Nano-porous carbon sphere as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of porous carbon materials, and discloses a nano-porous carbon sphere as well as a preparation method and application thereof. The average particle size of the nano-porous carbon spheres is 20-800nm, the specific surface area is 50-5000m < 2 > / g, the pore volume is 0.2-2.0 cm < 3 > / g, and the graphitization degree ID / IG is 0.5-1.8. The method comprises the following steps: taking a halogenated polyolefin polymer as a raw material, preparing polymer nano-spheres by using a precipitation method, carbonizing the polymer nano-spheres at a low temperature through a hydrothermal method, and further carbonizing the polymer nano-spheres in an inert gas atmosphere. The nano-porous carbon spheres prepared by the method have good sphericity and a microporous / mesoporous structure; the method is simple in process, convenient to operate and low in equipment requirement, can be used for large-scale preparation, and has the application prospect of industrial production.

Description

[0001] This application is a divisional application of the invention patent application with the application date of April 18, 2018, application number 201810349697.1, and invention name “A nanoporous carbon sphere, its preparation method and application”. Technical Field

[0002] The present invention belongs to the technical field of porous carbon materials, and in particular relates to a nano porous carbon sphere and a preparation method and application thereof. Background Art

[0003] Porous carbon materials are widely used in the fields of catalyst carriers, catalysts, supercapacitors, lithium-ion batteries, solar cells, etc. due to their high specific surface area, high porosity, good electrical and thermal conductivity, and adjustable pore size and surface properties. Porous graphitized carbon is a type of porous carbon material. It is a spherical carbon particle with a surface rich in mesopores formed by multiple high-temperature calcinations of adsorbed polymers using silica gel as a template. Porous carbon spheres were initially used as a stationary phase for liquid chromatography, and later they were also used in the fields of energy storage, adsorbents, and drug carriers.

[0004] There are many methods for preparing porous carbon spheres, which can be generally classified into two categories: one is to prepare porous carbon spheres by thermal decomposition of carbon source under high temperature conditions under the protection of inert gas, and the second is to prepare porous carbon spheres by low temperature pyrolysis of polymers or other substances or catalytic decomposition of organic compounds in a high-pressure reactor. Chemical vapor deposition, arc discharge and laser etching belong to the first category of methods, among which chemical vapor deposition is widely used. The size, morphology and yield of porous carbon spheres can be controlled by adjusting the temperature, carbon source flow rate, precipitation time and the time of carbon spheres in the reactor. It is also common to prepare porous carbon spheres using water or an organic solvent as a reaction medium in a high-temperature and high-pressure reactor. Chinese patents CN101698479 and CN101875489 disclose a method for preparing micron-sized carbon spheres. Glucose is dissolved in an aqueous solution of zinc salt, and then the mixture is loaded into a reactor and kept warm at about 200°C for 3 to 10 hours to obtain carbon spheres with a particle size of 5 to 10 mm. The size of the carbon spheres can be controlled by the concentration of glucose or zinc salt.

[0005] Compared with the traditional carbon sphere preparation methods, namely chemical vapor deposition, arc discharge and laser etching, which have low yield, harsh experimental conditions and high cost, the hydrothermal / solvothermal method has many advantages. However, the carbon sources of the hydrothermal method are generally small molecule sugars and natural polymers, and the prepared porous carbon spheres cannot meet the different requirements of many fields. Summary of the invention

[0006] The present invention provides a nanoporous carbon sphere, wherein the average particle size of the nanoporous carbon sphere is 20 to 800 nm, and the specific surface area is 50 to 5000 m2 / g, pore volume is 0.2~2.0cm 3 / g;

[0007] For example, the average particle size is 50 to 500 nm, preferably 50 to 300 nm; illustratively, the average particle size is 100 nm, 110 nm, 160 nm, 200 nm, 300 nm;

[0008] For example, the specific surface area is 200 to 3000 m 2 / g, preferably 500 to 1500 m 2 / g; illustratively, the specific surface area is 600m 2 / g、800m 2 / g、1100m 2 / g、1200m 2 / g、1300m 2 / g;

[0009] For example, the pore volume is 0.3 to 1.8 cm 3 / g, preferably 0.4 to 1.0 cm 3 / g; illustratively, the pore volume is 0.4cm 3 / g, 0.6cm 3 / g, 0.7cm 3 / g, 0.8cm 3 / g, 0.9cm 3 / g.

[0010] According to the present invention, the nanoporous carbon sphere has a physical structure in which micropores and mesopores coexist.

[0011] According to the present invention, the nanoporous carbon spheres contain graphite structures in addition to amorphous carbon, and the degree of graphitization (detected by the relative intensity ID / IG of the D peak and the G peak in the Raman spectrum) ID / IG is 0.5-1.8, preferably 0.6-1.5, and more preferably 0.8-1.2.

[0012] The present invention also provides a method for preparing the above-mentioned nanoporous carbon spheres. The method uses a halogenated polyolefin polymer as a precursor to prepare the nanoporous carbon spheres. The method has a simple operation process. The prepared nanoporous carbon spheres contain a graphite structure in addition to amorphous carbon and have a high degree of graphitization.

[0013] The method for preparing the nanoporous carbon spheres comprises the following steps:

[0014] (1) Using a halogenated polyolefin polymer as a precursor, preparing a nano-spherical halogenated polyolefin polymer;

[0015] (2) subjecting the nano-spherical halogenated polyolefin polymer to a hydrothermal reaction, drying to obtain a powder, and carbonizing the powder to obtain nanoporous carbon spheres;

[0016] Alternatively, the nano-spherical halogenated polyolefin polymer is directly carbonized to obtain nano-porous carbon spheres.

[0017] According to the present invention, the method specifically comprises the following steps:

[0018] (1) fully dissolving a precursor halogenated polyolefin polymer in a good solvent thereof to obtain a mixed solution, and then injecting the mixed solution into a poor solvent of the precursor to obtain nanospheres of the halogenated polyolefin polymer; further removing or concentrating the solvent to obtain a nanosphere-shaped halogenated polyolefin polymer powder or concentrated solution;

[0019] (2) taking the concentrated solution of the above polymer and placing it in a high-pressure hydrothermal reactor to obtain a liquid containing a black precipitate through a hydrothermal reaction, then removing the supernatant, washing, and drying to obtain a black powder; placing the above black powder in a tubular furnace for carbonization treatment to prepare nanoporous carbon spheres;

[0020] Alternatively, the polymer powder is directly placed in a tubular furnace for carbonization treatment to prepare nanoporous carbon spheres.

[0021] According to the preparation method of the present invention, the mass sum of the three elements of carbon, hydrogen and halogen in the halogenated polyolefin polymer is not less than 90% of the mass of the halogenated polyolefin polymer;

[0022] The mass of the halogen element accounts for 40 to 85% of the mass of the halogenated polyolefin polymer, preferably, 45 to 80%, and more preferably, 60 to 70%;

[0023] The halogen element is selected from one, two or more of F, Cl, Br and I, preferably Cl or Br;

[0024] The molar ratio of the halogen to carbon is (0.5-2.0):1, preferably (0.5-1.8):1, (0.5-1.0):1, illustratively, 0.60:1, 0.68:1, 0.92:1.

[0025] According to the preparation method of the present invention, the halogenated polyolefin polymer includes but is not limited to halogenated polyolefins and halogenated polyhaloolefins;

[0026] Preferably, the polyolefin in the halogenated polyolefin is a poly-α-olefin, for example, one, two or more of polyethylene, polypropylene, poly-1-butene, poly-1-pentene, poly-1-hexene, poly-1-heptene, poly-1-octene, poly-1-nonene, poly-1-decene, poly-1-undecene and copolymers thereof;

[0027] Preferably, the halogen in the polyhaloolefin in the halogenated polyhaloolefin is selected from chlorine or bromine, and the polyhaloolefin is selected from one, two or more of polyvinyl chloride, polyvinyl bromide, poly-1,1-dichloroethylene, poly-1,2-dichloroethylene, poly-1,1,2-trichloroethylene, poly-3-chloropropylene, poly-3-bromopropylene, polychloroprene, polybromoprene, etc.;

[0028] For example, the halogenated polyolefin polymer includes, but is not limited to, one, two or more of halogenated polyethylene, halogenated polypropylene, halogenated poly-1-butene, halogenated polyvinyl chloride, halogenated poly-1,1-dichloroethylene, halogenated poly-1,2-dichloroethylene, halogenated poly-1,1,2-trichloroethylene, halogenated poly-3-chloropropylene, halogenated polychloroprene, halogenated polyvinyl bromide, halogenated poly-3-bromopropylene, and halogenated polybromobutylene;

[0029] Preferably, the halogenated polyolefin polymer includes but is not limited to one, two or more of chlorinated polyethylene, chlorinated polypropylene, chlorinated poly-1-butene, chlorinated polyvinyl chloride, chlorinated poly-1,1-dichloroethylene, chlorinated poly-1,2-dichloroethylene, chlorinated poly-1,1,2-trichloroethylene, chlorinated poly-3-chloropropylene, chlorinated polychloroprene, chlorinated polyvinyl bromide, chlorinated poly-3-bromopropylene, chlorinated polybromobutylene, brominated polyethylene, brominated polypropylene, brominated poly-1-butene, brominated polyvinyl chloride, brominated poly-1,1-dichloroethylene, brominated poly-1,2-dichloroethylene, brominated poly-1,1,2-trichloroethylene, brominated poly-3-chloropropylene, brominated polychloroprene, brominated polyvinyl bromide, brominated poly-3-bromopropylene, and brominated polybromobutylene; preferably, the halogenated polyolefin polymer is selected from chlorinated polyethylene, chlorinated polypropylene, chlorinated polyvinyl chloride, brominated polyethylene or brominated polypropylene; illustratively, the halogenated polyolefin polymer is selected from chlorinated polyethylene and chlorinated polypropylene.

[0030] According to the preparation method of the present invention, the halogenated polyolefin polymer can be in the form of powder, porous powder, fiber or block.

[0031] According to the preparation method of the present invention, the good solvent includes but is not limited to aromatic hydrocarbons, amides and chlorinated hydrocarbons; for example, one, two or more selected from tetrahydrofuran, toluene, xylene, chloroform, trichlorobenzene, o-dichlorobenzene, p-dichlorobenzene, 2,4-dichlorophenol, dimethyl sulfoxide, N,N-dimethylformamide and N,N-dimethylacetamide; illustratively, selected from tetrahydrofuran, xylene or dimethyl sulfoxide.

[0032] According to the preparation method of the present invention, the poor solvent includes but is not limited to alcohols, ketones, ethers, alkanes, and esters; for example, one, two or more selected from water, ammonia, methanol, ethanol, propanol, butanol, ethylene glycol, propylene glycol, glycerol, isopropanol, n-octanol, benzyl alcohol, acetone, butanone, n-hexane, cyclohexane, methyl ether, ethyl ether, n-propyl ether, n-butyl ether, ethyl acetate, and butyl acetate; illustratively, selected from water, methanol or acetone.

[0033] According to the preparation method of the present invention, the concentration of the halogenated polyolefin polymer in the good solvent is 0.0005-20wt%, for example 0.005-10wt%, and illustratively, the concentration is 0.9wt%, 1wt%, or 10wt%.

[0034] According to the preparation method of the present invention, the volume ratio of the good solvent to the poor solvent is (1:1) to (1:10000); for example, (1:2) to (1:2000), (1:5) to (1:500), (1:8) to (1:100), (1:10) to (1:50).

[0035] According to the preparation method of the present invention, the specific operation of fully dissolving in step (1) is: adding the precursor halogenated polyolefin polymer to its good solvent under stirring conditions, and heating to reflux;

[0036] The heating temperature is 40-150°C, preferably 60-120°C, and illustratively, the temperature is 60°C or 120°C;

[0037] The reflux time is 1 to 5 hours, preferably 2 to 4 hours, and illustratively, the time is 2 hours.

[0038] According to the preparation method of the present invention, the specific operation of injecting all the mixed solution into the poor solvent of the precursor in step (1) is: rapidly injecting the mixed solution into the rapidly stirred poor solvent;

[0039] The stirring speed is 300 to 2000 r / min, preferably 500 to 1500 r / min, and illustratively, the stirring speed is 800 r / min.

[0040] According to the preparation method of the present invention, step (2) further comprises adding an alkaline compound to the polymer concentrate before the concentrate is placed in the high-pressure hydrothermal reactor;

[0041] The alkaline compound includes, but is not limited to, one, two or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, sodium bicarbonate, potassium bicarbonate, calcium bicarbonate, magnesium bicarbonate, sodium carbonate, potassium carbonate, calcium carbonate, magnesium carbonate, and ammonia water; preferably, the alkaline compound is selected from sodium hydroxide, potassium hydroxide, sodium bicarbonate, potassium bicarbonate, sodium carbonate, potassium carbonate or ammonia water; illustratively, it is selected from sodium hydroxide or potassium hydroxide;

[0042] The molar concentration of the basic compound in the poor solvent is 0 to 10 mol / L, preferably 0 to 5 mol / L.

[0043] According to the preparation method of the present invention, during the hydrothermal reaction in step (2), the heating rate of the high-pressure reactor in the muffle furnace is 1 to 20°C / min, illustratively 1, 5, 10, 15 or 20°C / min;

[0044] The temperature of the hydrothermal reaction is 200-400°C, preferably 250-350°C, and illustratively 350°C;

[0045] The hydrothermal reaction time is 1 to 10 hours, preferably 2 to 8 hours, illustratively 3 hours, 6 hours, or 8 hours.

[0046] According to the preparation method of the present invention, the conditions for the carbonization treatment in step (2) are: slowly increasing the temperature under an inert atmosphere;

[0047] The inert atmosphere is achieved by introducing an inert gas into the tube furnace system.

[0048] The inert gas is one, two or more of nitrogen, argon and helium; preferably nitrogen;

[0049] The flow rate of the inert gas is 1 to 100 mL / min, for example 5 to 60 mL / min, 10 to 20 mL / min;

[0050] The slow heating rate is 1-20°C / min, preferably 1-10°C / min, for example 10°C / min;

[0051] The carbonization temperature is 200-1000°C, preferably 250-800°C, such as 500°C, 600°C, 800°C;

[0052] The carbonization time is 1 to 10 hours, preferably 2 to 7 hours, for example 3 hours.

[0053] The present invention also provides nano porous carbon spheres prepared by the method.

[0054] The present invention also provides applications of the nanoporous carbon spheres, such as in the fields of ion chromatography stationary phase, lithium ion battery electrodes, capacitor electrodes, catalysts, drug carriers, gas adsorption, sewage treatment, etc.

[0055] The beneficial effects of the present invention are as follows: the method for preparing nano porous carbon spheres using halogenated polyolefin polymers as precursors provided by the present invention uses halogenated polyolefin polymers as raw materials, firstly prepares polymer nanospheres by precipitation method, then carbonizes polymer nanoparticles at low temperature by hydrothermal method, and then further carbonizes the nanoparticles in an inert gas atmosphere; most halogenated polyolefin polymers will melt and collapse during the carbonization process and cannot maintain their original morphology, while the advantage of the present invention is that the polymer nanospheres are firstly carbonized by hydrothermal method to maintain the spherical morphology of the nanospheres; then the nanospheres are fully carbonized in an inert gas atmosphere, thereby reducing the carbonization time in the inert gas and greatly reducing the use cost of the inert gas. Even if an inert atmosphere is used, the flow rate of the inert gas can be greatly reduced, thereby simplifying the carbonization conditions; the present invention has simple process, convenient operation, low equipment requirements, can be prepared on a large scale, and has application prospects for industrial production.

[0056] The nanoporous carbon spheres prepared by the method have good sphericity, microporous and mesoporous structures, and the particle size and specific surface area can be controlled; the nanoporous carbon spheres contain graphite structures in addition to amorphous carbon, have a high degree of graphitization, and have good electrical conductivity. The carbon spheres can be used in many fields such as ion chromatography stationary phases, lithium ion battery electrodes, capacitor electrodes, catalysts, drug carriers, gas adsorption, and sewage treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 This is a scanning electron microscope image of the nanoporous carbon spheres prepared in Example 1.

[0058] Figure 2 This is a transmission electron microscopy image of the nanoporous carbon spheres prepared in Example 1.

[0059] Figure 3 This is the nitrogen adsorption-desorption curve of the nanoporous carbon spheres prepared in Example 1.

[0060] Figure 4 This is the Raman image of the nanoporous carbon spheres prepared in Example 1.

[0061] Figure 5 This is a scanning electron microscope image of the carbon material prepared in Comparative Example 1. DETAILED DESCRIPTION

[0062] The material of the present invention and its preparation method and application will be described in further detail below in conjunction with specific examples. It should be understood that the following examples are only for exemplary description and explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies realized based on the above content of the present invention are included in the scope that the present invention is intended to protect.

[0063] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0064] Some instrument information is as follows:

[0065] Scanning electron microscope: Hitachi, Japan, instrument models are HITACHI-S4800, HITACHI-S1510;

[0066] Transmission electron microscope: JEOL JEM-2011, Japan Electron Co., Ltd.

[0067] BET surface area measuring instrument: Quantachrome Instruments, USA, instrument models are NOVA3200e and iQ;

[0068] Low-temperature matrix-isolated Raman spectroscopy: HORIBA Jobin Yvon, France, instrument model is LabRAMARAMIS.

[0069] Example 1

[0070] 1g of chlorinated polypropylene (the mass content of chlorine element is 70wt%, the Cl / C molar ratio is 0.92:1) is dissolved in 100ml of tetrahydrofuran, fully stirred and heated to 60°C, nitrogen is used as a protective gas for condensation and reflux, and fully dissolved for 2 hours; 1000ml of acetone is placed in a beaker and stirred rapidly, and the tetrahydrofuran solution in which the chlorinated polypropylene is dissolved is quickly injected into the rapidly stirred acetone using a disposable syringe; after all the solution is injected, chlorinated polypropylene nanospheres are obtained; the above-mentioned chlorinated polypropylene nanospheres are taken 100 ml of the solution was added with 100 ml of distilled water, and poured into a rotary evaporator for vacuum distillation to completely evaporate tetrahydrofuran and acetone; the remaining solution was poured into a 50 ml high-pressure reactor, and the temperature was raised to 350 ° C at 10 ° C per minute, and the reaction was carried out for 8 hours to obtain a liquid containing a black precipitate, and then the supernatant was removed, washed with an ethanol solution, and dried to obtain a black powder; the black powder was placed in a quartz tube of a tubular furnace, and the system was filled with nitrogen at a nitrogen flow rate of 10 to 20 mL / min to make the quartz tube free of active gases such as oxygen. The black powder was heated at a rate of 10 ° C / min to a final carbonization temperature of 800 ° C, and kept at this temperature for 3 hours. The temperature was slowly lowered under nitrogen to obtain nanoporous carbon spheres.

[0071] Figure 1 This is a scanning electron microscope image of the nanoporous carbon spheres prepared in Example 1. Figure 2 This is a transmission electron microscope image of the nanoporous carbon spheres prepared in Example 1. Figure 3 is the nitrogen adsorption-desorption curve of the nanoporous carbon sphere prepared in Example 1, Figure 4 This is the Raman image of the nanoporous carbon spheres prepared in Example 1.

[0072] Depend on Figure 1-4 It can be concluded that the average particle size of the nanoporous carbon spheres prepared in this embodiment is 100 nm and the specific surface area is 1200 m 2 / g, pore volume is 0.9cm 3 / g, ID / IG is 1.3.

[0073] Example 2

[0074] 1g of chlorinated polypropylene (the mass content of chlorine element is 70wt%, and the Cl / C molar ratio is 0.92:1) is dissolved in 100ml of dimethyl sulfoxide, fully stirred and heated to 120°C, nitrogen is used as a protective gas for condensation and reflux, and fully dissolved for 2 hours; 1000ml of acetone is placed in a beaker and stirred rapidly, and the dimethyl sulfoxide solution in which the chlorinated polypropylene is dissolved is quickly injected into the rapidly stirred acetone using a disposable syringe; after all the solution is fully injected, chlorinated polypropylene nanospheres are obtained; 100ml of the above solution containing chlorinated polypropylene nanospheres is taken, poured into a rotary evaporator for reduced pressure distillation, and the remaining solution is poured into a 50ml high-pressure reactor, and the temperature is increased to 350°C at 10°C per minute, and the reaction is performed for 8 hours to obtain a liquid containing black precipitates, and then the supernatant is removed, washed with an ethanol solution, and dried to obtain a black powder; the black powder is placed in a quartz tube of a tubular furnace, and nitrogen is filled into the system, and the nitrogen flow rate is 10-20mL / min, so that there is no active gas such as oxygen in the quartz tube. The black powder was heated at a rate of 10°C / min to a final carbonization temperature of 800°C and kept constant at this temperature for 3 hours. The temperature was slowly lowered under nitrogen to obtain nanoporous carbon spheres.

[0075] The average particle size of the nanoporous carbon spheres prepared in this example is 200 nm, and the specific surface area is 800 m 2 / g, pore volume is 0.8cm 3 / g, ID / IG is 1.0.

[0076] Example 3

[0077] 1g of chlorinated polyethylene (the mass content of chlorine element is 60wt%, and the Cl / C molar ratio is 0.68:1) is dissolved in 100ml of xylene, fully stirred and heated to 120°C, nitrogen is used as a protective gas for condensation and reflux, and fully dissolved for 2 hours; 1000ml of methanol is placed in a beaker and stirred rapidly, and the xylene solution in which the chlorinated polyethylene is dissolved is quickly injected into the rapidly stirred distilled water with a disposable syringe; after all the solution is fully injected, chlorinated polyethylene nanospheres are obtained; 100ml of the above solution containing chlorinated polyethylene nanospheres is taken, poured into a rotary evaporator for reduced pressure distillation, and the remaining solution is poured into a 50ml high-pressure reactor, heated to 350°C at 20°C per minute, reacted for 6 hours, and a liquid containing black precipitate is obtained, and then the supernatant is removed, washed with an ethanol solution, and dried to obtain a black powder; the black powder is placed in a quartz tube of a tubular furnace, and the system is filled with nitrogen at a nitrogen flow rate of 20 to 30mL / min to make the quartz tube free of active gases such as oxygen. The chlorinated polypropylene was heated at a rate of 10°C / min to a final carbonization temperature of 800°C, and kept at this temperature for 3 hours, and then slowly cooled under nitrogen to obtain nanoporous carbon spheres.

[0078] The average particle size of the nanoporous carbon spheres prepared in this example is 300 nm, and the specific surface area is 600 m 2 / g, pore volume is 0.4cm 3 / g, ID / IG is 0.8.

[0079] Example 4

[0080] 1g of chlorinated polypropylene (the mass content of chlorine element is 70wt%, the Cl / C molar ratio is 0.92:1) is dissolved in 100ml of tetrahydrofuran, fully stirred and heated to 60°C, nitrogen is used as a protective gas for condensation and reflux, and fully dissolved for 2 hours; 1000ml of distilled water is placed in a beaker and stirred rapidly, and the tetrahydrofuran solution in which the chlorinated polypropylene is dissolved is quickly injected into the rapidly stirred distilled water with a disposable syringe; after all the solution is injected, chlorinated polypropylene nanospheres are obtained; the above-mentioned chlorinated polypropylene nanospheres are taken 100ml of the solution was poured into a rotary evaporator for vacuum distillation to completely evaporate tetrahydrofuran; the remaining solution was poured into a 50ml high-pressure reactor, 0.05mol NaOH was added, and the temperature was raised from 20℃ to 350℃ per minute, and the reaction was carried out for 8 hours to obtain a liquid containing a black precipitate, and then the supernatant was removed, washed with an ethanol solution, and dried to obtain a black powder; the black powder was placed in a quartz tube of a tubular furnace, and the system was filled with nitrogen at a nitrogen flow rate of 20-30mL / min to make the quartz tube free of active gases such as oxygen. The black powder was heated at a rate of 10℃ / min to a final carbonization temperature of 600℃, and kept constant at this temperature for 3 hours. The temperature was slowly lowered under nitrogen to obtain nanoporous carbon spheres.

[0081] The average particle size of the nanoporous carbon spheres prepared in this example is 100 nm, and the specific surface area is 1300 m 2 / g, pore volume is 0.8cm 3 / g, ID / IG is 1.1.

[0082] Example 5

[0083] Dissolve 1g of chlorinated polypropylene (the mass content of chlorine element is 60wt%, Cl / C molar ratio is 0.60:1) in 100ml of tetrahydrofuran, stir thoroughly and heat to 60℃, condense and reflux with nitrogen as protective gas, and fully dissolve for 2 hours; Put 1000ml of distilled water in a beaker and stir rapidly, and use a disposable syringe to quickly inject the tetrahydrofuran solution dissolved in chlorinated polypropylene into the rapidly stirred distilled water; When all the solutions are fully injected, chlorinated polypropylene nanospheres are obtained; Take 100ml of the above solution containing chlorinated polypropylene nanospheres, pour it into a rotary evaporator for reduced pressure distillation, and completely evaporate the solvent to obtain white powder; Put the white powder into the quartz tube of a tubular furnace, fill the system with nitrogen, and the nitrogen flow rate is 20-30mL / min, so that there is no active gas such as oxygen in the quartz tube. Heat the chlorinated polypropylene at a rate of 10℃ / min, raise the temperature to the final carbonization temperature of 600℃, and keep it constant at this temperature for 3 hours. Slowly cool down under nitrogen to obtain nanoporous carbon spheres.

[0084] The average particle size of the nanoporous carbon spheres prepared in this example is 110 nm, and the specific surface area is 1100 m 2 / g, pore volume is 0.7cm 3 / g, ID / IG is 1.0.

[0085] Example 6

[0086] 10g of chlorinated polypropylene (the mass content of chlorine element is 70wt%, the Cl / C molar ratio is 0.92:1) is dissolved in 100ml of tetrahydrofuran, fully stirred and heated to 60°C, nitrogen is used as a protective gas for condensation and reflux, and fully dissolved for 2 hours; 1000ml of distilled water is placed in a beaker and stirred rapidly, and the tetrahydrofuran solution in which chlorinated polypropylene is dissolved is quickly injected into the rapidly stirred distilled water with a disposable syringe; after all the solution is injected, chlorinated polypropylene nanospheres are obtained; the above-mentioned 100 ml of the solution of chlorinated polypropylene nanospheres was poured into a rotary evaporator for vacuum distillation to completely evaporate tetrahydrofuran; the remaining solution was poured into a 50 ml high-pressure reactor, heated to 350 ° C at 20 ° C per minute, reacted for 3 hours, and a liquid containing black precipitate was obtained. The supernatant was removed, washed with ethanol solution, and dried to obtain black powder; the black powder was placed in a quartz tube of a tubular furnace, and the system was filled with nitrogen at a nitrogen flow rate of 1 to 10 mL / min to make the quartz tube free of active gases such as oxygen. The black powder was heated at a rate of 10 ° C / min to a final carbonization temperature of 500 ° C, and kept constant at this temperature for 3 hours. The temperature was slowly lowered under nitrogen to obtain nanoporous carbon spheres.

[0087] The average particle size of the nanoporous carbon spheres prepared in this example is 160 nm, and the specific surface area is 800 m 2 / g, pore volume is 0.6cm 3 / g, ID / IG is 0.7.

[0088] Comparative Example 1

[0089] 1g of chlorinated polypropylene raw material (the mass content of chlorine element is 70wt%, and the Cl / C molar ratio is 0.92:1) is placed in the quartz tube of the tube furnace, and the system is filled with nitrogen to make the quartz tube free of active gases such as oxygen. The chlorinated polypropylene is heated at a rate of 10°C / min to the final carbonization temperature of 800°C, and kept at this temperature for 3 hours. The temperature is slowly lowered under nitrogen to obtain a carbon material without a nanosphere structure.

[0090] By comparing Example 1 ( Figure 5 ) It can be seen that nanoporous carbon spheres cannot be prepared by directly carbonizing halogenated polyolefin polymers as precursors in an inert gas.

[0091] The above is an explanation of the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing nanoporous carbon spheres, characterized in that: The method comprises the following steps: (1) Using a halogenated polyolefin polymer as a precursor, preparing a nano-spherical halogenated polyolefin polymer; (2) subjecting the nano-spherical halogenated polyolefin polymer to a hydrothermal reaction, drying to obtain a powder, and carbonizing the powder to obtain nanoporous carbon spheres; Alternatively, the nano-spherical halogenated polyolefin polymer is directly carbonized to obtain nano-porous carbon spheres; The nanoporous carbon spheres have an average particle size of 20 to 800 nm and a specific surface area of ​​50 to 5000 m 2 / g, pore volume is 0.2~2.0cm 3 / g.

2. The preparation method according to claim 1, characterized in that: The method specifically comprises the following steps: (1) fully dissolving a precursor halogenated polyolefin polymer in a good solvent thereof to obtain a mixed solution, and then injecting the mixed solution into a poor solvent of the precursor to obtain nanospheres of the halogenated polyolefin polymer; further removing or concentrating the solvent to obtain a nanosphere-shaped halogenated polyolefin polymer powder or concentrated solution; (2) taking the concentrated solution of the above polymer and placing it in a high-pressure hydrothermal reactor to obtain a liquid containing a black precipitate through a hydrothermal reaction, then removing the supernatant, washing, and drying to obtain a black powder; placing the above black powder in a tubular furnace for carbonization treatment to prepare nanoporous carbon spheres; Alternatively, the polymer powder is directly placed in a tubular furnace for carbonization treatment to prepare nanoporous carbon spheres.

3. The preparation method according to claim 1 or 2, characterized in that: In the halogenated polyolefin polymer, the sum of the mass of the three elements of carbon, hydrogen and halogen is not less than 90% of the mass of the halogenated polyolefin polymer; The mass of the halogen element accounts for 40-85% of the mass of the halogenated polyolefin polymer, and the halogen element is selected from one, two or more of F, Cl, Br and I; the molar ratio of the halogen to carbon is (0.5-2.0):1; The halogenated polyolefin polymers include but are not limited to halogenated polyolefins and halogenated polyhaloolefins; Wherein, the polyolefin in the halogenated polyolefin is a poly-α-olefin, for example, one, two or more of polyethylene, polypropylene, poly-1-butene, poly-1-pentene, poly-1-hexene, poly-1-heptene, poly-1-octene, poly-1-nonene, poly-1-decene, poly-1-undecene and copolymers thereof; Wherein, the halogen in the polyhaloolefin in the halogenated polyhaloolefin is selected from chlorine or bromine, and the polyhaloolefin is selected from one, two or more of polyvinyl chloride, polyvinyl bromide, poly-1,1-dichloroethylene, poly-1,2-dichloroethylene, poly-1,1,2-trichloroethylene, poly-3-chloropropylene, poly-3-bromopropylene, polychloroprene, polybromoprene, etc.; Preferably, the halogenated polyolefin polymer includes, but is not limited to, one, two or more of halogenated polyethylene, halogenated polypropylene, halogenated poly-1-butene, halogenated polyvinyl chloride, halogenated poly-1,1-dichloroethylene, halogenated poly-1,2-dichloroethylene, halogenated poly-1,1,2-trichloroethylene, halogenated poly-3-chloropropylene, halogenated polychloroprene, halogenated polyvinyl bromide, halogenated poly-3-bromopropylene, and halogenated polybromobutylene; Preferably, the halogenated polyolefin polymer includes, but is not limited to, one, two or more of chlorinated polyethylene, chlorinated polypropylene, chlorinated poly-1-butene, chlorinated polyvinyl chloride, chlorinated poly-1,1-dichloroethylene, chlorinated poly-1,2-dichloroethylene, chlorinated poly-1,1,2-trichloroethylene, chlorinated poly-3-chloropropylene, chlorinated polychloroprene, chlorinated polyvinyl bromide, chlorinated poly-3-bromopropylene, chlorinated polybromobutylene, brominated polyethylene, brominated polypropylene, brominated poly-1-butene, brominated polyvinyl chloride, brominated poly-1,1-dichloroethylene, brominated poly-1,2-dichloroethylene, brominated poly-1,1,2-trichloroethylene, brominated poly-3-chloropropylene, brominated polychloroprene, brominated polyvinyl bromide, brominated poly-3-bromopropylene, and brominated polybromobutylene; Preferably, the halogenated polyolefin polymer may be in the form of powder, porous powder, fiber or block.

4. The preparation method according to claim 2 or 3, characterized in that: The good solvent is not limited to aromatic hydrocarbons, amides and chlorinated hydrocarbons; preferably, one, two or more selected from tetrahydrofuran, toluene, xylene, chloroform, trichlorobenzene, o-dichlorobenzene, p-dichlorobenzene, 2,4-dichlorophenol, dimethyl sulfoxide, N,N-dimethylformamide and N,N-dimethylacetamide; The poor solvent includes but is not limited to alcohols, ketones, ethers, alkanes, and esters; preferably, one, two or more selected from water, ammonia, methanol, ethanol, propanol, butanol, ethylene glycol, propylene glycol, glycerol, isopropanol, n-octanol, benzyl alcohol, acetone, butanone, n-hexane, cyclohexane, methyl ether, ethyl ether, n-propyl ether, n-butyl ether, ethyl acetate, and butyl acetate; The concentration of the halogenated polyolefin polymer in the good solvent is 0.0005 to 20 wt %; The volume ratio of the good solvent to the poor solvent is (1:1) to (1:10000).

5. The preparation method according to any one of claims 2 to 4, characterized in that: The specific operation of fully dissolving in step (1) is: adding the precursor halogenated polyolefin polymer to its good solvent under stirring conditions, and heating to reflux; the heating temperature is 40 to 150° C., and the reflux time is 1 to 5 hours; The specific operation of injecting all the mixed solution into the poor solvent of the precursor in step (1) is: rapidly injecting the mixed solution into the rapidly stirred poor solvent; the stirring speed is 300 to 2000 r / min.

6. The preparation method according to any one of claims 2 to 5, characterized in that: Step (2) further comprises adding a basic compound to the polymer concentrate before the concentrate is placed in the high pressure hydrothermal reactor; The alkaline compound includes, but is not limited to, one, two or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, sodium bicarbonate, potassium bicarbonate, calcium bicarbonate, magnesium bicarbonate, sodium carbonate, potassium carbonate, calcium carbonate, magnesium carbonate, and ammonia water; preferably, the alkaline compound is selected from sodium hydroxide, potassium hydroxide, sodium bicarbonate, potassium bicarbonate, sodium carbonate, potassium carbonate or ammonia water; The molar concentration of the alkaline compound in the poor solvent is 0 to 10 mol / L; During the hydrothermal reaction in step (2), the heating rate of the high-pressure reactor in the muffle furnace is 1 to 20° C. / min; The temperature of the hydrothermal reaction is 200 to 400° C., and the time of the hydrothermal reaction is 1 to 10 hours; The conditions of the carbonization treatment in step (2) are: slowly heating up in an inert atmosphere; The inert atmosphere is achieved by introducing an inert gas into the tubular furnace system, wherein the inert gas is one, two or more of nitrogen, argon and helium; the flow rate of the inert gas is 1 to 100 mL / min; The slow heating rate is 1-20°C / min; the carbonization temperature is 200-1000°C, and the time is 1-10 hours.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The average particle size of the nanoporous carbon spheres is 50 to 500 nm, preferably 50 to 300 nm; And / or, the specific surface area is 200 to 3000m 2 / g, preferably 500 to 1500 m 2 / g; And / or, the pore volume is 0.3 to 1.8 cm 3 / g, preferably 0.4 to 1.0 cm 3 / g.

8. The preparation method according to any one of claims 1 to 6, characterized in that: The nanoporous carbon sphere has a physical structure in which micropores and mesopores coexist.

9. The preparation method according to any one of claims 1 to 6, characterized in that: The nanoporous carbon spheres contain graphite structures in addition to amorphous carbon, and the degree of graphitization (detected by the relative intensity ID / IG of the D peak and the G peak in the Raman spectrum) ID / IG is 0.5-1.8, preferably 0.6-1.5, and more preferably 0.8-1.

2.

10. The preparation method according to any one of claims 7 to 9, characterized in that: The nano porous carbon sphere is used in the fields of ion chromatography stationary phase, lithium ion battery electrode, capacitor electrode, catalyst, drug carrier, gas adsorption or sewage treatment.

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