Preparation methods and applications of atomically Lewis acid-base modified functional carbon materials

Abstract

This invention discloses a method for preparing functional carbon materials with atomically dispersed Lewis acid-base sites, comprising: (1) polymer preparation to obtain a polymer sample; (2) polymer modification to obtain a modified polymer sample; (3) polymer carbonization: the modified polymer sample is heat-treated in a non-oxidizing atmosphere to carbonize the modified polymer sample; after carbonization, the system is naturally cooled; then, after washing and drying, the target functional carbon material is obtained. This invention utilizes atomically dispersed Lewis acidic metal sites and basic N sites to modify carbon materials in situ. The prepared functional carbon material has a large specific surface area, well-developed pore structure, abundant acid-base sites, and an atomically distributed structure, which can significantly improve the density of functional sites on the surface of the carbon material and its adsorption efficiency for boron, phosphorus, and metal impurities. Its application in the purification of chlorosilanes can greatly reduce the load of subsequent distillation and impurity removal, and improve the yield and quality of high-purity chlorosilanes.

Description

Technical Field

[0001] This invention relates to the field of polycrystalline silicon production technology, specifically to a method for preparing and applying functional carbon materials with atomic-level Lewis acid-base site modification. Background Technology

[0002] With the rapid development of the global economy, the supply of conventional fossil energy such as coal and oil is becoming increasingly tight, bringing serious environmental problems. Developing new energy sources has become an urgent priority. Solar energy has the advantages of being abundant, clean, and sustainable, and the photovoltaic industry based on solar energy has developed rapidly, becoming an important direction for the development of the new energy industry. Polycrystalline silicon is the basic raw material for the photovoltaic new energy industry, and the impurity content in polycrystalline silicon will significantly affect the photoelectric conversion efficiency of solar cells. In particular, the current photovoltaic market is undergoing a transformation from P...

[0003] The shift from P-type to N-type cells has significantly increased the demand for N-type silicon. Compared to the silicon used in P-type cells, N-type silicon has higher requirements in terms of donor impurities, acceptor impurities, and bulk metal concentration. Therefore, effectively removing impurities from polycrystalline silicon is crucial.

[0004] The production processes of polycrystalline silicon mainly include chemical methods (modified Siemens process and silane process) and physical methods (metallurgical process). The mainstream production process is the modified Siemens process, which accounts for more than 80% of the total polycrystalline silicon production. The modified Siemens process synthesizes trichlorosilane (hereinafter referred to as chlorosilane) from industrial silicon powder and hydrogen chloride at a certain temperature. After separation and purification, it is then subjected to vapor deposition in a high-temperature reduction furnace to obtain the polycrystalline silicon product.

[0005] Currently, most of the boron, phosphorus, and metal impurities in chlorosilanes are removed by multi-stage distillation. However, since the boiling points of boron and phosphorus impurities are close to those of chlorosilanes, it is necessary to increase the reflux ratio and reduce the yield during distillation to ensure quality indicators, which consumes a lot of energy and cannot guarantee stable quality. Therefore, in actual purification operations, other impurity removal processes are usually combined.

[0006] Adsorption is widely used in the polysilicon industry due to its advantages such as simple operation and low energy consumption. The key to adsorption purification is the development of highly efficient adsorbents. Activated carbon has a high specific surface area and pore structure, and its physicochemical properties are stable, making it a widely used adsorption material. The type and number of surface groups on activated carbon are important factors affecting its adsorption performance. Conventional activated carbon has relatively few surface groups and needs to be modified to meet the requirements of adsorption and impurity removal.

[0007] Currently, the publicly disclosed methods mainly include: using oxidants such as ozone, nitric acid, and hydrogen peroxide to modify the surface of activated carbon. After introducing oxygen-containing groups on the surface, the activated carbon can selectively adsorb trimethylchlorosilane from silicon tetrachloride, thereby purifying silicon tetrachloride. The oxygen-containing groups include, but are not limited to, one or more of carboxyl, ester, hydroxyl, carbonyl, aldehyde, ether, and ketone groups. Alternatively, the activated carbon is N-modified by sequentially impregnating it with amides, quaternary ammonium salts, amine-containing phosphoric acid, and sulfur-containing compounds in a stepwise impregnation process. Then, the impregnated samples are subjected to ammonia... Nitrogen-containing activated carbon samples can be obtained by high-temperature heat treatment under nitrogen; alternatively, activated carbon can be modified with quaternary ammonium salt cationic surfactants to adsorb anionic pollutants in wastewater, wherein the quaternary ammonium salt compound is one of hexadecyltrimethylammonium bromide, hexadecylpyridine bromide, or tetrabutylammonium bromide; or, activated carbon can be modified with nitric acid to introduce basic groups and nitroso groups, which can achieve the adsorption and removal of boron and phosphorus impurities in chlorosilanes. Furthermore, impregnating the modified activated carbon with organic active components such as diphenylthiocarbazone, triethylamine, triphenylchloromethane, and diphenylchloromethane can achieve better purification results.

[0008] In summary, targeted functional modification of activated carbon can regulate the properties of surface functional groups, thus positively impacting the adsorption performance of target impurities. However, the modification efficiency of the aforementioned activated carbon modification schemes is relatively low, and they cannot significantly increase the number of functional groups on the material surface. Post-loading functional molecules can effectively compensate for this deficiency, but it inevitably clogs the material's pores, reducing the material's specific surface area. Furthermore, the post-loaded active components are not firmly attached to the carbon support surface, and there is a risk of loss during adsorption. Summary of the Invention

[0009] The technical problem to be solved by this invention is to address the above-mentioned shortcomings of the existing technology by providing a method for preparing functional carbon materials with atomic-level Lewis acid-base site modification and its application. This method utilizes atomically dispersed Lewis acidic metal sites and basic N sites to modify carbon materials in situ. The prepared functional carbon materials have a large specific surface area, well-developed pore structure, abundant acid-base sites, and an atomically distributed structure. This can significantly improve the density of functional sites on the surface of carbon materials and their adsorption efficiency for boron, phosphorus, and metal impurities. When applied to the purification of chlorosilanes, it can greatly reduce the load of subsequent distillation and impurity removal, and improve the yield and quality of high-purity chlorosilanes.

[0010] The technical solution of the present invention to solve the above-mentioned technical problems is:

[0011] According to one aspect of the present invention, a method for preparing an atomically Lewis acid-base modified functional carbon material is provided, comprising:

[0012] (1) Polymer preparation: Nitrogen-containing vinyl monomer acrylonitrile, oxygen-containing vinyl monomer and divinylbenzene were added to an organic solvent to obtain a mixed solution; peroxide was added to the mixed solution as an initiator, and the mixture was stirred thoroughly for at least 2 hours under nitrogen protection to obtain a transparent solution; the transparent liquid was transferred to a high-pressure reactor, and heated under nitrogen protection to initiate the monomer polymerization reaction; after the reaction was completed, the system was allowed to cool down naturally, and after natural drying, it was dried and crushed to obtain a polymer sample;

[0013] (2) Polymer modification: Add compounds of Group IB, IIB or IIIA metals to a mixed solution of melamine resin and phenolic resin and stir thoroughly to dissolve; then add ammonium chloride as a resin curing agent and stir thoroughly to dissolve to obtain a modified mixed solution; use an impregnation method to impregnate the modified mixed solution into the polymer sample obtained after drying in step (1); transfer the impregnated sample to a high-pressure reactor, heat it, and perform curing treatment; after the curing treatment is completed, the system is allowed to cool down naturally to obtain the modified polymer sample;

[0014] (3) Polymer carbonization: The modified polymer sample was heat-treated in a non-oxidizing atmosphere to carbonize the modified polymer sample; after carbonization, the system was cooled naturally; then, after washing and drying, the target functional carbon material was obtained.

[0015] Preferably, in step (1), the oxyvinyl monomer is one or a mixture of two of itaconic acid or methyl acrylate.

[0016] Preferably, in step (1), the organic solvent is a mixture of ethyl acetate, ethyl acetate / toluene, ethyl acetate / xylene, ethyl acetate / trimethylene, ethyl acetate / hexane, ethyl acetate / heptane, or ethyl acetate / octane, wherein the mass ratio of toluene, xylene, trimethylene, hexane, heptane, or octane to ethyl acetate is (0–0.3):1.

[0017] Preferably, in step (1), the mass ratio of nitrogen-containing vinyl monomer, oxygen-containing vinyl monomer, divinylbenzene and organic solvent is (1.5–3.5):(0.25–0.85):(0.15–0.65):15.

[0018] Preferably, in step (1), the peroxide is one or a mixture of two of benzoyl peroxide or acetophenone peroxide, and the mass of the peroxide is 0.5%–2% of the sum of the masses of the vinyl monomers.

[0019] Preferably, in step (1), the transparent liquid is transferred to a high-pressure reactor and heated under nitrogen protection using a programmed temperature rise method to initiate a monomer polymerization reaction in the transparent liquid, specifically including:

[0020] After the transparent liquid is transferred to a high-pressure reactor, the air inside the reactor is replaced with nitrogen.

[0021] According to the programmed temperature rise process, the temperature is first raised to 70–90°C at a heating rate of 3–5°C / min to initiate monomer polymerization, and then held at this temperature for 8–10 hours.

[0022] Then, heat to 100–130°C at a heating rate of 5°C / min and age for at least 6 hours.

[0023] Preferably, in step (1), after natural drying, the polymer sample is further dried and crushed to obtain the polymer sample, specifically including:

[0024] The blocky solid obtained after natural cooling is taken out and naturally dried for 48–72 hours, then dried at 100°C for 6–12 hours, and then crushed to 20–40 mesh to obtain the polymer sample.

[0025] Preferably, in step (2), the compound of group IB, IIB or IIIA metal is one or more of the nitrate, acetate or acetylacetone compounds of copper, zinc, silver, cadmium, aluminum, gallium or indium metals.

[0026] Preferably, in step (2), the melamine resin and phenolic resin are respectively their water or ethanol solutions, and their mass fractions are both 30%–50%; the sum of the impregnation amounts of melamine resin and phenolic resin is 3%–20% of the mass of the polymer sample, and the mass ratio of melamine resin and phenolic resin in the impregnation solution is (0–1.5):1.

[0027] Preferably, in step (2), the mass of the metal is 0.25%–3% of the sum of the masses of the polymer sample, melamine resin, and phenolic resin, and the mass of the ammonium chloride is 2%–5% of the sum of the masses of the melamine resin and phenolic resin.

[0028] Preferably, in step (2), the temperature is increased to carry out a curing process, specifically as follows:

[0029] The temperature is increased to 90–120℃ at a heating rate of 3–5℃ / min for curing treatment, and the curing time is 4–6h.

[0030] Preferably, in step (3), the non-oxidizing atmosphere is one or more of nitrogen, ammonia, argon, and helium, and the gas hourly space velocity of the atmosphere is 10–30 h⁻¹. –1 .

[0031] Preferably, in step (3), heat treatment is performed to carbonize the modified polymer sample, specifically as follows:

[0032] The samples were pretreated by heating to 250–300℃ at a heating rate of 5–10℃ / min for 3–5 hours.

[0033] Then, the temperature is increased to 400–500℃ at a heating rate of 0.5–2℃ / min and held for 1–2 hours;

[0034] Then, the temperature is raised to 600–1100℃ to carbonize the sample for 2–3 hours.

[0035] According to another aspect of the invention, an application of an atomically Lewis acid-base modified functional carbon material is provided for the purification of chlorosilanes to remove most of the boron, phosphorus and metal impurities from the chlorosilanes.

[0036] Preferably, the purification of chlorosilanes to remove most of the boron, phosphorus, and metal impurities from the chlorosilanes includes the following steps:

[0037] S1, Weigh a certain amount of the functional carbon material and place it in a purification container, then introduce high-purity nitrogen to replace the air in the purification container;

[0038] S2, then inject 40 times the amount of chlorosilane to be purified, seal the system, stir, and perform adsorption treatment on the chlorosilane to be purified. The adsorption temperature is set to 10–50℃, the stirring speed is set to 20–200rpm, and the adsorption time is controlled to 1–24h.

[0039] S3. After adsorption is complete, filter to recover the adsorbent and obtain purified chlorosilane.

[0040] The method for preparing atomically Lewis acid-base modified functional carbon materials of the present invention has at least the following advantages compared with the prior art:

[0041] 1) High material modification efficiency. This method adopts a carbon material preparation + in-situ modification strategy, which simultaneously achieves the functional modification of the material during the carbon material preparation process. Compared with the conventional post-modification strategy of activated carbon, the modification efficiency is higher and the modification effect is better.

[0042] 2) Superior physical structure of the material. First, the carbon material precursor is a cross-linked polymer. In particular, aromatic or aliphatic alkanes are added as pore-forming agents during polymerization to increase the pore structure of the material, which can greatly improve the specific surface area. Second, melamine resin and phenolic resin are used to modify the polymer sample. After high-temperature curing of the resin, the structural strength of the polymer can be further improved, so that the material retains a rich three-dimensional pore structure after high-temperature carbonization. Finally, the polymer sample and the resin introduced by subsequent impregnation also have a relatively rich number of oxygen-containing groups. These oxygen-containing groups can act as oxidants during the subsequent high-temperature carbonization process to oxidize and etch the carbon material matrix, resulting in a richer pore structure. After carbonization, the material has a three-level pore structure of micropores-mesopores-macropores. The rich pore structure and high specific surface area can improve the mass transfer effect and facilitate the adsorption of impurities.

[0043] 3) Abundant and dispersed functional sites. Carbon precursors contain abundant nitrogen-containing structural units (cyano groups). After high-temperature heat treatment, a large number of cyano units on the molecular chain are transformed into more stable structural nitrogen sites (such as pyridine nitrogen, pyrrole nitrogen, and graphitic nitrogen), which are retained in the carbonized material. Secondly, the melamine resin introduced by impregnation onto the polymer sample surface, after high-temperature carbonization, also transforms a large number of nitrogen-containing groups (amine groups, imino groups) in its molecular structure into more stable structural nitrogen sites, achieving in-situ doping on the carbon material surface. Simultaneously, an ammonia atmosphere provides a nitrogen-rich environment, further promoting nitrogen atom doping on the carbon material. The numerous nitrogen sites doped on the carbon material surface can anchor metal atoms, forming a stable metal-N coordination structure. The strong carrier coordination effect makes the metal atom center exhibit significant electron deficiency, becoming Lewis acid sites, while free N sites, due to their electron-rich characteristics, become Lewis base sites. These abundant and highly dispersed Lewis acid-base sites effectively adsorb phosphorus, boron, and metal impurities, improving impurity removal efficiency.

[0044] 4) Stable functional site structure. During high-temperature carbonization, N atoms, due to their similar size to C atoms, can be easily doped into the carbon lattice, forming stable lattice N sites. The N sites doped on the carbon surface anchor the metal center through strong bonding with metal atoms, forming a stable metal-N coordination structure, which makes the metal sites stably dispersed and less prone to aggregation and loss. Attached Figure Description

[0045] Figure 1 This is a schematic flowchart of the preparation method of atomic-level Lewis acid-base modified functional carbon materials in the embodiments of the present invention;

[0046] Figure 2The images shown are scanning electron microscope (SEM) and transmission electron microscope (TEM) images of the carbon material obtained in the embodiments of the present invention. (a) and (b) are SEM images of the material at different magnifications; (c) is a spherical aberration corrected SEM image, in which bright spots represent monodisperse metal atom images; and (d) is an elemental distribution map of the material surface. Detailed Implementation

[0047] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0048] In addressing the shortcomings of existing technologies, such as low modification efficiency and inability to significantly increase the number of functional groups on the material surface, while post-loading of functional molecules can effectively compensate for this deficiency, it inevitably clogs material pores and reduces the specific surface area. Furthermore, the post-loaded active components are not firmly attached to the carbon support surface, and there is a risk of loss during adsorption. Considering the acid-base properties of boron and phosphorus impurities, this invention provides a method for preparing atomically Lewis acid-base modified functional carbon materials, comprising:

[0049] (1) Polymer preparation: Nitrogen-containing vinyl monomer acrylonitrile, oxygen-containing vinyl monomer and crosslinking agent divinylbenzene are added to an organic solvent to obtain a mixed solution; peroxide is added to the mixed solution as an initiator, and the mixture is stirred thoroughly for at least 2 hours under nitrogen protection.

[0050] h, a transparent solution is obtained; the transparent liquid is transferred to a high-pressure reactor, and heated under nitrogen protection by programmed temperature rise to initiate the monomer polymerization reaction of the transparent liquid; after the reaction is completed, the system is cooled naturally, dried naturally, and then dried and crushed to obtain a polymer sample;

[0051] (2) Polymer modification: Add compounds of Group IB, IIB or IIIA metals to a mixed solution of melamine resin and phenolic resin and stir thoroughly to dissolve; then add ammonium chloride as a resin curing agent and stir thoroughly to dissolve to obtain a modified mixed solution; use an impregnation method to impregnate the modified mixed solution into the polymer sample obtained after drying in step (1); transfer the impregnated sample to a high-pressure reactor, heat it, and perform curing treatment; after the curing treatment is completed, the system is allowed to cool down naturally to obtain the modified polymer sample;

[0052] (3) Polymer carbonization: The modified polymer sample was heat-treated in a non-oxidizing atmosphere to carbonize the modified polymer sample; after carbonization, the system was cooled naturally; then, after washing and drying, the target functional carbon material was obtained.

[0053] Furthermore, the present invention also discloses an application of the above-described atomic-level Lewis acid-base modified functional carbon material for the purification of chlorosilanes to remove most of the boron, phosphorus and metal impurities from the chlorosilanes.

[0054] Example 1

[0055] like Figure 1 As shown in the figure, this embodiment discloses a method for preparing atomically Lewis acid-base modified functional carbon materials, including:

[0056] (1) Polymer preparation: At room temperature, a certain amount of nitrogen-containing vinyl monomer acrylonitrile, oxygen-containing vinyl monomer and crosslinking agent divinylbenzene are added to an organic solvent to obtain a mixed solution; a certain amount of peroxide is added to the mixed solution as an initiator, and the mixture is stirred thoroughly for at least 2 hours under nitrogen protection to obtain a transparent solution;

[0057] The transparent liquid is transferred to a high-pressure reactor and heated under nitrogen protection to initiate monomer polymerization.

[0058] After the reaction was completed, the system was allowed to cool down naturally, and after natural drying, it was dried and crushed to obtain the polymer sample.

[0059] (2) Polymer modification: A certain amount of IB, IIB or IIIA metal compounds are added to a mixed solution of melamine resin and phenolic resin, and stirred thoroughly to dissolve. The metal species are stabilized and uniformly dispersed by utilizing the abundant amine, hydroxyl and other functional groups in the resin system.

[0060] Then, a certain amount of ammonium chloride is added as a resin curing agent, and the mixture is stirred thoroughly to dissolve it, thus obtaining a modified mixed solution.

[0061] An impregnation method was used to impregnate the modified mixed solution into the polymer sample obtained after drying in step (1);

[0062] The impregnated sample was transferred to a high-pressure reactor, heated, and cured.

[0063] After the curing process is completed, the system is allowed to cool naturally to obtain the modified polymer sample;

[0064] (3) Polymer carbonization: The modified polymer sample was placed in a quartz tube furnace and heat-treated in a non-oxidizing atmosphere throughout the process to carbonize the modified polymer sample.

[0065] After carbonization, the system cooled down naturally.

[0066] After washing and drying, the target functional carbon material was obtained, and its scanning and transmission electron microscopy test results are as follows: Figure 2 As shown.

[0067] Depend on Figure 2 As can be seen from scanning electron microscope images at different magnifications, the prepared functional carbon material has a rich porous structure. Meanwhile, aberration-corrected scanning transmission electron microscope images show that the Lewis acidic metal sites (taking Al as an example) in the material are dispersed as individual atoms (highlights in the image), and the surface elemental distribution map also shows a uniform distribution of N sites and metal sites. All of these factors will effectively increase the number of adsorption sites and improve the material's adsorption effect on impurities.

[0068] In this embodiment, the high-pressure reactors mentioned in steps (1) and (2) are stainless steel high-pressure reactors with polytetrafluoroethylene lining to prevent the introduction of impurities.

[0069] In some embodiments, in step (1), the oxyvinyl monomer is one or a mixture of two of itaconic acid or methyl acrylate.

[0070] In some embodiments, in step (1), the organic solvent is a mixture of ethyl acetate, ethyl acetate / toluene, ethyl acetate / xylene, ethyl acetate / trimethylene, ethyl acetate / hexane, ethyl acetate / heptane, or ethyl acetate / octane, wherein toluene, xylene, trimethylene, hexane, heptane, or octane are porogens, and the mass ratio of toluene, xylene, trimethylene, hexane, heptane, or octane to ethyl acetate is (0–0.3):1.

[0071] In some embodiments, in step (1), the mass ratio of nitrogen-containing vinyl monomer, oxygen-containing vinyl monomer, divinylbenzene to organic solvent is (1.5–3.5):(0.25–0.85):(0.15–0.65):15.

[0072] In some embodiments, in step (1), the peroxide is one or a mixture of two of benzoyl peroxide or acetophenone peroxide, and the mass of the peroxide is 0.5%–2% of the sum of the masses of the vinyl monomers.

[0073] In some embodiments, in step (1), the transparent liquid is transferred to a high-pressure reactor and heated under nitrogen protection to initiate a monomer polymerization reaction, specifically including:

[0074] After the transparent liquid is transferred to a high-pressure reactor, the air inside the reactor is replaced with nitrogen.

[0075] According to the programmed temperature rise process, the temperature is first raised from room temperature to 70–90°C at a heating rate of 3–5°C / min to initiate monomer polymerization, and then held at this temperature for 8–10 hours to allow the transparent liquid to quickly initiate the polymerization reaction in a short time and generate high-density oligomer units.

[0076] Then, the temperature is increased to 100–130°C at a heating rate of 5°C / min and aged for at least 6 hours to promote the cross-linking reaction between oligomer units, extend the polymer molecular chain, and enhance the polymer structural strength.

[0077] In some embodiments, in step (1), after natural drying, the polymer sample is further dried and crushed to obtain a polymer sample, specifically including:

[0078] The blocky solid obtained after natural cooling is taken out and naturally dried for 48–72 hours, then dried at 100°C for 6–12 hours, and then crushed to 20–40 mesh to obtain the polymer sample.

[0079] In some embodiments, in step (2), the compound of a Group IB, IIB, or IIIA metal is one or more of a nitrate, acetate, or acetylacetone compound of copper, zinc, silver, cadmium, aluminum, gallium, or indium.

[0080] In some embodiments, in step (2), melamine resin and phenolic resin are respectively their water or ethanol solutions, each with a mass fraction of 30%–50%; the sum of the impregnation amounts of melamine resin and phenolic resin is 3%–20% of the mass of the polymer sample, and the mass ratio of melamine resin to phenolic resin in the impregnation solution is (0–1.5):1.

[0081] In some embodiments, in step (2), the mass of the metal is 0.25%–3% of the sum of the masses of the polymer sample, melamine resin, and phenolic resin, and the mass of the ammonium chloride is 2%–5% of the sum of the masses of the melamine resin and phenolic resin.

[0082] In some implementations, step (2) involves heating to perform a curing process, specifically as follows:

[0083] The material is cured by heating from room temperature to 90–120°C at a heating rate of 3–5°C / min for 4–6 hours. This process improves the structural strength of the polymer by introducing a thermosetting resin skeleton, which helps maintain the pore structure of the material during high-temperature carbonization. At the same time, the introduction of melamine resin can bring abundant nitrogen-containing structural units, which helps to increase the nitrogen site content on the surface of the carbonized material and improve the stability and dispersion of surface metal sites.

[0084] In some embodiments, in step (3), the non-oxidizing atmosphere is one or more of nitrogen, ammonia, argon, and helium, and the gas hourly space velocity of the atmosphere is 10–30 h⁻¹.–1 .

[0085] In some embodiments, in step (3), heat treatment is performed to carbonize the modified polymer sample, specifically:

[0086] The sample was pretreated by heating from room temperature to 250–300℃ at a heating rate of 5–10℃ / min for 3–5 hours. During this stage, the oxygen-containing groups on the polymer chain will rapidly initiate cross-linking cyclization reactions between adjacent cyano groups, and the nitrogen and oxygen groups on the molecular chain will be reconstructed and cured. Due to the presence of oxygen-containing monomers, this process does not depend on an oxidizing atmosphere and the molecular chain reconstruction effect is better.

[0087] Then, the temperature is increased to 400–500℃ at a heating rate of 0.5–2℃ / min and held for 1–2 hours. This process mainly completes the cross-linking reaction between polymer molecular chains and melamine resin and phenolic resin, constructing a primary graphitized structure, avoiding the violent decomposition reaction caused by direct one-step high-temperature carbonization, which is beneficial to improving the yield of carbon materials.

[0088] Then, the temperature is raised to 600–1100℃ to carbonize the sample for 2–3 hours.

[0089] In this embodiment, in step (3), deionized water is used to wash the carbonized products.

[0090] The method for preparing atomically Lewis acid-base modified functional carbon materials in this embodiment has at least the following advantages compared to existing technologies:

[0091] 1) High material modification efficiency. This method adopts a carbon material preparation + in-situ modification strategy, which simultaneously achieves the functional modification of the material during the carbon material preparation process. Compared with the conventional post-modification strategy of activated carbon, the modification efficiency is higher and the modification effect is better.

[0092] 2) Superior physical structure of the material. First, the carbon material precursor (i.e., the polymer sample) is selected as a cross-linked polymer. In particular, aromatic or aliphatic alkanes are added as pore-forming agents during the polymerization process to increase the pore structure of the material, which can greatly improve the specific surface area of ​​the material. Second, melamine resin and phenolic resin are selected to modify the polymer sample. After the resin is cured at high temperature, it can further improve the structural strength of the polymer, so that the material retains a rich three-dimensional pore structure after high-temperature carbonization. Finally, the polymer and the resin introduced by subsequent impregnation also have a relatively rich number of oxygen-containing groups. These oxygen-containing groups can act as oxidants in the subsequent high-temperature carbonization process to oxidize and etch the carbon material matrix, resulting in a richer pore structure. After carbonization, the material has a three-level pore structure of micropores-mesopores-macropores. The rich pore structure and high specific surface area can make the mass transfer effect better and more conducive to impurity adsorption.

[0093] 3) Abundant and dispersed functional sites. Carbon precursors contain abundant nitrogen-containing structural units (cyano groups). After high-temperature heat treatment, a large number of cyano units on the molecular chain are transformed into more stable structural nitrogen sites (such as pyridine nitrogen, pyrrole nitrogen, and graphitic nitrogen), which are retained in the carbonized material. Secondly, the melamine resin introduced by impregnation onto the polymer sample surface, after high-temperature carbonization, also transforms a large number of nitrogen-containing groups (amine groups, imino groups) in its molecular structure into more stable structural nitrogen sites, achieving in-situ doping on the carbon material surface. Simultaneously, an ammonia atmosphere provides a nitrogen-rich environment, further promoting nitrogen atom doping on the carbon material. The numerous nitrogen sites doped on the carbon material surface can anchor metal atoms, forming a stable metal-N coordination structure. The strong carrier coordination effect makes the metal atom center exhibit significant electron deficiency, becoming Lewis acid sites, while free N sites, due to their electron-rich characteristics, become Lewis base sites. These abundant and highly dispersed Lewis acid-base sites effectively adsorb phosphorus, boron, and metal impurities, improving impurity removal efficiency.

[0094] 4) Stable functional site structure. During high-temperature carbonization, N atoms, due to their similar size to C atoms, can be easily doped into the carbon lattice, forming stable lattice N sites. The N sites doped on the carbon surface anchor the metal center through strong bonding with metal atoms, forming a stable metal-N coordination structure, which makes the metal sites stably dispersed and less prone to aggregation and loss.

[0095] Example 2

[0096] This embodiment discloses the application of an atomically Lewis acid-base modified functional carbon material for the purification of chlorosilanes to remove most of the boron, phosphorus and metal impurities from chlorosilanes.

[0097] In some embodiments, the application of the atomically Lewis acid-base modified functional carbon material includes the following steps:

[0098] S1, Weigh a certain amount of the functional carbon material and place it in a purification container, then introduce high-purity nitrogen to replace the air in the purification container;

[0099] S2, then inject 40 times the amount of chlorosilane to be purified, seal the system, stir, and perform adsorption treatment on the chlorosilane to be purified. The adsorption temperature is set to 10–50℃, the stirring speed is set to 20–200rpm, and the adsorption time is controlled to 1–24h.

[0100] S3. After adsorption is complete, filter to recover the adsorbent and obtain purified chlorosilane.

[0101] Subsequently, the impurity content in the chlorosilane before and after adsorption was analyzed using the ICP-OES method, and the impurity adsorption rate was calculated based on the difference (i.e., the impurity content in the chlorosilane to be purified and the impurity content in the purified chlorosilane). The formula for calculating the adsorption rate is as follows:

[0102] Impurity adsorption rate (%) = [(Initial impurity content in chlorosilane before adsorption - Impurity content in chlorosilane after adsorption) / (Initial impurity content in chlorosilane before adsorption)] * 100%.

[0103] Example 3

[0104] This embodiment discloses a method for preparing atomically Lewis acid-base modified functional carbon materials, including:

[0105] (1) Add acrylonitrile, methyl acrylate and divinylbenzene to a three-necked round-bottom flask containing a mixed solution of ethyl acetate and toluene, and stir until homogeneous; under nitrogen protection, add benzoyl peroxide as an initiator and stir thoroughly for 2 hours to obtain a transparent solution;

[0106] The above transparent solution was transferred to a stainless steel high-pressure reactor with a polytetrafluoroethylene liner, and the air inside the reactor was replaced with nitrogen. Then, the temperature was increased according to the programmed temperature rise process. First, the temperature was increased from room temperature to 80°C at a rate of 5°C / min to initiate monomer polymerization, and then held at the target temperature for 8 hours. Then, the temperature was increased to 130°C at a rate of 5°C / min for aging for 6 hours.

[0107] After the reaction was completed, the system was allowed to cool down naturally. The resulting blocky solid was then removed and dried naturally for 72 hours. It was then dried in a forced-air oven at 100°C for 12 hours. The dried white solid sample was then crushed to 20–40 mesh for later use, yielding the polymer sample.

[0108] In this embodiment, in the mixed solution of ethyl acetate and toluene, the mass ratio of ethyl acetate to toluene is 9:2; the mass ratio of acrylonitrile, methyl acrylate, divinylbenzene to the organic mixed solution is 3:0.5:0.45:15; and the mass of benzoyl peroxide is 1.5% of the sum of the masses of acrylonitrile, methyl acrylate, and divinylbenzene.

[0109] (2) Add a certain amount of aluminum nitrate and ammonium chloride to the mixed solution of melamine resin and phenolic resin and stir thoroughly to dissolve; then, using an impregnation method, impregnate the mixed solution into the polymer sample obtained after drying in step (1), transfer the impregnated sample to a stainless steel high-pressure reactor with a polytetrafluoroethylene liner, and heat it from room temperature to 100°C at a heating rate of 5°C / min for curing treatment for 6 hours; after the curing treatment is completed, the system is allowed to cool down naturally to obtain the modified polymer sample;

[0110] In this embodiment, melamine resin and phenolic resin are aqueous solutions, each with a mass fraction of 50%. The sum of their impregnation amounts is 10% of the polymer sample mass, and the mass ratio of melamine resin to phenolic resin in the impregnation solution is 0.75:1. The mass of metallic Al is 1% of the sum of the masses of the polymer sample, melamine resin, and phenolic resin. The mass of the curing agent ammonium chloride is 3% of the sum of the masses of melamine resin and phenolic resin.

[0111] (3) Weigh a certain amount of the modified polymer sample and place it in a quartz tube furnace under an ammonia atmosphere, wherein the ammonia gas space velocity is 15 h⁻¹. –1 Then, the sample was pretreated by heating from room temperature to 280℃ at a heating rate of 10℃ / min for 3 hours; then, the temperature was increased to 450℃ at a heating rate of 0.5℃ / min and held for 1.5 hours; after that, the temperature was increased to 600℃ for carbonization treatment and held for 2 hours; after carbonization, the system was allowed to cool naturally; and the carbonization product was thoroughly washed with deionized water and dried to obtain the target functional carbon material, denoted as FC-1.

[0112] Example 4

[0113] This embodiment discloses a method for preparing functional carbon materials with atomic-level Lewis acid-base site modification. The difference between this method and the method described in Example 3 is that:

[0114] The mass ratio of ethyl acetate to toluene in step (1) was changed from 9:2 to 9:1, and the resulting functional carbon material was designated as FC-2.

[0115] Example 5

[0116] This embodiment discloses a method for preparing functional carbon materials with atomic-level Lewis acid-base site modification. The difference between this method and the method described in Example 3 is that:

[0117] Replace toluene in step (1) with octane, and the resulting functional carbon material is denoted as FC-3.

[0118] Example 6

[0119] This embodiment discloses a method for preparing functional carbon materials with atomic-level Lewis acid-base site modification. The difference between this method and the method described in Example 3 is that:

[0120] Replace toluene in step (1) with n-heptane, and control the mass ratio of ethyl acetate to n-heptane to be 8:2. The resulting functional carbon material is denoted as FC-4.

[0121] Example 7

[0122] This embodiment discloses a method for preparing functional carbon materials with atomic-level Lewis acid-base site modification. The difference between this method and the method described in Example 3 is that:

[0123] The mass ratio of acrylonitrile, methyl acrylate, divinylbenzene and organic mixed solution in step (1) is changed from 3:0.5:0.45:15 to 3:0.25:0.45:15, and the resulting functional carbon material is denoted as FC-5.

[0124] Example 8

[0125] This embodiment discloses a method for preparing functional carbon materials with atomic-level Lewis acid-base site modification. The difference between this method and the method described in Example 3 is that:

[0126] The impregnation amount of melamine resin and phenolic resin in step (2) was changed from 10% of the polymer mass to 20%, and the resulting functional carbon material was designated as FC-6.

[0127] Example 9

[0128] This embodiment discloses a method for preparing functional carbon materials with atomic-level Lewis acid-base site modification. The difference between this method and the method described in Example 3 is that:

[0129] The mass ratio of melamine resin to phenolic resin in step (2) was changed from 0.75:1 to 1.5:1, and the resulting functional carbon material was designated as FC-7.

[0130] Example 10

[0131] This embodiment discloses a method for preparing functional carbon materials with atomic-level Lewis acid-base site modification. The difference between this method and the method described in Example 3 is that:

[0132] The mass of metallic Al in step (2) is changed from 1% of the sum of the masses of polymer, melamine resin and phenolic resin to 3%, and the resulting functional carbon material is designated as FC-8.

[0133] Example 11

[0134] This embodiment discloses a method for preparing functional carbon materials with atomic-level Lewis acid-base site modification. The difference between this method and the method described in Example 3 is that:

[0135] The heat treatment atmosphere in step (3) is changed from ammonia to nitrogen, and the resulting functional carbon material is denoted as FC-9.

[0136] Example 12

[0137] This embodiment discloses a method for preparing functional carbon materials with atomic-level Lewis acid-base site modification. The difference between this method and the method described in Example 3 is that:

[0138] The material pretreatment temperature in step (3) was changed from 280℃ to 250℃, and the resulting functional carbon material was denoted as FC-10.

[0139] Example 13

[0140] This embodiment discloses a method for preparing functional carbon materials with atomic-level Lewis acid-base site modification. The difference between this method and the method described in Example 3 is that:

[0141] The material pretreatment time at 280℃ in step (3) was changed from 3h to 5h, and the resulting functional carbon material was denoted as FC-11.

[0142] Example 14

[0143] This embodiment discloses a method for preparing functional carbon materials with atomic-level Lewis acid-base site modification. The difference between this method and the method described in Example 3 is that:

[0144] The carbonization temperature in step (3) is changed from 600℃ to 800℃, and the resulting functional carbon material is denoted as FC-12.

[0145] Example 15

[0146] This embodiment discloses a method for preparing functional carbon materials with atomic-level Lewis acid-base site modification. The difference between this method and the method described in Example 3 is that:

[0147] The carbonization temperature in step (3) is changed from 600℃ to 1000℃, and the resulting functional carbon material is denoted as FC-13.

[0148] Example 16

[0149] This embodiment discloses a method for preparing functional carbon materials with atomic-level Lewis acid-base site modification. The difference between this method and the method described in Example 3 is that:

[0150] In step (1), replace ethyl acetate and toluene with ethyl acetate, that is, remove toluene;

[0151] The mass ratio of acrylonitrile, methyl acrylate, divinylbenzene and organic mixed solution in step (1) is changed from 3:0.5:0.45:15 to 3.5:0.25:0.65:15;

[0152] The impregnation amount of melamine resin and phenolic resin in step (2) is changed from 10% of the polymer mass to 3%;

[0153] The mass ratio of melamine resin to phenolic resin in step (2) is changed from 0.75:1 to 1.25:1;

[0154] The mass of metallic Al in step (2) is changed from 1% of the sum of the masses of the polymer, melamine resin, and phenolic resin to 0.25%.

[0155] The heat treatment atmosphere in step (3) is changed from ammonia to nitrogen and argon;

[0156] Change the material pretreatment temperature in step (3) from 280℃ to 300℃;

[0157] The material pretreatment time at 280℃ in step (3) is changed from 3 hours to 3.5 hours;

[0158] Change the carbonization temperature in step (3) from 600℃ to 700℃;

[0159] The resulting functional carbon material is designated FC-14.

[0160] Example 17

[0161] This embodiment discloses a method for preparing functional carbon materials with atomic-level Lewis acid-base site modification. The difference between this method and the method described in Example 3 is that:

[0162] Change the mass ratio of ethyl acetate to toluene in step (1) from 9:2 to 9:1;

[0163] The mass ratio of acrylonitrile, methyl acrylate, divinylbenzene and organic mixed solution in step (1) is changed from 3:0.5:0.45:15 to 1.5:0.85:0.15:15;

[0164] The impregnation amount of melamine resin and phenolic resin in step (2) is changed from 10% of the polymer mass to 15%;

[0165] The mass ratio of melamine resin to phenolic resin in step (2) is changed from 0.75:1 to 0:1, that is, melamine resin is removed;

[0166] In step (2), the mass of metallic Al is changed from 1% of the sum of the masses of the polymer, melamine resin, and phenolic resin to 2%.

[0167] Change the material pretreatment temperature in step (3) from 280℃ to 230℃;

[0168] The material pretreatment time at 280℃ in step (3) is changed from 3h to 4h;

[0169] The carbonization temperature in step (3) is changed from 600℃ to 900℃, and the resulting functional carbon material is denoted as FC-15.

[0170] Comparative Example 1

[0171] The preparation steps of Comparative Example 1 are the same as those of Example 3, except that:

[0172] The acrylonitrile monomer in step (1) is simply removed to illustrate the effect of the change in the polymer monomer on the adsorption performance of the carbon material. The resulting carbon material is denoted as SC-1.

[0173] Comparative Example 2

[0174] The preparation steps for Comparative Example 2 are the same as those for Example 3, except that:

[0175] The only difference is that the mass ratio of ethyl acetate to toluene in step (1) is changed from 9:2 to 5:5. This is to illustrate the effect of excessive porogen on the adsorption performance of carbon materials. The resulting carbon material is denoted as SC-2.

[0176] Comparative Example 3

[0177] The preparation steps for Comparative Example 3 are the same as those for Example 3, except that:

[0178] The step of heating to 130℃ and aging for 6 hours in step (1) was removed to illustrate the effect of polymerization conditions on the adsorption performance of carbon materials. The resulting carbon material is denoted as SC-3.

[0179] Comparative Example 4

[0180] The preparation steps for Comparative Example 4 are the same as those for Example 3, except that:

[0181] The only change in step (1) is to modify “take out the lumpy solid obtained from polymerization and dry it naturally for 72 hours, and then dry it in a forced-air oven at 100°C for 12 hours” to “take out the lumpy solid obtained from polymerization and dry it directly in a forced-air oven at 100°C for 24 hours”. The purpose is to illustrate the effect of drying method on the adsorption performance of carbon material. The resulting carbon material is denoted as SC-4.

[0182] Comparative Example 5

[0183] The preparation steps of Comparative Example 5 are the same as those of Example 3, except that:

[0184] The aluminum nitrate metal salt in step (2) is simply removed to illustrate the effect of metal addition on the adsorption performance of carbon materials. The resulting carbon material is denoted as SC-5.

[0185] Comparative Example 6

[0186] The preparation steps of Comparative Example 6 are the same as those of Example 3, except that:

[0187] The phenolic resin in step (2) is simply removed to illustrate the effect of the introduction of phenolic resin on the structure and adsorption performance of carbon materials. The resulting carbon material is denoted as SC-6.

[0188] Comparative Example 7

[0189] The preparation steps of Comparative Example 7 are the same as those of Example 3, except that:

[0190] The step of “heating to 450℃ at a heating rate of 0.5℃ / min and holding for 1.5h” in step (3) is removed. The purpose is to illustrate the effect of the carbonization process on the structure and adsorption performance of the carbon material. The resulting carbon material is denoted as SC-7.

[0191] Comparative Example 8

[0192] The preparation steps of Comparative Example 8 are basically the same as those of Example 3, except that:

[0193] The only difference is that the aluminum nitrate metal salt in step (2) is removed, and step (4) is added after step (3). The content is: the aluminum nitrate aqueous solution is immersed in the carbonized product, and then the temperature is raised to 600℃ at a heating rate of 2℃ / min for heat treatment. The heat treatment time is maintained for 2h. After the heat treatment is completed, the system is cooled down naturally. The mass of the metal Al is 2% of the mass of the carbonized product.

[0194] The purpose of this comparative example is to illustrate the effect of metal loading order on the adsorption performance of carbon materials, and the resulting carbon material is denoted as SC-8.

[0195] Comparative Example 9

[0196] Comparative Example 9 used a commercially available brand of coal with the following specifications: strength 97.8%, ash content 8.9%, and specific surface area ~1230 m². 2 / g, with pore sizes concentrated at 2nm and below, crushed to 20 mesh for later use, the sample is designated as SC-9.

[0197] Comparative Example 10

[0198] Comparative Example 10 used a commercially available brand of coconut shell charcoal with the following specifications: strength 98.4%, ash content 0.3%, and specific surface area ~1400 m². 2 / g, with pore sizes concentrated at 2nm and below, crushed to 20 mesh for later use, the sample is designated as SC-10.

[0199] The carbon materials obtained in Examples 3-15 and Comparative Examples 1-10 were used for the purification of chlorosilanes to adsorb and remove most of the boron, phosphorus, and metal impurities from the chlorosilanes. The steps included:

[0200] S1. Weigh 1g of carbon material and place it in a dry three-necked round-bottom flask. Then, introduce high-purity nitrogen to displace the air in the flask.

[0201] S2. After the replacement is completed, inject 40g of the chlorosilane to be purified into it with a syringe. Seal the system, stir, and perform adsorption treatment on the chlorosilane to be purified. The adsorption temperature is set to 20℃, the stirring speed is set to 50rpm, and the adsorption time is 12h.

[0202] S3. After adsorption is complete, filter to recover the adsorbent and obtain purified chlorosilane.

[0203] S4. The impurity content in the chlorosilane before and after adsorption was analyzed by ICP-OES, and the impurity adsorption rate was calculated based on the difference. The formula for calculating the adsorption rate is as follows:

[0204] Impurity adsorption rate (%) = [(Initial impurity content in chlorosilane before adsorption - Impurity content in chlorosilane after adsorption) / (Initial impurity content in chlorosilane before adsorption)] * 100%

[0205] The data on the removal of impurities from chlorosilanes by the different carbon materials used as adsorbents are shown in Table 1. The chlorosilanes to be purified used in each test were taken from the same batch of samples. The metal removal rate refers to the removal rate of the total content of metals such as iron, nickel, copper, and zinc in chlorosilanes.

[0206] Table 1

[0207]

[0208]

[0209] Table 1 shows that the nitrogen (N) content in carbon materials has a significant impact on their adsorption performance. For example, reducing the introduction of nitrogen-containing components (such as acrylonitrile and melamine resin) during the preparation of FC-15 and SC-1 reduces the adsorption of boron (B) impurities and metals. Furthermore, it indirectly reduces the adsorption of phosphorus (P) impurities by affecting the dispersion and morphology of Lewis acid metal sites on the material surface. Increasing the carbonization temperature also leads to significant nitrogen loss, as seen in FC-13, where the adsorption effect is noticeably reduced. The polymer drying process and the addition of pore-forming agents primarily affect the pore structure of the material. For example, in SC-2 and SC-4, excessive toluene as a pore-forming agent reduces the pore size, and excessively rapid drying reduces the pore structure of the carbon material, both of which weaken the adsorption kinetics and worsen the adsorption effect on impurities. The adsorption results of SC-5 indicate that the addition of Lewis acid metal Al is crucial for the adsorption of P impurities. Combining the adsorption results of Examples 1-17 with those of Comparative Examples 9 and 10, it is evident that the Lewis acid-base modified functional carbon material exhibits significantly better impurity adsorption performance than conventional commercial activated carbon, demonstrating the effectiveness of the modification strategy employed in this invention. Differences in adsorption performance among other comparative examples can be compared based on their specific implementation steps, and will not be elaborated upon here.

[0210] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A method for preparing an atomically Lewis acid-base modified functional carbon material, comprising: (1) Polymer preparation: Nitrogen-containing vinyl monomer acrylonitrile, oxygen-containing vinyl monomer and divinylbenzene are added to an organic solvent to obtain a mixed solution; Add peroxide as an initiator to the mixed solution and stir thoroughly for at least 2 hours under nitrogen protection to obtain a transparent solution; The transparent liquid was transferred to a high-pressure reactor and heated under nitrogen protection to initiate monomer polymerization. After the reaction, the system was allowed to cool naturally, dried naturally, and then dried and crushed to obtain polymer samples. (2) Polymer modification: Add compounds of Group IB, IIB or IIIA metals to a mixed solution of melamine resin and phenolic resin and stir thoroughly to dissolve; then add ammonium chloride as a resin curing agent and stir thoroughly to dissolve to obtain a modified mixed solution; An impregnation method was used to impregnate the modified mixed solution into the polymer sample obtained after drying in step (1); The impregnated sample was transferred to a high-pressure reactor, heated, and cured. After curing, the system cooled naturally to obtain the modified polymer sample. (3) Polymer carbonization: The modified polymer sample was heat-treated in a non-oxidizing atmosphere to carbonize the modified polymer sample; after carbonization, the system was cooled naturally; then, after washing and drying, the target functional carbon material was obtained.

2. The method for preparing atomically Lewis acid-base modified functional carbon materials according to claim 1, characterized in that, In step (1), the oxyvinyl monomer is one or a mixture of two of itaconic acid or methyl acrylate.

3. The method for preparing atomically Lewis acid-base modified functional carbon materials according to claim 1, characterized in that, In step (1), the organic solvent is a mixture of ethyl acetate, ethyl acetate / toluene, ethyl acetate / xylene, ethyl acetate / trimethylene, ethyl acetate / hexane, ethyl acetate / heptane, or ethyl acetate / octane, wherein the mass ratio of toluene, xylene, trimethylene, hexane, heptane, or octane to ethyl acetate is (0–0.3):

1.

4. The method for preparing atomically Lewis acid-base modified functional carbon materials according to claim 1, characterized in that, In step (1), the mass ratio of nitrogen-containing vinyl monomer, oxygen-containing vinyl monomer, divinylbenzene and organic solvent is (1.5–3.5):(0.25–0.85):(0.15–0.65):

15.

5. The method for preparing atomically Lewis acid-base modified functional carbon materials according to claim 1, characterized in that, In step (1), the peroxide is one or a mixture of two of benzoyl peroxide or acetophenone peroxide, and the mass of the peroxide is 0.5%–2% of the sum of the masses of the vinyl monomers.

6. The method for preparing atomically Lewis acid-base modified functional carbon materials according to claim 1, characterized in that, In step (1), the transparent liquid is transferred to a high-pressure reactor and heated under nitrogen protection to initiate the monomer polymerization reaction of the transparent liquid, specifically including: After the transparent liquid is transferred to a high-pressure reactor, the air inside the reactor is replaced with nitrogen. According to the programmed temperature rise process, the temperature is first raised to 70–90°C at a heating rate of 3–5°C / min to initiate monomer polymerization, and then held at this temperature for 8–10 hours. Then, heat to 100–130°C at a heating rate of 5°C / min and age for at least 6 hours.

7. The method for preparing atomically Lewis acid-base modified functional carbon materials according to claim 1, characterized in that, In step (1), after natural drying, the polymer sample is further dried and crushed to obtain the following: The blocky solid obtained after natural cooling is taken out and naturally dried for 48–72 hours, then dried at 100°C for 6–12 hours, and then crushed to 20–40 mesh to obtain the polymer sample.

8. The method for preparing atomically Lewis acid-base modified functional carbon materials according to claim 1, characterized in that, In step (2), the compound of group IB, IIB or IIIA metal is one or more of the nitrate, acetate or acetylacetone compounds of copper, zinc, silver, cadmium, aluminum, gallium or indium metal.

9. The method for preparing atomically Lewis acid-base modified functional carbon materials according to claim 1, characterized in that, In step (2), melamine resin and phenolic resin are respectively their water or ethanol solutions, and their mass fractions are both 30%–50%; the sum of the impregnation amounts of melamine resin and phenolic resin is 3%–20% of the mass of the polymer sample, and the mass ratio of melamine resin and phenolic resin in the impregnation solution is (0–1.5):

1.

10. The method for preparing atomically Lewis acid-base modified functional carbon materials according to claim 1, characterized in that, In step (2), the mass of the metal is 0.25%–3% of the sum of the masses of the polymer sample, melamine resin, and phenolic resin, and the mass of the ammonium chloride is 2%–5% of the sum of the masses of the melamine resin and phenolic resin.

11. The method for preparing atomically Lewis acid-base modified functional carbon materials according to claim 1, characterized in that, In step (2), the temperature is increased to carry out a curing process, specifically as follows: The temperature is increased to 90–120℃ at a heating rate of 3–5℃ / min for curing treatment, and the curing time is 4–6h.

12. The method for preparing atomically Lewis acid-base modified functional carbon materials according to claim 1, characterized in that, In step (3), the non-oxidizing atmosphere is one or more of nitrogen, ammonia, argon, helium, and the like, and the gas volume space velocity of the atmosphere is 10-30 h –1 .

13. The method for preparing atomically Lewis acid-base modified functional carbon materials according to claim 1, characterized in that, In step (3), heat treatment is performed to carbonize the modified polymer sample, specifically as follows: The samples were pretreated by heating to 250–300℃ at a heating rate of 5–10℃ / min for 3–5 hours. Then, the temperature is increased to 400–500℃ at a heating rate of 0.5–2℃ / min and held for 1–2 hours; Then, the temperature is raised to 600–1100℃ to carbonize the sample for 2–3 hours.

14. The application of a functional carbon material with atomic-level Lewis acid-base site modification as described in any one of claims 1-13, characterized in that, Used for the purification of chlorosilanes to remove most of the boron, phosphorus, and metal impurities from them.

15. The application of the functional carbon material with atomic-level Lewis acid-base site modification according to claim 14, characterized in that, Includes the following steps: S1, Weigh a certain amount of the functional carbon material and place it in a purification container, then introduce high-purity nitrogen to replace the air in the purification container; S2, then inject 40 times the amount of chlorosilane to be purified, seal the system, stir, and perform adsorption treatment on the chlorosilane to be purified. The adsorption temperature is set to 10–50℃, the stirring speed is set to 20–200rpm, and the adsorption time is controlled to 1–24h. S3. After adsorption is complete, filter to recover the adsorbent and obtain purified chlorosilane.

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