Method and device for continuously preparing carbon material

Abstract

Provided in the present invention is a method for continuously preparing a carbon material. The method comprises: 1) providing an inert substance to a reactor, wherein the inert substance is a high-temperature resistant substance and is not involved in the growth reaction of the carbon material; 2) providing a catalyst and introducing a gas into the reactor, such that the inert substance and the catalyst continuously move under the action of the gas, and the carbon material is grown with the interaction of the catalyst with the gas at a certain temperature in a fluidized manner, wherein the gas comprises a carbon source gas, a reducing gas and a protective gas; 3) controlling the gas to separate the carbon materials with different mass from the inert substance; 4) keeping the inert substance at a certain material level in the reactor, and continuously discharging part of the carbon materials; and 5) repeating steps 2) - 4) to achieve the continuous preparation of the carbon material. The method for preparing a carbon nanomaterial of the present invention constructs a uniform fluidization field, and has the characteristics of a short preparation period, a low production cost and a high production efficiency.

Description

A method and device for continuously preparing carbon material Technical Field

[0001] The present invention relates to a method and device for preparing carbon materials and a method for monitoring the status of a reactor. The method for preparing carbon nanomaterials of the present invention constructs a uniform fluidized field and has the characteristics of short preparation cycle, low production cost and high production efficiency. Background Art

[0002] Carbon materials, represented by carbon nanotubes, are widely used in new energy, chips, composite materials, and other areas of national defense strategy and livelihoods. While fluidized beds are currently the best method for large-scale carbon nanotube production, the small size and easy agglomeration of carbon nanotubes within fluidized beds lead to uneven production quality, difficulties in continuous production, and low production efficiency, which are the main challenges currently faced. Furthermore, the quality of fluidization directly determines the quality of carbon nanotube growth. Poor fluidization results in uneven cluster size, further exacerbating the bottleneck of continuous growth.

[0003] Currently, conventional methods to improve fluidization quality include changing internal components, optimizing bed structure, and external vibration, but it is still difficult to change the uniformity of heat and mass transfer, which in turn makes it impossible to grow carbon nanotubes uniformly and continuously on a large scale.

[0004] Therefore, it is urgent to propose a method to construct a fluidized field to continuously and uniformly grow carbon materials at low cost.

[0005] Summary of the Invention

[0006] The purpose of the present invention is to provide a method and device for continuously preparing carbon materials, which can solve the problem in the prior art that carbon materials cannot be grown continuously and uniformly in a fluidized field.

[0007] The present invention reduces the agglomeration of growing carbon materials by placing inert particles to space the catalyst, regulates the size of carbon material aggregates, and improves fluidization quality. Simultaneously, the gas is controlled to separate carbon materials of varying mass from the inert substance, enabling continuous and stable batch production of carbon materials. The carbon material preparation process of the present invention is simple and stable, and the process conditions are easily controlled, enabling batch production. The carbon materials obtained using the method and apparatus of the present invention exhibit high yield, large specific surface area, and a high aspect ratio.

[0008] Another object of the present invention is to provide a method for monitoring the reactor state during carbon nanotube growth. This method utilizes the differences in material fluidization at different gas velocities during carbon nanotube growth, combines capacitance values ​​measured by electrode sensors with an image reconstruction algorithm to enable real-time monitoring of the void fraction within the reactor. This allows precise control of the reaction process by adjusting reaction parameters.

[0009] Therefore, one aspect of the present invention provides a method for continuously preparing a carbon material, the method comprising:

[0010] 1) providing an inert substance to a reactor, wherein the inert substance is a high temperature resistant substance and does not participate in the growth reaction of the carbon material;

[0011] 2) providing a catalyst and introducing a gas into the reactor, causing the inert substance and the catalyst to continuously move under the action of the gas, and causing the catalyst and the gas to interact and fluidize and grow into the carbon material at a certain temperature, wherein the gas includes a carbon source gas, a reducing gas, and a protective gas;

[0012] 3) controlling the gas to separate carbon materials of different qualities from inert substances;

[0013] 4) Maintaining the inert material at a certain level in the reactor and continuously discharging part of the carbon material;

[0014] 5) Repeat steps 2)-4) to achieve continuous preparation of carbon materials.

[0015] Another aspect of the present invention provides an apparatus for continuously preparing carbon materials, the apparatus comprising a main reactor for performing a CVD reaction and a collector for collecting carbon materials, the main reactor comprising an input end, an outflow end, and a reactor body, the reactor body comprising a reaction zone and a separation zone, gas and catalyst being supplied to the reaction zone via the input end; the outflow end being located above the separation zone, the separation zone being connected to the collector via a connecting pipe via the outflow end;

[0016] The collector includes a filter, and the filter is used to separate the carbon material from the tail gas discharged from the main reactor.

[0017] Another aspect of the present invention provides a carbon material prepared by the method of the present invention.

[0018] Another aspect of the present invention provides a method for monitoring the status of the apparatus for continuously preparing carbon materials according to the present invention, the method comprising the following steps:

[0019] a) Initial data collection: record the capacitance value C of the set gas source respectively m , the capacitance value of carbon nanotubes C n ;

[0020] b) real-time data collection: placing an electrode assembly on the outer wall of the separation zone of the reactor body, with the electrode assembly at a height H from the bottom of the reactor; recording a capacitance value C measured by the electrode assembly, and converting the capacitance value C into a mathematical signal;

[0021] c) Image reconstruction: performing an algorithm iteration on the mathematical signal obtained in step b) to calculate the dielectric constant ε of each unit, and then performing image reconstruction to obtain the void ratio P in the reactor at the corresponding time, and calculating the characteristic value θ based on the void ratio P;

[0022] d) Data adjustment: comparing the eigenvalue θ obtained in step c with the standard eigenvalue θs. When the eigenvalue θ is outside the range of the standard eigenvalue θs, adjusting parameters to make the eigenvalue within the range of the standard eigenvalue θs.

[0023] In a preferred embodiment, the electrode assembly converts the measured capacitance value C into a voltage signal, and performs analog-to-digital conversion on the voltage signal through phase-sensitive demodulation and a low-pass filter to obtain a mathematical signal.

[0024] In a preferred embodiment, the value range of H is 10D≤H≤30D, wherein D is the diameter of the reaction zone of the reactor.

[0025] In a preferred embodiment, the characteristic value calculation formula is:

[0026] Wherein θ is the characteristic value, P is the porosity of the reactor, and H0 is the height of the reactor; for wound carbon nanotubes, the standard characteristic value θs is [2, 7], and for arrayed carbon nanotubes, the standard characteristic value θs is [5, 10].

[0027] In a preferred embodiment, P is calculated according to the C normalization formula and the image reconstruction formula,

[0028] The normalization formula of C is: r =(CC m ) / (C n -C m ) Formula (3)

[0029] The image reconstruction formula is:

[0030] In formula (4), C r is the normalized value of capacitance C, g(i) is the pixel grayscale value of the dielectric constant distribution image in the measured field, S(i) is the average sensitivity of the medium at the microelement i, δ i is the area of ​​infinitesimal element i. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Hereinafter, the present invention will be described with reference to the accompanying drawings.

[0032] In the attached figure:

[0033] FIG1 is a schematic diagram of a conical fluidized bed main reactor according to one embodiment of the present invention, wherein the separation zone and the reaction zone have different pipe diameters;

[0034] FIG2 is a schematic diagram of a conical fluidized bed main reactor according to one embodiment of the present invention, wherein the separation zone and the reaction zone have the same pipe diameter;

[0035] FIG3 is a schematic diagram of a cylindrical fluidized bed main reactor according to one embodiment of the present invention, wherein the separation zone and the reaction zone have different pipe diameters, and the reaction zone has a distribution plate;

[0036] FIG4 is a schematic diagram of a conical fluidized bed main reactor and a continuous collection device according to one embodiment of the present invention;

[0037] FIG5 is a schematic diagram of the fluidization of spherical particles and the continuous growth of carbon nanotubes in a conical fluidized bed with a distribution plate;

[0038] FIG6 is a schematic diagram of the fluidization of non-spherical particles and the continuous growth of carbon nanotubes in a distributed plate conical fluidized bed;

[0039] FIG7 is a schematic diagram of the fluidization of a porous medium in a distributed plate conical fluidized bed and the continuous growth of carbon nanotubes;

[0040] FIG8 is a schematic diagram of a non-distributed plate non-conical or flat-bottomed fluidized bed according to one embodiment of the present invention, wherein the catalyst is added through an input port located at the top of the reactor;

[0041] FIG9 is an experimental statistical diagram showing the change of the characteristic value θ of the reactor state over time;

[0042] FIG10 is a schematic structural diagram of a device for monitoring the status of a reactor according to one embodiment of the present invention. DETAILED DESCRIPTION

[0043] A method for continuously preparing a carbon material, the method comprising:

[0044] 1) providing an inert substance to a reactor, wherein the inert substance is a high temperature resistant substance and does not participate in the growth reaction of the carbon material;

[0045] 2) providing a catalyst and introducing a gas into the reactor, causing the inert substance and the catalyst to continuously move under the action of the gas, and causing the catalyst and the gas to interact and fluidize and grow into the carbon material at a certain temperature, wherein the gas includes a carbon source gas, a reducing gas, and a protective gas;

[0046] 3) controlling the gas to separate carbon materials of different qualities from inert substances;

[0047] 4) Maintaining the inert material at a certain level in the reactor and continuously discharging part of the carbon material;

[0048] 5) Repeat steps 2)-4) to achieve continuous preparation of carbon materials.

[0049] The method for continuously preparing carbon materials is described below:

[0050] In the present invention, the term "carbon material" includes at least one carbon nanotube or graphene. The preparation of different carbon materials can be achieved by fine-tuning the catalyst elements and reaction conditions.

[0051] (1) Provide inert substances

[0052] The inert material is heat-resistant and does not participate in the growth reaction of the carbon material. By placing inert material particles between the catalyst and the growing carbon material, the present invention reduces agglomeration of the growing carbon material, regulates the size of carbon material aggregates, such as carbon nanotubes, and improves fluidization quality. The inert material can include spherical particles or non-spherical materials. The non-spherical materials include porous media materials, which are either monolithic or dispersed. Under the action of the gas source, they undergo reciprocating motion along the length of the fluidized bed or a free-fluidizing state.

[0053] The inert material includes at least one selected from the group consisting of ceramics, high-temperature resistant metals, high-temperature alloys, rocks, gypsum, silica, high-carbon materials, and lightweight aggregates. Ceramics include, but are not limited to, alumina, zirconia, and titanium oxide. Rocks include, but are not limited to, marble and granite. High-temperature resistant metals include, but are not limited to, refractory metals such as tungsten, molybdenum, tantalum, niobium, vanadium, chromium, titanium, and zirconium. High-temperature alloys include, but are not limited to, chromium-nickel-molybdenum alloys and chromium-manganese-molybdenum alloys. High-carbon materials include, but are not limited to, graphene, carbon black, carbon nanotubes, and activated carbon. Lightweight aggregates can be categorized by their source as follows: industrial waste residue lightweight aggregates, such as fly ash ceramsite, self-igniting coal gangue, expanded slag beads, coal slag, and their lightweight sands; natural lightweight aggregates, such as pumice, volcanic slag, and their lightweight sands; and artificial lightweight aggregates, such as shale ceramsite, clay ceramsite, expanded perlite, and their lightweight sands. The inert material may also include composite materials, such as carbon-carbon composites or ceramic-based composites, and minerals or processed minerals, such as perlite and pumice.

[0054] Specific examples of the inert substance include hollow glass microspheres, floating beads, hollow ceramic microspheres, perlite, natural zeolite, artificial zeolite, molecular sieves, diatomaceous earth, pumice, expanded vermiculite, lightweight refractory materials, carbon black, activated carbon, and coconut shell charcoal.

[0055] Most preferably, the inert substance is at least one substance selected from the group consisting of high carbon substances, coconut shell carbon, alumina particles, floating beads particles and perlite particles.

[0056] In a preferred embodiment, the average bulk density of the inert material is at least 1.5 times that of the carbon material. Since the inert material has a high bulk density and a large weight, while the generated carbon material has a low density and a light weight, the inert material and the carbon material can be separated in the separation step by gas control.

[0057] In a preferred embodiment, the inert substance is a porous medium with a porosity of 30-90%.

[0058] In a preferred embodiment, the inert material is a non-spherical or spherical particle with an average particle size of 0.1 μm to 5000 μm, preferably 100-2000 μm. Preferably, the inert material is a non-spherical or spherical particle, and by controlling the shape, density, and size of the spherical particles, a stepped stratified fluidization can be formed in the fluidized bed. In a preferred embodiment, the inert material is a uniform spherical particle of a plurality of different particle sizes, and the particle size is 30-150 mesh.

[0059] The method for providing the inert substance of the present invention is not particularly limited and may be any conventional method known in the art as long as it can meet the purpose of the present invention.

[0060] (2) providing a catalyst and introducing a gas into the reactor, so that the inert substance and the catalyst continue to move under the action of the gas, and the catalyst interacts with the gas to fluidize and grow into the carbon material at a certain temperature, wherein the gas includes a carbon source gas, a reducing gas and a protective gas.

[0061] Gas and catalyst are provided into the reactor from the input end, and the gas and catalyst can be independently inputted from the input end, or the gas and catalyst can be mixed and inputted. The independent input mode of the catalyst includes at least one of the following modes: direct input, spray input mixed with liquid, and co-input with gas. The independent input means that the catalyst and the gas source are inputted separately through their respective pipelines. Direct input means that the catalyst is inputted separately, spray input mixed with liquid means that the catalyst is mixed with liquids such as water and then inputted into the fluidized bed in the form of a spray, and co-input with gas means that the catalyst is mixed with inert gases such as nitrogen and then inputted into the fluidized bed. The present invention has no particular restrictions on the input mode of gas and catalyst, and conventional input modes in the art can be used, as long as the purpose of the present invention can be met.

[0062] The gas comprises a carbon source gas, a reducing gas, and a protective gas. The carbon source gas is a hydrocarbon or alcohol mobile phase. Preferably, the carbon source gas comprises at least one gas selected from the group consisting of propylene, ethylene, propane, carbon monoxide, carbon dioxide, and methane; more preferably, propylene or ethylene. Preferably, the reducing gas comprises at least one gas selected from the group consisting of hydrogen and carbon monoxide. Preferably, the protective gas comprises nitrogen or argon. In the present invention, the gas may also comprise a vaporized liquid phase.

[0063] The catalyst can be a catalyst commonly used in the art for catalyzing a carbon source to generate a carbon material through a CVD reaction. The catalyst includes a powder catalyst and a liquid catalyst. The powder catalyst includes at least one of iron, cobalt, nickel and their precursors, and the liquid catalyst precursor includes a metallocene organic compound and / or a carbonyl metal organic compound, preferably ferrocene, pentacarbonyl iron, tetracarbonyl nickel, and octacarbonyl dicobalt. In a preferred embodiment of the present invention, the catalyst includes at least one compound selected from the following group: a metallocene organic compound and / or a carbonyl metal organic compound, preferably ferrocene, pentacarbonyl iron, tetracarbonyl nickel, and octacarbonyl dicobalt. The metallocene organic compound and / or the carbonyl metal organic compound are dispersed in a low temperature zone to form uniform nano-scale catalyst particles, and a few-walled or single-walled carbon material can be obtained without consuming more processes and costs to prepare the catalyst.

[0064] In a preferred embodiment, the catalyst enters the reaction zone in a gaseous form. In a preferred embodiment, the catalyst enters the reaction zone in a gaseous form after being heated to 120-500°C.

[0065] The predetermined temperature is at least a temperature that reaches the growth temperature of the carbon material. A heating device may be provided outside the reaction zone to provide the set temperature required for the growth of the carbon material. The temperature range is 500-1500°C. In the presence of a fluidized inert substance, the catalyst and the gas interact and fluidize to grow the carbon material under the conditions within this temperature range.

[0066] (3) controlling the gas to separate carbon materials of different masses from inert substances;

[0067] Since the generated carbon material and inert substance have different weights, the carbon material and inert substance can be separated by controlling the gas, and the lighter carbon material leaves the reactor under the entrainment of the gas flow, while the heavier inert substance remains in the reactor body.

[0068] In the present invention, the separation of the carbon material from the inert particles is achieved by controlling the flow rate or changing the diameter of the main tube.

[0069] The flow rate control refers to achieving different separation effects by changing different intake speeds, including setting pulse intake and sinusoidal function intake.

[0070] Changing the main body tube diameter means setting fluidized bed tube diameters of different tube diameters under the condition of constant gas source flow rate to achieve separation of the carbon material and the inert substance. Preferably, the tube diameter of the separation zone is set to be larger than the tube diameter of the reaction zone, which is conducive to separation and sedimentation.

[0071] 4) Maintain inert materials in the reactor and continuously discharge part of the carbon material

[0072] The inert material is retained in the reactor, and the generated carbon material is discharged from the reactor through an outflow end. The outflow end can be connected to a collector through a connecting pipe to achieve a better separation effect.

[0073] 5) Repeat steps 2)-4) to achieve continuous preparation of carbon materials.

[0074] Repeat steps (d)-(f) to maintain continuous feeding of the catalyst and gas and continuous discharge of the carbon material in the reactor to achieve continuous preparation of the carbon material.

[0075] Another aspect of the present invention provides an apparatus for continuously preparing carbon materials, the apparatus comprising a main reactor for performing a CVD reaction and a collector for collecting the carbon materials, the main reactor comprising an input end, an outflow end, and a reactor body, the reactor body comprising a reaction zone and a separation zone, the gas and catalyst being supplied to the reaction zone via the input end; the outflow end being located above the separation zone, the separation zone being connected to the collector via a connecting pipe via the outflow end;

[0076] The collector includes a filter, and the filter is used to separate the carbon material from the tail gas discharged from the main reactor.

[0077] The specific components of the apparatus for continuously preparing carbon materials are described below:

[0078] (1) Main reactor

[0079] In the present invention, the main reactor refers to a reactor suitable for preparing carbon nanotubes by CVD reaction using a catalyst to catalyze the cracking of a carbon source. In this reactor, at a suitable temperature, such as 500-1100°C, preferably 650-900°C, and more preferably 700-800°C, the carbon source grows carbon nanotubes on a catalyst support under the action of the catalyst.

[0080] In the present invention, the main reactor can be a fluidized bed reactor. Preferably, the reactor has an aspect ratio of height to diameter of 5-25:1, preferably 10-20:1, and more preferably 12-15:1. The reactor can be cylindrical or conical. Preferably, the fluidized bed reactor is a conical reactor with a conical bottom structure, and the cone angle of the cone bottom is preferably 5° to 50°.

[0081] The main reactor comprises an input end, an outflow end, and a reactor body, wherein the reactor body comprises a reaction zone and a separation zone. The input end can be configured as a gas input end and a catalyst input end, respectively. The gas input end can be located at the bottom of the reactor, and the catalyst input end can be combined with the gas input end or provided separately.

[0082] Gas enters the main reactor through a gas input port located at the bottom of the main reactor. There are no particular restrictions on the form of the input gas. The carbon source gas, reducing gas, and / or shielding gas can be introduced as a mixed gas, or a certain volume of carbon source gas, reducing gas, and / or shielding gas can be introduced sequentially.

[0083] In the present invention, the protective gas input port and the carbon source gas input port can be provided separately or fed together. Preferably, the gas inlet includes a carbon source gas input port and a protective gas input port, wherein the carbon source gas input port and the protective gas input port are arranged at multiple points at the bottom of the main reactor to facilitate fluidized reaction and heat conduction.

[0084] The catalyst input can be located anywhere in the reaction zone of the main reactor. The catalyst input can be arranged in multiple layers within the main reactor and / or at multiple points on the same layer, which facilitates fluidized reaction and heat conduction. In the main reactor of the present invention, the reaction zone and separation zone are connected, the separation zone is located above the reaction zone, and the diameter of the separation zone is at least equal to that of the reaction zone. Preferably, the diameter of the separation zone is larger than the diameter of the reaction zone. Preferably, the diameter of the separation zone is 1-5 times the diameter of the reaction zone.

[0085] The outflow end is arranged on one side of the separation zone of the main reactor and is located at the upper part of the separation zone. The separation zone is connected with the collector through the outflow end via a connecting pipe.

[0086] In the present invention, there is no particular limitation on the types of the input end, the output end, and the feeding device, as long as the feeding device is suitable for feeding the catalyst and the gas.

[0087] The main reactor of the present invention is preferably a fluidized bed reactor with a distribution plate, wherein the inert material and the carbon material are located on the same side of the distribution plate. The pore size of the distribution plate is at least smaller than that of the inert material, allowing the inert material to be positioned above the distribution plate while distributing or dispersing the fluid on the plate in a predetermined manner. In a cylindrical or conical fluidized bed with a distribution plate, the catalyst and gas are preferably fed independently, with the feeds for the two materials located on either side of the distribution plate, with the catalyst feed located on the upper side of the distribution plate and the gas feed preferably located on the lower side.

[0088] Preferably, the main reactor further comprises a conical bottom, and the conical bottom is a conical structure. Preferably, the main reactor has a conical bottom with a conical structure, and the conical bottom has a conical structure, and the angle of the conical bottom is preferably 5° to 50°.

[0089] Preferably, a heating device is provided outside the reaction zone to provide a set temperature required for the growth of the carbon material.

[0090] (2) Collector

[0091] In the present invention, the carbon material is continuously collected in the collector from the separation zone of the reactor through the connecting pipe. The collector includes at least a filter for separating the carbon material from the exhaust gas discharged from the main reactor. The filter includes a filter screen, a metal filter, a ceramic filter, etc.

[0092] There is no particular limitation on the collectors and filters applicable to the present invention, including but not limited to temperature-resistant filter bags, stainless steel filters, etc., as long as the purpose of collecting and filtering carbon materials of the present invention can be achieved.

[0093] The present invention reduces the agglomeration of growing carbon materials by placing inert particles to space the catalyst, regulates the size of carbon nanotube aggregates, and improves fluidization quality. This also facilitates cleaning of the distribution plate and prevents clogging. It further increases the uniformity of contact temperature between particles, resulting in more uniform growth. Because the inert particles have a larger particle size and density than the carbon material aggregates, smaller particles, driven by larger particles, can be better fluidized. Controlling the gas source allows for the separation of materials of varying mass, thereby achieving continuous growth of carbon materials. This technical solution addresses the existing problem of achieving uniform and continuous growth of carbon materials.

[0094] The carbon material prepared according to the method of the present invention has the advantages of high yield, large specific surface area, and high aspect ratio. The process of the present invention is simple, the conditions are easy to control, the product stability is good, the production efficiency is significantly improved, and continuous batch production can be achieved.

[0095] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings:

[0096] Figure 1 shows a schematic diagram of a conical fluidized bed main reactor according to one embodiment of the present invention, wherein the conical fluidized bed main reactor includes a main body 102 and a conical bottom 101, the main body 102 includes a reaction zone 1022 and a separation zone 1021, the reaction zone 1022 and the separation zone 1021 are connected, the diameter of the separation zone 1021 is larger than the diameter of the reaction zone 1022; a heating device 15 is provided on the outside of the reaction zone 1022 to provide the set temperature required for the growth of the carbon material.

[0097] Figure 2 shows a schematic diagram of a conical fluidized bed main reactor according to one embodiment of the present invention, wherein the conical fluidized bed main reactor includes a main body and a conical bottom 11, the main body includes a reaction zone 1022 and a separation zone 1021, the reaction zone 1022 and the separation zone 1021 are connected, and the diameter of the separation zone 1021 is the same as the diameter of the reaction zone 1022.

[0098] 3 shows a schematic diagram of a cylindrical fluidized bed main reactor according to one embodiment of the present invention, wherein the separation zone and the reaction zone have different pipe diameters, wherein the reaction zone has a distribution plate 104 , and gas and catalyst are fed into the reactor from an input end 11 .

[0099] Figure 4 shows a schematic diagram of a conical fluidized bed main reactor and a continuous collection device according to one embodiment of the present invention, wherein the diameter D1 of the separation zone in the fluidized bed reactor 10 is larger than the diameter D2 of the reaction zone, the input end 11 is arranged as a gas input end 111 and a catalyst input end 112, the separation zone is connected to the collector 13 through a connecting pipe 12, and the collector 13 has a filter 131.

[0100] Figure 5 shows a schematic diagram of the fluidization of spherical particles and the continuous growth of carbon nanotubes in a conical fluidized bed with a distribution plate, wherein the fluidized bed reactor 10 is divided into a conical bottom 101, a reactor body 102, and an outflow end 103. Spherical inert particles 14 are loaded in the reaction zone, and the carbon material obtained by the reaction enters the collector 13 through a connecting pipe from the outflow end 103.

[0101] 6 shows a schematic diagram of the fluidization of non-spherical particles and the continuous growth of carbon nanotubes in a distribution plate conical fluidized bed. The reaction zone has a distribution plate 104, and non-spherical inert particles 14 are loaded above the distribution plate. The carbon material 16 obtained by the reaction is collected in a collector.

[0102] FIG7 shows a schematic diagram of fluidization of a porous medium and continuous growth of carbon nanotubes in a distributed plate conical fluidized bed, wherein the porous medium 14 is loaded in the reaction zone.

[0103] 8 shows a schematic diagram of a non-distributed plate non-conical or flat-bottom fluidized bed according to one embodiment of the present invention, wherein the catalyst is added through the input port 112 located at the top of the reactor, and the gas is input through the input port 111 located at the bottom of the reaction zone.

[0104] In a specific embodiment, an inert substance is placed in the reaction zone, an inert gas is introduced into the fluidized bed through the input end, the temperature is raised to a set temperature, catalyst particles are continuously input and gas is introduced to continuously grow the carbon material; the gas source velocity is controlled to achieve separation of the carbon material and the inert substance; the carbon material enters a collector through the outflow end of the fluidized bed, and the carbon material is continuously collected.

[0105] The following describes the method for monitoring the status of the device:

[0106] Figure 9 shows an experimental statistical graph of the characteristic value θ, reflecting the growth state of carbon nanotubes in the reactor, changing over time. Based on this statistical graph, the characteristic value θ can be used to determine the state of the fluidized bed. Based on extensive experimental statistics, the standard characteristic value θs is set within a specific range (θ1≤θs≤θ2). When preparing carbon nanotubes, if the θ value calculated in real time is within the θs range, no parameter adjustment is required. If the θ value calculated in real time is outside the θs range, the θ value is restored to the θs range by adjusting parameters such as temperature, pressure, and airflow volume V2. By adjusting various parameters to ensure that the characteristic value θ remains within the specified range, carbon nanotube growth can be promoted, resulting in the preparation of carbon nanotubes with more stable performance.

[0107] Theoretically, the relationship between the capacitance and the dielectric constant is shown in formula (1): C = K·ε = F(ε) Formula (1)

[0108] In formula (1), C represents the capacitance, K is the characteristic constant, and ε is the dielectric constant of the carbon nanotube when fluidized, where K depends on the electrode structure. The dielectric constant can be calculated from the measured C value.

[0109] ε can also be expressed as: ε=(V1 / V)*ε1+(V2 / V)*ε2=ε2+(V1 / V)*(ε1-ε2) Formula (2)

[0110] In formula (2), ε1 and ε2 are the dielectric constants of discrete phase carbon nanotubes and continuous phase airflow, respectively, V1 and V2 are the volumes of discrete phase carbon nanotubes and continuous phase airflow, respectively, V = V1 + V2; where ε1 is the dielectric constant of carbon nanotubes, which is a known value, and ε2 is related to C m Related, is a known value, V2 can be measured, and the volume V1 of the carbon nanotube can be calculated by this formula.

[0111] Theoretically, V1 / V is the porosity (P) of the reactor, which is related to the characteristic value θ. Therefore, the state of the reactor can be monitored by measuring the capacitance value C using the electrode assembly, and precise control of the reaction process can be achieved by adjusting the reaction parameters.

[0112] During real-time monitoring, the electrode sensor converts the measured capacitance value C into a voltage signal, and converts the signal into digital form through phase-sensitive demodulation and a low-pass filter, which is then transmitted to an image reconstruction computer to obtain a mathematical signal. The obtained mathematical signal is iteratively calculated using an algorithm to determine the dielectric constant of each unit, and then image reconstruction is performed to obtain the void ratio of the fluidized bed at different times, and the required characteristic value is calculated based on the void ratio.

[0113] The normalized formula of C is: r =(CC m ) / (C n -C m ) Formula (3);

[0114] The image reconstruction formula is:

[0115] In formula (4), C r is the normalized value of capacitance C, g(i) is the pixel grayscale value of the dielectric constant distribution image in the measured field, assuming that each microelement i has the same sensitivity, then g(i)=(δ i -ε1) / (ε2-ε1), g(i)∈[0,1], s(i) is the average sensitivity of the medium at the infinitesimal i, s(i)=(CC m ) / δ i , δ i is the area of ​​the infinitesimal element i. The infinitesimal element i can be a small rectangle, δ i =dxdy, the average sensitivity of the medium at the infinitesimal element i is a known value, and the area of ​​the infinitesimal element i is a known value. According to formula (4), we can get The derivation process of the image reconstruction formula is detailed on page 17 of Liu Xiaomin's master's thesis "Capacitance Tomography Algorithm and Its Application in Two-Phase Flow Detection".

[0116] After algorithm iteration, the void ratio P of the reactor is:

[0117] Where g(i) is the pixel grayscale value of the dielectric constant image at position i; the reactor is divided into z equal parts along the longitudinal direction, and each part is used to display the proportional relationship between carbon nanotubes and gas in the form of an image. Therefore, the sum should be divided by the number of parts Z to obtain the porosity value of the entire reactor.

[0118] The calculation formula of the characteristic value θ is:

[0119] Where θ is the characteristic value, H0 is the reactor height;

[0120] For the arrayed carbon nanotubes, the void ratio P is about 50%, and for the entangled carbon nanotubes, the void ratio P is about 20%, both of which are statistically calculated results.

[0121] After extensive experimental statistics, it was found that for wound carbon nanotubes, the standard eigenvalue θs is [2, 7], and for arrayed carbon nanotubes, the standard eigenvalue θs is [5, 10]. That is, for wound carbon nanotubes, when the eigenvalue θ calculated by real-time measurement is within the range of 2≤θ≤7, no parameter adjustment is required. When the eigenvalue θ calculated by real-time measurement is outside this range, the θ value can be restored to the above range by adjusting parameters such as temperature, pressure, and airflow volume. For arrayed carbon nanotubes, when the eigenvalue θ calculated by real-time measurement is within the range of 5≤θ≤10, no parameter adjustment is required. When the eigenvalue θ calculated by real-time measurement is outside this range, the θ value can be restored to the above range by adjusting parameters such as temperature, pressure, and airflow volume V2.

[0122] The method for monitoring the state of a reactor provided by the present invention utilizes an electrical capacitance tomography device to monitor the state inside the reactor. It can not only obtain the state of the material inside the reactor in real time, including gas velocity, fluidization state, etc., to monitor the reaction process, but also calculate the void ratio during the fluidization process of carbon nanotubes to achieve precise flow control. This also avoids the "temperature runaway" phenomenon caused by rapid reaction in industrial production, improves the efficiency and safety of the reaction process, and achieves good economic and practical benefits.

[0123] The present invention also provides a device for monitoring the status of a reactor, the device comprising at least a main reactor, an electrode assembly, a capacitance test module, a data processor, and an image reconstruction computer. The electrode assembly comprises four parts: a test electrode, an insulating pipe, a radial electrode, and a grounded shield. The test electrode comprises at least one of a rectangular sensor, a rotating electrode sensor, and a microsensor. The number of test electrodes is n, and the value range of n is n≥6. The electrode assembly converts the measured capacitance value C into a voltage signal, and performs analog-to-digital conversion on the voltage signal through phase-sensitive demodulation and a low-pass filter to obtain a mathematical signal.

[0124] As shown in Figure 10, the device for monitoring the status of the reactor includes a main reactor, an electrode assembly 17, a capacitance testing module 15, a data processor 8 and an image reconstruction computer 7, wherein the main reactor includes a reactor cone bottom 11, a reactor reaction zone 18 and a reactor separation zone 6, a heating system 16 is set outside the reaction zone, an inert substance 14 is located at the bottom of the reactor, and the gas source enters the reactor through the air intake system 9. The electrode assembly 17 is placed on the outer wall of the reactor, and the height of the electrode assembly 17 from the bottom of the reactor is H. The capacitance testing module 15 displays the measured capacitance value C, which is processed by the data processor 8 and transmitted to the image reconstruction computer 7 for algorithm iteration and image reconstruction to obtain the real-time porosity and characteristic value of the fluidized bed.

[0125] The present invention will be further described below with reference to specific examples. It should be understood that these examples are intended to illustrate the present invention only and are not intended to limit the scope of the present invention. For experimental methods in the following examples where specific conditions are not specified, conventional conditions or conditions recommended by the manufacturer are generally used. Ratios and percentages are based on molar amounts unless otherwise stated.

[0126] Raw material source and preparation:

[0127] (1) Inert substances:

[0128] Ceramic spherical particles (particle size 500μm-1000μm), products of Shandong Qitai Industrial Ceramics Co., Ltd., specifications: 0.5-1mm;

[0129] High carbon material (particle size 200 μm-400 μm), product of Shandong Dazhan Nanomaterial Co., Ltd., number: GTY-301;

[0130] Alumina (particle size 0.2mm-3mm), products of Shandong Qitai Industrial Ceramics Co., Ltd., specifications: 0.5-1mm, 1mm, 2mm, 3mm;

[0131] Floating beads 40-100 mesh, products of Dongying Wanjia Energy Saving Materials Co., Ltd., specifications: 40-100 mesh;

[0132] Perlite 70-90 mesh, product of Xinyang City Shihe District Houpu Mining Materials Factory, specification: 70-90 mesh;

[0133] The particle size of coconut shell carbon particles is 10-60 mesh, and it is a product of Changge Tanernuo Catalytic Technology Co., Ltd. with a specification of 30-110 mesh.

[0134] (2) Catalyst

[0135] Ferric nitrate, cobalt nitrate, aluminum nitrate, ammonia water, and ammonium carbonate were all purchased from Zibo Aiken Economic and Trade Co., Ltd.; purified water was produced by Shandong Dazhan Nanomaterials Co., Ltd. through distillation and purification.

[0136] The micronized catalyst was prepared by the following method:

[0137] Mix ferric nitrate, cobalt nitrate, aluminum nitrate and purified water according to the ratio and dissolve them until they are uniform and free of particles to form an acid solution;

[0138] Ammonia water, ammonium carbonate and purified water are mixed according to the proportions and dissolved evenly without particles to form lye;

[0139] Precipitation titration: Control the pH titration by controlling the flow rate of acid and alkali solution. After the titration is completed, age for 2-4 hours;

[0140] Filter press: The mixture after titration reaction is passed through a plate and frame or centrifuge to filter out most of the water and collect the filter cake;

[0141] Drying and roasting: The filter cake is dried and roasted at high temperature. After roasting, it is crushed into particles with uniform particle size and packaged.

[0142] (3) Gas:

[0143] Hydrogen: purchased from Zibo Anze Special Gas Co., Ltd.

[0144] Propylene: purchased from Shandong Jingbo Petrochemical Co., Ltd.

[0145] Nitrogen: purchased from Praxair (Qingdao) Industrial Gas Co., Ltd.

[0146] (4) Device

[0147] The device for monitoring the status of the reactor adopts the capacitance tomography ECVT produced by Tech4Imaging Company of the United States.

[0148] Example 1:

[0149] Example 1 was conducted using the apparatus shown in FIG4 . Spherical ceramic particles (particle size 100 μm-300 μm) were introduced into a fluidized bed. Nitrogen was then introduced into fluidized bed 10 through gas input port 111 for 5-20 minutes (1000 L / min) to displace residual oxygen within the fluidized bed, maintaining a continuous fluidized state for the spherical ceramic particles. The temperature was then raised to a set temperature of 660°C and stabilized. The fluidized bed was controlled to incorporate a powdered catalyst (50-80 mesh) through catalyst input port 112. Furthermore, a mixture of hydrogen, propylene, and nitrogen in a ratio of 1:6:7 was introduced through gas source input port 111 at a controlled gas rate of 320 L / h to achieve fluidized growth of carbon nanotubes. Separation was achieved in the separation zone. The carbon nanotubes exited the fluidized bed through the outlet port and passed through connecting pipe 12 into collector 13 for collection. The exhaust gas then passed through filter 131 and exited the collector. The catalyst and gas source are continuously introduced to achieve continuous and uniform preparation of carbon nanotubes.

[0150] Example 2:

[0151] Example 2 was conducted using the apparatus shown in FIG4 . 20 kg of high-carbon material (particle size 200 μm-400 μm) was introduced into the fluidized bed. Nitrogen was then introduced into the fluidized bed 10 through gas source input 111 for 5-20 minutes (500 L / min) to displace residual oxygen within the fluidized bed, maintaining a continuous fluidized state for the high-carbon material. The temperature was then raised to a set temperature of 660°C and stabilized. The fluidized bed was controlled by introducing a powdered catalyst (80-100 mesh) through catalyst input 112. Furthermore, a mixture of hydrogen, propylene, and nitrogen in a ratio of 1:7:10 was introduced through gas source input 111. The gas velocity was controlled to achieve fluidized growth of carbon nanotubes. Separation was achieved in the separation zone. The carbon nanotubes exited the fluidized bed through the outlet port and passed through connecting pipe 12 into collector 13 for collection. The exhaust gas then passed through filter 131 and exited the collector. The catalyst (0.9-1.1 kg / h) and gas source (900 L / min) were continuously introduced to achieve continuous and uniform preparation of carbon nanotubes.

[0152] Example 3:

[0153] Example 3 was conducted using the apparatus shown in Figure 4. 1-30 g of alumina (particle size 0.2 mm-3 mm) was introduced into the fluidized bed. Nitrogen was then introduced into the fluidized bed 10 through gas source input 111 for 5-20 minutes (100 L / h) to displace residual oxygen within the bed, maintaining a continuous fluidized state of the alumina. The temperature was then raised to a set temperature of 670°C and stabilized. The fluidized bed was controlled by introducing a powdered catalyst (80-100 mesh) through catalyst input 112. Furthermore, a mixture of hydrogen, propylene, and nitrogen in a ratio of 5:8:10 was introduced through gas source input 111. The gas velocity was controlled to achieve fluidized growth of carbon nanotubes. Separation occurred in the separation zone. The carbon nanotubes exited the fluidized bed through the outlet port and passed through connecting pipe 12 into collector 13 for collection. The exhaust gas then passed through filter 131 and exited the collector. The catalyst and gas source (230 L / h) were continuously introduced to achieve continuous and uniform preparation of carbon nanotubes.

[0154] Example 4:

[0155] Example 4 was conducted using the apparatus shown in FIG4 . Floating beads (10 g in total) of 40-100 mesh were introduced into the fluidized bed. Nitrogen was then introduced into the fluidized bed 10 through gas source input 111 for 5-20 minutes (100-200 L / h) to dislodge residual oxygen within the bed, maintaining a continuous fluidized state of the alumina. The temperature was then raised to a set temperature of 670°C and stabilized. The fluidized bed was controlled by introducing a powdered catalyst (80-100 mesh) through catalyst input 112. Furthermore, a mixture of hydrogen, propylene, and nitrogen in a ratio of 5:8:10 was introduced through gas source input 111. The gas velocity was controlled to achieve fluidized growth of carbon nanotubes. Separation was achieved in the separation zone. The carbon nanotubes exited the fluidized bed through the outlet port and passed through connecting pipe 12 into collector 13 for collection. The exhaust gas then passed through filter 131 and exited the collector. The catalyst and gas source (280 L / h) were continuously introduced to achieve continuous and uniform preparation of carbon nanotubes.

[0156] Example 5

[0157] Example 5 was conducted using the apparatus shown in FIG4 . Perlite (10 g total mass) of 70-90 mesh was introduced into the fluidized bed. Nitrogen was then introduced into the fluidized bed 10 through gas source input 111 for 5-20 minutes (150 L / h) to displace residual oxygen within the fluidized bed, maintaining a continuous fluidized state of the alumina. The temperature was then raised to a set temperature of 670°C and stabilized. The fluidized bed was controlled by introducing a powdered catalyst (80-100 mesh) through catalyst input 112. Reducing gas (hydrogen) was then introduced for 5 minutes (50 L / h). After reduction, a mixture of propylene and nitrogen (8:15) was introduced through gas source input 111. The gas velocity was controlled to achieve fluidized growth of carbon nanotubes. Separation occurred in the separation zone. The carbon nanotubes exited the fluidized bed at the outlet and passed through connecting pipe 12 into collector 13 for collection. The exhaust gas then passed through filter 131 and exited the collector. The catalyst and gas source (230 L / h) were continuously introduced to achieve continuous and uniform preparation of carbon nanotubes.

[0158] Example 6

[0159] Example 6 was conducted using the apparatus shown in FIG4 . Coconut shell carbon particles (particle size 10-60 mesh) were introduced into the fluidized bed. Nitrogen was then introduced into the fluidized bed 10 through gas source input 111 for 5-20 minutes (1000 L / min) to displace residual oxygen within the fluidized bed, ensuring an oxygen-free environment and maintaining a continuous fluidized state for the unloaded catalyst particles. The temperature was then raised to a set temperature of 660°C and stabilized. The fluidized bed was controlled to introduce a powdered catalyst (50-80 mesh) through catalyst input 112. Furthermore, a mixture of hydrogen, propylene, and nitrogen in a ratio of 1:6:7 was introduced through gas source input 111. The gas velocity was controlled to achieve fluidized growth of carbon nanotubes. Separation was achieved in the separation zone. The carbon nanotubes exited the fluidized bed at the first end 103 of the fluidized bed and passed through connecting pipe 12 into collector 13 for collection. The exhaust gas then passed through filter 131 and exited the collector. The catalyst and gas source are continuously introduced to achieve continuous and uniform preparation of carbon nanotubes.

[0160] Comparative Example

[0161] The comparative example was also conducted using the apparatus shown in FIG4 . Nitrogen gas was introduced into the fluidized bed 10 from the gas source input port 111 for 5-20 minutes (100 L / h) to drive out residual oxygen in the fluidized bed. The temperature was then raised to a set temperature of 670°C and stabilized. The fluidized bed was controlled by introducing a powdered catalyst (80-100 mesh) from the catalyst input port 112. Furthermore, a mixture of hydrogen, propylene, and nitrogen in a ratio of 5:8:10 was introduced from the gas source input port 111. The gas velocity was controlled to achieve fluidized growth of carbon nanotubes, and separation was achieved in the separation zone. The carbon nanotubes exited the fluidized bed at the first end 103 of the fluidized bed and passed through the connecting pipe 12 into the collector 13 for collection. The exhaust gas then passed through the filter 131 and exited the collector. The catalyst and gas source (230 L / h) were continuously introduced to achieve continuous and uniform carbon nanotube production.

[0162] Product performance testing

[0163] (1) Four-probe resistivity:

[0164] The resistivity of the product is tested using the four-probe method according to the national standard GB / T 39978-2021 Nanotechnology Carbon Nanotube Powder Resistivity;

[0165] (2) Specific surface area test:

[0166] The specific surface area of ​​the product was tested using a nitrogen physical adsorption instrument according to the national standard GB / T 10722;

[0167] (3) Micromorphology test:

[0168] The diameter of carbon nanotubes was determined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM);

[0169] (4)Magnification

[0170] The ratio is calculated by dividing the output of carbon material product by the input of carbon source material.

[0171] The performance tests of the products obtained in Examples 1-6 and Comparative Examples were carried out, and the results are shown in the following table:

[0172] The above results show that the addition of inert materials aids fluidization. Without inert particles, the carbon material yield is extremely low. However, the addition of inert materials increases the yield, increases the specific surface area, and decreases the resistivity. The best results were achieved using high-carbon materials, alumina, floating beads, perlite, and coconut shell carbon as inert materials.

[0173] Example 7:

[0174] Example 7 was carried out using the apparatus shown in Figure 1. Coconut shell carbon particles (particle size 10-60 mesh) were introduced into the fluidized bed. The coconut shell carbon particles at the cone bottom 101 of the main reactor were in a continuous fluidized state under the action of gas. The heating device 15 raised the temperature to a set temperature of 660 degrees Celsius and stabilized it. The fluidized bed was controlled to input a powdered catalyst (50-80 mesh) from the catalyst input end, and a mixture of hydrogen, propylene and nitrogen in a ratio of 1:6:7 was input from the gas source input end. The gas velocity was controlled to be 320 L / h to achieve fluidized growth of carbon nanotubes and separation in the separation zone. The catalyst and gas source were continuously introduced to achieve continuous and uniform preparation of carbon nanotubes. The reaction lasted for 120 hours. Each group of experiments was repeated 5 times to detect the reaction process, the mass content of H2 in the tail gas, and the performance of the carbon nanotube product.

[0175] In this series of embodiments, the wound carbon nanotubes use a catalyst with an iron-cobalt active component and an alumina pellet carrier; the arrayed carbon nanotubes use a catalyst with an iron-cobalt active component and a flaky alumina carrier.

[0176] Analysis of related properties of wrapped carbon nanotubes

[0177] During the growth of carbon nanotubes in different experiments, the volume content of H2 in the exhaust gas was analyzed every hour and the results were as follows:

[0178] Analysis of related properties of carbon nanotube arrays

[0179] During the growth of carbon nanotubes in different experiments, the volume content of H2 in the exhaust gas was analyzed every hour and the results were as follows:

[0180] Example 8

[0181] Example 7 is carried out using the device shown in Figure 10, that is, a device for monitoring the state of the reactor is added on the basis of Figure 1, coconut shell carbon particles (particle size 10-60 mesh) are placed in the fluidized bed, and the coconut shell carbon particles 14 at the cone bottom 11 of the main reactor are continuously fluidized under the action of gas. The heating device 16 raises the temperature to the set temperature of 660 degrees Celsius and stabilizes it. The fluidized bed is controlled to input a powdered catalyst (50-80 mesh) from the catalyst input end, and a mixed gas of hydrogen, propylene and nitrogen in a ratio of 1:6:7 is input through the air intake system 9 to achieve carbonization. Nanotubes are fluidized and grown, and the electrode assembly 17 is placed on the outer wall of the reactor. The height of the electrode assembly 17 from the bottom of the reactor is H = 10m. The capacitance value Cm of the gas source and the capacitance value Cn of the carbon nanotubes are recorded, and these initial values ​​are input into the data processor. The capacitance test module 15 displays the real-time measured capacitance value C, and the dielectric constant ε is calculated and input into the computer. The data processor automatically converts the capacitance C value and transmits the converted corresponding data to the image reconstruction computer. s(i) is transmitted to the reconstruction computer to obtain the real-time porosity and characteristic value of the fluidized bed.

[0182] When preparing entangled carbon nanotubes, observe whether the characteristic value θ displayed by the image reconstruction computer is within the range of 2≤θ≤7. If it exceeds this range, adjust the volume V2 parameter of the gas source to return θ to the above range. The reaction is continued for 100 hours. The properties of the entangled carbon nanotubes prepared by the reaction are as follows:

[0183] Analysis of related properties of wrapped carbon nanotubes

[0184] During the growth of carbon nanotubes in different experiments, the volume content of H2 in the exhaust gas was analyzed every hour and the results were as follows:

[0185] When preparing array carbon nanotubes, observe whether the characteristic value θ displayed by the image reconstruction computer is within the range of 5≤θ≤10. If it exceeds this range, adjust the temperature T of the reactor to return θ to the above range, and continue the reaction for 150 hours.

[0186] Analysis of related properties of carbon nanotube arrays

[0187] During the growth of carbon nanotubes in different experiments, samples were taken every hour to analyze the volume content of H2 in the exhaust gas.

[0188] The standard deviations of various parameters of wrapped carbon nanotubes and arrayed carbon nanotubes were calculated, and the results are as follows:

[0189] By comparing the performance of the carbon nanotubes prepared in Example 7 and Example 8, it can be seen that since Example 8 adds a device for monitoring the reactor status to the reactor device used in Example 7, the characteristic value θ of the reaction process can be timely controlled within the set target range. Therefore, the standard deviation of the various properties of the carbon nanotubes prepared in Example 8 is more stable and the control range is finer than that in Example 7.

[0190] The process for preparing carbon materials of the present invention, the raw material dosage and process parameters thereof are not limited to the above-mentioned embodiments. After reading the above-mentioned teachings of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A method for continuously preparing a carbon material, the method comprising: 1) providing an inert substance to a reactor, wherein the inert substance is a high temperature resistant substance and does not participate in the growth reaction of the carbon material; 2) providing a catalyst and introducing a gas into a reactor, so that the inert substance and the catalyst are continuously moved under the action of the gas, and the catalyst and the gas interact with each other at a certain temperature to fluidize and grow into the carbon material, wherein the gas includes a carbon source gas, a reducing gas and a protective gas; 3) controlling the gas to separate carbon materials of different qualities from inert substances; 4) Maintaining the inert material at a certain level in the reactor and continuously discharging part of the carbon material; 5) Repeat steps 2)-4) to achieve continuous preparation of carbon materials.

2. The method of claim 1, wherein step 3) is performed by controlling the gas flow rate or changing the reactor tube diameter.

3. The method of claim 1, wherein the catalyst is at least one compound selected from the group consisting of metallocene organic compounds and / or metal carbonyl organic compounds, preferably ferrocene, iron pentacarbonyl, nickel tetracarbonyl, dicobalt octacarbonyl.

4. The method of claim 1, wherein the inert material comprises at least one selected from the group consisting of ceramics, high temperature resistant metals, high temperature alloys, rocks, gypsum, silica, high carbon materials, lightweight aggregates; and / or The average bulk density of the inert material is at least 1.5 times that of the carbon material.

5. The method of claim 1, wherein: The inert substance is a porous medium with a porosity of 20%-90%; and / or The inert substance is a particle with an average particle size of 0.1 μm-5000 μm, preferably 100-2000 μm.

6. The method of claim 1, wherein the carbon source gas comprises at least one gas selected from the group consisting of propylene, ethylene, propane, carbon monoxide, carbon dioxide and methane; and / or the reducing gas comprises at least one gas selected from the group consisting of hydrogen, carbon monoxide; and / or the protective gas comprises nitrogen, argon; and / or the carbon material is a carbon nanotube or graphene.

7. An apparatus for the method according to any one of claims 1 to 6, comprising a main reactor for performing a CVD reaction and a collector for collecting carbon materials, the main reactor having an input end, an outflow end and a reactor body, the reactor body comprising a reaction zone and a separation zone, and gas and catalyst are provided to the reaction zone through the input end; The outflow end is located at the upper part of the separation zone, and the separation zone is connected with the collector through the outflow end via a connecting pipe; The collector comprises a filter, and the filter is used to separate the carbon material from the tail gas discharged from the main reactor.

8. The apparatus according to claim 7, wherein the main reactor is a fluidized bed reactor having a distribution plate, wherein the inert substance and the carbon material are located on the same side of the distribution plate.

9. The device according to claim 7 or 8, wherein the main reactor is a conical reactor with a conical bottom, and preferably the angle of the cone bottom is 5° to 50°.

10. A carbon material prepared by the method according to any one of claims 1 to 6.

11. A method for monitoring the status of the device according to claim 7, the method comprising the following steps: a) Initial data collection: record the capacitance value C of the set gas source respectively m , the capacitance value C of carbon nanotubes n ; b) real-time data collection: placing an electrode assembly on the outer wall of the separation zone of the reactor body, with the electrode assembly at a height H from the bottom of the reactor; recording the capacitance value C measured by the electrode assembly, and converting the capacitance value C into a mathematical signal; c) Image reconstruction: the mathematical signal obtained in step b) is subjected to algorithm iteration to calculate the dielectric constant ε of each unit, and then image reconstruction is performed to obtain the void ratio P in the reactor at the corresponding time, and the required characteristic value θ is calculated through the void ratio P; d) Data adjustment: Compare the eigenvalue θ obtained in step c with the standard eigenvalue θs. When the eigenvalue θ is outside the range of the standard eigenvalue θs, adjust the parameters so that the eigenvalue is within the range of the standard eigenvalue θs.

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