A method for preparing a pore size tunable porous carbon material

Abstract

The application discloses a preparation method of a pore size adjustable porous carbon material, and comprises the following steps: (1) adding a condensed ring aromatic compound containing both nitro and amino groups into an aromatic compound containing both nitro and amino groups, uniformly mixing, and then mixing and heating with a strong dehydrating agent at high temperature to a molten state; or adding an inorganic salt compound into an aromatic compound containing both nitro and amino groups, uniformly mixing, and then mixing and heating with a strong dehydrating agent at high temperature to a molten state; (2) performing secondary heating on the mixed material in the molten state at 220-1000 DEG C, and obtaining a porous carbon material with a continuous structure after sufficient reaction. The method can adjust the pore size of the synthesized porous carbon material by adjusting the type and proportion of the added monomers, can increase the pore size of the obtained porous carbon material by about 1.5 times on the basis of the initial pore size or reduce the pore size by more than 3 times, and can meet the pore size requirements in different application scenarios. The porous carbon material prepared by the method can be used as a catalytic material, an electrochemical energy storage material or a heat insulation material.

Description

Technical Field

[0001] This invention relates to a method for preparing porous carbon materials with adjustable pore size. Background Technology

[0002] Carbon materials, abundant in nature and possessing advantages such as good electrical and thermal conductivity, corrosion resistance, and low density, are widely used in various fields. To meet diverse application needs, the concept of porosity has been introduced into the structural construction of carbon materials, greatly enhancing their performance. With in-depth research on carbon nanomaterials, they have evolved from initially disordered channel activated carbon materials towards highly ordered, high-porosity, and tunable pore size. Leveraging their unique advantages such as high specific surface area, abundant pore structure, sufficient reactive sites, good chemical stability, and controllable porous structure, they are widely used in adsorption, separation, catalysis, electrochemistry, and biosensing.

[0003] Studies have shown that the pore morphology and specific surface area of ​​porous carbon materials are key factors affecting their application performance, and pore size is an important manifestation of specific surface area. Therefore, preparing porous carbon materials with specified pore sizes is of great significance. Existing methods for preparing porous carbon materials are mainly divided into two categories: template-based methods and template-free methods. Template-based methods involve combining a template agent with a carbon precursor and then carbonizing it at high temperature under an inert gas atmosphere to obtain pores of different sizes and morphologies. By changing the size of the template agent, the pore size can be controlled, ultimately resulting in porous carbon materials with ordered and uniform pore size distribution. However, this method has a relatively complex synthesis process, and the preparation and removal of the template are costly. Furthermore, template-free methods using biomass or polymers as raw materials, while simple in synthesis and relatively low in cost, suffer from the limitation that the pore size and distribution of biomass are entirely dependent on its own structure. The porous carbon materials prepared by this method have disordered pore size distribution, low adjustability, and difficult-to-control morphology, thus limiting their application range to some extent. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide a low-cost method for preparing porous carbon materials with quantitatively controllable pore size, which can prepare porous carbon materials with a specified pore size as needed.

[0005] Technical solution: The method for preparing porous carbon materials with adjustable pore size according to the present invention includes the following steps:

[0006] (1) Add a polycyclic aromatic hydrocarbon containing both nitro and amino groups to an aromatic compound containing both nitro and amino groups, mix well, and then mix with a strong dehydrating agent at high temperature and heat to a molten state.

[0007] Alternatively, an inorganic salt compound can be added to an aromatic compound containing both nitro and amino groups, mixed well, and then mixed with a strong dehydrating agent at high temperature and heated to a molten state.

[0008] (2) The above-mentioned molten mixture is heated twice at 220℃~1000℃, and after sufficient reaction, a porous carbon material with a continuous structure is obtained.

[0009] In step (1), the aromatic compound is one or a combination of several of p-nitroaniline, m-nitroaniline or o-nitroaniline.

[0010] In step (1), the polycyclic aromatic hydrocarbons containing both nitro and amino groups are: 4-nitro-1-naphthylamine, 1-nitro-2-naphthylamine, 3-nitro-1-naphthylamine, 3-nitro-2-naphthylamine, 5-nitro-1-naphthylamine, 6-nitro-2-naphthylamine, 8-nitro-2-naphthylamine, 4-bromo-2-nitro-1-naphthylamine, 2-bromo-4-nitro-1-naphthylamine, 2-methyl-4-nitro-1-naphthylamine, 3- One or a combination of several of the following: nitronaphthalene-1-carboxylic acid, 5-nitroindene-2-amine, 4-nitrodiphenylamine, 2-nitrodiphenylamine, 5-nitroquinoline-3-amine, 6-nitroquinoline-2-amine, 7-nitroquinoline-3-amine, 8-nitroquinoline-3-amine, 4-nitro-biphenyl-2-amine, 3-nitrobiphenyl-4-amine, 7-nitro-9H-fluorene-2-amine, or 3-nitro-9H-fluorene-2-amine.

[0011] In step (1), the salt compound is one or a combination of several of sodium chloride, potassium chloride, calcium chloride, magnesium chloride, or barium chloride.

[0012] In step (1), the temperature of the mixed heating is not lower than 200℃.

[0013] In step (1), in the reaction system of aromatic compounds, condensed ring aromatics containing nitro and amino groups, the mass ratio of the sum of the masses of aromatic compounds, condensed ring aromatics containing nitro and amino groups to the mass ratio of the strong dehydrating agent is 1:1.23.

[0014] In step (1), the mass ratio of aromatic compound to strong dehydrating agent in the reaction system of aromatic compound and salt compound is 1:1.23. The mass of the salt compound is only related to the target pore size and is independent of the mass of the other reactants.

[0015] In step (1), the strong dehydrating agent is concentrated sulfuric acid (mass fraction of 98%).

[0016] In step (1), in the reaction system of aromatic compounds, condensed-ring aromatics containing nitro and amino groups, as the mass ratio of condensed-ring aromatics containing nitro and amino groups to aromatic compounds gradually increases, the specific surface area of ​​the prepared porous carbon material gradually decreases and the pore size gradually increases; when the mass ratio of condensed-ring aromatics containing nitro and amino groups to aromatic compounds reaches 1:1, the pore size of the synthesized porous carbon material is the largest; as the mass ratio of condensed-ring aromatics containing nitro and amino groups to aromatic compounds continues to increase, the pore size of the porous carbon material does not increase significantly.

[0017] In step (1), in the reaction system of aromatic compounds and salt compounds, as the mass ratio of salt compounds to aromatic compounds gradually increases, the specific surface area of ​​the prepared porous carbon material gradually increases and the pore size gradually decreases; when the mass ratio of salt compounds to aromatic compounds reaches 7:15, the pore size of the synthesized porous carbon material is the smallest; as the mass ratio of salt compounds to aromatic compounds continues to increase, the pore size of the porous carbon material does not decrease significantly.

[0018] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: The method of the present invention controls the pore size of the synthesized porous carbon material by adjusting the type and proportion of added monomers. The pore size of the obtained porous carbon material can be increased by about 1.5 times or decreased by more than 3 times based on the initial pore size, so as to meet the pore size requirements under different application scenarios. That is, the porous carbon material with the target pore size generated can meet the pore size requirements of carbon materials under different application conditions. The porous carbon material prepared by the method of the present invention can be used as a catalytic material, an electrochemical energy storage material, and a heat insulation material. Attached Figure Description

[0019] Figure 1 The images shown are scanning electron microscope (SEM) images of the porous carbon materials prepared in Examples 1-3 and their corresponding pore size distribution diagrams.

[0020] Figure 2 The images shown are scanning electron microscope (SEM) images of the porous carbon materials prepared in Examples 4-7 and their corresponding pore size distribution diagrams. Detailed Implementation

[0021] Example 1

[0022] A method for preparing porous carbon materials includes the following steps:

[0023] (1) Take 3g of p-nitroaniline and place it in a porcelain boat, add 3.69g of concentrated sulfuric acid to it; place the porcelain boat in the center of the hot table, heat it to 200℃, and remove the porcelain boat from the hot table after the reactants have completely melted and mixed evenly.

[0024] (2) After the heating platform reaches 500℃, the porcelain boat containing the reactants is placed back on the heating platform. The molten reactants rapidly boil and expand, generating substances such as... Figure 1 The porous carbon material shown in the scanning electron microscope image exhibits a surface morphology of mutually compressed foam structure (indicating that the material has a tunable porous structure), with an average pore size of approximately 43.6 μm. This pore size is its initial pore size, and the following examples are all based on pore size control using this porous carbon material.

[0025] Example 2

[0026] The method for preparing porous carbon materials with adjustable pore size according to the present invention includes the following steps:

[0027] (1) Take 3g of p-nitroaniline and 0.2g of 4-nitro-1-naphthylamine (the mass ratio of p-nitroaniline to 4-nitro-1-naphthylamine is 15:1) and place them in a porcelain boat, then add 3.94g of concentrated sulfuric acid; place the porcelain boat in the center of the hot table, heat it to 200℃, and remove the porcelain boat from the hot table after the reactants have completely melted and mixed evenly.

[0028] (2) After the heating platform reaches 500℃, the porcelain boat containing the reactants is placed back on the heating platform. The molten reactants rapidly boil and expand, generating substances such as... Figure 1 b. The porous carbon material shown in the scanning electron microscope image has a surface morphology of mutually compressed foam structure with an average pore size of approximately 53.5 μm.

[0029] Example 3

[0030] The method for preparing porous carbon materials with adjustable pore size according to the present invention includes the following steps:

[0031] (1) Take 1.5g of p-nitroaniline and 1.5g of 4-nitro-1-naphthylamine (the mass ratio of p-nitroaniline to 4-nitro-1-naphthylamine is 1:1) and place them in a porcelain boat, then add 3.69g of concentrated sulfuric acid; place the porcelain boat in the center of the hot table, heat it to 200℃, and remove the porcelain boat from the hot table after the reactants have completely melted and mixed evenly.

[0032] (2) After the heating platform reaches 500℃, the porcelain boat containing the reactants is placed back on the heating platform. The molten reactants rapidly boil and expand, generating substances such as... Figure 1 The porous carbon material shown in the scanning electron microscope image has a surface morphology of mutually compressed foam structure, with an average pore size of approximately 63.2 μm.

[0033] Example 4

[0034] The method for preparing porous carbon materials with adjustable pore size according to the present invention includes the following steps:

[0035] (1) Take 3g of p-nitroaniline and 0.2g of sodium chloride (the mass ratio of p-nitroaniline to sodium chloride is 15:1) and place them in a porcelain boat, then add 3.69g of concentrated sulfuric acid; place the porcelain boat in the center of the hot table, heat it to 200℃, and remove the porcelain boat from the hot table after the reactants have completely melted and mixed evenly.

[0036] (2) After the heating platform reaches 500℃, the porcelain boat containing the reactants is placed back on the heating platform. The molten reactants rapidly boil and expand, generating substances such as... Figure 2 The porous carbon material shown in the scanning electron microscope image has a surface morphology of mutually compressed foam structure with an average pore size of approximately 37.1 μm.

[0037] Example 5

[0038] The method for preparing porous carbon materials with adjustable pore size according to the present invention includes the following steps:

[0039] (1) Take 3g of p-nitroaniline and 1g of sodium chloride (the mass ratio of p-nitroaniline to sodium chloride is 3:1) and place them in a porcelain boat, then add 3.69g of concentrated sulfuric acid; place the porcelain boat in the center of the hot table, heat it to 200℃, and remove the porcelain boat from the hot table after the reactants have completely melted and mixed evenly.

[0040] (2) After the heating platform reaches 500℃, the porcelain boat containing the reactants is placed back on the heating platform. The molten reactants rapidly boil and expand, generating substances such as... Figure 2 b. The porous carbon material shown in the scanning electron microscope image has a surface morphology of mutually compressed foam structure with an average pore size of about 22.4 μm.

[0041] Example 6

[0042] The method for preparing porous carbon materials with adjustable pore size according to the present invention includes the following steps:

[0043] (1) Take 3g of p-nitroaniline and 1.4g of sodium chloride (the mass ratio of p-nitroaniline to sodium chloride is 15:7) and place them in a porcelain boat, then add 3.69g of concentrated sulfuric acid; place the porcelain boat in the center of the hot table, heat it to 200℃, and remove the porcelain boat from the hot table after the reactants have completely melted and mixed evenly.

[0044] (2) After the heating platform reaches 500℃, the porcelain boat containing the reactants is placed back on the heating platform. The molten reactants rapidly boil and expand, generating substances such as... Figure 2 The porous carbon material shown in the scanning electron microscope image has a surface morphology of mutually compressed foam structure with an average pore size of approximately 16.5 μm.

[0045] Example 7

[0046] The method for preparing porous carbon materials with adjustable pore size according to the present invention includes the following steps:

[0047] (1) Take 1g of p-nitroaniline and 3g of sodium chloride (the mass ratio of p-nitroaniline to sodium chloride is 1:3) and place them in a porcelain boat, then add 1.23g of concentrated sulfuric acid; place the porcelain boat in the center of the hot table, heat it to 200℃, and remove the porcelain boat from the hot table after the reactants have completely melted and mixed evenly.

[0048] (2) After the heating platform reaches 500℃, the porcelain boat containing the reactants is placed back on the heating platform. The molten reactants rapidly boil and expand, generating substances such as... Figure 2 The porous carbon material shown in the d scanning electron microscope image has a surface morphology of mutually compressed foam structure with an average pore size of approximately 17.5 μm.

Claims

1. A method for preparing a porous carbon material with adjustable pore size, characterized in that, The steps include the following: (1) Take 3g of p-nitroaniline and sodium chloride and place them in a porcelain boat, then add 3.69g of concentrated sulfuric acid to it; place the porcelain boat in the center of the hot table, heat it to 200℃, and remove the porcelain boat from the hot table after the reactants have completely melted and mixed evenly. (2) After the heating platform is heated to 500°C, the ceramic boat containing the reactants is placed back on the heating platform. The molten reactants boil and expand rapidly to obtain porous carbon material. When the amount of sodium chloride added is 0.2g, the average pore size of the porous carbon material is 37.1μm. When the amount of sodium chloride added is 1g, the average pore size of the porous carbon material is 22.4μm. When the amount of sodium chloride added is 1.4g, the average pore size of the porous carbon material is 16.5μm.

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