Manufacturing apparatus comprising recirculation line of hydrogen generated during manufacture of methane and solid carbon from carbon dioxide, manufacturing method using same, and solid carbon manufactured thereby

Abstract

The present invention relates to a manufacturing apparatus comprising a recirculation line of hydrogen generated during the manufacture of methane and solid carbon from carbon dioxide, a manufacturing method using same, and solid carbon manufactured thereby. More specifically, the manufacturing apparatus comprises: a gas supplier for supplying a mixed gas comprising carbon dioxide and hydrogen; a first reactor for synthesizing carbon dioxide and hydrogen in the mixed gas supplied from the gas supplier into hydrocarbons according to a controlled supply ratio; a first gas separator for separating hydrocarbons from products and unreacted materials of the first reactor; a second reactor for generating solid carbon through decomposition of the hydrocarbons separated by the first gas separator; a second gas separator for recovering and storing hydrocarbons through gas separation of gas generated after reaction and unreacted hydrocarbons from the second reactor; and a recirculation line for recirculating at least one of gas by-products, unreacted carbon dioxide, and hydrogen generated from the first reactor, the first gas separator, the second reactor, and the second gas separator to the gas supplier.

Description

A manufacturing apparatus including a recirculation line for hydrogen generated during the production of methane and solid carbon from carbon dioxide, a manufacturing method using the same, and solid carbon produced by the same

[0001] The present invention relates to a manufacturing apparatus comprising a hydrogen recirculation line for hydrogen generated during the manufacturing of solid carbon from carbon dioxide, a manufacturing method using the same, and solid carbon produced thereby, which can significantly reduce the amount of hydrogen input by applying the blue-green hydrogen generated during the manufacturing process to carbon dioxide methanation technology, while simultaneously manufacturing solid carbon such as high-quality and high-value-added carbon nanotubes (SWCNTs), nanocarbon materials such as graphene, or carbon-coated silicon anode materials from carbon dioxide.

[0002] Conventional carbon dioxide methanation technology is a reaction in which carbon dioxide and hydrogen react to produce methane and water, and it is one of the carbon capture and utilization technologies for carbon dioxide reduction.

[0003] Since methane can be used as a fuel for city gas and gas mobility, existing city gas infrastructure and gas station infrastructure can be utilized as is. In Japan, four carbon dioxide methanation demonstration centers are currently operating, centered around gas companies, and research and development efforts are also being made at domestic and international research institutes.

[0004] Meanwhile, conventional technologies for producing nano-carbon materials (or carbon coatings on silicon anodes) and blue-green hydrogen through methane pyrolysis involve a reaction in which methane (1 carbon atom + 4 hydrogen atoms) is thermally decomposed at high temperatures to form a carbon coating on the surface of carbon materials or silicon anodes, during which blue-green hydrogen, a type of clean hydrogen, is produced. Furthermore, carbon materials and carbon-coated silicon anodes can be utilized as core materials for secondary batteries, and blue-green hydrogen can be used as hydrogen energy.

[0005] For example, BASF Inc. is preparing for commercialization in 2030, and research institutes at home and abroad are also conducting research for the commercialization of the technology.

[0006] However, processes for the chemical conversion of carbon dioxide result in final products (hydrocarbons, polymers, alcohols, etc.) being at a disadvantage in terms of price relative to the process, so process technology is required to convert to high-priced target products.

[0007] In addition, nano-carbon materials such as single-walled carbon nanotubes (2,000,000 won / kg) have very high prices, so while economic feasibility can be secured if they can be converted from carbon dioxide, there is a problem that it is difficult to produce high-quality carbon nanotubes through one-step direct conversion.

[0008]

[0009] Meanwhile, high-value-added material conversion technology utilizing carbon dioxide (CO2) is attracting attention as a key strategy for realizing carbon neutrality.

[0010] In particular, the two-stage tandem process, which involves reducing CO2 to methane (CH4) and then pyrolyzing it to convert it into single-walled carbon nanotubes (SWCNTs), is an efficient technology capable of simultaneously achieving the utilization of carbon dioxide and the production of high-performance carbon materials. However, existing processes have limitations in that they lack systematic analysis and control strategies regarding how the conditions of the CO2 methanation reaction in the upstream stage (reaction temperature, inflow gas ratio, etc.) affect the growth of SWCNTs in the downstream stage.

[0011] Furthermore, the CO2 methanation reaction results in varying CH4 yields and fluctuating hydrogen (H2) concentrations in the products depending on temperature and input gas composition. This significantly affects the growth mechanisms, crystallinity, and diameter distribution of solid carbon, such as the carbon deposition rate in subsequent CH4 thermal decomposition reactions, as well as carbon coatings on graphene, carbon nanotubes, and silicon anodes. In particular, the presence of excess H2 disrupts the chemical equilibrium of the CH4 thermal decomposition reaction, leading to a problem where the crystallinity of solid carbon is reduced.

[0012] Therefore, there is a need for technology to quantitatively analyze and optimize the causal relationship between the upstream methanation reaction conditions and the downstream solid carbon properties.

[0013] The present invention has been devised to solve the problems described above.

[0014] One objective is to manufacture high-quality, high-value-added nanocarbon materials (carbon nanotubes, graphene, etc.) and silicon anode carbon coatings from carbon dioxide, while simultaneously significantly reducing the amount of hydrogen input by reusing the blue-green hydrogen generated during the manufacturing process in carbon dioxide methanation technology.

[0015] Another objective of the present invention is to not only recycle the blue-green hydrogen generated during the methanation process of carbon dioxide, but also to conserve overall hydrogen energy resources by separating hydrogen from the water generated from the first reactor through water electrolysis and adding additional hydrogen.

[0016] Another objective of this invention is to enhance economic efficiency by recycling carbon monoxide and unreacted carbon dioxide, which are gas byproducts generated during the methanation process of carbon dioxide, into input gases through recirculation, in addition to hydrogen, and to achieve carbon neutrality by reducing carbon dioxide emissions in this process.

[0017] One objective of the present invention is to analyze and control the effect of changes in the methanation reaction conditions of CO2 in the first reaction step on the physical properties of carbon nanotubes (CNTs), nanocarbon materials such as graphene, or carbon-coated silicon anode materials produced in the second continuous step of a continuous process of first and second reaction steps for converting CO2 into carbon nanotubes (CNTs), nanocarbon materials such as graphene, or carbon-coated silicon anode materials.

[0018] Another objective of the present invention is to investigate the effect of the relative concentration composition of CH4 and H2 according to changes in the CO2 methanation reaction temperature and H2 / CO2 ratio in the first reaction step on the CH4 thermal decomposition reaction in the second reaction step, and based on this, to provide a basis for process design that can control the crystallinity and structural characteristics of nanocarbon materials such as carbon nanotubes (CNTs) and graphene or carbon-coated silicon anode materials.

[0019] Another objective of the present invention is to establish a precision-controlled resource recycling process technology capable of simultaneously improving greenhouse gas conversion efficiency and the quality of the produced carbon material.

[0020] One objective of the present invention is to analyze and control the effect of changes in the methanation reaction conditions of CO2 in the first reaction step on the physical properties of the carbon nanotubes (CNTs), nanocarbon materials such as graphene, or carbon-coated silicon anode materials produced in the second continuous step of a continuous process of first and second reaction steps for converting CO2 into carbon nanotubes (CNTs), nanocarbon materials such as graphene, or carbon-coated silicon anode materials.

[0021] Another objective of the present invention is to investigate the effect of the relative concentration composition of CH4 and H2 according to changes in the CO2 methanation reaction temperature and H2 / CO2 ratio in the first reaction step on the CH4 thermal decomposition reaction in the second reaction step, and based on this, to provide a basis for process design that can control the crystallinity and structural characteristics of nanocarbon materials such as carbon nanotubes (CNTs) and graphene or carbon-coated silicon anode materials.

[0022] A manufacturing apparatus according to the present invention, comprising a recirculation line for hydrogen generated during the production of methane and solid carbon from carbon dioxide, comprises: a gas supplyer for supplying a mixed gas containing carbon dioxide and hydrogen; a first reactor for synthesizing carbon dioxide and hydrogen in the mixed gas supplied from the gas supplyer into hydrocarbons according to a controlled supply ratio; a first gas separator for separating hydrocarbons from the products and unreacted materials of the first reactor; a second reactor for producing solid carbon through the decomposition of hydrocarbons separated from the first gas separator; a second gas separator for recovering and storing hydrocarbons through gas separation of unreacted hydrocarbons and gas generated after reaction from the second reactor; and a recirculation line for recirculating at least one of the gas byproducts, unreacted carbon dioxide, and hydrogen generated from the first reactor, the first gas separator, the second reactor, and the second gas separator to the gas supplyer.

[0023] The carbon dioxide of the mixed gas according to the present invention is obtained through the capture of exhaust gas, and the hydrogen is obtained by a water electrolysis method.

[0024] The present invention is characterized by being synthesized into a hydrocarbon through a methanation reaction of carbon dioxide and hydrogen in the above-mentioned mixed gas.

[0025] The present invention is characterized in that the recirculation line comprises a first recirculation line for electrolyzing water generated from the first reactor and recirculating hydrogen separated through electrolysis to the gas supply.

[0026] The present invention is characterized in that the recirculation line includes a second recirculation line for recirculating gas byproducts and unreacted gas separated from the first gas separator to the gas supply.

[0027] The present invention is characterized in that the recirculation line comprises a third recirculation line for recirculating the products, namely carbon monoxide and hydrogen, to the gas supply unit through gas separation by the second gas separator from the unreacted hydrocarbon products, including hydrogen, which is a product, and unreacted hydrocarbon products, after the reaction by the second reactor.

[0028] The present invention is characterized by including a storage device for storing separated unreacted hydrocarbons when gas is separated by the second gas separator according to the present invention.

[0029] The supply ratio of carbon dioxide and hydrogen supplied from the gas supply device to the first reactor according to the present invention is characterized by being supplied within the range of 1:4 to 1:8.

[0030] When carbon dioxide and hydrogen are supplied from the gas supply device according to the present invention to the first reactor, the carrier gas is characterized as being nitrogen (N2) or argon (Ar) gas having a flow rate of 0.5 to 3 times that of carbon dioxide.

[0031] The first reactor according to the present invention is characterized in that the reaction temperature is maintained within the range of 300 to 400℃ and the reaction pressure is maintained within the range of 1 to 50 bar.

[0032] The first reactor according to the present invention is provided with a first catalyst, wherein the first catalyst is a transition metal catalyst comprising at least one of Ni, Co, Ru, Rh, and Rb.

[0033] The first reactor according to the present invention further comprises a first catalyst support for the first catalyst, wherein the first catalyst support is an oxide comprising at least one of SiO2, Al2O3, CeO2, TiO2, and ZrO2.

[0034] The reaction temperature in the second reactor according to the present invention is characterized by being maintained within the range of 700 to 1000℃.

[0035] The second reactor according to the present invention is provided with a second catalyst, wherein the second catalyst is a transition metal catalyst comprising at least one of Fe, Cu, Ni, Co, and Ru.

[0036] The second reactor according to the present invention is further provided with a second catalyst support for the second catalyst, wherein the second catalyst support is an oxide comprising at least one of SiO2, Al2O3, and MgO.

[0037] The second reactor according to the present invention is characterized by further including, depending on the type of product, a single-atom catalyst or an organometallic catalyst (ferrocene) for carbon nanotube synthesis, silicon and silicon oxide for silicon carbon coating, carbon black for graphene-carbon black composite material synthesis, and Cu foil for graphene synthesis.

[0038] A manufacturing method using a manufacturing apparatus including a recirculation line for hydrogen generated during the production of methane and solid carbon from carbon dioxide according to the present invention comprises: (a) a mixed gas supply step for supplying a mixed gas containing carbon dioxide and hydrogen to a first reactor by means of a gas supply device; (b) a first reaction step for converting carbon dioxide and hydrogen into hydrocarbons through a methanation reaction by the first reactor; (c) a first gas separation step for separating at least one of the substances among the hydrocarbon containing methane synthesized from the first reactor, carbon monoxide from a by-reaction, unreacted carbon dioxide, and hydrogen through a first gas separator; and (d) a second reaction step for supplying the gas separated through the first gas separator to a second reactor and producing solid carbon through the thermal decomposition of the hydrocarbon containing methane through the second reactor; wherein the hydrocarbon yield and the conversion rate of carbon dioxide into hydrocarbons are controlled according to the ratio of carbon dioxide and hydrogen and the reaction temperature in the first reaction step of step (b).

[0039] The supply ratio of carbon dioxide and hydrogen supplied from the gas supply device to the first reactor according to the present invention is characterized by being supplied within the range of 1:4 to 1:8.

[0040] The reaction temperature in the first reactor according to the present invention is set within the range of 300 to 400°C, and the yield of methane and the change in the conversion rate of carbon dioxide to methane are evaluated according to the supply ratio of carbon dioxide and hydrogen and the set reaction temperature.

[0041] The reaction temperature in the second reactor according to the present invention is set to 700 to 1000℃, and when the reaction temperature in the second reactor is fixed at 1000℃, the gas flow rate is controlled within the range of 200 to 400 sccm according to the relative ratio of methane concentration and hydrogen concentration.

[0042] The present invention is characterized by including a recirculation step for recirculating at least one of a gas byproduct, unreacted carbon dioxide, and a water tank from the first reactor, the first gas separator, the second reactor, and the second gas separator according to the present invention to the supply step.

[0043] When carbon dioxide and hydrogen are supplied from the gas supply device according to the present invention to the first reactor, the carrier gas is characterized in that nitrogen (N2) is 10% or argon (Ar) is 50% relative to the total gas.

[0044] The solid carbon produced by the manufacturing apparatus including a recirculation line for hydrogen generated during the production of methane and solid carbon from carbon dioxide according to the present invention and the manufacturing method according thereto is characterized by comprising a carbon nanotube, a nanocarbon material such as graphene, and a carbon-coated silicon anode material.

[0045] According to the present invention, a manufacturing apparatus including a recirculation line for hydrogen generated during the production of methane and solid carbon from carbon dioxide, a manufacturing method using the same, and thereby, while simultaneously producing solid carbon, the amount of hydrogen input can be significantly reduced by applying the blue-green hydrogen generated during the manufacturing process to the carbon dioxide methanation technology.

[0046] In addition, the present invention not only recycles the blue-green hydrogen generated during the methanation process of carbon dioxide, but also promotes the conservation of overall hydrogen energy resources by separating hydrogen from the water generated from the first reactor through water electrolysis and adding additional hydrogen.

[0047] In addition, the present invention can enhance economic efficiency by recycling not only hydrogen but also gas by-products and unreacted gases generated during the methanation process of carbon dioxide into input gas through recirculation, and achieve carbon neutrality by reducing carbon dioxide emissions in this process.

[0048] In addition, the present invention provides a method for manufacturing solid carbon comprising a two-stage continuous process of carbon dioxide methanation and methane pyrolysis, which enables the control of physical properties of nanocarbon materials such as carbon nanotubes (CNTs) and graphene or carbon-coated silicon anode materials according to carbon dioxide conversion conditions. By precisely controlling the CO2 methanation conditions in the first reaction stage and, accordingly, controlling the physical properties of nanocarbon materials such as carbon nanotubes (CNTs) and graphene or carbon-coated silicon anode materials produced through CH4 pyrolysis in the second reaction stage, the precision of the greenhouse gas conversion process and the quality of the resulting product can be improved simultaneously.

[0049] In addition, the present invention allows for the design of the crystallinity of high-value-added materials, such as nanocarbon materials like carbon nanotubes (CNTs) and graphene, or carbon-coated silicon anode materials, according to reaction conditions, and thereby can be utilized as a carbon material manufacturing technology capable of customized production.

[0050] Furthermore, by establishing a causal relationship between CO2 conversion conditions and the properties of nanocarbon materials such as carbon nanotubes (CNTs) and graphene, or carbon-coated silicon anode materials, the present invention can make a substantial contribution to the optimized design of carbon resource utilization technology, automation of process control, and enhancement of industrial scalability.

[0051] In addition, the present invention not only recycles the blue-green hydrogen generated during the methanation process of carbon dioxide, but also promotes the conservation of overall hydrogen energy resources by separating hydrogen from the water generated from the first reactor through water electrolysis and adding additional hydrogen.

[0052] FIG. 1 is a conceptual diagram showing a manufacturing apparatus including a recirculation line for hydrogen generated during the production of methane and solid carbon from carbon dioxide according to the present invention.

[0053] FIG. 2 is a conceptual diagram showing the inflow gas path and the recirculation line for hydrogen, gas byproducts, and untreated gas in a manufacturing apparatus according to the present invention.

[0054] FIG. 3 is a conceptual diagram showing a methanation process by a first reactor in a manufacturing apparatus according to the present invention, and a manufacturing process of carbon nanotubes (CNTs) and carbon-coated silicon anode material using methane in a second reactor as a continuous process.

[0055] FIG. 4 is a process flow diagram illustrating a method for manufacturing solid carbon comprising a two-stage continuous process of carbon dioxide methanation reaction and methane pyrolysis reaction, which enables control of physical properties of nanocarbon materials such as carbon nanotubes (CNTs) and graphene or carbon-coated silicon anode materials according to carbon dioxide conversion conditions according to the present invention.

[0056] FIG. 5 is a process flow diagram showing a recirculation step through a first to third recirculation line in a manufacturing method according to the present invention,

[0057] FIG. 6 is a schematic diagram showing a methanation process by a first reactor and a pyrolysis process by a second reactor in a manufacturing method according to the present invention.

[0058] FIG. 7 is a diagram showing an analysis of SiO2 used as a catalyst support in the process of methanating carbon dioxide in a manufacturing apparatus according to the present invention, including the surface appearance of the SiO2 catalyst support, BET and BJH graphs showing the specific surface area size distribution of SiO2,

[0059] FIG. 8 is a diagram showing the analysis of Ni / SiO2 used as a catalyst in the process of methanating carbon dioxide in a manufacturing apparatus according to the present invention, including the surface appearance of the Ni-supported catalyst, a TPR result graph to determine the reduction temperature of the Ni / SiO2 catalyst, and an XRD graph showing the presence or absence of metallic Ni depending on the reduction of Ni / SiO2.

[0060] FIG. 9 is a diagram showing the analysis of MgO used as a catalyst support in the process of methanating carbon dioxide in a manufacturing apparatus according to the present invention, including the surface appearance of the MgO catalyst support and BET and BJH analysis graphs showing the pore characteristics of the MgO catalyst support.

[0061] FIG. 10 is a diagram showing the analysis of Fe-Mo / MgO used as a catalyst in the process of synthesizing CNTs by methane pyrolysis generated in the manufacturing apparatus according to the present invention, including the surface of Fe-Mo / MgO, an H2-PTR result graph for determining the reduction temperature of the Fe-Mo / MgO catalyst, and an XRD graph for determining the degree of dispersion of metal particles depending on the reduction of Fe-Mo / MgO.

[0062] FIGS. 11 and 12 are drawings showing carbon nanotubes produced according to the reaction temperature of the second reactor in a manufacturing apparatus according to the present invention, where CCNT-700, CCNT-750, CCNT-800, CCNT-850, and CCNT-900℃ represent CNTs synthesized at 700, 750, 800, 850, and 900℃, respectively.

[0063] FIG. 13 is a diagram showing the results of Raman analysis on the crystallinity of carbon nanotubes according to the reaction temperature of the second reactor in the manufacturing apparatus according to the present invention.

[0064] FIG. 14 is a graph showing the distribution of CO2 conversion rate, CH4 yield, CH4 selectivity (forward reaction), and CO selectivity (side reaction) after the CO2 methanation reaction in the manufacturing method according to the present invention.

[0065] FIG. 15 is a graph showing the distribution of CH4 concentration relative to CO2 after the CO2 methanation reaction in the manufacturing method according to the present invention.

[0066] FIG. 16 is a graph showing the distribution of the ratio of H2 concentration to CH4 after the CO2 methanation reaction in the manufacturing method according to the present invention.

[0067] FIG. 17 is a diagram showing the analysis results of carbon nanotubes after the pyrolysis reaction in the second reaction step according to FIG. 15.

[0068] FIG. 18 is a diagram showing the analysis results of carbon nanotubes after the pyrolysis reaction in the second reaction step according to FIG. 16.

[0069] FIG. 19 is a drawing showing carbon-coated silicon among solid carbon produced by the apparatus and method for producing methane and solid carbon from carbon dioxide according to the present invention.

[0070] FIG. 20 is a drawing showing graphene among the solid carbon produced by the apparatus and method for producing methane and solid carbon from carbon dioxide according to the present invention.

[0071] In order to explain the operational advantages of the present invention and the objectives achieved by the implementation of the present invention, preferred embodiments of the present invention are illustrated below and examined with reference thereto.

[0072] First, the terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention; singular expressions may include plural expressions unless the context clearly indicates otherwise. Furthermore, in this application, terms such as "comprising" or "having" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0073] In describing the present invention, if it is determined that a detailed description of related known components or functions may obscure the essence of the invention, such detailed description is omitted.

[0074]

[0075] As illustrated in FIGS. 1 and 2, a manufacturing apparatus including a recirculation line (RL) for hydrogen produced during the production of methane and solid carbon from carbon dioxide according to the present invention comprises a gas supply unit (10), a first reactor (20), a first gas separator (30), a second reactor (40), a second gas separator (50), and a recirculation line (RL).

[0076]

[0077] As shown in FIGS. 1 to 3, the gas supply device (10) according to the present invention is configured to supply a mixed gas containing carbon dioxide.

[0078] The mixed gas supplied from the gas supply unit (10) may include carbon dioxide and hydrogen. In this case, the carbon dioxide may be supplied through a carbon dioxide separation process from exhaust gas emitted from a factory or industrial facility. That is, the carbon dioxide may be supplied through carbon dioxide capture.

[0079] In addition, hydrogen can be produced through water electrolysis using electricity generated from renewable energy sources such as solar or wind power, and the hydrogen produced in this way can be supplied.

[0080] Accordingly, the gas supply unit (10) supplies carbon dioxide and hydrogen, separated and produced in the manner described above, to the first reactor (20).

[0081] In particular, carbon dioxide and hydrogen supplied from the gas supply unit (10) to the first reactor (20) can be supplied in a predetermined ratio. In this case, it is preferable that the supply ratio of carbon dioxide and hydrogen be supplied within the range of 1:4 to 1:8.

[0082] According to the first reaction equation below, it is desirable that hydrogen be supplied at a ratio of at least four times that of carbon dioxide.

[0083] However, along with the forward reaction as in reaction equation 1, a reverse water gas reaction as a side reaction as in reaction equation 3 may occur in the first reactor (20). Therefore, it is desirable to supply hydrogen in a range of 4 to 8 times the carbon dioxide, taking into account the side reaction of reaction equation 3.

[0084] The carbon monoxide generated through the side reaction and the carbon monoxide generated after the reaction by the second reactor (40) described later are each recirculated through the second recirculation line (RL2) and the third recirculation line (RL3), and can produce methane and water in the first reactor (20) as shown in reaction equation 2 below.

[0085]

[0086] [Reaction Equation 1]

[0087] Carbon dioxide : CO2 + 4H2 → CH4 + H2O

[0088]

[0089] [Reaction Equation 2]

[0090] Carbon monoxide: CO + 3H2 → CH4 + H2O

[0091]

[0092] [Reaction Equation 3]

[0093] Carbon dioxide : CO2 + H2 → CO + H2O

[0094]

[0095] Additionally, when supplying carbon dioxide and hydrogen from the gas supply unit (10), the carrier gas may be nitrogen (N2) or argon (Ar) gas with a flow rate of 0.5 to 3 times that of carbon dioxide. In this case, the total flow rate is preferably 100 to 1,000 sccm based on the reactor.

[0096] As illustrated in FIGS. 1 to 3, the first reactor (20) according to the present invention is configured to convert carbon dioxide and hydrogen supplied from a gas supply unit (10) into methane through thermal decomposition.

[0097] The first reactor (20) may be connected to a gas supply unit (10) and pipes to allow carbon dioxide and hydrogen to be introduced. To this end, it may include a first reaction unit (21) connected to the pipes and a first heat supply unit (23) for supplying heat to the first reaction unit (21).

[0098] Inside the first reaction section (21), a transition metal catalyst is provided as the first catalyst (C1), and the forward reaction according to reaction formula 1 and the side reaction according to reaction formula 3 can be generated through the transition metal catalyst, which is the first catalyst (C1).

[0099] It is preferable that the metal transition catalyst for this purpose include at least one of Ni, Co, Ru, Rh, and Rb. In addition, carbon monoxide recirculated through the second and third recirculation lines (RL3) described later can produce methane and hydrogen through the forward reaction according to reaction scheme 2.

[0100] In this case, the first reactor (20) may be further equipped with a first catalyst support to increase the active site of the transition metal and prevent catalyst deactivation during long-term operation. This catalyst support may be an oxide and may include at least one of SiO2, Al2O2, CeO2, TiO2, and ZrO2.

[0101] In addition, it is desirable to synthesize the catalyst using the dry and wet impregnation methods, which are the simplest and most well-known methods, so that no additional costs are incurred in the catalyst manufacturing process.

[0102] In this case, it is also possible to control the reaction rate while increasing the amount of catalyst to enhance the methane production effect.

[0103] By adjusting various process conditions as described above, not only can reaction conditions be optimized, but the operating costs of the process can also be reduced.

[0104] Furthermore, it is desirable that the reaction temperature inside the first reactor (20) be maintained within the range of 300 to 450°C, and the reaction pressure be maintained within the range of 1 to 50 bar. In this case, it is desirable that hydrogen be supplied at least four times more than carbon dioxide as described above to increase the methane production effect.

[0105] In this case, at the reaction pressure, hydrocarbons such as C1, i.e., methane (CH4), are produced under atmospheric pressure conditions, and hydrocarbons of C2 to C10 can be produced under pressurized conditions of 2 to 50 bar.

[0106] Finally, after the reaction by the first reactor (20), carbon monoxide may be produced as a byproduct with hydrocarbons including methane, and carbon dioxide and hydrogen may be included as unreacted gases.

[0107] In particular, water (H2O) is also produced after the reaction by the first reactor (20), and hydrogen can be separated from the water by a water electrolysis device (60), and the separated hydrogen can be recirculated to the gas supply device (10) to the first reactor (20). That is, the water produced from the first reactor (20) separates hydrogen through the water electrolysis device (60), and the separated hydrogen is recirculated to the gas supply device (10) to the first reactor (20) through the first recirculation line (RL1), thereby reducing the amount of newly supplied hydrogen and thereby reducing the cost for hydrogen supply.

[0108]

[0109] As illustrated in FIGS. 1 to 3, the first gas separator (30) according to the present invention is configured to separate hydrocarbons including methane synthesized from the first reactor (20) from a mixture of unreacted carbon dioxide and carbon monoxide, which is a byproduct, through gas separation.

[0110] That is, after the reaction by the first reactor (20) in the first gas separator (30), the product may include not only hydrocarbons including methane, but also carbon monoxide, unreacted carbon dioxide, and hydrogen from by-reactions.

[0111] Therefore, the first gas separator (30) separates hydrocarbons (CH4, C2H2, C3H6, etc.) containing methane and hydrogen and supplies them to the second reactor (40).

[0112] In this case, carbon monoxide and unreacted carbon dioxide separated from the first gas separator (30) can be recirculated to the gas supply unit (10) and the first reactor (20) through the second recirculation line (RL). That is, carbon dioxide and carbon monoxide separated from the first gas separator (30) can be recirculated through the second recirculation line (RL2) and used in the methanation process in the first reactor (20). Furthermore, by recirculating the carbon dioxide and carbon monoxide without releasing them into the atmosphere, carbon dioxide capture for carbon neutrality becomes possible.

[0113] As illustrated in FIGS. 1 to 3, the second reactor (40) according to the present invention is configured to decompose hydrocarbons including methane separated from the first gas separator (30) to produce nanocarbon materials and carbon-coated silicon cathode materials.

[0114] The second reactor (40) may include a second reaction section (41) and a second heat supply section (43) for supplying heat to the second reaction section (41).

[0115] A second catalyst (C2) is provided in the second reaction section (41) of the second reactor (40), and such second catalyst (C2) may be a transition metal catalyst. The transition metal catalyst that is the second catalyst (C2) may include at least one of Fe, Cu, Ni, Co, Ru, and Mo.

[0116] In this case, the second reactor (40) may be further equipped with a second catalyst support to increase the active site of the transition metal and prevent catalyst deactivation during long-term operation. This second catalyst support may be an oxide and may include at least one of SiO2, Al2O3, and MgO.

[0117] In particular, in the second reactor (40), a transition metal catalyst and a second catalyst support can be used as the second catalyst (C2) as described above, but depending on the type of material to be synthesized, it is also possible to use a single-atom catalyst for single-wall carbon nanotube synthesis, an organometallic catalyst (ferrocene), silicon and silicon oxide for silicon carbon coating, carbon black for graphene-carbon black composite material synthesis, or Cu foil for graphene synthesis.

[0118] Meanwhile, it is desirable to maintain the reaction temperature in the second reactor (40) within the range of 700 to 1050℃.

[0119] In addition, the carbon source in the second reactor (40) is a hydrocarbon such as CH4, C2H2, C3H6 including methane, and the flow rate may be 10 to 1,000 sccm. However, the gas flow rate as described above may vary depending on the process conditions of the first reactor (20).

[0120] Under these reaction conditions, carbon monoxide and hydrogen are produced in the second reactor (40) after reaction, and unreacted hydrocarbons, etc. may be included.

[0121] In particular, the second reactor (40) can produce nanocarbon materials such as carbon nanotubes (CNTs) and graphene, or carbon-coated silicon anode materials (average particle size 30 nm to 200 nm). In this case, for nanocarbon materials, the synthesis time can be adjusted to a range of 5 to 60 min depending on the material characteristics.

[0122] In addition, in the case of carbon coating on silicon anode material, the carbon deposition time can be adjusted to control the thickness of the carbon coating layer, and the deposition time can be adjusted in the range of 5 to 120 min.

[0123]

[0124] As illustrated in FIGS. 1 to 3, the second gas separator (50) according to the present invention is configured to store hydrocarbons including methane in a storage device (70) through gas separation of the gas generated after reaction from the second reactor (40), namely carbon monoxide, hydrogen, and unreacted hydrocarbons.

[0125] That is, the second gas separator (50) separates the carbon monoxide, hydrogen, and unreacted hydrocarbons generated after the reaction in the second reactor (40), and the carbon monoxide and hydrogen among them can be recirculated to the gas supply unit (10) to the first reactor (20) through the third recirculation line (RL3).

[0126] In addition, hydrocarbons including methane separated from the second gas separator (50) can be stored in a storage device (70).

[0127]

[0128] As described above, the manufacturing apparatus according to the present invention can methanate carbon dioxide through the first reactor (20) and, through a continuous process, use the methane in the second reactor (40) to produce high-quality solid carbon, that is, nanocarbon materials such as carbon nanotubes (CNTs) and graphene as shown in FIG. 19 and FIG. 20, or carbon-coated silicon anode materials.

[0129] In addition, gas byproducts from each reactor and gas separator are recirculated through a recirculation line (RL). As described above, this recirculation line (RL) recirculates hydrogen separated by electrolyzing water generated from the first reactor (20) to the gas supply unit (10) and the first reactor (20) through the first recirculation line (RL1).

[0130] Additionally, carbon dioxide and carbon monoxide from the mixed gas from the first reactor (20) can be separated by the first gas separator (30), and these substances can be recirculated to the gas supply unit (10) to the first reactor (20) through the second recirculation line (RL2).

[0131] In addition, hydrogen and carbon monoxide generated from the second reactor (40) can be separated through the second gas separator (50), and these substances can be recirculated to the gas supply unit (10) to the first reactor (20) through the third recirculation line (RL3).

[0132] That is, the manufacturing apparatus according to the present invention not only manufactures high-quality nanocarbon materials such as carbon nanotubes (CNTs) and graphene or carbon-coated silicon anode materials through a continuous process using carbon dioxide as a carbon source, but also recirculates hydrogen, carbon dioxide, and carbon monoxide through a recirculation line (RL) and utilizes them as feed gases for manufacturing methane and nanocarbon materials such as carbon nanotubes (CNTs) and graphene or carbon-coated silicon anode materials, thereby reducing the production costs of nanocarbon materials such as carbon nanotubes (CNTs) and graphene or carbon-coated silicon anode materials.

[0133]

[0134] Meanwhile, the attached Fig. 7 shows the results of analyzing the surface and pore characteristics of SiO2, which is the first catalyst support in the first reactor (20), indicating that it is a support that can evenly disperse metal without aggregation when supporting it, and Fig. 8 shows the results of analyzing the surface of the transition metal catalyst Ni / SiO2, which is the first catalyst (C1), and XRD analysis before and after reduction at 500°C, indicating that the reduction temperature of Ni / SiO2 is 400°C and that it changed from the NiO phase to the Ni phase after reduction at 500°C.

[0135] Additionally, the attached FIG. 9 shows the results of surface and pore characteristic analysis of MgO, which is the second catalyst support in the second reactor (40), indicating that it is a support that can evenly disperse metal without aggregation when supported, and FIG. 10 shows the results of catalyst analysis indicating the surface and degree of dispersion of Fe-Mo / MgO, which is the second catalyst (C2). The XRD graph results indicate that even after calcination at 500°C, Fe-Mo is well dispersed without aggregation, allowing for the synthesis of thin carbon nanotubes (CNT).

[0136] FIGS. 11 and 12 show carbon nanotubes produced according to the reaction temperature in the second reactor (40), and it can be seen that the higher the reaction temperature, the higher the quality of the carbon nanotubes produced. In particular, it can be seen that single-walled carbon nanotubes (SWCNTs) are synthesized at 900°C or higher.

[0137] Figure 13 shows the results of Raman analysis indicating the crystallinity and diameter of carbon nanotubes (CNT) according to the reaction temperature. In this case, it can be confirmed that the crystallinity improves as the reaction temperature increases, and a large amount of FWCNT is synthesized.

[0138] The results of the attached FIGS. 17 and 18 are the results of setting the reaction temperature in the first reactor to 300 to 450°C, setting the ratio of carbon dioxide to hydrogen to 1:5, and setting the reaction temperature in the second reactor to 700 to 900°C.

[0139]

[0140] Meanwhile, as illustrated in FIGS. 1 to 6, the method for producing methane and solid carbon from carbon dioxide according to the present invention comprises (a) a mixed gas supply step (S100), (b) a first reaction step (S200) for methanating carbon dioxide, (c) a first gas separation step (S300) for separating methane and hydrocarbons, etc., and (d) a second reaction step (S400) for producing solid carbon through the thermal decomposition of hydrocarbons including methane.

[0141]

[0142] First, as illustrated in FIGS. 1 to 6, (a) the mixed gas supply step (S100) according to the present invention is a process for supplying a mixed gas containing carbon dioxide and hydrogen to a first reactor (20) by means of a gas supply device (10).

[0143] (a) In step (S100), the gas supply unit (10) is configured to supply a mixed gas containing carbon dioxide.

[0144] The mixed gas supplied from the gas supply unit (10) may include carbon dioxide and hydrogen. In this case, the carbon dioxide may be supplied through a carbon dioxide separation process from exhaust gas emitted from a factory or industrial facility. That is, the carbon dioxide may be supplied through carbon dioxide capture.

[0145] In addition, hydrogen can be produced through water electrolysis using electricity generated from renewable energy sources such as solar or wind power, and the hydrogen produced in this way can be supplied.

[0146] Accordingly, the gas supply unit (10) supplies carbon dioxide and hydrogen, separated and produced in the manner described above, to the first reactor (20).

[0147] In particular, carbon dioxide and hydrogen supplied from the gas supply unit (10) to the first reactor (20) can be supplied in a predetermined ratio. In this case, it is preferable that the supply ratio of carbon dioxide and hydrogen be supplied within the range of 1:4 to 1:8.

[0148] According to the first reaction equation below, it is desirable that hydrogen be supplied at a ratio of at least four times that of carbon dioxide.

[0149] However, along with the main reaction as in reaction equation 1, a reverse water gas reaction as a side reaction as in reaction equation 3 may occur in the first reactor (20). Therefore, it is desirable to supply hydrogen in a range of 4 to 8 times the carbon dioxide, taking into account the side reaction of reaction equation 3.

[0150] The carbon monoxide generated through the side reaction and the carbon monoxide generated after the reaction by the second reactor (40) described later are each recirculated through the second recirculation line (RL2) to the third recirculation line (RL3), and can produce methane and water in the first reactor (20) as shown in reaction equation 2 below.

[0151]

[0152] [Reaction Equation 1]

[0153] Carbon dioxide : CO2 + 4H2 → CH4 + H2O

[0154]

[0155] [Reaction Equation 2]

[0156] Carbon dioxide : CO2 + H2 → CO + H2O

[0157]

[0158] In addition, when carbon dioxide and hydrogen are supplied from the gas supply unit (10), the carrier gas may be 10% nitrogen (N2) or 50% argon (Ar) relative to the total gas. In this case, the total flow rate is preferably 200 to 400 sccm based on the reactor.

[0159]

[0160] Next, as illustrated in FIGS. 1 to 6, (b) the first reaction step (S200) according to the present invention is a process for converting carbon dioxide and hydrogen into methane through thermal decomposition by a first reactor.

[0161] (b) In the first reaction step (S200), the first reactor (20) may be connected to a gas supply unit (10) and pipes, etc., to allow carbon dioxide and hydrogen to be introduced. To this end, it may include a first reaction unit (21) connected to the pipes and a first heat supply unit (23) for supplying heat to the first reaction unit (21).

[0162] Inside the first reaction section (21), a transition metal catalyst is provided as the first catalyst (C1), and the main reaction according to reaction formula 1 and the side reaction according to reaction formula 3 can occur on the transition metal catalyst, which is the first catalyst (C1). For this purpose, it is preferable that the metal transition catalyst includes at least one of Ni, Co, Ru, Rh, and Rb. In addition, carbon monoxide recirculated through the second and third recirculation lines (RL3), which will be described later, can produce methane and hydrogen according to reaction formula 3.

[0163]

[0164] [Reaction Equation 3]

[0165] Carbon monoxide: CO + 3H2 → CH4 + H2O

[0166]

[0167] In this case, the first reactor (20) may be further equipped with a first catalyst support to increase the active site of the transition metal and prevent catalyst deactivation during long-term operation. This catalyst support may be an oxide and may include at least one of SiO2, Al2O2, CeO2, TiO2, and ZrO2.

[0168] In addition, it is desirable to synthesize the catalyst using the dry and wet impregnation methods, which are the simplest and most well-known methods, so that no additional costs are incurred in the catalyst manufacturing process.

[0169] In this case, it is also possible to control the reaction rate while increasing the amount of catalyst to enhance the methane production effect.

[0170] By adjusting various process conditions as described above, not only can reaction conditions be optimized, but the operating costs of the process can also be reduced.

[0171] Furthermore, it is desirable that the reaction temperature inside the first reactor (20) be maintained within the range of 300 to 400°C, and the reaction pressure be maintained within the range of 1 to 50 bar. In this case, it is desirable that hydrogen be supplied at least four times the amount of carbon dioxide as described above to increase the methane production effect.

[0172] In this case, at the reaction pressure, hydrocarbons such as C1, i.e., methane (CH4), are produced under atmospheric pressure conditions, and hydrocarbons of C2 to C10 can be produced under pressurized conditions of 2 to 50 bar.

[0173] Finally, after the reaction by the first reactor (20), carbon monoxide may be produced as a byproduct with hydrocarbons including methane, and carbon dioxide and hydrogen may be included as unreacted gases.

[0174] In particular, water (H2O) is also produced after the reaction by the first reactor (20), and hydrogen can be separated from the water by a water electrolysis device (60), and the separated hydrogen may include a first recirculation step (R-1) for recirculation to the gas supply device (10) to the first reactor (20). That is, in the first recirculation step, the water produced from the first reactor (20) separates hydrogen through the water electrolysis device (60), and the separated hydrogen is recirculated to the gas supply device (10) to the first reactor (20) through the first recirculation line (RL1) to reduce the amount of newly supplied hydrogen, thereby reducing the cost for hydrogen supply.

[0175]

[0176] As illustrated in FIGS. 1, 2, 4, and 5, (c) the first gas separation step (S300) according to the present invention is a process for separating hydrocarbons including methane synthesized from the first reactor, carbon monoxide from a by-reaction, unreacted carbon dioxide, and hydrogen through the first gas separator.

[0177] (c) In the first gas separation step (S300), the first gas separator (30) is configured to separate the hydrocarbon containing methane synthesized from the first reactor (20) from the mixed gas of unreacted carbon dioxide and carbon monoxide, which is a byproduct, through gas separation.

[0178] That is, after the reaction by the first reactor (20) in the first gas separator (30), the product may include not only hydrocarbons including methane, but also carbon monoxide, unreacted carbon dioxide, and hydrogen from by-reactions.

[0179] Therefore, the first gas separator (30) separates hydrocarbons (CH4, C2H2, C3H6, etc.) containing methane and hydrogen and supplies them to the second reactor (40).

[0180] In this case, the carbon monoxide and unreacted carbon dioxide separated from the first gas separator (30) may be recirculated to the gas supply unit or the first reactor (20) through the second recirculation line (RL). That is, the carbon dioxide and carbon monoxide separated from the first gas separator (30) are recirculated through the second recirculation line (RL2) so that they can be used in the methanation process in the first reactor (20), and carbon dioxide for carbon neutrality can be captured by recirculating the carbon dioxide and carbon monoxide without releasing them into the atmosphere.

[0181]

[0182] As illustrated in FIGS. 1 to 6, the (d) second reaction step (S400) according to the present invention is a process for producing a carbon nanomaterial such as carbon nanotubes (CNTs) or graphene or a carbon-coated silicon anode material by supplying a gas separated through a first gas separator to a second reactor and pyrolyzing a hydrocarbon including methane through the second reactor.

[0183] (d) In the second reaction step, the second reactor (40) can decompose hydrocarbons including methane separated from the first gas separator (30) to produce nanocarbon materials and carbon-coated silicon anode materials.

[0184] The second reactor (40) may include a second reaction section (41) and a second heat supply section (43) for supplying heat to the second reaction section (41).

[0185] A second catalyst (C2) is provided in the second reaction section (41) of the second reactor (40), and such second catalyst (C2) may be a transition metal catalyst. The transition metal catalyst that is the second catalyst (C2) may include at least one of Fe, Cu, Ni, Co, Ru, and Mo.

[0186] In this case, the second reactor (40) may be further equipped with a second catalyst support to increase the active site of the transition metal and prevent catalyst deactivation during long-term operation. This second catalyst support may be an oxide and may include at least one of SiO2, Al2O3, and MgO.

[0187] In particular, in the second reactor (40), a transition metal catalyst and a second catalyst support can be used as the second catalyst (C2) as described above, but depending on the type of material to be synthesized, it is also possible to use a single-atom catalyst for single-wall carbon nanotube synthesis, an organometallic catalyst (ferrocene), silicon and silicon oxide for silicon carbon coating, carbon black for graphene-carbon black composite material synthesis, or Cu foil for graphene synthesis.

[0188] Meanwhile, it is desirable to maintain the reaction temperature in the second reactor (40) within the range of 700 to 1000℃.

[0189] In addition, the carbon source in the second reactor (40) is a hydrocarbon such as CH4, C2H2, C3H6 including methane, and the gas flow rate may be 10 to 1,000 sccm. However, the gas flow rate as described above may vary depending on the process conditions of the first reactor (20).

[0190] In particular, when the reaction temperature in the second reactor is 1000℃, the gas flow rate can be maintained at 300 to 400 sccm, and in this case, it can be controlled by considering the relative ratio of methane concentration and hydrogen concentration.

[0191] Under these reaction conditions, carbon monoxide and hydrogen are produced in the second reactor (40) after reaction, and unreacted hydrocarbons, etc. may be included.

[0192] In particular, in the second reactor (40), nanocarbon materials such as carbon nanotubes (CNTs) and graphene, or carbon-coated silicon anode materials (average particle size 30 nm to 200 nm) can be produced. In this case, for nanocarbon materials, the synthesis time can be adjusted to a range of 5 to 60 min depending on the material characteristics.

[0193] In addition, for the carbon coating of silicon anode material, the carbon deposition time can be adjusted to control the thickness of the carbon coating layer, and the deposition time can be adjusted in the range of 5 to 120 min.

[0194]

[0195] As illustrated in FIGS. 2, 4 and 5, the second gas separator (50) according to the present invention may further include (e) a second gas separation step (S500) for separating gases produced after reaction from the second reactor (40), namely carbon monoxide, hydrogen, and unreacted hydrocarbons.

[0196] (e) The second gas separation step (S500) may include a storage step (S5100) for storing carbon monoxide, hydrogen, and unreacted hydrocarbons separated through the second gas separator in a storage device.

[0197] In this case, the second gas separator (50) may further be provided with a third recirculation step (R-3) for generating carbon monoxide and hydrogen after the reaction and separating unreacted hydrocarbons, and for recirculating the separated carbon monoxide and hydrogen to the gas supply unit (10) to the first reactor (20) through the third recirculation line (RL3).

[0198]

[0199] Through a method for manufacturing solid carbon comprising a two-stage continuous process of carbon dioxide methanation and methane pyrolysis reactions, which enables the control of physical properties of nanocarbon materials such as carbon nanotubes (CNTs) and graphene or carbon-coated silicon anode materials according to the carbon dioxide conversion conditions according to the present invention configured as described above, carbon dioxide is methanated, and high-quality solid carbon can be manufactured using methane in a second reactor through a continuous process. Through the above manufacturing method, nanocarbon materials such as carbon nanotubes (CNTs) and graphene or carbon-coated silicon anode materials can be manufactured.

[0200] In addition, gas byproducts from each reactor and gas separator are recirculated through a recirculation line (RL). As described above, this recirculation line (RL) recirculates hydrogen separated by electrolyzing water generated from the first reactor (20) to the gas supply unit (10) to the first reactor (20) through the first recirculation line (RL1). Furthermore, carbon dioxide and carbon monoxide from the mixed gas from the first reactor (20) are separated by the first gas separator (30), and these substances can be recirculated to the gas supply unit (10) to the first reactor (20) through the second recirculation line (RL2). Additionally, hydrogen and carbon monoxide generated from the second reactor (40) are separated through the second gas separator (50), and these substances can be recirculated to the gas supply unit (10) to the first reactor (20) through the third recirculation line (RL3).

[0201] That is, the manufacturing apparatus according to the present invention not only manufactures high-quality nanocarbon materials, namely single-walled carbon nanotubes or carbon coatings of silicon anode materials, through a continuous process using carbon dioxide as a carbon source, but also recirculates hydrogen, carbon dioxide, and carbon monoxide through a recirculation line (RL) and utilizes them as feed gases to manufacture methane and nanocarbon materials, namely single-walled carbon nanotubes or carbon-coated silicon anode materials, thereby reducing the production cost of nanocarbon materials, etc.

[0202]

[0203] The drawings in FIGS. 14 to 18 show that, according to the manufacturing method according to the present invention, the ratio of carbon dioxide to hydrogen in (b) the first reaction step (S200) and the reaction temperature in (b) the first reaction step (S200) allow for the control of the methane yield and the conversion rate of carbon dioxide to methane, thereby enabling the control of physical properties of nanocarbon materials such as carbon nanotubes (CNTs) and graphene, or carbon-coated silicon anode materials.

[0204] In other words, in the first reactor, the physical properties of nanocarbon materials such as carbon nanotubes (CNTs) and graphene, or carbon-coated silicon anode materials, can be controlled solely by the reaction conditions, namely the reaction temperature and the ratio of carbon dioxide to hydrogen.

[0205] To this end, (b) in the first reaction step, the reaction temperature of the first reactor can be set within the range of 300 to 400℃, and the ratio of carbon dioxide to hydrogen (H2 / CO2), i.e., the feed ratio, can be set within 1:4 to 1:8.

[0206] Table 1 below sets six temperature variables by increasing the reaction temperature from 300°C to 400°C in increments of 20°C, and sets the ratio of carbon dioxide to hydrogen to five mole ratios of reactants, such as 4, 5, 6, 7, and 8. Accordingly, the analysis results for 30 cases according to each reaction temperature and each ratio of carbon dioxide to hydrogen are shown in Figures 14 to 18.

[0207] 300℃320℃340℃360℃380℃400℃1 : 4CASE ​​1CASE 6CASE 11CASE 16CASE 21CASE 261 : 5CASE 2CASE 7CASE 12CASE 17CASE 22CASE 271 : 6CASE 3CASE 8CASE 13CASE 18CASE 23CASE 281 : 7CASE 4CASE ​​9CASE 14CASE ​​19CASE 24CASE ​​291 : 8CASE 5CASE 10CASE 15CASE 20CASE 25CASE 30

[0208] First, in FIG. 14, (a) shows the CO2 conversion rate distribution after the CO2 methanation reaction in the first reactor of the first reaction step (S200) (b) for 30 cases in Table 1, and FIG. 14 (b) shows the yield distribution of CH4 after the CO2 methanation reaction in the first reactor of the first reaction step (S200) (b). Also, FIG. 14 (c) shows the distribution of CH4 selectivity (forward reaction) and CO selectivity (side reaction) after the CO2 methanation reaction in the first reactor of the first reaction step (S200) (b) for 30 cases in Table 1.

[0209] It can be seen that the CO2 conversion rate in Fig. 14 (a) increases as the reaction temperature increases and as the ratio of carbon dioxide to hydrogen increases.

[0210] In addition, it can be seen that the CH4 yield in Figure 14 (b) increases as the reaction temperature increases and as the ratio of carbon dioxide to hydrogen increases.

[0211] In addition, it can be seen that the CH4 selectivity (forward reaction) in Figure 14 (c) generally increases as the reaction temperature increases and the ratio of carbon dioxide to hydrogen increases, whereas the CO selectivity (side reaction) generally increases as the reaction temperature decreases and the ratio of carbon dioxide to hydrogen decreases, contrary to the CH4 selectivity (forward reaction).

[0212]

[0213] In Fig. 15, (a) shows the distribution of the ratio of CH4 concentration to CO2 after the CO2 methanation reaction in (b) the first reaction step (S200) for 30 cases in Table 1, and (b) shows the three-dimensional distribution of (a).

[0214] That is, as the reaction temperature in the first reactor increases and the ratio of carbon dioxide to hydrogen increases, the ratio of CH4 (CH4 / CO2) concentration to CO2 increases, and in each of the 30 cases, the CH4 / CO2 concentration distribution can be introduced into the second reactor of the (d) second reaction stage (S400).

[0215] Figure 17 shows the Raman spectrum and scanning electron microscope (SEM) results to analyze the trends in the properties of carbon nanotubes (CNTs) in 6, 18, and 30 cases (CASE 16 -> CASE 18 -> CASE 26) when the CH4 concentration relative to CO2 increases. In Figure 17, it can be seen that even when (b) the methanation tendency in the first reaction step (S200) is excellent, highly crystalline carbon nanotubes (CNTs) are not synthesized in (d) the second reaction step (S400), and this is due to the incomplete thermal decomposition reaction of CH4 caused by the H2 introduced in (d) the second reaction step (S400).

[0216]

[0217] In Fig. 16, (a) shows the distribution of the ratio of H2 concentration to CH4 after the CO2 methanation reaction in (b) the first reaction step (S200) for 30 cases in Table 1, and (b) shows the three-dimensional distribution of (a).

[0218] That is, as the reaction temperature in the first reactor decreases and the ratio of carbon dioxide to hydrogen increases, the ratio of H2 (H2 / CH4) concentration to CH4 increases, and in each of the 30 cases, the H2 / CH4 concentration distribution can be introduced into the second reactor of the (d) second reaction stage (S400).

[0219] Figure 18 shows the Raman spectrum and scanning electron microscope (SEM) results to analyze the trends in the physical properties of carbon nanotubes (CNTs) in cases 26, 18, and 10 where the H2 concentration relative to CH4 increases. In Figure 18, the same trend can be observed in cases where the H2 concentration relative to CH4 increases to verify the influence of H2 confirmed in 'CASE 26 -> CASE 18 -> CASE 10', and it can be concluded that it is desirable to minimize the influence of H2 in order to manufacture highly crystalline carbon nanotubes (CNTs).

[0220]

[0221] Meanwhile, the attached Fig. 17 shows the results of analyzing the surface and pore characteristics of SiO2, which is the first catalyst support in the first reactor (20), indicating that it is a support that can evenly disperse metal without aggregation when supporting it, and Fig. 8 shows the results of XRD analysis of the surface of the transition metal catalyst Ni / SiO2, which is the first catalyst (C1), before and after reduction at 500°C, indicating that the reduction temperature of Ni / SiO2 is 400°C and that it changed from the NiO phase to the Ni phase after reduction at 500°C.

[0222] Additionally, the attached FIG. 9 shows the results of surface and pore characteristic analysis of MgO, which is the second catalyst support in the second reactor (40), indicating that it is a support that can evenly disperse metal without aggregation when supported, and FIG. 10 shows the results of catalyst analysis indicating the surface and degree of dispersion of Fe-Mo / MgO, which is the second catalyst (C2). The XRD graph results indicate that even after calcination at 500°C, Fe-Mo is well dispersed without aggregation, allowing for the synthesis of thin carbon nanotubes (CNT).

[0223] FIGS. 11 and 12 show carbon nanotubes produced according to the reaction temperature in the second reactor (40), and it can be seen that the higher the reaction temperature, the higher the quality of the carbon nanotubes produced. In particular, it can be seen that single-walled carbon nanotubes (SWCNTs) are synthesized at 900°C or higher.

[0224] Figure 13 shows the results of Raman analysis indicating the crystallinity and diameter of carbon nanotubes (CNT) according to the reaction temperature. In this case, it can be confirmed that the crystallinity improves as the reaction temperature increases, and a large amount of FWCNT is synthesized.

[0225] The results of the attached FIGS. 17 to 13 are the results of setting the reaction temperature in the first reactor to 300 to 450°C, setting the ratio of carbon dioxide to hydrogen to 1:5, and setting the reaction temperature in the second reactor to 700 to 900°C.

[0226]

[0227] Figures 19 and 20 attached illustrate embodiments of solid carbon produced by the apparatus and method for producing methane and solid carbon from carbon dioxide according to the present invention.

[0228] When attempting to manufacture CNTs in a two-step reaction, the solid carbon according to FIGS. 19 and 20 is loaded with a metal catalyst such as Fe, Mo, Ni, or Co onto a support such as MgO, Al2O3, or SiO2 and heat-treated at a temperature of 700 to 1200 degrees.

[0229] In this case, Fig. 19 shows silicon coated with solid carbon, i.e., a carbon coating material. After loading Si or SiOx into a two-stage reactor, if the reaction is carried out at 900–1000°C for 1–5 hours, hydrocarbons can be naturally coated on the silicon surface at high temperatures.

[0230] Figure 20 shows that when carbon black is loaded into a two-stage reactor and reacted at 900–1100°C for 1–4 hours, hydrocarbons are coated on the surface of the carbon black, and solid carbon, i.e., graphene, can be formed as the remaining hydrogen tears the coated film.

[0231] That is, the solid carbon according to the present invention can produce high-quality and high-value-added materials such as carbon nanotubes (CNTs), nanocarbon materials such as graphene, or carbon-coated silicon anode materials.

[0232]

[0233] As such, the present invention has been described with reference to an embodiment illustrated in the drawings, but this is merely illustrative, and those skilled in the art will understand that various modifications and equivalent alternative embodiments are possible therefrom.

[0234] Therefore, the true scope of technical protection of the present invention should be determined by the technical concept of the appended claims.

Claims

1. A gas supply unit for supplying a mixed gas containing carbon dioxide and hydrogen; A first reactor for synthesizing carbon dioxide and hydrogen in the mixed gas supplied from the above gas supply unit into hydrocarbons according to a controlled supply ratio; A first gas separator for separating hydrocarbons from the products and unreacted materials of the first reactor; A second reactor for producing solid carbon through the decomposition of hydrocarbons separated from the first gas separator; A second gas separator for recovering and storing hydrocarbons by separating the gas generated after reaction from the second reactor and unreacted hydrocarbons; and A manufacturing apparatus comprising a recirculation line for recirculating at least one of the gas byproducts generated from the first reactor, first gas separator, second reactor and second gas separator, unreacted carbon dioxide and hydrogen to the gas supply; and a recirculation line for hydrogen generated during the production of methane and solid carbon from carbon dioxide.

2. In Paragraph 1, A manufacturing apparatus comprising a recirculation line for hydrogen generated during the production of methane and solid carbon from carbon dioxide, characterized in that the carbon dioxide of the above-mentioned mixed gas is obtained through the capture of exhaust gas, and the hydrogen is obtained through a water electrolysis method.

3. In Paragraph 1, A manufacturing apparatus comprising a recirculation line for hydrogen generated during the production of methane and solid carbon from carbon dioxide, characterized by synthesizing hydrocarbons through a methanation reaction with carbon dioxide and hydrogen in the above-mentioned mixed gas.

4. In Paragraph 1, A manufacturing apparatus comprising a recirculation line for hydrogen produced during the production of methane and solid carbon from carbon dioxide, the above recirculation line including a first recirculation line for electrolyzing water produced from the first reactor and recirculating hydrogen separated through electrolysis to the gas supply.

5. In Paragraph 1, A manufacturing apparatus comprising a recirculation line for hydrogen produced during the production of methane and solid carbon from carbon dioxide, wherein the above recirculation line includes a second recirculation line for recirculating gas byproducts and unreacted gas separated from the first gas separator to the gas supply.

6. In Paragraph 1, A manufacturing apparatus comprising a recirculation line for hydrogen produced during the production of methane and solid carbon from carbon dioxide, the above recirculation line comprising a third recirculation line for recirculating the products, carbon monoxide and hydrogen, to the gas supply unit through gas separation by the second gas separator from the unreacted hydrocarbon products, after the reaction by the second reactor.

7. In Paragraph 6, A manufacturing apparatus comprising a recirculation line for hydrogen generated during the production of methane and solid carbon from carbon dioxide, comprising a storage device for storing separated unreacted hydrocarbons during gas separation by the second gas separator above.

8. In Paragraph 1, A manufacturing apparatus comprising a recirculation line for hydrogen generated during the production of methane and solid carbon from carbon dioxide, characterized in that the supply ratio of carbon dioxide and hydrogen supplied from the above gas supply unit to the above first reactor is supplied within the range of 1:4 to 1:

8.

9. In Paragraph 1, A manufacturing apparatus comprising a recirculation line for hydrogen generated during the production of methane and solid carbon from carbon dioxide, characterized in that when carbon dioxide and hydrogen are supplied from the above gas supply unit to the above first reactor, the carrier gas is nitrogen (N2) or argon (Ar) gas having a flow rate of 0.5 to 3 times that of carbon dioxide.

10. In Paragraph 1, In the first reactor above, the reaction temperature is maintained within the range of 300 to 400℃, and A manufacturing apparatus comprising a recirculation line for hydrogen generated during the production of methane and solid carbon from carbon dioxide, characterized in that the reaction pressure is maintained within the range of 1 to 50 bar.

11. In Paragraph 1, The above-mentioned first reactor is equipped with a first catalyst, The above-mentioned first catalyst is a transition metal catalyst comprising at least one of Ni, Co, Ru, Rh, and Rb, and a manufacturing apparatus including a recirculation line for hydrogen generated during the production of methane and solid carbon from carbon dioxide.

12. In Paragraph 11, A manufacturing apparatus comprising a first catalyst support for the first catalyst in the first reactor, wherein the first catalyst support is an oxide comprising at least one of SiO2, Al2O3, CeO2, TiO2, and ZrO2, and a recirculation line for hydrogen generated during the production of methane and solid carbon from carbon dioxide.

13. In Paragraph 1, A manufacturing apparatus comprising a recirculation line for hydrogen generated during the production of methane and solid carbon from carbon dioxide, characterized in that the reaction temperature in the second reactor is maintained within the range of 700 to 1000℃.

14. In Paragraph 1, The above-mentioned second reactor is equipped with a second catalyst, The above second catalyst is a transition metal catalyst comprising at least one of Fe, Cu, Ni, Co, and Ru, and a manufacturing apparatus including a recirculation line for hydrogen generated during the production of methane and solid carbon from carbon dioxide.

15. In Paragraph 14, The second reactor is further provided with a second catalyst support for the second catalyst, The above second catalyst support is an oxide comprising at least one of SiO2, Al2O3, and MgO, and is a manufacturing apparatus including a recirculation line for hydrogen generated during the production of methane and solid carbon from carbon dioxide.

16. In Paragraph 1, A manufacturing apparatus comprising a recirculation line for hydrogen generated during the production of methane and solid carbon from carbon dioxide, characterized in that the second reactor further comprises, depending on the type of product, a single-atom catalyst or an organometallic catalyst (ferrocene) for carbon nanotube synthesis, silicon and silicon oxide for silicon carbon coating, carbon black for graphene-carbon black composite material synthesis, and Cu foil for graphene synthesis. 17.(a) A mixed gas supply step for supplying a mixed gas containing carbon dioxide and hydrogen to a first reactor by means of a gas supply device; (b) A first reaction step for converting carbon dioxide and hydrogen into hydrocarbons through a methanation reaction by the first reactor above; (c) a first gas separation step for separating at least one of a hydrocarbon including methane synthesized from the first reactor, carbon monoxide from a by-reaction, unreacted carbon dioxide, and hydrogen through a first gas separator; and (d) a second reaction step for supplying the gas separated through the first gas separator to a second reactor and generating solid carbon through the thermal decomposition of hydrocarbons including methane through the second reactor; comprising, A method for producing methane and solid carbon from carbon dioxide comprising a two-stage continuous process of carbon dioxide methanation reaction and methane pyrolysis reaction, which enables control of physical properties of nanocarbon materials such as carbon nanotubes (CNTs) and graphene or carbon-coated silicon anode materials according to carbon dioxide conversion conditions, characterized by controlling the hydrocarbon yield and the conversion rate of carbon dioxide into hydrocarbons according to the ratio of carbon dioxide and hydrogen and the reaction temperature in the first reaction step of step (b) above.

18. In Paragraph 17, A method for producing methane and solid carbon from carbon dioxide capable of controlling the physical properties of nanocarbon materials such as carbon nanotubes (CNTs) and graphene, or carbon-coated silicon anode materials, according to carbon dioxide conversion conditions, characterized in that the supply ratio of carbon dioxide and hydrogen supplied from the gas supply unit to the first reactor is supplied within the range of 1:4 to 1:

8.

19. In Paragraph 18, A method for producing methane and solid carbon from carbon dioxide, characterized by setting the reaction temperature in the first reactor above within the range of 300 to 400℃ and evaluating the change in methane yield and the conversion rate of carbon dioxide to methane according to the supply ratio of carbon dioxide and hydrogen and the set reaction temperature.

20. In Paragraph 19, The reaction temperature in the second reactor above is set to 700 to 1000℃, but, When the reaction temperature in the second reactor above is fixed at a high temperature of 1000℃, A method for producing methane and solid carbon from carbon dioxide, characterized in that the above gas flow rate is controlled within the range of 200 to 400 sccm according to the relative ratio of methane concentration and hydrogen concentration.

21. In Paragraph 17, A method for producing methane and solid carbon from carbon dioxide, comprising a recirculation step for recirculating at least one of gas byproducts, unreacted carbon dioxide, and water tank from the first reactor, first gas separator, second reactor, and second gas separator to the supply step.

22. In Paragraph 17, A method for producing methane and solid carbon from carbon dioxide, characterized in that when carbon dioxide and hydrogen are supplied from the gas supply unit to the first reactor, the carrier gas is 10% nitrogen (N2) or 50% argon (Ar) relative to the total gas.

23. Solid carbon produced by the manufacturing apparatus and manufacturing method according to any one of claims 1 to 22, characterized in that it comprises carbon nanotubes, nanocarbon materials such as graphene, and carbon-coated silicon anode materials.

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