A method for regulating the specific surface area of ​​carbon materials

Abstract

The present invention belongs to the field of carbon materials, and particularly relates to a method for regulating the specific surface area of ​​carbon materials. The method comprises reacting at least one aromatic compound with an aldehyde and a phenol in a solvent under the action of a catalyst to prepare the carbon material, wherein the aromatic compound contains a benzene ring with two substitutable sites; or the aromatic compound contains a benzene ring with a halogen or electron-withdrawing group. The specific surface area of ​​the carbon material prepared by the method of the invention is 504 to 889 m 2 / g, and the diameter and specific surface area of ​​the carbon material can be effectively adjusted through parameters such as raw material type, ratio and concentration.

Description

Technical Field

[0001] The present invention belongs to the field of carbon materials, and in particular relates to a method for regulating the specific surface area of ​​carbon materials. Background Art

[0002] Carbon materials are non-metallic materials derived primarily from organic materials such as coal, petroleum, or their processed products through a series of processing steps. Their primary component is carbon. Carbon materials are abundant, simple to prepare, and environmentally friendly. They exhibit controllable surface area, excellent electrical conductivity, and stable cycling performance, making them ideal for supercapacitor electrode materials. Examples of these carbon materials include activated carbon, carbon nanotubes, graphene, carbon fibers, and carbides.

[0003] Activated carbon is mainly derived from carbon-containing organic matter (including synthetic and natural) carbonized under an inert gas atmosphere, and then processed by a series of physical and chemical methods, such as the porous carbon material prepared based on aromatic compound monomers disclosed in CN106554004B and its preparation method and use, the porous polymer prepared from aromatic monomer compounds or the porous polymer prepared from aromatic monomer compounds and low-dimensional carbon nanocomposites are formed into porous carbon materials by a gradual temperature increase program in an inert atmosphere, and the preparation method of phenolic resin-based oxygen-doped microporous carbon electrode material disclosed in CN111170318B, 3-fluorophenol and hexamethylenetetramine are stirred at room temperature, and then hydrothermally polymerized to obtain fluorophenolic resin, which is washed and dried, carbonized, activated with alkaline inorganic substances, and acid-washed, washed and dried to obtain microporous carbon electrode materials. When carbon materials are used as electrode materials, their specific surface area and pore structure have an important influence on electrode performance. Normally, using higher activation temperatures and longer activation times increases the specific surface area and pore size of carbon materials. However, blindly increasing the temperature and time consumes a lot of energy, which is not conducive to large-scale production. Therefore, further controlling the specific surface area of ​​carbon materials remains a major challenge. Summary of the Invention

[0004] In order to overcome the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to provide a method for effectively regulating the specific surface area of ​​carbon materials.

[0005] In order to solve the above technical problems, the present invention provides a method for regulating the specific surface area of ​​a carbon material. In the presence of a catalyst, at least one aromatic compound is reacted with an aldehyde and a phenol in a solvent to prepare a carbon material, wherein the aromatic compound contains a benzene ring and has two substitutable sites on the benzene ring; or the aromatic compound contains a benzene ring and has a halogen or an electron-withdrawing group on the benzene ring.

[0006] The beneficial effects of the present invention are as follows: the method provided by the present invention can achieve effective control of the specific surface area of ​​the carbon material, and the specific surface area of ​​the carbon material prepared by the above method is 504~889m 2 / g. Application of this carbon material in supercapacitor electrodes can significantly improve electrode performance. As a method for regulating the specific surface area of ​​carbon materials, it features abundant raw materials, low preparation costs, simple processes, and an environmentally friendly synthesis process, making it suitable for mass production. DETAILED DESCRIPTION

[0007] In order to explain the technical content, achieved objectives and effects of the present invention in detail, the following description is given in conjunction with the implementation methods.

[0008] A method for regulating the specific surface area of ​​a carbon material comprises reacting at least one aromatic compound with an aldehyde and a phenol in a solvent in the presence of a catalyst to prepare the carbon material, wherein the aromatic compound contains a benzene ring with two substitutable sites; or the aromatic compound contains a benzene ring with a halogen or an electron-withdrawing group.

[0009] In an optional embodiment, the method comprises the following steps:

[0010] S1, mixing the aromatic compound, the catalyst, the aldehyde and the phenol in the solvent to obtain a mixed solution;

[0011] S2, heating the mixed solution to react to obtain polymer microspheres;

[0012] S3. Carbonizing the polymer microspheres under an inert gas atmosphere to obtain the carbon material.

[0013] In a preferred embodiment, the step S2 is: heating the mixed solution to 100-200° C. and reacting for 6-24 hours to obtain microspheres.

[0014] In a preferred embodiment, the step S3 is: carbonizing the microspheres at 600-1200° C. in an inert atmosphere for 1-8 hours to obtain the carbon material.

[0015] In an optional embodiment, the electron withdrawing group is selected from N + One of R, R'R", NO2, CF3, CN, SO3H, CHO, COR, COOH, COOR, CONRR', BR"'R"", wherein the aforementioned R, R' and R" are all alkyl groups, R"' and R"" are hydroxyl groups, amino groups or alkyl groups, and further, the alkyl group can be methyl, ethyl, propyl, butyl, isopropyl or isobutyl.

[0016] Among them, an aromatic compound containing a benzene ring with only two substitutable sites or an aromatic compound containing a benzene ring with an aluminum plastic or electron-withdrawing group on the benzene ring is used as a structural regulator. By introducing a group to pre-occupy the substitutable sites on the benzene ring or passivate the benzene ring, the substitution reaction on the benzene ring is inhibited, thereby achieving the purpose of controlling the cross-linking density of the polymer microspheres.

[0017] Conventional phenols, such as phenol, 3-aminophenol, resorcinol, cardanol, m-cresol, 3-hydroxyphenylboronic acid, bisphenol A, and bisphenol F, contain at least three substitution sites on each benzene ring. Under the action of formaldehyde and a catalyst, they can undergo a cross-linking reaction, forming a cross-linked network structure. This structure is thermally stable and difficult to decompose. Therefore, the porous structure formed by carbonization is relatively small, resulting in a low specific surface area. However, aromatic compounds containing benzene rings with only two substitutable sites, or aromatic compounds containing benzene rings with halogens or electron-withdrawing groups on the benzene rings, are used as structural modifiers. Because these aromatic compounds have only two substitutable sites on their benzene rings and cannot form a cross-linked structure, or because the presence of halogens or electron-withdrawing groups on the benzene rings can weaken the substitution reaction on the benzene rings, copolymerization with phenols can introduce a non-cross-linked, linear structure into the structure, thereby regulating the polymer structure and achieving a better decomposition effect under high temperature conditions.

[0018] Further carbon materials (such as carbon microspheres) are prepared by carbonization. Since the substitution sites of the benzene rings in the polymer part of the microspheres are suppressed, the cross-linking density of the polymer microspheres is reduced. Therefore, during the high-temperature carbonization cracking process, the molecular segments and benzene rings can be more effectively cracked. A large amount of carbon, hydrogen, etc. can pass through the carbon layer in the form of oxides, thereby achieving effective space sacrifice and generating a large number of pores, thereby converting the sacrificed space into specific surface area.

[0019] However, if the structure modifier has too few substitution sites on the benzene ring, such as only one active site, it is not conducive to improving the specific surface area of ​​the carbon material. For example, an aromatic compound with only one active site has a functionality of 1 and cannot form a polymer, so it can only be grafted onto the end of the polymer, making it difficult to regulate the polymer backbone structure and thus having an unsatisfactory effect on the pore structure of the carbon material. Moreover, using too many aromatic compounds with a single active site can also reduce the molecular weight of the polymer, which can easily cause structural collapse during cracking, thus failing to improve the specific surface area.

[0020] The present invention achieves the purpose of regulating the specific surface area of ​​the carbon material by regulating the spatial structure of the carbon material precursor. The high specific surface area can provide sufficient active sites for ion adsorption, which is beneficial to regulating electrolyte diffusion and ion transfer efficiency. Therefore, the carbon material prepared by the method of the present invention can be used as an electrode material to effectively improve the capacitance performance and rate performance of the supercapacitor.

[0021] In this embodiment, the specific surface area of ​​the carbon material can be effectively controlled by adjusting the type and amount of the structure modifier. During the reaction process, the key to spheroidization lies in the formation of a dilute solution reaction system. That is, by adjusting the amount of aromatic compound, aldehyde, phenol, and catalyst added, the size of the microspheres can also be controlled.

[0022] In an optional embodiment, the aromatic compound is represented by the general formula (1):

[0023]

[0024] wherein R1 is selected from one of hydroxyl, amino, NHR, NRR', and OR; one of R2, R4, and R6 is a halogen or an activated group, and the others are H; R3 and R5 are H, an activated group, or a halogen;

[0025] R1 is one of hydroxyl, amino, NHR, NRR′, and OR; R2 is an activating group; two of R3, R4, R5, and R6 are H, and two are activating groups, passivating groups, or halogens;

[0026] In another optional embodiment, R1 is one of hydroxyl, amino, NHR, NRR′, and OR; R4 is an activating group; two of R2, R3, R5, and R6 are H, and two are activating groups or passivating groups;

[0027] In another optional embodiment, R1 is one of hydroxyl, amino, NHR, NRR′, and OR; R3 is an activating group; one of R2, R4, and R6 is a halogen or a passivating group, and R5 is H or an activating group, a passivating group, or a halogen;

[0028] The activated group is one of hydroxyl, amino, alkyl, NHR, NRR', and OR;

[0029] The passivation group is N + One of RR′R″, NO2, CF3, CN, SO3H, CHO, COR, COOH, COOR, CONRR′, BR″′R″″;

[0030] The R, R' and R" are alkyl groups, R"' and R"" are hydroxyl groups, amino groups or alkyl groups. Furthermore, the alkyl group can be methyl group, ethyl group, propyl group, butyl group, isopropyl group or isobutyl group.

[0031] In another optional embodiment, the aromatic compound is represented by the general formula (1):

[0032]

[0033] Wherein, the substituents R1, R2, R3, R4, R5, and R6 contain at least one benzene ring, and each benzene ring in the aromatic compound contains two substitutable active sites.

[0034] In a preferred embodiment, the aromatic compound is selected from at least one of 3,5-dichlorocatechol, 4,5-dichlorocatechol, o-nitrophenol, 5-fluoro-2-nitrophenol, 5-fluoro-2-nitroaniline, 5-bromo-2-nitrophenol, 3-fluoro-2-nitrophenol, 3-bromo-2-nitrophenol, 4-nitrophenol, 3-chloro-4-nitrophenol, 3-fluoro-4-nitrophenol, 3-iodo-4-nitrophenol, 2-fluoro-4-hydroxybenzonitrile, 3,5-difluoro-4-cyanophenol, 5-bromo-3-fluoro-2-nitroaniline, 2-nitroaniline, 4-aminobenzonitrile, 2-aminobenzonitrile, 4-aminophenylboric acid, 2-hydroxyphenylboric acid, 4-hydroxyphenylboric acid, and 2-aminophenylboric acid.

[0035] In one embodiment, the aldehyde is selected from at least one of formaldehyde, paraformaldehyde, benzaldehyde, acetaldehyde, propionaldehyde, and butyraldehyde, and the solvent is selected from at least one of water, ethanol, methanol, acetone, tetrahydrofuran, methane, and chloroform. Preferably, the solvent is water, which reduces the use of organic solvents, reduces costs and pollution, and has better environmental benefits.

[0036] In one embodiment, the catalyst is selected from at least one of aqueous ammonia, sodium hydroxide, potassium hydroxide, barium hydroxide, magnesium hydroxide, oxalic acid, hydrochloric acid, sulfuric acid, phosphoric acid, phosphonic acid, benzenesulfonic acid and p-toluenesulfonic acid.

[0037] In one embodiment, the ratio of the molar number of the aldehyde to the sum of the molar numbers of the aromatic compound and the phenol is greater than 1. In this embodiment, since the amount of aldehyde added is less than that of the aromatic compound, only a low molecular weight polymer is produced. This polymer has a low molecular weight and a low cross-linking density, which enables more efficient cracking of the molecular segments and benzene rings of the polymer during the high-temperature carbonization process, thereby increasing the pores of the carbon microspheres and increasing the specific surface area.

[0038] Example 1

[0039] A method for regulating the specific surface area of ​​a carbon material comprises adding 0.02 g of 3,5-dichlorocatechol, 0.18 g of phenol, 0.25 g of a 37% formaldehyde solution, and 0.1 g of a 25% ammonia solution to 20 mL of water and mixing the mixture; adding the mixture to a high-pressure reactor, heating it to 180°C for 24 hours to obtain polymer microspheres; and carbonizing the polymer microspheres at 800°C for 4 hours under a nitrogen atmosphere to obtain carbon material T1. The specific surface area of ​​the prepared carbon material T1 is 565 m 2 / g.

[0040] Example 2

[0041] A method for regulating the specific surface area of ​​a carbon material comprises adding 0.05 g of 3,5-dichlorocatechol, 0.15 g of phenol, 0.25 g of a 37% formaldehyde solution, and 0.1 g of a 25% ammonia solution to 20 mL of water; adding the mixture to a high-pressure reactor, heating it to 180°C for 24 hours to obtain polymer microspheres; and carbonizing the polymer microspheres at 800°C for 4 hours under a nitrogen atmosphere to obtain carbon microspheres T2. The specific surface area of ​​the prepared carbon microspheres T2 is 656 m 2 / g.

[0042] Example 3

[0043] A method for regulating the specific surface area of ​​a carbon material comprises adding 0.1 g of 3,5-dichlorocatechol, 0.1 g of phenol, 0.25 g of a 37% formaldehyde solution, and 0.1 g of a 25% ammonia solution to 20 mL of water and mixing; adding the mixture to a high-pressure reactor, heating it to 180°C for 24 hours to obtain polymer microspheres; and carbonizing the polymer microspheres at 800°C for 4 hours under a nitrogen atmosphere to obtain carbon material T3. The specific surface area of ​​the prepared carbon material T3 is 761 m 2 / g.

[0044] Example 4

[0045] A method for regulating the specific surface area of ​​a carbon material comprises adding 0.05 g of 3,5-dichlorocatechol, 0.15 g of phenol, 0.25 g of a 37% formaldehyde solution, and 0.1 g of a 25% ammonia solution to 20 mL of water; adding the mixture to a high-pressure reactor, heating it to 180°C for 24 hours to obtain polymer microspheres; and carbonizing the polymer microspheres at 900°C for 5 hours under a nitrogen atmosphere to obtain carbon material T4. The specific surface area of ​​the prepared carbon material T4 is 802 m 2 / g.

[0046] Example 5

[0047] A method for regulating the specific surface area of ​​a carbon material comprises adding 0.05 g of 5-fluoro-2-nitrophenol, 0.1 g of resorcinol, 0.25 g of a 37% formaldehyde solution, and 0.1 g of a 25% ammonia solution to 20 mL of water; adding the mixture to a high-pressure reactor, heating it to 120°C for 24 hours to obtain polymer microspheres; and carbonizing the polymer microspheres at 800°C for 4 hours under a nitrogen atmosphere to obtain carbon material T5. The specific surface area of ​​the prepared carbon material T5 is 684 m 2 / g.

[0048] Example 6

[0049] A method for regulating the specific surface area of ​​a carbon material comprises adding 0.05 g of 2-aminobenzonitrile, 0.1 g of resorcinol, 0.25 g of a 37% formaldehyde solution, and 0.1 g of a 25% ammonia solution to 20 mL of water; adding the mixture to a high-pressure reactor, heating it to 120°C for 24 hours to obtain polymer microspheres; and carbonizing the polymer microspheres at 800°C for 4 hours under a nitrogen atmosphere to obtain carbon material T6. The specific surface area of ​​the prepared carbon material T6 is 702 m 2 / g.

[0050] Example 7

[0051] A method for regulating the specific surface area of ​​a carbon material comprises adding 0.2 g of 4-aminophenylboronic acid, 0.1 g of phenol, 0.25 g of a 37% formaldehyde aqueous solution, and 0.1 g of a 25% ammonia aqueous solution to 20 mL of water; adding the mixture to a high-pressure reactor, heating it to 120°C for 24 hours to obtain polymer microspheres; and carbonizing the polymer microspheres at 900°C for 5 hours under a nitrogen atmosphere to obtain carbon material T7. The specific surface area of ​​the prepared carbon material T7 is 889 m 2 / g.

[0052] Example 8

[0053] A method for regulating the specific surface area of ​​a carbon material comprises adding 0.1 g of 4-fluorophenol, 0.1 g of phenol, 0.25 g of a 37% formaldehyde solution, and 0.1 g of a 25% ammonia solution to 20 mL of water. The mixture is added to an autoclave and heated to 120°C for 24 hours to produce polymer microspheres. The polymer microspheres are then carbonized at 900°C for 5 hours under a nitrogen atmosphere to produce carbon material T8. The prepared carbon material T8 has a specific surface area of ​​766 m2 / g.

[0054] Comparative Example 1

[0055] A method for regulating the specific surface area of ​​a carbon material comprises adding 0.2 g of phenol, 0.25 g of a 37% formaldehyde aqueous solution, and 0.1 g of a 25% ammonia solution to 20 mL of water and mixing the mixture; adding the mixture to an autoclave, heating it to 180°C for 24 hours to obtain polymer microspheres; and carbonizing the polymer microspheres at 800°C for 4 hours under a nitrogen atmosphere to obtain carbon material T9. The specific surface area of ​​the prepared carbon material T9 is 504 m 2 / g.

[0056] Comparative Example 2

[0057] A method for regulating the specific surface area of ​​a carbon material comprises adding 0.2 g of phenol, 0.25 g of a 37% formaldehyde aqueous solution, and 0.1 g of a 25% ammonia solution to 20 mL of water and mixing the mixture; adding the mixture to an autoclave, heating it to 180°C for 24 hours to obtain polymer microspheres; and carbonizing the polymer microspheres at 900°C for 5 hours under a nitrogen atmosphere to obtain carbon material T10. The specific surface area of ​​the prepared carbon material T10 is 552 m 2 / g.

[0058] In summary, the carbon material prepared by the present invention uses an aromatic compound containing a benzene ring with only two substitutable sites, or an aromatic compound containing a benzene ring and containing a halogen or electron-withdrawing group on the benzene ring as a structural modifier. By introducing a group to pre-occupy the substitutable site on the benzene ring or passivate the benzene ring, the substitution reaction on the benzene ring is inhibited. In addition, the aromatic compound used also contains an electrophilic group, which can undergo an electrophilic substitution reaction, thereby removing hydrogen ions from the aromatic ring. By controlling the substitution reaction of the benzene ring, the cross-linking density of the polymer microspheres is controlled. The cross-linking density of the polymer microspheres is reduced, so that during the high-temperature carbonization and cracking process, the molecular chain segments and benzene rings can be more effectively cracked, thereby achieving effective space sacrifice and generating a large number of pores, achieving the effect of converting the sacrificed space into specific surface area. The method of the present invention can be used to regulate the pore structure and specific surface area of ​​the carbon material. The prepared carbon material can be used as a supercapacitor electrode material. The high specific surface area will help to increase the energy density of the electrode material, thereby improving the performance of the supercapacitor. As a method to regulate the specific surface area of ​​carbon materials, it has abundant raw materials, low preparation cost, simple process, green and environmentally friendly synthesis process, and is suitable for mass production.

[0059] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention specification, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for regulating the specific surface area of ​​a carbon material, characterized in that: In the presence of a catalyst, at least one aromatic compound is reacted with an aldehyde and a phenol in a solvent to prepare a carbon material; The aromatic compound contains a benzene ring and the benzene ring has two substitutable sites; Or, the aromatic compound contains a benzene ring and the benzene ring contains a halogen or an electron-withdrawing group; The aromatic compound is represented by the general formula (1): ； wherein R1 is one of hydroxyl, amino, NHR, NRR', and OR; one of R2, R4, and R6 is a halogen or an electron-withdrawing group, and the others are H; and R3 and R5 are H or an activating group or a halogen; Alternatively, R1 is one of hydroxyl, amino, NHR, NRR', and OR; R2 is an activating group; two of R3, R4, R5, and R6 are H, and two are activating groups, electron-withdrawing groups, or halogens; Alternatively, R1 is one of hydroxyl, amino, NHR, NRR', and OR; R4 is an activating group; two of R2, R3, R5, and R6 are H, and two are activating groups or electron-withdrawing groups; Alternatively, R1 is one of hydroxyl, amino, NHR, NRR', and OR; R3 is an activating group; one of R2, R4, and R6 is a halogen or an electron-withdrawing group, and R5 is H or an activating group or an electron-withdrawing group or a halogen; The activated group is one of hydroxyl, amino, alkyl, NHR, NRR', and OR; The electron-withdrawing group is N + One of RR´R´´, NO2, CF3, CN, SO3H, CHO, COR, COOH, COOR, CONRR´, BR´´´R´´´´; R, R' and R'' are alkyl groups, and R''' and R'''' are hydroxyl groups, amino groups or alkyl groups.

2. A method for regulating the specific surface area of ​​a carbon material, characterized in that: In the presence of a catalyst, at least one aromatic compound is reacted with an aldehyde and a phenol in a solvent to prepare a carbon material; The aromatic compound contains a benzene ring and the benzene ring has two substitutable sites; Alternatively, the aromatic compound contains a benzene ring and the benzene ring contains an electron-withdrawing group; The aromatic compound is represented by the general formula (1): ； Wherein, the substituents R1, R2, R3, R4, R5, and R6 contain at least one benzene ring, and each benzene ring in the aromatic compound contains two substitutable active sites.

3. The method according to claim 1, characterized in that The phenol is selected from one of phenol, 3-aminophenol, resorcinol, cardanol, m-cresol, 3-hydroxyphenylboric acid, bisphenol A and bisphenol F.

4. The method according to claim 1, characterized in that The aromatic compound is selected from at least one of 3,5-dichlorocatechol, 4,5-dichlorocatechol, o-nitrophenol, 5-fluoro-2-nitrophenol, 5-fluoro-2-nitroaniline, 5-bromo-2-nitrophenol, 3-fluoro-2-nitrophenol, 3-bromo-2-nitrophenol, 4-nitrophenol, 3-chloro-4-nitrophenol, 3-fluoro-4-nitrophenol, 3-iodo-4-nitrophenol, 2-fluoro-4-hydroxybenzonitrile, 3,5-difluoro-4-cyanophenol, 5-bromo-3-fluoro-2-nitroaniline, 2-nitroaniline, 4-aminobenzonitrile, 2-aminobenzonitrile, 4-aminophenylboric acid, 2-hydroxyphenylboric acid, 4-hydroxyphenylboric acid, and 2-aminophenylboric acid.

5. The method according to claim 1, characterized in that: The aldehyde is selected from at least one of formaldehyde, paraformaldehyde, benzaldehyde, acetaldehyde, propionaldehyde and butyraldehyde, and the solvent is selected from at least one of water, ethanol, methanol, acetone, tetrahydrofuran, methane and chloroform.

6. The method according to claim 1, characterized in that The catalyst is selected from at least one of ammonia water, sodium hydroxide, potassium hydroxide, barium hydroxide, magnesium hydroxide, oxalic acid, hydrochloric acid, sulfuric acid, phosphoric acid, phosphonic acid, benzenesulfonic acid and p-toluenesulfonic acid.

7. The method according to claim 1, characterized in that: The ratio of the number of moles of the aldehyde to the sum of the number of moles of the aromatic compound plus the phenol is greater than 1.

8. The method according to claim 1, characterized in that: The molar ratio of the aldehyde to the aromatic compound is greater than 1.

9. The method according to claim 1, characterized in that: The steps include: S1, mixing the aromatic compound, the catalyst, the aldehyde and the phenol in the solvent to obtain a mixed solution; S2, heating the mixed solution to react to obtain polymer microspheres; S3. Carbonizing the polymer microspheres under an inert gas atmosphere to obtain the carbon material.

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