CN112169756B - Microporous granular carbon and preparation method thereof - Google Patents

Microporous granular carbon and preparation method thereof Download PDF

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CN112169756B
CN112169756B CN202011050518.8A CN202011050518A CN112169756B CN 112169756 B CN112169756 B CN 112169756B CN 202011050518 A CN202011050518 A CN 202011050518A CN 112169756 B CN112169756 B CN 112169756B
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phase solution
water
carbon
oil
microporous
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CN112169756A (en
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靳紫恒
江霞
谢玲玲
常玉龙
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Sichuan University
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    • B01J20/28069—Pore volume, e.g. total pore volume, mesopore volume, micropore volume
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    • B01J20/2808—Pore diameter being less than 2 nm, i.e. micropores or nanopores
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Abstract

The invention belongs to the field of environment-friendly materials, and particularly relates to microporous granular carbon and a preparation method thereof. The invention aims to solve the technical problem of providing microporous granular carbon and a preparation method thereof, and the preparation method comprises the following steps: A. emulsifying a chitosan solution or a polyvinyl alcohol solution, an oil-in-water emulsifier and an organic solvent to obtain an internal phase solution; mixing a water-in-oil emulsifier and an organic solvent to obtain an external phase solution; mixing the cross-linking agent and the external phase solution to obtain a curing bath; B. respectively injecting the internal phase solution and the external phase solution into an injection tube and a collecting tube of the capillary microfluidic chip to form monodisperse water-oil emulsion, and injecting the monodisperse water-oil emulsion into a curing bath to perform a crosslinking reaction with a crosslinking agent to prepare particles; C. washing, drying and carbonizing the particles to obtain the microporous granular carbon. The method can obtain the microporous granular carbon, and has the advantages of simple method, easy operation and no pollution.

Description

Microporous granular carbon and preparation method thereof
Technical Field
The invention belongs to the field of environment-friendly materials, and particularly relates to microporous granular carbon and a preparation method thereof.
Background
Over the past decades, an excess of greenhouse gases in the atmosphere has led to significant global climate change. In data of the government Special Committee for climate Change (IPCC), flue gas emitted by industry accounts for global CO produced by fuel236% of the discharge amount. Among various carbon dioxide removal technologies, post-combustion capture is most applicable to the power industry. CO 22Post-combustion capture techniques include adsorption, membrane separation, and absorption. Among them, the adsorption method is most widely used because of its simple operation and regeneration process and low cost. Among the numerous adsorbents, manyPore carbon is usually towards CO2The heat of adsorption is lower than 25kJ/mol, and the energy saving can be realized in a plurality of adsorption-desorption cycles. In addition, the porous carbon has good CO2Adsorption capacity, and high chemical and thermal stability.
But most of the porous carbon materials are in the form of fine powder, have irregular shapes and have wider size distribution range. Such materials tend to suffer from low heat and mass transfer rates and mechanical attrition during adsorption, resulting in higher bed pressure drop. Preparing the porous carbon material into a spherical shape having a uniform size can reduce the surface area to volume ratio while alleviating the above-described problems due to the material morphology and size. The method of preparing Carbon Spheres (CSs) is generally a hydrothermal carbonization method, by which high temperature and high pressure are required to prepare carbon spheres, and the particle size monodispersity of the resulting spheres is poor. Furthermore, chemical or physical activation is typically required after hydrothermal carbonization to create sufficient micropores to adsorb CO2. Therefore, there is a need for a simple, green and accurate method for preparing carbon spheres with controlled size, uniform morphology, narrow size distribution and developed pore structure to enhance carbon dioxide capture in flue gas.
In recent years, microfluidic technology has provided a very promising and simple approach. The microfluidic droplet technology has the advantages of small volume, no sample diffusion, stable reaction conditions, less cross contamination among samples, rapid mixing and the like, and can produce microspheres with adjustable pore structures and smart functions in a continuous system. CN201510140330.5 discloses microparticles with micron/nanometer graded pores, which are formed and pore-formed by a microfluidic system and have uniform size. However, the pore-forming mechanism of the microsphere is derived from larger pores of the precursor, and further pore-shrinking steps such as carbonization and the like are not performed, the pore diameter of the micron-sized pores is 20-500 mu m, and the pore diameter of the nano-sized pores is 5-1000 nm, so that the microsphere is not suitable for adsorption of gas molecules. CN201811240572.1 discloses a method for preparing chitosan microspheres with high specific surface area, in which the specific surface area of the microspheres is adjusted by the content of alcohol in the curing bath, but the invention does not disclose the pore structure information of the microspheres, and the microporous structure cannot be observed by scanning electron microscope images.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a microporous structure granular carbon and a microfluidic preparation method. The microporous structure of the granular carbon obtained by the method is derived from micelle stably wrapping nano organic droplets formed by a chitosan solution or a polyvinyl alcohol solution and an oil-in-water emulsifier after high-speed homogeneous emulsification.
The first technical problem to be solved by the present invention is to provide a method for preparing microporous granular carbon. The method comprises the following steps:
A. emulsifying a chitosan solution or a polyvinyl alcohol solution, an oil-in-water emulsifier and an organic solvent to obtain an internal phase solution; mixing a water-in-oil emulsifier and an organic solvent to obtain an external phase solution; mixing the cross-linking agent and the external phase solution to obtain a curing bath;
B. respectively injecting the internal phase solution and the external phase solution into an injection tube and a collecting tube of the capillary microfluidic chip to form monodisperse water-oil emulsion, and injecting the monodisperse water-oil emulsion into a curing bath to perform a crosslinking reaction with a crosslinking agent to prepare particles;
C. washing, drying and carbonizing the particles to obtain the microporous granular carbon.
Specifically, in step a of the above method for preparing microporous granular carbon, the chitosan solution is formed by adding chitosan into water containing acetic acid for dissolution.
Further, in the step a of the method for preparing microporous granular carbon, the acetic acid is 1-2% of the total volume of water and acetic acid.
Specifically, in the step a of the method for preparing microporous granular carbon, the mass concentration of chitosan in the chitosan solution is 1-3%.
Specifically, in the step a of the method for preparing microporous granular carbon, the polyvinyl alcohol solution is prepared by dissolving 1-4 g of polyvinyl alcohol in 100mL of water.
Specifically, in the step a of the method for preparing microporous granular carbon, the oil-in-water emulsifier is at least one of F127 (Chinese name: polyoxyethylene polyoxypropylene ether block copolymer), P123 (Chinese name: polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer), F108 (Chinese name: polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer), OP-10 (Chinese name: octylphenol polyoxyethylene ether) or tween 80.
Specifically, in the step a of the method for preparing microporous granular carbon, the oil-in-water emulsifier is 1-5% of the total volume of the oil-in-water emulsifier and the chitosan solution or the polyvinyl alcohol solution.
Specifically, in step a of the above method for preparing microporous granular carbon, the organic solvent is at least one of n-octane, n-octanol, ethyl acetate, or soybean oil.
Specifically, in the step a of the method for preparing microporous granular carbon, the organic solvent is 2-20% of the volume of the internal phase solution. The amount of organic solvent added is referred to only as the organic solvent in the internal phase solution.
Specifically, in the step a of the method for preparing microporous granular carbon, the rotation speed of the emulsification is 10000rpm or more. Preferably 10000-16000 rpm. The emulsifying time is 30-60 s.
Specifically, in the step A of the method for preparing the microporous granular carbon, the water-in-oil emulsifier is Span80 (Chinese name: sorbitan monooleate).
Specifically, in the step a of the method for preparing microporous granular carbon, the water-in-oil emulsifier is 2-12% of the volume of the external phase solution.
Specifically, in step a of the method for preparing microporous granular carbon, the crosslinking agent is at least one of glutaraldehyde, genipin, or sodium tripolyphosphate.
Specifically, in the step a of the method for preparing microporous granular carbon, the crosslinking agent is 0.5-2% of the volume of the curing bath.
Specifically, in the step B of the method for preparing microporous granular carbon, the injection flow rate of the internal phase solution is 0.5-2.5 mL/h, and the injection flow rate of the external phase solution is 20-40 mL/h.
Specifically, in the step B of the method for preparing the microporous granular carbon, the diameter of an injection port is 150-200 μm, and the diameter of a collecting pipe is 500-550 μm. Preferably, the injection port has a diameter of 180 μm and the collection tube has a diameter of 550. mu.m.
Specifically, in the step B of the method for preparing the microporous granular carbon, the curing and crosslinking reaction is carried out for 1-4 hours.
Specifically, in the step C of the method for preparing microporous granular carbon, the organic solvent, petroleum ether and water which are the same as those in the step a are sequentially used for washing.
Specifically, in the step C of the method for preparing microporous granular carbon, the drying is any one of freeze drying, heat drying and vacuum drying. Preferably freeze-dried.
Specifically, in the step C of the method for preparing microporous granular carbon, the carbonization temperature is 600-900 ℃. The carbonization time is 1-4 h.
Specifically, in the step C of the method for preparing the microporous granular carbon, the temperature rise rate of carbonization is 5-20 ℃/min.
The second technical problem to be solved by the present invention is to provide microporous granular carbon prepared by the above method for preparing microporous granular carbon.
Preferably, the microporous granular carbon has a pore diameter of 0.5 to 0.7nm and a pore volume of 0.15 to 0.25cm3(ii) in terms of/g. Furthermore, the particle size is 85-110 μm. When chitosan is used as a raw material, the nitrogen atom content of the obtained microporous granular carbon is 2-4%. The nitrogen content is the proportion of nitrogen in the sum of C, N, O, H elements.
The third technical problem to be solved by the invention is to provide the application of the microporous granular carbon in carbon dioxide adsorption.
According to the method, micelle formed by a chitosan solution or a polyethylene glycol solution and an oil-in-water emulsifier after high-speed homogeneous emulsification is used for wrapping nano organic liquid drops for pore forming, high-speed liquid phase shearing is used, the formed nano liquid drops occupy the space in particles, the organic solvent is removed along with subsequent washing to form pores, and subsequent carbonization is further reduced, so that micropores are formed. The method can effectively solve the pollution problems that strong acid and strong alkali are needed in the traditional chemical activation method, hydrofluoric acid is needed to remove the template in the hard template method, and the like. The method adopts the microfluidic technology to carry out accurate forming, and can be conveniently controlledSpherical shape and size, and wide application range. The method adopts chitosan or polyvinyl alcohol as a carbon source, the preparation process is simple and easy to control, the chitosan contains nitrogen naturally, the subsequent complex process of nitrogen doping can be omitted, and the nitrogen doping of the carbon material can further improve the content of the alkaline functional groups on the surface of the carbon, so that the CO content can be improved2The amount of adsorption of (3). The microporous granular carbon obtained by the method has the advantages that the majority of pore diameters are micropore pore diameters, and the carbon can react with CO at the temperature of 25-35 DEG C2The adsorption capacity reaches 1.0-1.2 mmol/g, and after ten times of adsorption and desorption circulation, the adsorption capacity is still stabilized at 98% of the first adsorption capacity.
Drawings
FIG. 1 is a schematic process for preparing microporous granular carbon by a microfluidic chip;
FIG. 2 is a graph showing the nitrogen adsorption and desorption curves of carbon spheres formed by 10% by volume of the oil phase in the internal phase in example 1;
FIG. 3 is the surface topography of carbon spheres formed with 10% by volume oil phase in the internal phase of example 1; a. the morphology of the microspheres under 500 times of magnification; b. the surface topography of the microspheres under 2000 times of magnification;
FIG. 4 is the CO of carbon spheres formed with 10% by volume oil phase in the internal phase of example 12An adsorption curve;
FIG. 5 is a graph showing the adsorption and desorption of nitrogen from carbon spheres formed in example 2 in which the internal phase contains 5% by volume of the oil phase;
FIG. 6 is the CO of carbon spheres formed with 5% by volume oil phase in the internal phase of example 22An adsorption curve;
FIG. 7 is a graph showing the adsorption and desorption of nitrogen from carbon spheres having an internal phase of 2% by volume of the oil phase in example 3;
FIG. 8 is the CO of carbon spheres formed with the internal phase of 2% by volume oil phase in example 32An adsorption curve;
FIG. 9 shows CO in the 900 ℃ carbonized carbon pellet in example 42Adsorption profile.
Detailed Description
The invention discloses a method for preparing microporous structure granular carbon by microfluidics, which comprises the following steps:
A. high-speed homogeneous emulsification to prepare an internal phase solution: mixing chitosan solution or polyvinyl alcohol water solution containing oil-in-water emulsifier with organic solvent, and emulsifying in homogenizing emulsifying machine to obtain inner phase solution;
preparing an external phase solution and a curing bath: adding the water-in-oil emulsifier into the organic solvent, and uniformly mixing to obtain an external phase solution; the curing bath is that the cross-linking agent is added into the external phase solution;
B. preparation of monodisperse particles: respectively injecting the internal phase solution and the external phase solution into an injection tube and a collecting tube of the capillary microfluidic chip to form monodisperse water/oil emulsion, and injecting the monodisperse emulsion into a curing bath to perform a crosslinking reaction with a crosslinking agent to obtain particles;
C. washing, freeze-drying and carbonizing the formed particles: and (3) separating the particles from the curing bath, washing with the corresponding organic solvent, petroleum ether and deionized water respectively to remove the redundant oil phase on the surfaces of the particles and in the pore channels, drying, carbonizing in a tubular furnace, heating to the carbonization temperature of 600-900 ℃ to obtain microporous granular carbon, naturally cooling, and storing in a drying oven.
In the method, because the chitosan is insoluble in water, acetic acid is required to be added for assisting dissolution. The addition amount of the acetic acid is 1-2% of the total volume of the water and the acetic acid. When the raw material is polyvinyl alcohol, acetic acid is not required to be added for assisting dissolution, and the polyvinyl alcohol is directly added into water to prepare a polyvinyl alcohol aqueous solution.
In the method of the present invention, the purpose of emulsification is to break the organic solvent into fine droplets to wrap the organic solvent inside chitosan or polyvinyl alcohol, and the wrapped organic solvent is removed by subsequent washing to form pores. In order to form micropores finally, it is necessary to make the organic solvent into fine droplets as much as possible, so that it is necessary to control the emulsification rotation speed, and if the rotation speed is too low, microporous carbon cannot be finally prepared. The invention needs to control the rotating speed to be more than 10000rpm when emulsification is carried out. Preferably 10000-16000 rpm. Meanwhile, the subsequent carbonization process can also play a role in reducing the pores, thereby finally obtaining the microporous carbon.
In the method, the flow velocity of the inner phase solution and the outer phase solution influences the size of microporous granular carbon, and if the flow velocity of the inner phase solution is too high and the flow velocity of the outer phase solution is too low, linear granules with longer length can be obtained; if the flow rate of the inner phase is too slow and the flow rate of the outer phase is too fast, the resulting material is very small. Meanwhile, the diameters of an injection tube and a collecting tube of the capillary microfluidic device also influence the particle size of a product. The flow rates of the inner phase solution and the outer phase solution can be regarded as the length of the control particles, and the diameters of the injection tube and the collection tube of the capillary microfluidic device can be regarded as the diameter of the control particles. The flow rate of the inner phase solution is controlled to be 0.5-2.5 mL/h, the flow rate of the outer phase solution is controlled to be 20-40 mL/h, when the diameter of an injection port of the capillary microfluidic device is 150-200 mu m and the diameter of a receiving tube is 500-550 mu m, the diameter of the injection port is preferably 180 mu m and the diameter of the receiving tube is preferably 550 mu m, and the spherical carbon with the particle size of micron level can be obtained. Of course, by controlling the flow rate of the inner phase solution and the flow rate of the outer phase solution, particles with the length of nanometer, millimeter, centimeter and the like can also be obtained. The flow rates of the inner phase solution and the outer phase solution and the diameters of an injection tube and a collection tube of the capillary microfluidic device can be reasonably controlled according to the requirement on the particle size of a product.
In the method, the organic solvent, the petroleum ether and the deionized water which correspond to each other are sequentially adopted for washing to remove the redundant oil phase on the particle surface and in the pore canal, so that pores are formed. The subsequent drying can be freeze drying, heating drying or vacuum drying. Preferably freeze-dried with minimal disruption to the shape. Then charring, wherein the first purpose of charring is to charr the chitosan or polyvinyl alcohol, and the second purpose of charring also plays a role of reducing pores, thereby finally preparing the microporous granular carbon. Preferably, the particles are placed in a tubular furnace and then heated to a carbonization temperature, so as to avoid the situation that the chitosan or polyethylene glycol is pyrolyzed quickly and the oil and carbon are more and less. Preferably, the temperature rise speed is 5-20 ℃/min.
The microporous granular carbon is prepared by the method. Further, the microporous granular carbon has a micropore diameter of 0.5 to 0.7nm and a micropore volume of 0.15 to 0.25cm3/g。
By controlling the flow rates of the internal phase solution and the external phase solution, and the diameters of the injection port and the collecting pipe, the particle size of the microporous granular carbon obtained by the method is micron grade, and the particle size is 85-110 mu m.
When chitosan is used as a raw material, the content of nitrogen atoms in the obtained microporous granular carbon is 2-4%. The nitrogen content is the proportion of nitrogen in the sum of C, N, O, H elements.
The invention also provides application of the microporous granular carbon in carbon dioxide adsorption. The obtained microporous granular carbon is CO-carbon composite material at 25-35 DEG C2The adsorption capacity reaches 1.0-1.2 mmol/g, and after ten times of adsorption and desorption circulation, the adsorption capacity is still stabilized at 98% of the first adsorption capacity.
Example 1
A2% chitosan solution containing 2% oil-in-water emulsifier F127 is uniformly mixed with n-octane, wherein the volume ratio of the n-octane is 10%. Emulsifying at 13000rpm for 60s under homogenizing emulsifier to obtain internal phase solution. Adding 6% of water-in-oil emulsifier Span80 into n-octane, and mixing uniformly to obtain an external phase solution. The curing bath was 2% cross-linker glutaraldehyde added to the external phase solution.
The inner phase fluid and the outer phase fluid are respectively injected into an injection pipe and a collecting pipe of the capillary microfluidic device to form monodisperse water/oil emulsion, the diameter of the conical tip of an injection port is 180 mu m, and the diameter of a receiving pipe is 550 mu m. Injecting the monodisperse emulsion into a curing bath to perform a crosslinking reaction with glutaraldehyde; the flow rate of the inner phase solution is 1mL/h, the flow rate of the outer phase solution is 30mL/h, and the curing and crosslinking reaction is 1 h; separating the microspheres from the curing bath, and respectively washing the microspheres for 2-3 times by using n-octane, petroleum ether and deionized water to remove redundant oil phases on the surfaces of the microspheres and in the pore canals; the microspheres were freeze dried. Placing the microspheres in a tube furnace, heating to 800 deg.C at 5 deg.C/min, keeping for 2 hr, naturally cooling, and storing in a drying oven.
As can be seen from FIG. 2, the carbon spheres have a better nitrogen adsorption and desorption curve, wherein the specific surface area is 576m2Per g, pore volume of the micropores is 0.22cm3Per g, total pore volume of 0.24cm3(ii) in terms of/g. As can be seen from fig. 3, the surface of the carbon sphere was very rough, and micro-and nano-scale pores were observed. As can be seen from FIG. 4, the carbon spheres are paired with CO2The saturated adsorption amount of (b) was 1.20 mmol/g.
Example 2
A2% chitosan solution containing 2% oil-in-water emulsifier F127 and n-octane were mixed uniformly, the volume ratio of n-octane was 5%. Emulsifying at 16000rpm for 60s in homogenizing emulsifying machine to obtain internal phase solution. Adding 6% of water-in-oil emulsifier Span80 into n-octane, and mixing uniformly to obtain an external phase solution. The curing bath was 2% cross-linker glutaraldehyde added to the external phase solution.
The inner phase fluid and the outer phase fluid are respectively injected into an injection pipe and a collecting pipe of the capillary microfluidic device to form monodisperse water/oil emulsion, the diameter of the conical tip of an injection port is 180 mu m, and the diameter of a receiving pipe is 550 mu m. Injecting the monodisperse emulsion into a curing bath to perform a crosslinking reaction with glutaraldehyde; the flow rate of the inner phase solution is 2mL/h, the flow rate of the outer phase solution is 40mL/h, and the curing and crosslinking reaction is 1 h; separating the microspheres from the curing bath, and respectively washing the microspheres for 2-3 times by using n-octane, petroleum ether and deionized water to remove redundant oil phases on the surfaces of the microspheres and in the pore canals; the microspheres were freeze dried. Placing the microspheres in a tube furnace, heating to 800 deg.C at 5 deg.C/min, keeping for 2 hr, naturally cooling, and storing in a drying oven.
As can be seen from FIG. 5, the carbon spheres have a better nitrogen adsorption and desorption curve, wherein the specific surface area is 450m2Per g, pore volume of the micropores was 0.17cm3(g) total pore volume of 0.19cm3(ii) in terms of/g. As can be seen from FIG. 6, the carbon spheres are paired with CO2The saturated adsorption amount of (b) was 1.10 mmol/g.
Example 3
A2% chitosan solution containing 2% oil-in-water emulsifier F127 was mixed with ethyl acetate at a volume ratio of 2%. Emulsifying at 16000rpm for 40s in homogenizing emulsifying machine to obtain internal phase solution. Adding 6% water-in-oil emulsifier Span80 into n-octane, and mixing to obtain external phase solution. The curing bath was 2% cross-linker glutaraldehyde added to the external phase solution.
The inner phase fluid and the outer phase fluid are respectively injected into an injection pipe and a collecting pipe of the capillary microfluidic device to form monodisperse water/oil emulsion, the diameter of the conical tip of an injection port is 180 mu m, and the diameter of a receiving pipe is 550 mu m. Injecting the monodisperse emulsion into a curing bath to perform a crosslinking reaction with glutaraldehyde; the flow rate of the inner phase solution is 1.5mL/h, the flow rate of the outer phase solution is 35mL/h, and the curing and crosslinking reaction is 1 h; separating the microspheres from the curing bath, and respectively washing the microspheres for 2-3 times by using n-octane, petroleum ether and deionized water to remove redundant oil phases on the surfaces of the microspheres and in the pore canals; the microspheres were freeze dried. Placing the microspheres in a tube furnace, heating to 800 deg.C at 5 deg.C/min, keeping for 2 hr, naturally cooling, and storing in a drying oven.
As can be seen from FIG. 7, the carbon spheres have a better nitrogen adsorption and desorption curve, wherein the specific surface area is 432m2Per g, pore volume of the micropores is 0.18cm3(g) total pore volume of 0.19cm3(ii) in terms of/g. As can be seen from FIG. 8, the carbon spheres are paired with CO2The saturated adsorption amount of (3) was 1.05 mmol/g.
Example 4
A2 percent chitosan solution containing 4 percent of oil-in-water emulsifier F127 is uniformly mixed with n-octanol, and the volume ratio of the n-octanol is 10 percent. Emulsifying at 13000rpm for 60s under homogenizing emulsifier to obtain internal phase solution. Adding 6% of water-in-oil emulsifier Span80 into n-octane, and mixing uniformly to obtain an external phase solution. The curing bath was 2% cross-linker glutaraldehyde added to the external phase solution.
The inner phase fluid and the outer phase fluid are respectively injected into an injection pipe and a collecting pipe of the capillary microfluidic device to form monodisperse water/oil emulsion, the diameter of the conical tip of an injection port is 180 mu m, and the diameter of a receiving pipe is 550 mu m. Injecting the monodisperse emulsion into a curing bath to perform a crosslinking reaction with glutaraldehyde; the flow rate of the inner phase solution is 1.3mL/h, the flow rate of the outer phase solution is 30mL/h, and the curing and crosslinking reaction is 1 h; separating the microspheres from the curing bath, and respectively washing the microspheres for 2-3 times by using n-octane, petroleum ether and deionized water to remove redundant oil phases on the surfaces of the microspheres and in the pore canals; the microspheres were freeze dried. Placing the microspheres in a tube furnace, heating to a carbonization temperature of 900 ℃ at a speed of 5 ℃/min, keeping for 2h, naturally cooling, and placing in a drying oven for storage. The carbon ball has a good nitrogen adsorption and desorption curve, wherein the specific surface area is 522m2Per g, pore volume of the micropores is 0.18cm3(g) total pore volume of 0.23cm3(ii) in terms of/g. As can be seen from FIG. 9, the carbon beads are paired with CO2The saturated adsorption amount of (3) was 1.05 mmol/g.

Claims (13)

1. A method of preparing microporous granular carbon, characterized by: the method comprises the following steps:
A. emulsifying the chitosan solution, an oil-in-water emulsifier F127 and an organic solvent to obtain an internal phase solution, wherein the emulsifying rotation speed is more than 10000rpm, the oil-in-water emulsifier F127 is 1-5% of the total volume of the oil-in-water emulsifier and the chitosan solution, the organic solvent is at least one of n-octane, n-octanol or ethyl acetate, and the organic solvent is 2-20% of the volume of the internal phase solution; mixing a water-in-oil emulsifier Span80 and n-octane to obtain an external phase solution, wherein the water-in-oil emulsifier Span80 accounts for 2-12% of the volume of the external phase solution; mixing the cross-linking agent and the external phase solution to obtain a curing bath;
B. respectively injecting the internal phase solution and the external phase solution into an injection tube and a collecting tube of the capillary microfluidic chip to form monodisperse water-oil emulsion, and injecting the monodisperse water-oil emulsion into a curing bath to perform a crosslinking reaction with a crosslinking agent to prepare particles;
C. washing, drying and carbonizing the particles to obtain the microporous granular carbon.
2. The method of making microporous particulate carbon of claim 1, wherein: in the step A, the chitosan solution is formed by adding chitosan into water containing acetic acid for dissolving, wherein the acetic acid is 1-2% of the total volume of the water and the acetic acid.
3. The method of making microporous particulate carbon of claim 1 or 2, wherein: in the step A, the mass concentration of chitosan in the chitosan solution is 1-3%.
4. The method of making microporous particulate carbon of claim 1 or 2, wherein: in the step A, the emulsifying rotating speed is 10000-16000 rpm.
5. The method of making microporous particulate carbon of claim 1 or 2, wherein: in the step B, the injection flow rate of the inner phase solution is 0.5-2.5 mL/h, and the injection flow rate of the outer phase solution is 20-40 mL/h.
6. The method of making microporous particulate carbon of claim 1 or 2, wherein: in the step B, the diameter of the injection port is 150-200 μm, and the diameter of the collection pipe is 500-550 μm.
7. The method of making microporous particulate carbon of claim 6, wherein: the diameter of the injection port was 180 μm and the diameter of the collection tube was 550. mu.m.
8. The method of making microporous particulate carbon of claim 1 or 2, wherein: in the step C, the washing is sequentially carried out by using the organic solvent, the petroleum ether and the water which are the same as those in the step A.
9. The method of making microporous particulate carbon of claim 1 or 2, wherein: in the step C, the drying is freeze drying, heating drying or vacuum drying.
10. The method of making microporous particulate carbon of claim 9, wherein: the drying is freeze drying.
11. The method of making microporous particulate carbon of claim 1 or 2, wherein: in the step C, the carbonization temperature is 600-900 ℃; the carbonization time is 1-4 h; the temperature rise rate of carbonization is 5-20 ℃/min.
12. The microporous granular carbon produced by the method for producing a microporous granular carbon according to any one of claims 1 to 11, characterized in that: the diameter of the micropore of the microporous granular carbon is 0.5-0.7 nm, and the pore volume of the micropore is 0.15-0.25 cm3/g。
13. Use of the microporous particulate carbon of claim 12 for adsorbing carbon dioxide.
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