Preparation device and preparation method of conductive carbon with curled lamellar structure

Abstract

The invention discloses a preparation device and a preparation method of a conductive carbon material with a curled lamellar structure, raw material gas enters a raw material gas inlet, the raw material gas obtains a higher ionization temperature under the action of a gas insulation waveguide and a waveguide / coaxial converter so as to control a proper ionization temperature, in the ionization process, carbon-hydrogen bonds of hydrocarbon compounds are broken, and in the ionization process, the carbon-hydrogen bonds of the hydrocarbon compounds are broken; due to the fact that a high-frequency microwave electric field continuously acts on the ionization cracking unification area, hydrogen ions formed by bond breaking are kept in a high-energy state to form stable and uniform thermal plasma, and in the high-temperature environment, broken carbon bonds can keep very high activity, so that chains or rings formed by carbon and carbon through chemical bonds can form uniform thermal plasma. Meanwhile, residual carbon-hydrogen bonds can be further broken at high temperature, the activity of broken bonds is kept, and a curled sheet with a multi-chain and multi-ring structure is formed by quickly generating dislocation in the further condensation and assembly process and is automatically assembled to form a relatively large network structure. The method can be used for efficiently producing the carbon conductive material with the curled lamellar structure at low production cost.

Description

Technical Field

[0001] The invention relates to the technical field of carbon materials, and in particular to a preparation device and a preparation method of conductive carbon with a curled sheet structure. Background Art

[0002] Generally, carbon materials (except diamond) have a certain conductivity and are often used to improve the conductivity of electrical insulating materials (such as resins, etc.), or for negative electrode materials, positive electrode packaging materials and conductive agents of batteries and secondary batteries (rechargeable lithium batteries). In recent years, with the vigorous development of the new energy industry, the demand for electric energy storage has increased sharply, and higher requirements have been put forward for high specific capacity (capacity per unit volume) and high charge and discharge cycle life of secondary batteries (rechargeable lithium batteries), which has greatly stimulated the application demand of conductive carbon materials in secondary batteries. Although, it is well known that gaseous hydrocarbons or liquid hydrocarbons can be partially oxidized (partially burned) under aerobic conditions, or both under anaerobic conditions and high temperature, they can be cracked to generate solid elemental carbon, hydrogen and some hydrocarbon by-products. However, it is not easy to obtain conductive carbon materials with excellent comprehensive performance. First of all, from the perspective of application requirements, secondary batteries have high requirements for the specific performance of conductive carbon materials: 1. High structurality to form a conductive network; 2. High DBP oil absorption value and BET specific surface area; 3. Good dispersibility. The use of microwave plasma generators to produce conductive carbon materials is the most efficient and economical.

[0003] Microwaves are electromagnetic waves that can form alternating electric and magnetic fields in their transmission space. A microwave plasma generator is a device that can transmit microwaves to a specific space and thereby form an electric field of sufficient intensity, causing the originally insulating gas to undergo ionization breakdown and discharge, and maintain this ionization state by continuously inputting microwave energy. However, in order to ensure or even further increase the plasma temperature, in addition to concentrating the local electric field distortion through the microwave transmission structure, it is also necessary to transmit a higher microwave power density as a whole to increase the microwave electric field intensity in the plasma generation area, but this will also lead to: unexpected breakdown in areas where we do not want gas ionization breakdown to occur, such as the microwave electric field intensity in microwave transmission devices (waveguides, etc.) will increase accordingly, greatly increasing the risk of gas ionization breakdown. Existing microwave plasma generators such as those with application numbers 200310105039.1, 201810678562.X, 200810046267.9 and 200810046268.3 all have the above problems in theory. This is not just a problem of limited input microwave power. If appropriate measures are not taken, the following situations will occur, such as: the diffusion of high-temperature plasma directly damages the waveguide and the excitation cavity; the plasma flows toward the source of the microwave, causing the waveguide to be broken down and burned, and the microwave generator and related devices to be damaged. In order to alleviate this contradiction, the usual microwave plasma generator can only use a certain solid isolation structure, that is, the "insulating medium", "discharge tube made of quartz, etc.", "quartz glass tube" and other structures described in the above patents, to isolate the high-temperature plasma from the waveguide and excitation cavity for transmitting and converting microwaves. The specific implementation is to use a solid material (quartz glass or similar performance material) that can both transmit microwaves and withstand high temperatures to make a solid isolation structure that can be set near the plasma.

[0004] When the above-mentioned existing microwave plasma generator is used for chemical reaction production, the solid isolation structure therein greatly limits the feasibility of application. The reason is that there are two ways to introduce the reaction raw materials into such a device, but due to structural limitations, these two ways of introducing the reaction raw materials will produce corresponding adverse consequences. The first one can be called: direct introduction and ionization, that is, the reaction raw materials are first introduced into the microwave device, and directly pass through the high microwave electric field area where the plasma is formed as expected, and are subjected to continuous microwave loading, so that the reaction raw materials are directly ionized in this area and reach the highest temperature before passing through; the second one can be called tail heating reaction, which only allows the carrier gas to pass through the high microwave electric field area where the plasma is formed, and the carrier gas forms an ionized tail after leaving this area, and then the raw material gas is heated by passing the reaction raw material into the ionized tail, or by passing the ionized tail into the reaction raw material. The following will specifically analyze the two methods of introducing reaction raw materials: First, using the direct introduction ionization method, when the reaction raw materials are directly ionized in the high microwave electric field area and reach the highest temperature, the corresponding chemical reaction will be completed, and the chemical reaction will often generate solid and liquid products. Although affected by the input of the reaction raw materials, the plasma and the products will move toward the outlet as a whole, but due to the rapid expansion of the plasma gas, turbulence and high-temperature diffusion, there will always be some solid or liquid products that will gain unexpected kinetic energy and move in all directions, causing a part of them to reach and adhere to the solid isolation structure, and these solid isolation structures need to be set in or near the area with higher microwave electric field intensity to isolate the plasma. Under this high-intensity microwave electric field condition, many reaction products can absorb microwaves, causing local temperatures to rise sharply and destroying the solid isolation structure; and conductive products such as carbon and silicon will form conductive coatings on the solid isolation structure, shielding microwaves, making it impossible for microwaves to be transmitted to the originally designed high microwave electric field intensity area, thereby failing to excite plasma; even breakdown and discharge caused by the conductive coatings may occur on the solid isolation structure, and very high instantaneous local temperature rise may occur, leading to damage to the solid isolation structure. Even if quartz glass or other high-temperature resistant and low-expansion coefficient materials are used, cracking damage may occur due to uneven thermal expansion due to the large temperature difference, or melting damage may occur due to local high temperatures. It can be seen that the existing devices cannot achieve this method of direct ionization. 2. Therefore, the wake heating reaction method is usually adopted in practical applications. However, it is well known that the radiation heat dissipation and convection heat dissipation losses of high-temperature fluids are very severe, that is, the temperature of the ionized wake when it contacts the reaction raw materials is much lower than its temperature in the high microwave electric field intensity area; in addition, the carrier gas as a gas has a very small heat capacity, and the ionization temperature increases, the density is lower, the heat capacity is smaller, and the temperature is easily reduced. Therefore, the actual flow ratio of the reaction raw material gas to the carrier gas that can be introduced must be very small; the relatively low temperature limits the chemical reactions that must be high temperature or the applications where high temperature can bring additional benefits, and the small flow ratio greatly limits the output and will lead to a significant increase in production costs.Therefore, the existing microwave plasma generator cannot meet the production requirements of conductive carbon with curled sheet structure. Summary of the invention

[0005] The present invention aims to solve the problem that microwave plasma generators in the prior art cannot meet the production demand of conductive carbon with a curled lamellar structure, and in particular to provide a preparation device and a preparation method for conductive carbon with a curled lamellar structure, wherein the raw gas is introduced into a second waveguide, a waveguide / coaxial converter, a high breakdown strength coaxial transmission section, and a low breakdown strength coaxial transmission section inside the device, and is finally directly ionized under the action of a high-intensity microwave electric field in an outlet ionization zone, and the microwaves continuously act on this zone, so that the chemical reaction in this zone obtains and maintains the highest temperature, forming a stable and uniform thermal plasma, and when the raw gas enters the outlet ionization zone, the chemical bonds between carbon and other elements are broken, In this high-temperature environment, the broken carbon bonds can maintain high activity to form carbon-carbon chains or rings. At the same time, due to turbulent tumbling, dislocation occurs during further condensation and assembly, thereby forming a curled sheet structure of carbon conductive materials with a multi-chain and multi-ring structure. Further use of high-breakdown strength raw gas and partial circulation can increase the breakdown resistance of the microwave transmission part and prevent the ionized atmosphere and the generated carbon material from flowing toward the source of the microwave. Further introduction and mixing of low-breakdown strength gas in the low-breakdown strength coaxial transmission section can deliberately create an area with lower breakdown strength, which becomes the short board of the wooden barrel principle and makes the high-temperature ionization in the outlet ionization zone more stable.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] The invention discloses a device for preparing conductive carbon with a curled sheet structure, comprising a microwave generator, an air-isolating waveguide, a waveguide / coaxial converter, a high breakdown strength coaxial transmission section and a low breakdown strength coaxial transmission section which are connected in sequence, wherein a coaxial inner conductor is arranged through the waveguide / coaxial converter, the high breakdown strength coaxial transmission section and the low breakdown strength coaxial transmission section, a raw material air inlet is arranged on the waveguide / coaxial converter, a control air inlet is arranged on the high breakdown strength coaxial transmission section or the low breakdown strength coaxial transmission section, and an outlet ionization zone is arranged on the low breakdown strength coaxial transmission section.

[0008] Preferably, the air-isolating waveguide comprises a first waveguide and a second waveguide, and a wave-transmitting air-isolating plate is arranged between the first waveguide and the second waveguide.

[0009] Preferably, the lower end of the waveguide / coaxial converter is connected to the anti-flow air pipe through a door twist block, an anti-flow hole is provided on the door twist block, and a λ / 4 anti-flow groove is provided at the upper end of the anti-flow hole; the lower end of the coaxial inner conductor passes through the anti-flow air pipe, and a dynamic sealing structure is provided at the lower end of the anti-flow air pipe.

[0010] Preferably, the waveguide / coaxial converter has an opening at the upper end and is connected to the lower end of the high breakdown strength coaxial transmission section, and the upper end of the high breakdown strength coaxial transmission section is connected to the lower end of the low breakdown strength coaxial transmission section.

[0011] Preferably, the high breakdown strength coaxial transmission section is provided with a plurality of air holes, a circulating air collecting hood is provided on the outer side of the air holes, a circulating air outlet is provided on the circulating air collecting hood, a raw material air inlet and a circulating air inlet are provided on the anti-circulation air pipe, the circulating air inlet is connected to the circulating air outlet through a circulating air pipe, and a cooling purifier, a circulating air pump and a circulating air regulating valve are provided on the circulating air pipe.

[0012] Preferably, a cooling collection bin is provided at the upper end of the outlet ionization zone.

[0013] The method for preparing conductive carbon with a curled sheet structure comprises the following steps:

[0014] Step 1: Inert gas is introduced through the raw material gas inlet and the control gas inlet, and the inert gas fills the second waveguide, the waveguide / coaxial converter, the high breakdown strength coaxial transmission section, the low breakdown strength coaxial transmission section, the outlet ionization zone and the internal space of the cooling collection bin to discharge the oxygen therein;

[0015] Step 2: After the oxygen content at the outlet ionization zone is less than 0.5%, the microwave generator is started, and the microwave passes through the gas isolation waveguide, the waveguide / coaxial converter, the high breakdown strength coaxial transmission section and the low breakdown strength coaxial transmission section in sequence, and the coaxial inner conductor is adjusted to adjust the microwave electric field intensity at the outlet ionization zone;

[0016] Step 3, stop introducing inert gas, introduce raw gas from the raw gas inlet, the raw gas fills the second waveguide and the inner space of the waveguide / coaxial converter, and flows into the low breakdown strength coaxial transmission section through the high breakdown strength coaxial transmission section, and at the same time, start the circulating gas pump to circulate part of the raw gas through the cooling purifier and the circulating gas pipe and return to the circulating gas inlet, adjust the circulating gas flow rate, make the circulating flow rate of the raw gas greater than the flow rate flowing into the low breakdown strength coaxial transmission section, and at the same time introduce control gas, the mixed gas of the raw gas and the control gas will fill the low breakdown strength coaxial transmission section, and adjust the flow rate of the control gas;

[0017] Step 4: When the mixed gas passes through the outlet ionization zone, it will be continuously ionized and generate high temperature, and chemical reaction will occur to produce a carbon conductive material with a curled sheet structure and by-product tail gas;

[0018] Step 5, tail gas post-treatment: the by-product tail gas and the control gas that did not participate in the reaction form a mixed tail gas, and the carbon conductive material carrying the curled sheet structure quickly leaves the outlet ionization zone and enters the cooling collection chamber for gas-solid separation.

[0019] Preferably, the inert gas is argon or nitrogen.

[0020] Preferably, the raw gas is any one or more of natural gas, methane, acetylene, CO / CO2.

[0021] Preferably, the intake volume of the raw gas: microwave power is 8-20 L / min: 12 KW, and the concentration of the raw gas is 3.8-80%.

[0022] Preferably, the flow rate of the circulating gas is 0-100 times the intake volume of the raw gas, and the flow rate of the control gas is 0-100 times the intake volume of the raw gas.

[0023] Preferably, the control gas is any one or more of hydrogen, argon, nitrogen, CO / CO2.

[0024] The beneficial effects of this technical solution are as follows:

[0025] 1. The preparation device of the conductive carbon with curled lamellar structure provided by the present invention directly passes the raw material gas into the ionization zone located in the outlet ionization zone, and directly ionizes it under the action of high-intensity microwave electric field, instead of using other carrier gases to ionize and then using waste heat to heat the raw material gas after leaving the microwave area. In this way, microwaves can continue to act on this area, so that the chemical reaction in this area reaches and maintains the highest temperature, forming a stable and uniform thermal plasma. At this time, the chemical bonds between the carbon element and other elements in the raw material gas are broken. In this high-temperature environment, the broken carbon bonds can maintain high activity to form carbon and carbon chains or rings. At the same time, due to turbulence and tumbling, the carbon element is dislocated in the process of further condensation and assembly, thereby forming a curled lamellar carbon conductive material with a multi-chain and multi-ring structure.

[0026] 2. The device for preparing conductive carbon with a curled sheet structure provided by the present invention adopts the method of introducing high breakdown strength raw gas into the device and filling the microwave transmission parts such as the second waveguide, waveguide / coaxial converter and high breakdown strength coaxial transmission section, which can effectively improve the electric field breakdown resistance of these parts. At the same time, a part of the raw gas is circulated at a large flow rate through an auxiliary circulating air pipe, a cooling purifier and a circulating air pump, which can prevent the ionized atmosphere and the generated carbon material from flowing toward the source of the microwave without increasing the amount of raw gas entering the outlet ionization zone, prevent the waveguide from being broken down and burned, and prevent the microwave generator and related devices from being damaged. In this way, it is even less likely that carbon materials or other solid and liquid products will diffuse into the wave-transmitting air-isolating plate, which can completely avoid: A. Being contaminated and damaged by additional microwave heating; B. Being contaminated to form a conductive film shielding, which leads to the obstruction of microwave transmission and the inability to reach the expected area; C. Being contaminated to form a conductive film causing breakdown discharge and instantaneous local high temperature, further preventing the device damage and unstable operation caused by the above situations.

[0027] 3. The preparation device of the conductive carbon with curled sheet structure provided by the present invention adopts the method of introducing a control gas with lower breakdown strength into the low breakdown strength coaxial transmission section and mixing it with the raw gas, and adjusting the ratio of the mixed gas to the raw gas, so as to adjust the breakdown strength of the mixed gas. At the same time, according to the microwave design, the high-density power lines and the high electric field strength area are located in the outlet ionization zone of the low breakdown strength coaxial transmission section, and the low-density power lines and the weak electric field strength area are located in other areas such as the high breakdown strength coaxial transmission section. In this way, the outlet ionization zone can become the area with the highest electric field intensity and the lowest breakdown strength in the entire microwave system, which becomes the short board of the wooden barrel principle, and makes the outlet ionization zone more stable while ensuring the high ionization temperature, thereby realizing continuous and stable production.

[0028] 4. The preparation device of the conductive carbon with a curled sheet structure provided by the present invention can control the chemical reaction area in the outlet ionization zone, and immediately discharge the product from the microwave device into a cooling collection bin when the reaction is completed. The product, especially the solid carbon product, will not enter the microwave device, and will not cause the material channels such as the waveguide / coaxial converter, the high breakdown strength coaxial transmission section and the low breakdown strength coaxial transmission section to be blocked by the solid product.

[0029] 5. In the preparation device of the conductive carbon with curled sheet structure provided by the present invention, the lower end of the waveguide / coaxial converter is connected to the anti-flow air pipe through a door twist block, the door twist block is provided with an anti-flow hole, and the upper end of the anti-flow hole is provided with a λ / 4 anti-flow groove; the lower end of the coaxial inner conductor passes through the anti-flow air pipe, and the lower end of the anti-flow air pipe is provided with a dynamic sealing structure; the anti-flow hole, λ / 4 anti-flow groove and anti-flow air pipe structure can prevent microwaves from leaking outward while allowing gas to pass through, and the lower end is blocked by a passive sealing structure, and the raw material gas can quickly pass through the door twist block after entering from the raw material air inlet, and effectively dissipate the heat of the door twist block while entering the interior of the microwave device, so that the device can operate stably for a long time.

[0030] 6. The preparation method of the conductive carbon with curled lamellar structure provided by the present invention obtains conductive carbon with curled lamellar structure, and the conductive carbon with curled lamellar structure includes conductive carbon monomer with lamellar curled structure and / or conductive carbon stack with lamellar curled structure. The microstructure of the conductive carbon with curled lamellar structure is a chain or ring formed by carbon atoms, and when further condensed and assembled into multi-chain or multi-ring to form a lamellar structure, dislocation and multiple curling occur to form a hollow three-dimensional structure; the conductive carbon monomer with lamellar curled structure is U or V-shaped folding, N or M or W-shaped folding, C or G-shaped curling, and the conductive carbon stack with lamellar curled structure is a combination type of curling with multiple foldings existing at the same time; on the one hand, compared with SP carbon black, Ketjen black, acetylene black, CNTs carbon nanotubes, etc., it has a more complex multi-chain or multi-ring structure, has more open boundaries and incomplete ring structures, can better contact and conduct with the ions of the material to be conductive, and can also form secondary connections between the conductive carbon materials. It forms a conductive network over a larger range and produces better conductive properties. On the other hand, compared with graphene, it has a smaller particle size, and the curled three-dimensional structure is not prone to the actual specific surface area reduction caused by the overlapping of two-dimensional sheets of graphene. It has better dispersibility and stable and effective specific surface area, as well as a larger actual sheet surface than ordinary carbon black particles, which can form effective point-to-surface contact with the ions of the material that needs to be conductive, which can further reduce resistance and improve conductivity. The hollow space in the conductive carbon with a curled sheet structure can allow the ions of the material that needs to be conductive to enter and exit smoothly, and both the inside and outside can effectively contact with the conductive material ions, further reducing resistance and improving conductivity. At the same time, it also has good elasticity and can form flexible contact with the conductive material ions. When the material that needs to be conductive changes in volume due to conduction, charging and discharging, thermal expansion and contraction, external force or other influences, no contact gap will appear, which can more stably maintain low resistivity and high conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the structure of the preparation device in the invention;

[0032] Figure 2 The structural diagram of the middle door twist block of the invention is shown;

[0033] Figure 3 The electron microscope photographs of the conductive carbon with curled lamellar structure and the carbon black with branched structure in the invention are compared;

[0034] Figure 4 This is an electron microscope photo of conductive carbon with a curled lamellar structure;

[0035] Figure 5 Schematic diagram of the size of the conductive carbon with curled sheet structure;

[0036] Figure 6 This is a 10,000-fold electron microscope photo of the conductive carbon with a curled lamellar structure (1μm scale);

[0037] Figure 7 This is a 20,000-fold electron microscope photo of the conductive carbon with a curled lamellar structure (500nm scale);

[0038] Figure 8 This is a 50,000-fold electron microscope photo of the conductive carbon with a curled lamellar structure (200nm scale);

[0039] Fig. 9 This is an 80,000-fold electron microscope photo of the conductive carbon with a curled lamellar structure (100 nm scale);

[0040] Fig.10 This is a simulation diagram of the microwave electric field distribution in the low breakdown strength coaxial transmission section and the exit ionization zone;

[0041] Fig.11 This is a simulation diagram of the deformation of the electric line distribution in the low breakdown strength coaxial transmission section and the exit ionization zone;

[0042] Among them: 1. microwave generator; 2. air-isolating waveguide; 201. first waveguide; 202. second waveguide; 203. wave-transmitting air-isolating plate; 3. waveguide / coaxial converter; 4. high breakdown strength coaxial transmission section; 5. low breakdown strength coaxial transmission section; 6. coaxial inner conductor; 7. raw material air inlet; 8. control air inlet; 9. outlet ionization zone; 10. door twist block; 11. anti-flow air pipe; 12. anti-flow hole; 13. λ / 4 anti-flow groove; 14. dynamic sealing structure; 15. air permeability; 16. circulating air collecting hood; 17. circulating air outlet; 1 8. Circulating air inlet; 19. Circulating air pipe; 20. Cooling purifier; 21. Circulating air pump; 22. Circulating air regulating valve; 23. Cooling collection bin; 301. Conductive carbon monomer with lamellar curling structure; 302. Conductive carbon stack with lamellar curling structure; 303. Branched carbon black; 401. U or V-shaped folding; 402. N or M or W-shaped folding; 403. C or G-shaped curling; 404. Combined curling; 501. Curled monomer length L; 502. Curled monomer width W; 503. Curled monomer height H; 504. Lamellar thickness δ. DETAILED DESCRIPTION

[0043] The present invention is further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

[0044] DBP oil absorption value: the volume of dibutyl phthalate absorbed by 100g of carbon black under specified test conditions (cm 3 ). It is used to characterize the aggregation degree of carbon black. The DBP value can calculate the void volume between carbon black aggregates, so it is a measure of the aggregation and agglomeration degree of carbon black. Therefore, generally, the higher the DBP oil absorption value, the stronger the structure and the better the conductivity.

[0045] EIS stands for electrochemical impedance spectroscopy. This data is positively correlated with resistivity, that is, the larger the EIS, the greater the resistivity and the worse the conductivity; it is negatively correlated with conductivity, that is, the smaller the EIS, the higher the conductivity and the better the conductivity.

[0046] BET specific surface area is the abbreviation of BET specific surface area test method, which is named because it is based on the famous BET theory.

[0047] When the raw gas introduced into the device is methane, the main reaction is: CH4→C+2H2;

[0048] When the raw gas introduced into the device is acetylene, the main reaction is: C2H2→2C+H2;

[0049] When the raw gas introduced into the device is CO, H2 needs to be mixed into the raw gas, or a gas containing 0.1%-100% H2 is used as the control gas. The main reaction is: CO+H2→C+H2O;

[0050] When the raw gas introduced into the device is CO2, H2 needs to be mixed into the raw gas, or a gas containing 0.1%-100% H2 is used as the control gas. The main reaction is: CO2+2H2→C+2H2O.

[0051] Examples 1-4 all use the following preparation devices and methods; Figure 1 and Figure 2 As shown: a device for preparing conductive carbon with a curled sheet structure, comprising a microwave generator 1, an air-isolating waveguide 2, a waveguide / coaxial converter 3, a high breakdown strength coaxial transmission section 4 and a low breakdown strength coaxial transmission section 5 connected in sequence, wherein the waveguide / coaxial converter 3, the high breakdown strength coaxial transmission section 4 and the low breakdown strength coaxial transmission section 5 are penetrated by a coaxial inner conductor 6, the waveguide / coaxial converter 3 is provided with a raw material air inlet 7, the high breakdown strength coaxial transmission section 4 or the low breakdown strength coaxial transmission section 5 is provided with a control air inlet 8, and the low breakdown strength coaxial transmission section 5 is provided with an outlet ionization zone 9.

[0052] The air-isolating waveguide 2 includes a first waveguide 201 and a second waveguide 202 , and a wave-transmitting air-isolating plate 203 is disposed between the first waveguide 201 and the second waveguide 202 .

[0053] Among them, the lower end of the waveguide / coaxial converter 3 is connected to the anti-flow air pipe 11 through a door twist block 10, and an anti-flow hole 12 is arranged on the door twist block 10, and a λ / 4 anti-flow groove 13 is arranged at the upper end of the anti-flow hole 12; the lower end of the coaxial inner conductor 6 passes through the anti-flow air pipe 11, and a dynamic sealing structure 14 is arranged at the lower end of the anti-flow air pipe 11.

[0054] The waveguide / coaxial converter 3 has an opening at the upper end and is connected to the lower end of the high breakdown strength coaxial transmission section 4 , and the upper end of the high breakdown strength coaxial transmission section 4 is connected to the lower end of the low breakdown strength coaxial transmission section 5 .

[0055] Among them, the high breakdown strength coaxial transmission section 4 is provided with a plurality of air holes 15, a circulating air collecting hood 16 is provided on the outside of the air hole 15, a circulating air outlet 17 is provided on the circulating air collecting hood 16, a raw material air inlet 7 and a circulating air inlet 18 are provided on the anti-circulation air pipe 11, the circulating air inlet 18 is connected to the circulating air outlet 17 through a circulating air pipe 19, and a cooling purifier 20, a circulating air pump 21 and a circulating air regulating valve 22 are provided on the circulating air pipe 19.

[0056] Wherein, a cooling collection chamber 23 is provided at the upper end of the outlet ionization zone 9 as shown.

[0057] The method for preparing conductive carbon with a curled sheet structure comprises the following steps:

[0058] Step 1: Inert gas is introduced through the raw material gas inlet 7 and the control gas inlet 8, and the inert gas fills the second waveguide 202, the waveguide / coaxial converter 3, the high breakdown strength coaxial transmission section 4, the low breakdown strength coaxial transmission section 5, the outlet ionization zone 9 and the internal space of the cooling collection chamber 23, and discharges the oxygen therein;

[0059] Step 2: After the oxygen content at the outlet ionization zone 9 is less than 0.5%, the microwave generator 1 is started, and the microwave passes through the gas isolation waveguide 2, the waveguide / coaxial converter 3, the high breakdown strength coaxial transmission section 4 and the low breakdown strength coaxial transmission section 5 in sequence, and the coaxial inner conductor 6 is adjusted to adjust the microwave electric field intensity at the outlet ionization zone 9; the coaxial inner conductor 6 is adjusted to adjust the relative height difference between the upper end surface of the coaxial inner conductor 6 and the upper edge of the outlet ionization zone 9, and the adjustable range of the relative height difference is ±50 mm;

[0060] like Fig.10 and Fig.11As shown, when microwaves are transmitted in the low breakdown strength coaxial transmission section 5, the microwave electric field intensity changes periodically and the intensity is low, the power line density and direction change periodically and the density is low, the microwave transmission space changes in the exit ionization zone 9, the electric field intensity and the power line cannot be distributed according to the original rules, the electric field and power line distribution near the upper end surface of the coaxial inner conductor 6 and the upper edge of the exit ionization zone 9 are distorted, and high-density aggregation is formed, so that the exit ionization zone 9 and the vicinity become a high electric field intensity zone with extremely high microwave electric field intensity; the relative height difference between the top of the coaxial inner conductor 6 and the upper edge of the exit ionization zone 9 can be changed by adjusting the height of the coaxial inner conductor 6 to enhance or weaken the microwave electric field intensity in the high electric field intensity zone; Due to the different design dimensions and processing accuracy of the low breakdown strength coaxial transmission section 5, the relationship between the relative height difference and the microwave electric field strength of the final high electric field strength zone is not fixed. Therefore, in practical applications, the relative height difference needs to be adjusted to maximize the microwave electric field strength of the high electric field strength zone. The adjustable range of the relative height difference is ±50mm. After the gas is ionized in the outlet ionization zone 9, it can absorb a large amount of microwave power, and the absorption is positively correlated with the electric field strength of the outlet ionization zone 9 and the nearby high electric field strength zone. The relative height difference is adjusted to make the ratio of the reflected microwave power to the output microwave power reach a relatively minimum, and the ratio is usually in the range of 1% to 50%.

[0061] Step 3, stop introducing inert gas, and introduce raw gas from the raw gas inlet 7, the raw gas fills the second waveguide 202 and the internal space of the waveguide / coaxial converter 3, and flows into the low breakdown strength coaxial transmission section 5 through the high breakdown strength coaxial transmission section 4, and at the same time, start the circulating gas pump 21 to make part of the raw gas circulate through the cooling purifier 20 and the circulating gas pipe 19 and return to the circulating gas inlet 18, adjust the circulating gas flow rate, so that the circulating flow rate of the raw gas is greater than the flow rate flowing into the low breakdown strength coaxial transmission section 5, and at the same time introduce control gas, the mixed gas of the raw gas and the control gas will fill the low breakdown strength coaxial transmission section 5, and adjust the flow rate of the control gas;

[0062] Step 4: When the mixed gas passes through the outlet ionization zone 9, it will be continuously ionized and generate high temperature, and chemical reaction will occur to produce a carbon conductive material with a curled sheet structure and by-product tail gas;

[0063] Step 5, tail gas post-treatment: the by-product tail gas and the control gas that does not participate in the reaction form a mixed tail gas, and the carbon conductive material carrying the curled sheet structure quickly leaves the outlet ionization zone 9 and enters the cooling collection chamber 23 for gas-solid separation.

[0064] Wherein, the inert gas is argon or nitrogen.

[0065] The raw gas may be any one or more of natural gas, methane, acetylene, and CO / CO2.

[0066] Among them, the intake volume of the raw gas: microwave power is 8-20L / min: 12KW, and the concentration of the raw gas is 3.8-80%.

[0067] The flow rate of the circulating gas is 0-100 times the intake volume of the raw gas, and the flow rate of the control gas is 0-100 times the intake volume of the raw gas.

[0068] Wherein, the control gas is any one or more of hydrogen, argon, nitrogen, CO / CO2.

[0069] like Figure 4 As shown, the preparation method of the conductive carbon with a curled lamellar structure provided by the present invention obtains the conductive carbon with a curled lamellar structure, and the conductive carbon with a curled lamellar structure includes a conductive carbon monomer with a curled lamellar structure 301 and / or a conductive carbon stack with a curled lamellar structure 302. The microstructure of the conductive carbon with a curled lamellar structure is a chain or ring formed by carbon atoms, and when further condensed and assembled into a multi-chain or multi-ring to form a lamellar structure, dislocation and multiple curling occur to form a hollow three-dimensional structure; the conductive carbon monomer with a curled lamellar structure is U or V-shaped folding 401, N or M or W-shaped folding 402, C or G-shaped curling 403, and the conductive carbon stack 302 with a curled lamellar structure is a combined curling 404 with multiple folds existing at the same time; on the one hand, compared with SP carbon black, Ketjen black, acetylene black, CNTs carbon nanotubes, etc., it has a more complex multi-chain or multi-ring structure, has more open boundaries and incomplete ring structures, can better contact and conduct electricity with the material ions to be conductive, and can also form the conductive The secondary connection between carbon materials forms a larger conductive network and produces better conductive performance. On the other hand, compared with graphene, it has a smaller particle size, and the curled three-dimensional structure is not prone to the actual specific surface area reduction caused by the overlapping of two-dimensional sheets of graphene. It has better dispersibility and stable and effective specific surface area, as well as a larger actual sheet surface than ordinary carbon black particles, which can form effective point-to-surface contact with the ions of the material that needs to be conductive, which can further reduce resistance and improve conductivity. The hollow space of the conductive carbon with a curled sheet structure can allow the ions of the material that needs to be conductive to enter and exit smoothly, and both the inside and the outside can effectively contact the ions of the conductive material, further reducing resistance and improving conductivity. At the same time, it also has good elasticity and can form flexible contact with the ions of the conductive material. When the volume of the material that needs to be conductive changes due to conduction, charging and discharging, thermal expansion and contraction, external force or other influences, no contact gap will appear, which can more stably maintain low resistivity and high conductivity.

[0070] like Figure 3 , Figure 5 , Figure 6 , Figure 7 , Figure 8 and Fig. 9As shown, the conductive carbon with a curled lamellar structure includes a conductive carbon monomer 301 with a curled lamellar structure and a conductive carbon stack 302 with a curled lamellar structure; the microstructure of the conductive carbon with a curled lamellar structure is a hollow three-dimensional structure formed by curling the lamellar layers for many times, and the lamellar layers are composed of carbon atoms arranged in a multi-ring manner in a hexagon or an incomplete hexagon to form a sheet; the conductive carbon monomer 301 with a curled lamellar structure is a lamellar layer folded in one direction to present an N, M or W-shaped fold 402, and the conductive carbon stack 302 with a curled lamellar structure is a combined curl 404 with multiple folds existing at the same time, and the middle curled monomer length L501 of the conductive carbon monomer 301 with a curled structure is 2000nm, the curled monomer width W502 is 2000nm, the curled monomer height H503 is 2000nm, and the lamellar thickness δ504 is 20nm.

[0071] Example 1

[0072] The intake amount and concentration of the raw gas, the flow rate of the control gas, the power of the microwave generator, the flow rate of the circulating gas, the temperature of the outlet ionization zone, and the electric field strength of the outlet ionization zone in Example 1 are shown in the following table. The obtained carbon conductive material with a curled sheet structure (such as Figure 3-Figure 9 The conductivity, BET specific surface area and DBP oil absorption value of the product are shown in the following table:

[0073]

[0074]

[0075] Since the main component of natural gas is methane, using methane alone during the implementation process, or using natural gas as raw gas, will not have a significant impact on the implementation results. Therefore, methane / natural gas can be treated as the same raw gas without special distinction.

[0076] It can be seen from the data of No. 1.1 in the table that when methane / natural gas is used as the raw gas, the circulating gas flow is too small, which will lead to the diffusion of pollutants, causing unexpected breakdown discharge and instantaneous local high temperature, resulting in unstable operation. According to the data of No. 1.2 to 1.4, it can be seen that the circulating gas flow rate ranges from 8 to 800L / min, which is equivalent to 1 to 100 times the intake volume of the raw gas. As the circulating gas flow rate increases, the operating stability is improved. However, from an economic point of view, when the circulating gas flow rate reaches 120L / min, which is 15 times the intake volume of the raw gas, stable operation can be achieved, and better product quality can be obtained, especially with good conductivity indicators. Therefore, this circulating gas flow data will continue to be used in the subsequent implementation process.

[0077] It can be seen from the data of No. 1.5 in the table that when methane / natural gas is used as the raw gas, the control gas flow rate is 0, that is, when the control gas is not introduced, the breakdown strength of the gas in different areas cannot be controlled according to the functional area, and the expected high breakdown strength area and low breakdown strength area are not formed, resulting in unstable operation. According to the data of No. 1.6 to 1.8, it can be seen that the control gas flow rate is from 8 to 800L / min, which is equivalent to 1 to 100 times the intake volume of the raw gas. As the control gas flow rate increases, the operation stability is improved. However, from an economic point of view, when the control gas flow rate reaches 60L / min, which is 7.5 times the intake volume of the raw gas, stable operation can be achieved, and better product quality can be obtained, especially with good conductivity indicators. Therefore, this control gas flow rate data will continue to be used in the subsequent implementation process.

[0078] From the data of sequence numbers 1.9 to 1.11 in the table, it can be seen that when methane / natural gas is used as the raw gas, when the intake volume of the raw gas is 8L / min, increasing the microwave power can improve the conversion rate and product quality, so the subsequent implementation process will continue to use this microwave power data. From the data of sequence numbers 1.11 to 1.13 in the table, it can be seen that when methane / natural gas is used as the raw gas, and the microwave power is 12kW, the quality of the raw gas intake is slightly better when the intake volume is small, but the yield of the obtained curled sheet structure carbon conductive material is too low, and the economic efficiency is low. The intake volume of the raw gas is 8L / min, which can achieve a better balance between product quality and output. Therefore, the subsequent implementation process will continue to use this raw gas intake data. From the data of sequence numbers 1.9 to 1.13, it can be seen that when methane / natural gas is used as the raw gas, the intake volume of the raw gas: microwave power is 8L / min:12kW, which is a better matching ratio, and it is also feasible to increase the intake volume of the raw gas and the microwave power in proportion at the same time.

[0079] It can be seen from the data of No. 1.11, 1.14 and 1.15 in the table that when methane / natural gas is used as the raw gas, any one of argon, hydrogen, nitrogen and CO / CO2 can be used as the control gas to achieve better product quality, especially good conductivity index.

[0080] From the data of No. 1.16 to 1.21 in the table, it can be seen that when methane / natural gas is used as the raw gas, any two or more mixed gases among argon, hydrogen, nitrogen, and CO / CO2 can be used as the control gas to obtain better product quality, especially good conductivity indicators. In particular, after adding CO / CO2, it can react with the hydrogen cracked from methane / natural gas to improve the yield.

[0081] It can be seen from the data of serial numbers 1.21 and 1.22 in the table that the raw gas intake volume: microwave power is 8L / min: 12kW, and the raw gas intake volume: microwave power is 16L / min: 24kW are both feasible, that is, it is feasible to increase the raw gas intake volume and microwave power proportionally at the same time.

[0082] Example 2

[0083] The intake amount and concentration of the raw gas, the flow rate of the control gas, the power of the microwave generator, the flow rate of the circulating gas, the temperature of the outlet ionization zone, and the electric field strength of the outlet ionization zone in Example 2 are shown in the following table. The obtained carbon conductive material with a curled sheet structure (such as Figure 3-Figure 9 The conductivity, BET specific surface area and DBP oil absorption value of the product are shown in the following table:

[0084]

[0085] From the data of No. 2.1 to No. 2.3 in the table, it can be seen that when acetylene is used as the raw material gas, the microwave power has little effect on the product quality. However, as shown in the data of No. 2.1, when the raw material gas intake volume: microwave power is 8L / min: 3kW, the conversion efficiency will be significantly reduced. Since acetylene cracking is an exothermic reaction, according to the data of No. 2.2, the raw material gas intake volume: microwave power is 8L / min: 6kW, a good yield and conversion rate can be obtained. Therefore, in the implementation process of using acetylene as the raw material gas, this raw material gas intake volume data will continue to be used.

[0086] From the data of No. 2.4 in the table, it can be seen that when acetylene is used as the raw gas, the control gas flow is 0, that is, when the control gas is not introduced, the breakdown strength of the gas in different areas cannot be controlled according to the functional area, and the expected high breakdown strength area and low breakdown strength area are not formed, resulting in unstable operation. According to the data of No. 2.5 to 2.7, when acetylene is used as the raw gas, if the control gas flow is too low, any one of argon, hydrogen and nitrogen can be used to obtain better product quality, especially with good conductivity indicators.

[0087] From the data of No. 2.7 to 2.10 in the table, it can be seen that when acetylene is used as the raw gas, any two or more mixed gases among argon, hydrogen, nitrogen, and CO / CO2 can be used as the control gas to obtain better product quality, especially good conductivity indicators. In particular, after adding CO / CO2, it can react with the hydrogen produced by cracking methane / natural gas, so that the yield is improved.

[0088] Example 3

[0089] The intake amount and concentration of the raw gas, the flow rate of the control gas, the power of the microwave generator, the flow rate of the circulating gas, the temperature of the outlet ionization zone, and the electric field strength of the outlet ionization zone in this Example 3 are shown in the following table. The obtained curled sheet structure carbon conductive material (such as Figure 3-Figure 9 The conductivity, BET specific surface area and DBP oil absorption value of the product are shown in the following table:

[0090]

[0091] It can be seen from the data of No. 3.1 to 3.3 in the table that when CO / CO2 is used as the raw material gas, hydrogen is required to generate carbon and water. Using hydrogen alone, or using a mixture of hydrogen and argon or nitrogen as a control gas, can achieve better product quality, especially good conductivity indicators.

[0092] Example 4

[0093] The intake amount and concentration of the raw gas, the flow rate of the control gas, the power of the microwave generator, the flow rate of the circulating gas, the temperature of the outlet ionization zone, and the electric field strength of the outlet ionization zone in this Example 4 are shown in the following table. The obtained carbon conductive material with a curled sheet structure (such as Figure 3-Figure 9 The conductivity, BET specific surface area and DBP oil absorption value of the product are shown in the following table:

[0094]

[0095]

[0096] It can be seen from the data of No. 4.1 to 4.3 in the table that when methane / natural gas, acetylene, and CO / CO2 are mixed as raw material gases, better product quality can be achieved, especially good conductivity indicators.

[0097] It can be seen from the data of No. 4.4 to 4.6 in the table that when methane / natural gas, acetylene, and CO / CO2 are mixed as raw material gases, since methane / natural gas and acetylene will produce hydrogen, using any one of argon, hydrogen, and nitrogen as the control gas alone can achieve better product quality, especially good conductivity indicators.

[0098] It can be seen from the data of No. 4.7 to 4.9 in the table that when methane / natural gas, acetylene, CO / CO2 are mixed as raw material gases, any two or more mixed gases of argon, hydrogen and nitrogen are used as control gases, better product quality can be achieved, especially good conductivity indicators.

[0099] Comparative Example

[0100] The performance comparison of conventional carbon materials, such as SP carbon black, Ketjen black EC300J, Ketjen black EC600JD, acetylene black (Hexing), CNTs carbon nanotubes and graphene with the conductive carbon material rich in curled sheet structure in this application is shown in the following table.

[0101]

[0102] From the above, it can be seen that the preparation method of the conductive carbon rich in curled lamellar structure obtained in the present application has a high structure to form a conductive network, a very high DBP oil absorption value and BET specific surface area and good dispersibility.

Claims

1. A device for preparing conductive carbon with a curled sheet structure, characterized in that: The invention comprises a microwave generator (1), an air-isolating waveguide (2), a waveguide / coaxial converter (3), a high breakdown strength coaxial transmission section (4) and a low breakdown strength coaxial transmission section (5) which are connected in sequence, wherein a coaxial inner conductor (6) is provided through the waveguide / coaxial converter (3), the high breakdown strength coaxial transmission section (4) and the low breakdown strength coaxial transmission section (5), a raw material air inlet (7) is provided on the waveguide / coaxial converter (3), a control air inlet (8) is provided on the high breakdown strength coaxial transmission section (4) or the low breakdown strength coaxial transmission section (5), and an outlet ionization zone (9) is provided on the low breakdown strength coaxial transmission section (5).

2. The device for preparing conductive carbon with a curled sheet structure according to claim 1, characterized in that: The air-isolating waveguide (2) comprises a first waveguide (201) and a second waveguide (202), and at least one wave-transmitting air-isolating plate (203) is arranged between the first waveguide (201) and the second waveguide (202).

3. The device for preparing conductive carbon with a curled sheet structure according to claim 2, characterized in that: The lower end of the waveguide / coaxial converter (3) is connected to the anti-flow air pipe (11) via a door twist block (10); an anti-flow hole (12) is provided on the door twist block (10); a λ / 4 anti-flow groove (13) is provided at the upper end of the anti-flow hole (12); the lower end of the coaxial inner conductor (6) passes through the anti-flow air pipe (11); a dynamic sealing structure (14) is provided at the lower end of the anti-flow air pipe (11).

4. The device for preparing conductive carbon with a curled sheet structure according to claim 3, characterized in that: The waveguide / coaxial converter (3) has an opening at the upper end and is connected to the lower end of the high breakdown strength coaxial transmission section (4); the upper end of the high breakdown strength coaxial transmission section (4) is connected to the lower end of the low breakdown strength coaxial transmission section (5).

5. The device for preparing conductive carbon with a curled sheet structure according to claim 4, characterized in that: The high breakdown strength coaxial transmission section (4) is provided with a plurality of air holes (15), a circulating air collecting hood (16) is provided outside the air holes (15), a circulating air outlet (17) is provided on the circulating air collecting hood (16), a raw material air inlet (7) and a circulating air inlet (18) are provided on the anti-flow air pipe (11), the circulating air inlet (18) is connected to the circulating air outlet (17) via a circulating air pipe (19), and a cooling purifier (20), a circulating air pump (21) and a circulating air regulating valve (22) are provided on the circulating air pipe (19).

6. The device for preparing conductive carbon with a curled sheet structure according to claim 5, characterized in that: A cooling collection bin (23) is provided at the upper end of the outlet ionization zone (9).

7. A method for preparing conductive carbon with a curled sheet structure, characterized in that: The following steps are involved: Step 1: Inert gas is introduced through the raw material gas inlet (7) and the control gas inlet (8), and the inert gas fills the inner space of the second waveguide (202), the waveguide / coaxial converter (3), the high breakdown strength coaxial transmission section (4), the low breakdown strength coaxial transmission section (5), the outlet ionization zone (9) and the cooling collection chamber (23), and discharges the oxygen therein; Step 2: After the oxygen content at the outlet ionization zone (9) is less than 0.5%, the microwave generator (1) is started, and the microwave passes through the gas isolation waveguide (2), the waveguide / coaxial converter (3), the high breakdown strength coaxial transmission section (4) and the low breakdown strength coaxial transmission section (5) in sequence, and the coaxial inner conductor (6) is adjusted to adjust the microwave electric field intensity at the outlet ionization zone (9); Step 3: Stop the introduction of inert gas, and introduce raw gas from the raw gas inlet (7), so that the raw gas fills the second waveguide (202) and the internal space of the waveguide / coaxial converter (3), and flows into the low breakdown strength coaxial transmission section (5) through the high breakdown strength coaxial transmission section (4). At the same time, start the circulating gas pump (21) to circulate part of the raw gas through the cooling purifier (20) and the circulating gas pipe (19) and return to the circulating gas inlet (18), adjust the circulating gas flow rate so that the circulating flow rate of the raw gas is greater than the flow rate flowing into the low breakdown strength coaxial transmission section (5), and at the same time introduce control gas, so that the mixed gas of the raw gas and the control gas will fill the low breakdown strength coaxial transmission section (5), and adjust the flow rate of the control gas; Step 4: When the mixed gas passes through the outlet ionization zone (9), it will be continuously ionized and generate high temperature, and chemical reaction will occur to produce a carbon conductive material with a curled sheet structure and by-product tail gas; Step 5, tail gas post-treatment: the by-product tail gas and the control gas that did not participate in the reaction form a mixed tail gas, and the carbon conductive material carrying the curled sheet structure quickly leaves the outlet ionization zone (9) and enters the cooling collection chamber (23) for gas-solid separation.

8. The method for preparing the conductive carbon with a curled sheet structure according to claim 7, characterized in that: The inert gas is argon or nitrogen; the raw gas is any one or more of natural gas, methane, acetylene, CO / CO2.

9. The method for preparing conductive carbon with a curled sheet structure according to claim 8, characterized in that: The intake volume of the raw gas: microwave power is 8-20 L / min: 12KW, and the concentration of the raw gas is 3.8-80%.

10. The method for preparing conductive carbon with a curled sheet structure according to claim 9, characterized in that: The flow rate of the circulating gas is 0-100 times the intake volume of the raw gas, and the flow rate of the control gas is 0-100 times the intake volume of the raw gas; the control gas is any one or more of hydrogen, argon, nitrogen, CO / CO2.

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