed and dried, thermosetting epoxy resin balls are obtained.

[0010] S2. The thermosetting epoxy resin balls obtained in step S1 are placed in an inactive gas atmosphere and carbonized to obtain the nitrogen-doped spherical activated carbon.

[0011] Optionally, the inactive gas is selected from at least one of nitrogen, argon, and helium.

[0012] Alternatively, the mixture droplets are cross-linked, cured, sphericalized, and dried in an oil column.

[0013] Optionally, in step S1, the epoxy resin is selected from at least one of glycidyl ether epoxy resin, glycidyl ester epoxy resin, glycidyl amine epoxy resin, linear aliphatic epoxy resin, and alicyclic epoxy resin.

[0014] Optionally, in step S1, the curing agent is selected from at least one of diethylenetriamine, triethylenetetramine, triethylamine, imidazole, polyetheramine, m-phenylenediamine, hexahydropyridine, and melamine.

[0015] Optionally, in step S1, the epoxy resin, curing agent, and organic solvent are in a weight ratio of 1:(0.1-1):(0.1-10).

[0016] Optionally, the weight ratio of the curing agent to the epoxy resin is selected from any value among 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, and 1:1, or any range between the two.

[0017] Optionally, the weight ratio of the epoxy resin to the organic solvent is selected from any value among 0.1:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, and 10:1, or any range between the two.

[0018] Optionally, in step S1, the organic solvent is selected from at least one of ethanol, acetone, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), tetrahydrofuran, and 1,4-dioxane.

[0019] Optionally, in step S1, the drying conditions include: a drying temperature of 90–180°C and a drying time of 1–24 hours.

[0020] Optionally, in step S2, the oil in the hot oil column is selected from at least one of kerosene, vegetable oil, white oil, transformer oil, and liquid paraffin.

[0021] The temperature of the hot oil column is 80–180°C.

[0022] Optionally, in step S2, the carbonization conditions include: a carbonization temperature of 600–1200°C and a carbonization time of 1–12 hours.

[0023] According to another aspect of this application, nitrogen-doped spherical activated carbon is prepared by the above-described preparation method, wherein the particle size of the nitrogen-doped spherical activated carbon is 0.4 to 1.5 mm.

[0024] Optionally, the nitrogen doping amount in the nitrogen-doped spherical activated carbon is 1 to 10 wt%.

[0025] Optionally, the amount of nitrogen doping in the nitrogen-doped spherical activated carbon is selected from any value among 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, and 10wt%, or any value between the two.

[0026] According to another aspect of this application, the above-mentioned nitrogen-doped spherical activated carbon is also provided for use in gas purification, water purification, blood purification, and catalyst support.

[0027] The beneficial effects that this application can produce include:

[0028] The method for preparing nitrogen-doped spherical activated carbon provided in this application is simple, can be operated continuously, and produces spherical activated carbon with uniform size. It can directly prepare nitrogen-doped spherical activated carbon without the need for an external nitrogen source, and has a high nitrogen doping content. Attached Figure Description

[0029] Figure 1 This is a photograph of the spherical activated carbon obtained in Example 1. Detailed Implementation

[0030] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0031] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0032] Example 1

[0033] S1: Dissolve 10g of glycidyl ether epoxy resin (model E44) and 5g of diethylenetriamine in 20g of ethanol to obtain a homogeneous mixed solution;

[0034] S2: Drop the above solution into a column of hot white oil at 100°C, causing the resin solution to shrink into a ball due to interfacial tension and solidify into a ball during the slow falling process;

[0035] S3: Collect the resin balls at the bottom of the oil column, cool to room temperature, wash, and dry at 120℃ to obtain dry resin balls;

[0036] S4: Place the dry resin balls in a nitrogen atmosphere, heat to 850℃, and hold at that temperature for 4 hours to obtain nitrogen-doped spherical activated carbon.

[0037] Figure 1 The image shows a physical sample of the spherical activated carbon obtained in Example 1, with an average particle size of 0.6 mm. The image shows that the spherical activated carbon has a uniform size. The nitrogen content in the spherical activated carbon obtained in Example 1 is 4.7% by mass.

[0038] Examples 2-5

[0039] It is basically the same as Example 1, except that the white oil in S1 is replaced with kerosene, vegetable oil, transformer oil and liquid paraffin in sequence. Otherwise, it is exactly the same as Example 1.

[0040] The average particle sizes of the nitrogen-doped spherical activated carbons obtained in Examples 2-5 were 0.58 mm, 0.65 mm, 0.62 mm and 0.6 mm, respectively; similar to Example 1, the spherical activated carbons obtained were of uniform size.

[0041] The nitrogen content in the spherical activated carbon obtained in Examples 2-5 was 4.7%, 4.6%, 4.65%, and 4.71%, respectively.

[0042] Example 6

[0043] It is basically the same as Example 1, except that the curing dose in S1 is increased to 10g, and the rest is exactly the same as Example 1.

[0044] The nitrogen-doped spherical activated carbon obtained in Example 6 had an average particle size of 1.05 mm, similar to Example 1, and the spherical activated carbon had uniform size. The mass content of nitrogen was 8.3%.

[0045] Example 7

[0046] The method is basically the same as in Example 1, except that the amounts of epoxy resin and diethylenetriamine in S1 are adjusted to 15g and 7.5g, respectively. Otherwise, it is exactly the same as in Example 1.

[0047] The nitrogen-doped spherical activated carbon obtained in Example 7 had an average particle size of 0.95 mm, similar to Example 1, and the spherical activated carbon had uniform size. The mass content of nitrogen was 4.8%.

[0048] Examples 8-14

[0049] It is basically the same as Example 1, except that the diethylenetriamine in S1 is replaced with triethylenetetramine, triethylamine, imidazole, polyetheramine, m-phenylenediamine, hexahydropyridine and melamine in sequence. Otherwise, it is exactly the same as Example 1.

[0050] The average particle sizes of the spherical activated carbons obtained in Examples 8-14 were 0.65 mm, 0.41 mm, 0.52 mm, 0.67 mm, 0.73 mm, 0.71 mm, and 0.84 mm, respectively, and the mass contents of nitrogen were 5.6%, 2.3%, 3.4%, 6.7%, 4.3%, 3.1%, and 8.5%, respectively.

[0051] Examples 15-19

[0052] The process is essentially the same as in Example 1, except that ethanol in S1 is replaced with acetone, DMF, DMSO, tetrahydrofuran and 1,4-dioxane in sequence. Otherwise, it is exactly the same as in Example 1.

[0053] The average particle sizes of the spherical activated carbons obtained in Examples 15-19 were 0.44 mm, 0.68 mm, 0.66 mm, 0.49 mm and 0.71 mm, respectively, and the mass contents of nitrogen were 4.5%, 5.2%, 4.8%, 4.7% and 4.6%, respectively.

[0054] Example 20

[0055] It is basically the same as Example 1, except that the amount of ethanol in S1 is replaced with 1g, and the rest is exactly the same as Example 1.

[0056] The spherical activated carbon obtained in Example 20 had an average particle size of 1.2 mm and a nitrogen content of 4.75% by mass.

[0057] Example 21

[0058] It is basically the same as Example 1, except that the oil column temperature in S2 is replaced with 80°C, otherwise it is exactly the same as Example 1.

[0059] The spherical activated carbon obtained in Example 21 had an average particle size of 0.48 mm and a nitrogen content of 3.43% by mass.

[0060] Example 22

[0061] It is basically the same as Example 1, except that the carbonization temperature in S3 is replaced with 1200°C, otherwise it is exactly the same as Example 1.

[0062] The spherical activated carbon obtained in Example 22 had an average particle size of 0.56 mm and a nitrogen content of 1.43% by mass.

[0063] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing nitrogen-doped spherical activated carbon, characterized in that, Includes the following steps: S1. A mixture containing epoxy resin, curing agent and organic solvent is dropped into a hot oil column, and the mixture droplets are cured into balls in the hot oil column. After being removed and dried, thermosetting epoxy resin balls are obtained. The oil in the hot oil column is selected from at least one of kerosene, vegetable oil, white oil, transformer oil, and liquid paraffin. The curing agent is selected from at least one of diethylenetriamine, triethylenetetramine, triethylamine, imidazole, polyetheramine, m-phenylenediamine, hexahydropyridine, and melamine; The temperature of the hot oil column is 80~180℃; S2. The thermosetting epoxy resin balls obtained in step S1 are placed in an inactive gas atmosphere and carbonized to obtain the nitrogen-doped spherical activated carbon.

2. The preparation method according to claim 1, characterized in that, In step S1, the epoxy resin is selected from at least one of glycidyl ether epoxy resin, glycidyl ester epoxy resin, glycidyl amine epoxy resin, linear aliphatic epoxy resin, and alicyclic epoxy resin.

3. The preparation method according to claim 1, characterized in that, In step S1, the epoxy resin, curing agent, and organic solvent are in a weight ratio of 1:(0.1~1):(0.1~10).

4. The preparation method according to claim 1, characterized in that, In step S1, the organic solvent is selected from at least one of ethanol, acetone, DMF, DMSO, tetrahydrofuran, and 1,4-dioxane.

5. The preparation method according to claim 1, characterized in that, In step S1, the drying conditions include: a drying temperature of 90~180℃ and a drying time of 1~24 h.

6. The preparation method according to claim 1, characterized in that, In step S2, the carbonization conditions include: a carbonization temperature of 600~1200℃ and a carbonization time of 1~12 h.

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