Production device for carbon material, production system for carbon material, carbon circulation system, production method for carbon material, and carbon circulation method

Abstract

[Problem] To provide a production device for a carbon material, a production system for a carbon material, and a production method for a carbon material that make it possible to efficiently produce a carbon material from carbon dioxide. [Solution] One aspect of the present invention provides a production device for a carbon material. The production device comprises a first reaction unit that produces carbon monoxide from carbon dioxide, a second reaction unit that produces a carbon material from carbon monoxide, and a gas line that connects the first reaction unit and the second reaction unit. The first reaction unit has at least one reactor that contains a reducing agent. By contact with a starting material gas that includes carbon dioxide, the reducing agent reduces the carbon dioxide to carbon monoxide and is oxidized, and by contact with a reducing gas that includes a reducing substance, the oxidized reducing agent is reduced.

Description

Carbon material manufacturing apparatus, carbon material manufacturing system, carbon circulation system, carbon material manufacturing method, and carbon circulation method

[0001] The present invention relates to a carbon material manufacturing apparatus, a carbon material manufacturing system, a carbon circulation system, a carbon material manufacturing method, and a carbon circulation method.

[0002] Carbon materials are widely used as conductive materials in electronic devices, filler materials for tires and inks, etc. For example, Patent Document 1 discloses a method for producing a carbon material by burning coal. However, in this method, the gas from which the carbon material is separated in the final step contains a large amount of carbon dioxide (CO ２ If this separated gas is released directly into the atmosphere, there is concern that the concentration of carbon dioxide in the atmosphere will increase, contributing to global warming.

[0003] In recent years, development of lithium ion secondary batteries has been underway. Active materials for use in positive and negative electrodes have also been actively studied to improve the performance of lithium ion secondary batteries. For example, Patent Document 2 discloses a method for producing a carbon-based negative electrode active material with excellent lithium ion acceptability. Patent Document 2 discloses a method in which petroleum-based or coal-based coke is pulverized, particle size adjusted, and then heat-treated.

[0004] For example, a carbon material produced by the method disclosed in Patent Document 1 can also be used as the carbon-based negative electrode active material. However, as described above, the use of such a method raises concerns that the concentration of carbon dioxide in the atmosphere will increase, contributing to global warming.

[0005] In addition, conventional smelting involves charging ore as a raw material and coke as a reducing agent into a blast furnace, melting the ore, and extracting the target metal. Coke is typically produced from coal (see Patent Document 2). Coal is a type of fossil fuel, and when burned, it generates a large amount of carbon dioxide. If this carbon dioxide is released directly into the atmosphere, the concentration of carbon dioxide in the atmosphere will increase, raising concerns that this could contribute to global warming.

[0006] JP 2014-19620 A International Publication No. 2009 / 022664 JP 2021-50279 A

[0007] In view of the above circumstances, the present invention provides a carbon material production apparatus, a carbon material production system, and a carbon material production method that can efficiently produce a carbon material from carbon dioxide.

[0008] Furthermore, according to the studies of the present inventors, a carbon-based negative electrode active material produced from coke has a low content of impurities (solid impurities) due to the relatively low impurity content of the coke itself. From the viewpoint of further improving the characteristics of lithium-ion secondary batteries, it is desirable to further reduce the content of solid impurities in the carbon-based negative electrode active material (carbon material). It is also desirable that the production thereof imposes a low burden on the environment. In view of the above circumstances, it has been decided to provide a carbon material production apparatus and the like that can produce a carbon material with an extremely low content of solid impurities while preventing a burden on the environment during production.

[0009] Furthermore, in view of the above circumstances, the present invention provides a carbon circulation system and a carbon circulation method that can efficiently produce target metals using carbon materials generated from exhaust gas.

[0010] According to one aspect of the present invention, there is provided an apparatus for producing a carbon material. The apparatus includes a first reaction section that produces carbon monoxide from carbon dioxide, a second reaction section that produces a carbon material from carbon monoxide, and a gas line connecting the first reaction section and the second reaction section. The first reaction section has at least one reactor that contains a reducing agent. The reducing agent reduces carbon dioxide to carbon monoxide upon contact with a raw material gas containing carbon dioxide and is oxidized, and the oxidized reducing agent is reduced upon contact with a reducing gas containing a reducing substance.

[0011] According to this embodiment, a carbon material can be efficiently produced from carbon dioxide.

[0012] According to another aspect of the present invention, there is provided an apparatus for producing a carbon material, comprising: a first reaction section for producing carbon monoxide from carbon dioxide; a second reaction section for producing a carbon material from the carbon monoxide; a gas line connecting the first reaction section and the second reaction section; and a pressure adjustment section provided midway along the gas line for increasing the pressure of a gas passing through the gas line.

[0013] According to this embodiment, a carbon material can be efficiently produced from carbon dioxide.

[0014] According to another aspect of the present invention, there is provided an apparatus for producing a carbon material, the apparatus comprising: a first reaction section for producing carbon monoxide from carbon dioxide; and a second reaction section for producing a carbon material from the carbon monoxide. The carbon material has a solid impurity content of 1 mass% or less.

[0015] According to this aspect, it is possible to produce a carbon material with an extremely low impurity content while preventing environmental impact during production. Furthermore, by effectively utilizing exhaust gas, it is possible to reduce its emissions and realize a circular economy (a material recycling-based society).

[0016] According to yet another aspect of the present invention, there is provided a carbon circulation system. The system includes a first reaction section that produces carbon monoxide from carbon dioxide contained in exhaust gas, a second reaction section that produces a carbon material from the carbon monoxide, and a smelting furnace that supplies ore together with the carbon material for smelting. The first reaction section contains a reductant that converts carbon dioxide produced by contact with the exhaust gas into carbon monoxide through a reduction reaction, and has at least one reactor that is capable of separating at least a portion of the oxygen element released from the carbon dioxide within the reduction reaction system. The reductant is a reductant that reduces carbon dioxide to carbon monoxide and is oxidized by contact with the exhaust gas, and the oxidized reductant is a reductant that is reduced by contact with a reducing gas containing a reducing substance.

[0017] According to this aspect, the target metal can be efficiently produced using the carbon material produced from the exhaust gas. Furthermore, by effectively utilizing the exhaust gas, the amount of exhaust gas emitted can be reduced, thereby realizing a circular economy (a material recycling-based society).

[0018] FIG. 1 is a schematic diagram showing the configuration of a first embodiment of a carbon material production system of the present invention. FIG. 2 is a schematic diagram showing the configuration of a first reactor in the first embodiment. FIG. 3 is a schematic diagram showing the configuration of a second embodiment of a carbon material production system of the present invention. FIG. 4 is a schematic diagram showing the configuration of a third embodiment of a carbon material production system of the present invention. FIG. 5 is a schematic diagram showing the configuration of a first reaction section in the fourth embodiment. FIG. 6 is a schematic diagram showing the configuration of a fifth embodiment of a carbon material production system of the present invention. FIG. 7 is a schematic diagram showing the configuration of a seventh embodiment of a carbon material production system of the present invention. FIG. 1 is a schematic diagram showing the configuration of a first embodiment of a carbon circulation system of the present invention. FIG. 2 is a schematic diagram showing the configuration of a second embodiment of a carbon circulation system of the present invention. FIG. 3 is a schematic diagram showing the configuration of a third embodiment of a carbon circulation system of the present invention. FIG. 4 is a schematic diagram showing the configuration of a fourth embodiment of a carbon circulation system of the present invention.

[0019] The carbon material production apparatus, carbon material production system, carbon circulation system, carbon material production method, and carbon circulation method of the present invention will be described in detail below with reference to preferred embodiments shown in the accompanying drawings. <Carbon Material Production System> First, the carbon material production system of the present invention will be described. <<First Embodiment>> First, a first embodiment of the carbon material production system of the present invention will be described. FIG. 1 is a schematic diagram showing the configuration of the first embodiment of the carbon material production system of the present invention. FIG. 2 is a schematic diagram showing the configuration of a first reactor in the first embodiment. The carbon material production system 10 shown in FIG. 1 is a production system for producing a carbon material, and includes a carbon material production apparatus 100 (hereinafter also simply referred to as "production apparatus 100"), an exhaust gas supply unit 1 that supplies exhaust gas (raw material gas containing carbon dioxide), and a reducing gas supply unit 2 that supplies reducing gas, both connected to the production apparatus 100. Note that, throughout this specification, the upstream side of the gas flow direction will also be referred to simply as the "upstream side," and the downstream side will also be referred to simply as the "downstream side."

[0020] The exhaust gas supply unit 1 is not particularly limited, but may be, for example, a CO2 exhaust gas supply unit from at least one facility selected from a garbage incineration plant, a paper factory, a cement factory, a steel mill, a smelter, a thermal power plant, an oil refinery, an ethylene cracker, a refinery, and a chemical plant. ｘ Examples of sources of exhaust gas include emission sources. Among these, furnaces (e.g., combustion furnaces, blast furnaces, converters) attached to steel mills, smelters, or thermal power plants are preferred as the exhaust gas supply unit 1. In furnaces, gases containing carbon dioxide are generated (evolved) during combustion, melting, refining, etc. of the contents. In the case of combustion furnaces (incinerators) at waste incineration plants, examples of the contents (waste) include plastic waste, food waste, municipal solid waste (MSW), discarded tires, biomass waste, household waste (futons, paper), building materials, etc. Note that these wastes may contain one type alone or two or more types.

[0021] Exhaust gas typically contains, in addition to carbon dioxide, other gas components such as nitrogen, oxygen, carbon monoxide, water vapor, and methane. The concentration of carbon dioxide contained in the exhaust gas is not particularly limited, but considering the production cost of the generated gas (conversion efficiency to carbon materials), it is preferably 1% by volume or more, and more preferably 5% by volume or more. Exhaust gas from a combustion furnace in a waste incineration plant typically contains 5% by volume to 15% by volume, 60% by volume to 70% by volume, 5% by volume to 10% by volume, and 15% by volume to 25% by volume of water vapor.

[0022] Exhaust gas from a blast furnace (blast furnace gas) is a gas generated when pig iron is produced in a blast furnace, and contains 5 to 45 volume % carbon dioxide, 55 to 60 volume % nitrogen, 10 to 40 volume % carbon monoxide, and 1 to 10 volume % hydrogen. Exhaust gas from a converter (converter gas) is a gas generated when steel is produced in a converter, and contains 15 to 20 volume % carbon dioxide, 50 to 80 volume % carbon monoxide, 15 to 25 volume % nitrogen, and 1 to 5 volume % hydrogen. Note that pure gas containing 100 volume % carbon dioxide may be used as the exhaust gas.

[0023] However, if exhaust gas is used, carbon dioxide that has conventionally been emitted into the atmosphere can be effectively utilized, thereby reducing the burden on the environment. Among these, from the viewpoint of carbon circulation, exhaust gas containing carbon dioxide generated in a steelworks or smelter is preferred. Furthermore, as for blast furnace gas and converter gas, untreated gas discharged from the furnace may be used as is, or, for example, treated gas (described later) after treatment to remove carbon monoxide and the like may be used. Untreated blast furnace gas and converter gas each have the gas composition described above, and treated gas has a gas composition close to the gas composition shown for exhaust gas from a combustion furnace. In this specification, all of the above gases (gases before being supplied to the manufacturing apparatus 100) are referred to as exhaust gas.

[0024] The reducing gas supply unit 2 is configured, for example, with a hydrogen generation device that generates hydrogen by electrolysis of water. A tank storing water is connected to this hydrogen generation device. The hydrogen generation device allows for the generation of large amounts of hydrogen relatively inexpensively and easily. Another advantage is that condensed water generated within the production apparatus 100 (as well as the carbon circulation system 1000 described below) can be reused. Note that, since the hydrogen generation device consumes a large amount of electrical energy, it is effective to use electricity as a renewable energy source. As renewable energy, electrical energy utilizing at least one selected from solar power generation, wind power generation, hydroelectric power generation, wave power generation, tidal power generation, biomass power generation, geothermal power generation, solar heat, and geothermal heat can be used.

[0025] The hydrogen generating device may also be a device that generates by-product hydrogen. Examples of devices that generate by-product hydrogen include a device that electrolyzes a sodium chloride solution, a device that steam reforms petroleum, and a device that produces ammonia. The reducing gas supply unit 2 may also be a coke oven. In this case, exhaust gas from the coke oven may be used as the reducing gas. This is because exhaust gas from a coke oven is primarily composed of hydrogen and methane, and contains 50% to 60% by volume of hydrogen.

[0026] The manufacturing apparatus 100 of this embodiment is an apparatus for manufacturing a carbon material and mainly includes a gas switching unit 3, two first reactors 4a and 4b (first reaction units 4), and one second reactor (second reaction unit) 5. The exhaust gas supply unit 1 is connected to the gas switching unit 3 via a gas line GL1, and the reducing gas supply unit 2 is connected to the gas switching unit 3 via a gas line GL2. At least one of a temperature control unit for adjusting the temperature of the gas passing through each of the gas lines GL1 and GL2, a pressurizing unit for pressurizing the gas, an impurity removal unit for removing impurities from the gas, and the like may be disposed along each of the gas lines GL1 and GL2. The gas switching unit 3 may be configured to include, for example, a branch gas line and a flow path opening / closing mechanism such as a valve provided along the branch gas line.

[0027] The gas switching unit 3 is connected to the inlet ports of the first reactors 4a and 4b via two gas lines GL3a and GL3b. With this configuration, the exhaust gas (raw material gas containing carbon dioxide) supplied from the exhaust gas supply unit 1 passes through the gas line GL1, the gas switching unit 3, and the gas lines GL3a and GL3b, and is supplied to each of the first reactors 4a and 4b. On the other hand, the reducing gas containing hydrogen (reducing substance) supplied from the reducing gas supply unit 2 passes through the gas line GL2, the gas switching unit 3, and the gas lines GL3a and GL3b, and is supplied to each of the first reactors 4a and 4b.

[0028] The first reactors 4a and 4b are capable of generating carbon monoxide from carbon dioxide (converting carbon dioxide to carbon monoxide). As shown in FIG. 2 , each of the first reactors 4a and 4b is configured as a multi-tubular reactor (fixed-bed reactor) including a plurality of tubes 41 each filled with (accommodating) a reducing agent (reductant) 4R and a housing 42 housing the plurality of tubes 41 in an internal space 43. This multi-tubular reactor ensures sufficient contact between the reducing agent 4R and the exhaust gas and reducing gas. As a result, the efficiency of converting carbon dioxide to carbon monoxide can be improved. The first reactors 4a and 4b may also be configured as a reactor (i.e., a simple reactor) in which the tubes 41 are omitted and the internal space 43 of the housing 42 is filled with the reducing agent 4R. The reducing agent 4R of this embodiment is preferably in the form of particles (granules), flakes, pellets, or the like. The reducing agent 4R having such a shape can increase the efficiency of filling the pipe body 41, and can further increase the contact area with the gas supplied into the pipe body 41.

[0029] When the reducing agent 4R is particulate, its volume average particle size is not particularly limited, but is preferably 1 mm or more and 50 mm or less, and more preferably 1 mm or more and 30 mm or less. In this case, the contact area between the reducing agent 4R and the exhaust gas (carbon dioxide) can be further increased, and the efficiency of converting carbon dioxide to carbon monoxide can be further improved. Similarly, regeneration (reduction) of the reducing agent 4R by a reducing gas containing a reducing substance can also be performed more efficiently. The particulate reducing agent 4R is preferably a compact produced by tumbling granulation, as this increases the sphericity.

[0030] The reducing agent 4R may be supported on a carrier. The material of the carrier may be any material that is not easily denatured by contact with exhaust gas (oxidizing gas) or reaction conditions, and examples of such materials include carbon materials (graphite, graphene, carbon black, carbon nanotubes, activated carbon, etc.), Mo ２ Carbides such as C, zeolites, montmorillonite, ZrO ２ , TiO ２ , V ２ O ５ , MgO, CeO ２ , Al ２ O ３ , SiO ２ and composite oxides containing these.

[0031] Among these, the constituent materials of the carrier include zeolite, montmorillonite, ZrO ２ , TiO ２ , V ２ O ５ , MgO, Al ２ O ３ , SiO ２ and composite oxides containing these are preferred. A support made of such a material is preferred in that it does not adversely affect the reaction of the reducing agent 4R and has excellent supportability for the reducing agent 4R. Here, the support does not participate in the reaction of the reducing agent 4R, but simply supports (holds) the reducing agent 4R. One example of such a form is a configuration in which at least a portion of the surface of the support is coated with the reducing agent 4R.

[0032] The reducing agent 4R contains at least one of a metal and a metal oxide (an oxygen carrier having oxygen ion conductivity). The at least one of the metal and the metal oxide is not particularly limited as long as it can reduce carbon dioxide. However, it preferably contains at least one metal element selected from Groups 3 to 13, more preferably at least one metal element selected from Groups 3 to 12, and even more preferably at least one element selected from lanthanum, titanium, vanadium, iron, copper, zinc, nickel, manganese, chromium, and cerium. Metal oxides or composite metal oxides containing iron and / or cerium are particularly preferred. These metal oxides are useful because they have particularly good carbon dioxide conversion efficiency to carbon monoxide. Here, the metal includes a simple metal consisting of only one of the above metal elements and an alloy consisting of two or more of the above metal elements.

[0033] In each of the first reactors 4a and 4b, the tube (cylindrical molded body) 41 may be made of the reducing agent 4R (at least one of a metal and a metal oxide) itself. Furthermore, a block-shaped, lattice-shaped (e.g., mesh-shaped, honeycomb-shaped) molded body may be made of the reducing agent 4R and placed in the housing 42. In these cases, the reducing agent 4R as a filler may be omitted or may be used in combination.

[0034] Among these, a configuration in which a mesh body is formed using the reducing agent 4R and placed in the housing 42 is preferred. In this configuration, it is possible to prevent an increase in the resistance to the passage of the exhaust gas and reducing gas within each of the first reactors 4a, 4b, while also ensuring sufficient opportunities for the reducing agent 4R to come into contact with the exhaust gas and reducing gas. The volumes of the two first reactors 4a, 4b are set to be approximately equal to each other and are appropriately set depending on the amount of exhaust gas to be treated (the size of the exhaust gas supply unit 1 and the size of the production apparatus 100). The volumes of the two first reactors 4a, 4b may also be made different depending on the types of exhaust gas and reducing gas, the performance of the reducing agent 4R, etc.

[0035] According to the above configuration, by switching the gas lines (flow paths) in the gas switching unit 3, for example, exhaust gas can be supplied via the gas line GL3a to the first reactor 4a containing the reducing agent 4R before oxidation, and reducing gas can be supplied via the gas line GL3b to the first reactor 4b containing the reducing agent 4R after oxidation. At this time, the reaction of the following formula 1 proceeds in the first reactor 4a, and the reaction of the following formula 2 proceeds in the first reactor 4b.

[0036] In the following formulas 1 and 2, the reducing agent 4R contains iron oxide (FeO ｘ－１ ) is shown as an example. Formula 1: CO ２ + FeO ｘ－１ → CO + FeO ｘ Formula 2: H ２ + FeO ｘ → H ２ O + FeO ｘ－１ Thereafter, by switching the gas lines in the opposite direction in the gas switching unit 3, the reaction of the above formula 2 can be caused to proceed in the first reactor 4a, and the reaction of the above formula 1 can be caused to proceed in the first reactor 4b. That is, the exhaust gas (raw material gas) and the reducing gas are alternately supplied to the first reactor 4a and the first reactor 4b.

[0037] The reactions shown in the above formulas 1 and 2 are both endothermic reactions. For this reason, the production apparatus 100 (carbon material production system 10) preferably further includes a reducing agent heating unit (not shown in FIG. 1 ) that heats the reducing agent 4R when the exhaust gas or reducing gas is brought into contact with the reducing agent 4R (i.e., when the exhaust gas or reducing gas reacts with the reducing agent 4R). By providing such a reducing agent heating unit, the temperature during the reaction between the exhaust gas or reducing gas and the reducing agent 4R can be maintained at a high temperature, thereby suitably preventing or suppressing a decrease in the efficiency of conversion of carbon dioxide to carbon monoxide and further promoting the regeneration of the reducing agent 4R by the reducing gas.

[0038] However, depending on the type of reducing agent 4R, the reactions shown in Equations 1 and 2 may be exothermic. In this case, the manufacturing apparatus 100 preferably has a reducing agent cooling unit that cools the reducing agent 4R instead of a reducing agent heating unit. By providing such a reducing agent cooling unit, deterioration of the reducing agent 4R can be suitably prevented during the reaction between the exhaust gas or reducing gas and the reducing agent 4R, thereby suitably preventing or suppressing a decrease in the efficiency of converting carbon dioxide to carbon monoxide, and further promoting the regeneration of the reducing agent 4R by the reducing gas. In other words, the manufacturing apparatus 100 preferably has a reducing agent temperature adjustment unit that adjusts the temperature of the reducing agent 4R depending on the type of reducing agent 4R (exothermic reaction or endothermic reaction).

[0039] Here, the conversion rate of carbon dioxide to carbon monoxide in the first reactors 4a, 4b is preferably 70% or more, more preferably 85% or more, and even more preferably 95% or more. The upper limit of the conversion rate of carbon dioxide to carbon monoxide is usually about 98%. Such a conversion rate can be set by adjusting the type of reducing agent 4R used, the concentration of carbon dioxide contained in the exhaust gas, the type of reducing substance, the concentration of the reducing substance contained in the reducing gas, the temperature of the first reactors 4a, 4b, the flow rates (flow speeds) of the exhaust gas and the reducing gas into the first reactors 4a, 4b, the timing of switching between the exhaust gas and the reducing gas, etc.

[0040] Gas lines GL4a and GL4b are connected to the outlet ports of the first reactors 4a and 4b, respectively, and these lines join at a gas junction J to form the gas line GL4. Valves (not shown) are provided midway along the gas lines GL4a and GL4b, as necessary. For example, by adjusting the opening of the valves, it is possible to set the passage speeds of the exhaust gas and reducing gas passing through the first reactors 4a and 4b (i.e., the treatment speed of the exhaust gas by the reducing agent 4R and the treatment speed of the reducing agent 4R by the reducing gas).

[0041] The gas line GL4 is connected to the inlet port of the second reactor 5. That is, the second reactor (second reaction section) 5 is connected to the first reactors 4a, 4b (first reaction section) via gas lines GL4a, GL4b and the gas line GL4. This allows the exhaust gases from the first reactors 4a, 4b to be supplied to the second reactor 5 as a mixed gas. The second reactor 5 is capable of producing (converting) a carbon material from carbon monoxide. Specifically, the second reactor 5 produces a carbon material from carbon monoxide contained in the mixed gas by the so-called Boudoir reaction shown in the following formula 3. Formula 3: 2CO ⇔ C + CO ２ The second reactor 5 can be a reactor similar to that described for the first reactors 4a and 4b. In this case, the tube 41 is filled with one or more of the following catalysts. Examples of the catalyst include: (1) tungsten, rhenium, osmium, tantalum, molybdenum, niobium, iridium, ruthenium, hafnium, technetium, rhodium, vanadium, chromium, zirconium, platinum, thorium, lutetium, titanium, palladium, protactinium, thulium, scandium, iron, yttrium, erbium, cobalt, holmium, nickel, dysprosium, terbium, curium, gadolinium, beryllium, manganese, americium, promethium, uranium, copper, samarium, gold, actinium, neodymium, berkelium, silver, germanium, praseodymium, lanthanum, californium, calcium, europium, ytterbium, Examples of the additive include elements (simple elements or complexes) containing cerium, strontium, barium, radium, aluminum, magnesium, plutonium, neptunium, antimony, zinc, lead, cadmium, thallium, bismuth, polonium, tin, lithium, indium, sodium, potassium, rubidium, gallium, cesium, silicon, or tellurium; (2) sulfides, borides, oxides, chlorides, hydroxides, nitrides, and organometallic compounds of the above elements; (3) mixtures of either (1) or (2) above with sulfur and / or sulfides (including organic sulfur compounds); and (4) mixtures of either (1) or (2) above with boron and / or borides (including organic boron compounds).

[0042] A pressure adjusting unit 8 is provided along the gas line GL4 to increase the pressure of the mixed gas passing through the gas line GL4. Increasing the pressure of the mixed gas can shift (tilt) the equilibrium of the reaction described in Equation 3 to the right, thereby further improving the production efficiency of the carbon material. Specifically, the pressure of the mixed gas after pressurization by the pressure adjusting unit 8 is preferably 0.1 MPaG or higher, more preferably 0.1 MPaG to 10 MPaG or lower, even more preferably 0.1 MPaG to 5 MPaG or lower, particularly preferably 0.1 MPaG to 3 MPaG or lower, and most preferably 0.1 MPaG to 2 MPaG or lower. The lower limit of the pressure may be 0.2 MPaG or higher, or may be 0.5 MPaG or higher. Adjusting the pressure of the mixed gas can further improve the production efficiency of the carbon material. The pressure adjusting unit 8 can be configured to include a valve, a pressure adjusting valve, etc. The pressure adjusting unit 8 may be provided as needed or may be omitted.

[0043] A cooler and a gas-liquid separator (not shown) for cooling the mixed gas may be provided along the gas line GL4. The cooler generates condensed water (liquid) by cooling the mixed gas. Such a cooler may include a jacket-type cooling device in which a jacket is arranged around a pipe through which a refrigerant passes, a multi-tube cooling device having a configuration similar to that of the first reactors 4a and 4b (see FIG. 2 ) in which the mixed gas passes through a pipe and the refrigerant passes around the pipe, an air fin cooler, or the like.

[0044] The gas-liquid separator separates condensed water from the mixed gas produced when the mixed gas is cooled in the cooler. The condensed water has the advantage of being able to dissolve and remove unwanted gas components (particularly carbon dioxide) remaining in the mixed gas. The gas-liquid separator can be configured, for example, as a simple container, a swirl-flow separator, a centrifugal separator, a surface tension separator, or the like. Among these, the gas-liquid separator is preferably configured as a simple container because of its simple configuration and low cost. In this case, a filter that allows the passage of gas but prevents the passage of liquid may be disposed at the gas-liquid interface in the container.

[0045] As described above, by removing water and unnecessary gas components from the mixed gas, a mixed gas having a higher concentration of carbon monoxide can be supplied to the second reactor 5. Therefore, it is possible to prevent or suppress a decrease in the efficiency of conversion of carbon monoxide to carbon materials, and to further increase the amount of carbon monoxide produced.

[0046] The second reaction temperature in the second reactor (second reaction section) 5 is preferably lower than the first reaction temperature in the first reactors 4a, 4b (first reaction section 4). In this case, the reaction heat in the first reactors 4a, 4b can be effectively utilized in the second reactor 5. Specifically, the second reaction temperature is preferably 850°C or lower, more preferably 600°C or lower, and even more preferably 400°C or lower. This improves the carbon material production efficiency while also increasing the heat utilization efficiency.

[0047] A gas line GL5 is connected to the outlet port of the second reactor 5. A produced gas discharge unit 6 that discharges the produced gas to the outside of the production apparatus 100 is connected to the end of the gas line GL5 opposite to the second reactor 5.

[0048] Next, a method of using the carbon material production system 10 (a method of producing a carbon material) will be described. [1] First, the gas line (flow path) is switched in the gas switching unit 3 to connect the exhaust gas supply unit 1 to the first reactor 4a, and the reducing gas supply unit 2 to the first reactor 4b. [2] Next, in this state, exhaust gas is supplied from the exhaust gas supply unit 1 to the first reactor 4a via the gas line GL1. In the first reactor 4a, the reducing agent 4R reduces carbon dioxide to carbon monoxide upon contact with the exhaust gas (raw material gas containing carbon dioxide). At this time, the reducing agent 4R is oxidized by contact with carbon dioxide.

[0049] The temperature (first reaction temperature) of the first reactor 4a (exhaust gas, reducing agent 4R) in the above step [2] is preferably 500°C or higher, more preferably 650°C or higher and 1100°C or lower, and even more preferably 700°C or higher and 1000°C or lower. Furthermore, the pressure (first reaction pressure) of the first reactor 4a (exhaust gas, reducing agent 4R) is preferably less than 1 MPaG, more preferably 0.9 MPaG or lower, and even more preferably 0.2 MPaG or higher and 0.8 MPaG or lower. Setting the reaction conditions within the above ranges can prevent or suppress, for example, a sudden temperature drop of the reducing agent 4R due to the endothermic reaction when converting carbon dioxide to carbon monoxide, thereby allowing the carbon dioxide reduction reaction in the first reactor 4a to proceed more smoothly.

[0050] [3] In parallel with the above steps [1] and [2], water (reducing gas raw material) is supplied from a tank to the hydrogen generator (reducing gas supply unit 2), and hydrogen is generated from the water. [4] Next, a reducing gas containing hydrogen is supplied from the hydrogen generator to the first reactor 4b via gas line GL2. In the first reactor 4b, the oxidized reducing agent 4R is reduced (regenerated) by contact with the reducing gas (hydrogen). At this time, water is generated. In this case, hydrogen may be produced on-site, or it may be purified at a different location and then supplied via a pipeline or cylinder. The hydrogen production method is not critical as long as it is green hydrogen. Furthermore, green hydrogen may be used for only a portion of the hydrogen.

[0051] The temperature (reaction temperature) of the first reactor 4b (reducing gas, reducing agent 4R) in the above step [4] is preferably 500°C or higher, more preferably 650°C or higher and 1100°C or lower, and even more preferably 700°C or higher and 1000°C or lower. Furthermore, the pressure (first reaction pressure) of the first reactor 4b (reducing gas, reducing agent 4R) is preferably less than 1 MPaG, more preferably 0.9 MPaG or lower, and even more preferably 0.2 MPaG or higher and 0.8 MPaG or lower. Setting the reaction conditions within the above ranges can prevent or suppress, for example, a sudden temperature drop of the reducing agent 4R due to an endothermic reaction when reducing (regenerating) the oxidized reducing agent 4R, thereby allowing the reduction reaction of the reducing agent 4R in the first reactor 4b to proceed more smoothly. In this embodiment, the above steps [2] to [4] constitute a first generation step of generating carbon monoxide from carbon dioxide.

[0052] [5] Next, the gases that have passed through the first reactors 4a and 4b are joined together to produce a mixed gas. At this point, the temperature of the mixed gas is usually 200°C or higher and 1000°C or lower. If the temperature of the mixed gas at this point is within the above range, it means that the temperature inside the first reactors 4a and 4b is maintained at a sufficiently high temperature, and it can be determined that the conversion of carbon dioxide to carbon monoxide by the reducing agent 4R and the reduction of the reducing agent 4R by the reducing gas are proceeding efficiently.

[0053] [6] Next, the mixed gas is passed through the pressure adjustment unit 8 via the gas line GL4. At this time, the pressure of the mixed gas increases. In this embodiment, this step [6] constitutes a pressure adjustment step of increasing the pressure of the gas (mixed gas) generated in the first production step. [7] Next, the mixed gas that has passed through the pressure adjustment unit 8 is supplied to the second reactor 5. In the second reactor 5, carbon monoxide is converted into a carbon material. In this embodiment, this step [7] constitutes a second production step of producing a carbon material from carbon monoxide. Then, the produced gas (mixed gas) containing the carbon material is discharged from the produced gas discharge unit 6 via the gas line GL5 to the outside of the production apparatus 100 and is used for the next step.

[0054] <<Second Embodiment>> Next, a second embodiment of the carbon material production system of the present invention will be described. Figure 3 is a schematic diagram showing the configuration of the second embodiment of the carbon material production system of the present invention. The carbon material production system 10 of the second embodiment will be described below, focusing on differences from the carbon material production system 10 of the first embodiment, and a description of similar points will be omitted.

[0055] In the second embodiment, gas lines GL6a and GL6b branch off from gas lines GL4a and GL4b and join at a gas junction J1 to form a gas line GL6. A switching valve is provided at the branch point between the gas lines GL4a and GL4b and the gas lines GL6a and GL6b. The exhaust gas discharged from the first reactors 4a and 4b passes through gas lines GL4a, GL4b, and GL4 and is supplied to the second reactor 5. The reducing gas discharged from the first reactors 4a and 4b passes through gas lines GL6a, GL6b, and GL6, and is returned to the reducing gas supply unit 2 after, for example, water is removed.

[0056] That is, in this embodiment, the exhaust gas (raw material gas) after passing through the first reactors 4a, 4b is separated from the reducing gas after passing through the first reactors 4a, 4b. The exhaust gas after passing through the first reactors 4a, 4b is supplied to the second reactor 5 without being merged with the reducing gas after passing through the first reactors 4a, 4b. With this configuration, exhaust gas with reduced water contamination can be supplied to the second reactor 5. Therefore, a decrease in the efficiency of conversion of carbon monoxide to carbon materials can be prevented or suppressed, and the amount of carbon monoxide produced can be further increased.

[0057] <<Third Embodiment>> Next, a third embodiment of the carbon material production system of the present invention will be described. Figure 4 is a schematic diagram showing the configuration of the third embodiment of the carbon material production system of the present invention. The carbon material production system 10 of the third embodiment will be described below, focusing on differences from the carbon material production system 10 of the first embodiment, and a description of similar points will be omitted. The carbon material production system 10 of the third embodiment includes a recovery section 9 instead of the generated gas discharge section 6.

[0058] The recovery unit 9 recovers the carbon material from the gas (product gas) generated in the second reactor 5. This recovery unit 9 can be configured, for example, by combining one or more of an elutriation device, a centrifugal separator, an electrostatic precipitator, and a filter device. The recovery unit 9 is connected to the gas line GL1 via the return gas line GL7. As described above, in the second reactor 5, a product gas containing carbon dioxide in addition to the carbon material is generated from carbon monoxide. Therefore, the product gas is separated into the carbon material and the product gas containing carbon dioxide by passing through the recovery unit 9.

[0059] The produced gas after the carbon material has been recovered in the recovery section 9 is returned to the first reactors 4a, 4b via the return gas line GL7 and the gas line GL1. With this configuration, the produced gas after passing through the recovery section 9 can be effectively utilized without being discarded. In particular, since the produced gas after passing through the recovery section 9 has a sufficiently high concentration of carbon dioxide, even if the produced gas is mixed with exhaust gas, a decrease in the efficiency of conversion of carbon dioxide to carbon monoxide in the first reactors 4a, 4b can be suitably prevented.

[0060] In the first reactors 4a and 4b, when exhaust gas (raw material gas) comes into contact with the reducing agent 4R, carbon monoxide is generated by a reduction reaction of carbon dioxide, and at least a portion of the oxygen element released from the carbon dioxide is captured by the reducing agent 4R. Thereafter, when a reducing gas comes into contact with the reducing agent 4R, the oxygen element is transferred to hydrogen (reducing substance), and water (oxide of the reducing substance) is generated. That is, in the first reactors 4a and 4b, at least a portion of the oxygen element can be separated within the carbon dioxide reduction reaction system (reaction field). A reactor capable of separating at least a portion of the oxygen element within such a carbon dioxide reduction reaction system may have the configuration shown in FIG. 5.

[0061] <<Fourth Embodiment>> Next, a fourth embodiment of the carbon material production system of the present invention will be described. Figure 5 is a schematic diagram showing the configuration of a first reactor in the fourth embodiment. The carbon material production system 10 of the fourth embodiment will be described below, focusing on differences from the carbon material production systems 10 of the first to third embodiments, and a description of similar points will be omitted.

[0062] 5 is composed of a reactor (also called a reaction cell, electrolytic cell, or electrochemical cell) in which a carbon dioxide reduction reaction is electrochemically carried out. The first reaction unit 4 has a housing 42, a cathode 45, an anode 46, and a solid electrolyte layer 47 provided within the housing 42, and a power supply 48 electrically connected to the cathode 45 and the anode 46. In this configuration, the space within the housing 42 is partitioned into left and right sections by the stack of the cathode (reduced body) 45, the anode 46, and the solid electrolyte layer 47.

[0063] The housing 42 is equipped with a cathode-side inlet port 421 a, a cathode-side outlet port 421 b, an anode-side inlet port 422 a, and an anode-side outlet port 422 b. The cathode-side inlet port 421 a and the cathode-side outlet port 421 b communicate with a cathode chamber in a left-side space within the housing 42, and the anode-side inlet port 422 a and the anode-side outlet port 422 b communicate with an anode chamber in a right-side space within the housing 42.

[0064] The cathode 45 and the anode 46 each include a conductive support and a catalyst supported on the support. The support may be made of a carbon material such as carbon fiber fabric (carbon cloth, carbon felt, etc.) or carbon paper. Examples of the catalyst include platinum group metals such as platinum, ruthenium, rhodium, palladium, osmium, and iridium; transition metals such as gold; alloys of these metals; and alloys of these metals with other metals.

[0065] The solid electrolyte layer 47 can be formed, for example, from a fluorine-based polymer membrane having sulfonic acid groups (such as Nafion (registered trademark)), a sulfonic acid ion-exchange resin membrane, or the like. It is preferable to use a power supply that generates electricity as renewable energy for the power supply 48. This can further improve the energy efficiency in producing the generated gas containing carbon valuables.

[0066] In the first reaction unit 4, when exhaust gas (carbon dioxide and water) is supplied from the cathode-side inlet port 421a, a reduction reaction of the carbon dioxide and water occurs due to the action of the catalyst and electrons supplied from the power source 48, producing carbon monoxide and hydrogen, as well as oxygen ions. The carbon monoxide and hydrogen are discharged from the cathode-side outlet port 421b to the gas line (gas line GL4), and the oxygen ions diffuse through the solid electrolyte layer 47 toward the anode 46. The oxygen ions that reach the anode 46 lose their electrons and are converted to oxygen, which is then discharged from the anode-side outlet port 422b.

[0067] In this configuration, the carbon monoxide and hydrogen discharged from the cathode-side outlet port 421b are supplied to the second reactor 5. In this case, a removal unit for removing hydrogen may be provided midway along the gas line GL4.

[0068] The carbon material production system 10 may be configured so that the reaction of the following formula 4 occurs in the first reaction section 4, and the reaction of the following formula 5 occurs in the second reaction section 5. Formula 4: CO ２ + H ２ → CO + H２ Equation 5: CO + H ２ → C + H ２ That is, the Bosch reaction can be performed through the first reaction section 4 and the second reaction section 5. The reaction of formula 4 and the reaction of formula 5 may occur simultaneously.

[0069] In this case, the first reaction section 4 and the second reaction section 5 can be reactors (heat exchangers) similar to those described for the first reactors 4a and 4b, respectively. Alternatively, a plate reactor, a plate-fin reactor, a spiral reactor, etc. can also be used. The catalyst that can be used preferably contains at least one metal element selected from groups 2 to 15, more preferably at least one metal element selected from groups 5 to 10, and even more preferably at least one metal element selected from nickel, molybdenum, chromium, cobalt, tungsten, vanadium, ruthenium, iridium, iron, etc.

[0070] The first reaction temperature in the first reaction section 4 is preferably 400° C. or higher and 1200° C. or lower, more preferably 500° C. or higher and 1000° C. or lower, even more preferably 600° C. or higher and 800° C. or lower, and particularly preferably 680° C. or higher and 700° C. The first reaction pressure in the first reaction section 4 is preferably 0.1 MPaG or higher and 5 MPaG or lower, more preferably 0.2 MPaG or higher and 4.5 MPaG or lower, even more preferably 0.25 MPaG or higher and 4 MPaG or lower, and particularly preferably 0.3 MPaG or higher and 3.5 MPaG or lower.

[0071] The second reaction temperature in the second reaction section 5 is preferably 400° C. or higher and 1000° C. or lower, more preferably 450° C. or higher and 900° C. or lower, even more preferably 500° C. or higher and 800° C. or lower, and particularly preferably 550° C. or higher and 700° C. The second reaction pressure in the second reaction section 5 is preferably 0.1 MPaG or higher and 5 MPaG or lower, more preferably 0.2 MPaG or higher and 4.5 MPaG or lower, even more preferably 0.25 MPaG or higher and 4 MPaG or lower, and particularly preferably 0.3 MPaG or higher and 3.5 MPaG or lower.

[0072] <<Fifth Embodiment>> Next, a fifth embodiment of the carbon material production system of the present invention will be described. Figure 6 is a schematic diagram showing the configuration of the fifth embodiment of the carbon material production system of the present invention. The carbon material production system 10 of the fifth embodiment will be described below, focusing on differences from the carbon material production systems 10 of the first to fourth embodiments, and a description of similar points will be omitted.

[0073] The carbon material production system 10 shown in Figure 6 is a production system for producing a carbon material, and includes a production apparatus 100, a blast furnace (gas supply unit) 101 connected to the production apparatus 100 and supplying exhaust gas (raw material gas containing carbon dioxide), and a reducing gas supply unit 2 supplying reducing gas. Note that, in this specification, the upstream side with respect to the gas flow direction will also be referred to simply as the "upstream side," and the downstream side will also be referred to simply as the "downstream side." Also, in this specification, "refining" performed to increase the purity of metals is also considered to be included in "smelting."

[0074] In this embodiment, the gas supply unit is described as a blast furnace (furnace related to a smelter) 101, but the gas supply unit may be another furnace related to a smelter. Preferred other furnaces include a shaft furnace, a converter, and an electric furnace. The gas supply unit may have a configuration similar to that of the exhaust gas supply unit 1. The blast furnace (blast furnace) 101 is connected to the gas switching unit 3 via a gas line GL1, and the reducing gas supply unit 2 is connected to the gas switching unit 3 via a gas line GL2. Therefore, in this embodiment, the exhaust gas supply unit 1 in the first to fourth embodiments can be read as the blast furnace 101.

[0075] A gas line GL5 is connected to the outlet port of the second reactor 5. In this embodiment, a recovery unit 9 is connected to the end of the gas line GL5 opposite the second reactor 5, instead of the product gas discharge unit 6. The recovery unit 9 recovers carbon materials from the gas (product gas) generated in the second reactor 5. This recovery unit 9 can be configured, for example, by combining one or more of an elutriation device, a centrifugal separator, an electrostatic precipitator, and a filter device. The recovery unit 9 is connected to the gas line GL1 via a return gas line GL8. As described above, in the second reactor 5, a product gas containing carbon dioxide in addition to the carbon materials is generated from carbon monoxide. Therefore, the product gas is separated into the carbon materials and the product gas containing carbon dioxide by passing through the recovery unit 9.

[0076] The product gas after the carbon material has been recovered in the recovery section 9 is returned to the first reactors 4a, 4b via the return gas line GL8 and the gas line GL1. With this configuration, the product gas after passing through the recovery section 9 can be effectively utilized without being discarded. As a result, carbon dioxide emissions can be reduced and a circular economy (a material-recycling society) can be realized. In particular, because the product gas after passing through the recovery section 9 has a sufficiently high concentration of carbon dioxide, even if it is mixed with exhaust gas, a decrease in the efficiency of carbon dioxide conversion to carbon monoxide in the first reactors 4a, 4b can be suitably prevented.

[0077] Furthermore, according to the above configuration, a carbon material with an extremely low content of solid impurities is produced. Specifically, the content of solid impurities in the carbon material is 1% by mass or less, preferably 0.1% by mass or less, and more preferably 0.01% by mass or less. The lower limit of the content of solid impurities in the carbon material is not particularly limited, but is typically 0.001% by mass or more. Carbon materials with such a low content of solid impurities can be used in various electronic devices, various molded products, etc., to prevent deterioration of their properties. Examples of solid impurities include at least one of copper, zinc, iron, nickel, aluminum, chromium, and alloys containing these.

[0078] Such carbon materials are suitable for use in at least one of secondary battery materials (e.g., negative electrode active materials, negative or positive electrode conductive additives), tire fillers, colorants for resin materials or rubber materials, UV protectants / absorbers, fuel cell electrode materials, and heat dissipation agents. For example, using the carbon material as a negative electrode active material in an ion secondary battery can prevent the occurrence of short circuits in the ion secondary battery and deterioration of charge / discharge characteristics. Furthermore, for example, using the carbon material as a tire filler can more effectively suppress deterioration of the elasticity and flexibility of the tire over time.

[0079] Next, a method for using the carbon material production system 10 (a method for producing a carbon material) will be described.

[11] First, a step similar to the above step [1] is performed.

[12] Next, a step similar to the above step [2] is performed.

[0080] The temperature (first reaction temperature) of the first reactor 4a (exhaust gas, reducing agent 4R) in the step

[12] is preferably set in the same manner as in the step [2]. The pressure (first reaction pressure) of the first reactor 4a (exhaust gas, reducing agent 4R) is also preferably set in the same manner as in the step [2].

[0081]

[13] A step similar to the step [3] above is carried out.

[14] A step similar to the step [4] above is carried out.

[0082] The temperature (reaction temperature) of the first reactor 4b (reducing gas, reducing agent 4R) in the step

[14] is preferably set in the same manner as in the step [4]. The pressure (first reaction pressure) of the first reactor 4b (reducing gas, reducing agent 4R) is also preferably set in the same manner as in the step [4].

[0083]

[15] Next, a step similar to the above step [5] is carried out.

[0084]

[16] Next, a step similar to the step [6] above is performed.

[17] Next, a step similar to the step [7] above is performed. In this embodiment, the produced gas (mixed gas) containing the carbon material is discharged to the recovery unit 9 via the gas line GL5.

[0085]

[18] Next, in the recovery section 9, the carbon material is separated and recovered from the produced gas containing the carbon material. As described above, the content of solid impurities in the carbon material is 1 mass % or less.

[19] Next, the produced gas from which the carbon material has been recovered in the recovery section 9 is returned to the first reactors 4a and 4b via the return gas line GL8 and the gas line GL1. This exhaust gas passes through the above steps

[11] to

[17] , and the carbon material is produced again.

[0086] <<Sixth Embodiment>> Next, a sixth embodiment of the carbon material production system of the present invention will be described. Fig. 7 is a schematic diagram showing the configuration of the sixth embodiment of the carbon material production system of the present invention. The carbon material production system 10 of the sixth embodiment will be described below, focusing on differences from the carbon material production system 10 of the fifth embodiment, and a description of similar points will be omitted.

[0087] In the sixth embodiment, gas lines GL6a and GL6b branch off from gas lines GL4a and GL4b and join at a gas junction J1 to form a gas line GL6. A switching valve is provided at the branch point between the gas lines GL4a and GL4b and the gas lines GL6a and GL6b. The exhaust gas discharged from the first reactors 4a and 4b passes through gas lines GL4a, GL4b, and GL4 and is supplied to the second reactor 5. The reducing gas discharged from the first reactors 4a and 4b passes through gas lines GL6a, GL6b, and GL6, and is returned to the reducing gas supply unit 2 after, for example, water is removed.

[0088] That is, in this embodiment, the exhaust gas after passing through the first reactors 4a, 4b is separated from the reducing gas after passing through the first reactors 4a, 4b. The exhaust gas after passing through the first reactors 4a, 4b is supplied to the second reactor 5 without being merged with the reducing gas after passing through the first reactors 4a, 4b. With this configuration, exhaust gas with reduced water contamination can be supplied to the second reactor 5. Therefore, it is possible to prevent or suppress a decrease in the efficiency of conversion of carbon monoxide to carbon materials and further increase the amount of carbon monoxide produced.

[0089] <<Seventh Embodiment>> Next, a seventh embodiment of the carbon material production system of the present invention will be described. Fig. 8 is a schematic diagram showing the configuration of the seventh embodiment of the carbon material production system of the present invention. The carbon material production system 10 of the seventh embodiment will be described below, focusing on differences from the carbon material production system 10 of the fifth embodiment, and a description of similar points will be omitted. The carbon material production system 10 of the seventh embodiment includes a separation section 11 that separates carbon dioxide from the exhaust gas, located midway along the gas line GL1 (upstream of the first reaction section 4).

[0090] By passing the exhaust gas through the separation section 11, the concentration of carbon dioxide in the exhaust gas can be increased. This can further improve the efficiency of converting carbon dioxide to carbon monoxide in the first reactors 4a, 4b. Methods for separating carbon dioxide from exhaust gas include, for example, a low-temperature separation (cryogenic) separator, a pressure swing adsorption (PSA) separator, a membrane separation separator, a temperature swing adsorption (TSA) separator, an amine absorption separator, and an amine adsorption separator, and these can be used alone or in combination of two or more.

[0091] In the fifth to seventh embodiments described above, in the first reactors 4a and 4b, when exhaust gas comes into contact with the reducing agent 4R, carbon monoxide is generated by a reduction reaction of carbon dioxide, and at least a portion of the oxygen element released from the carbon dioxide is captured by the reducing agent 4R. Thereafter, when a reducing gas comes into contact with the reducing agent 4R, the oxygen element is transferred to hydrogen (reducing substance), and water (oxide of the reducing substance) is generated. That is, in the first reactors 4a and 4b, at least a portion of the oxygen element can be separated within the carbon dioxide reduction reaction system (reaction field). The configuration shown in FIG. 5 can also be adopted as a reactor capable of separating at least a portion of the oxygen element within such a carbon dioxide reduction reaction system.

[0092] <Carbon Circulation System> Second, the carbon circulation system of the present invention will be described. <<First Embodiment>> First, the first embodiment of the carbon circulation system of the present invention will be described. Fig. 9 is a schematic diagram showing the configuration of the first embodiment of the carbon circulation system of the present invention. The carbon circulation system 1000 will be described below, focusing on the differences from the carbon material production systems 10 of the first to fourth embodiments, and a description of similar points will be omitted.

[0093] The carbon circulation system 1000 shown in Figure 9 is a system for producing (smelting) a target metal, and includes a blast furnace (melting furnace) 101 that supplies exhaust gas (gas containing carbon dioxide) and a reducing gas supply unit 2 that supplies reducing gas. Note that, in this specification, the upstream side with respect to the gas flow direction will also be referred to simply as the "upstream side," and the downstream side will also be referred to simply as the "downstream side." Also, in this specification, "refining" performed to increase the purity of a metal is also considered to be included in "smelting."

[0094] In this embodiment, the exhaust gas discharged from the blast furnace 101 is utilized. However, other furnaces attached to a steelworks or a refinery may also be used. Preferred examples of such other furnaces include a shaft furnace, a converter, and an electric furnace. In each furnace, exhaust gas is generated (produced) during melting, refining, and the like of its contents. The exhaust gas typically contains, in addition to carbon dioxide and carbon monoxide, other gas components such as nitrogen, oxygen, water vapor, and methane. The exhaust gas (blast furnace gas) from the blast furnace 101 is, for example, a gas generated during the production of pig iron in the blast furnace 101, and contains 5% to 45% by volume of carbon dioxide, 55% to 60% by volume of nitrogen, 10% to 40% by volume of carbon monoxide, and 1% to 10% by volume of hydrogen.

[0095] Furthermore, exhaust gas from a converter (converter gas) is a gas generated during steel production in a converter, and contains 15% to 20% by volume of carbon dioxide, 50% to 80% by volume of carbon monoxide, 15% to 25% by volume of nitrogen, and 1% to 5% by volume of hydrogen. The use of these exhaust gases allows for the effective use of carbon dioxide, which has traditionally been emitted into the atmosphere, thereby reducing the burden on the environment and further increasing the degree of material circulation. Furthermore, as for blast furnace gas and converter gas, untreated gas discharged from the furnace may be used as is, or treated gas after, for example, treatment to remove carbon monoxide and the like may be used. In this specification, all of these gases are referred to as exhaust gases.

[0096] The carbon circulation system 1000 of this embodiment further includes a gas switching unit 3, two first reactors 4a and 4b (first reaction units 4), and one second reactor (second reaction unit) 5. The blast furnace (blast furnace) 101 is connected to the gas switching unit 3 via a gas line GL1, and the reducing gas supply unit 2 is connected to the gas switching unit 3 via a gas line GL2. Therefore, in this embodiment, the exhaust gas supply unit 1 in the carbon material production system 10 can be read as the blast furnace 101.

[0097] In this embodiment, the second reaction temperature in the second reactor (second reaction section) 5 is preferably lower than the first reaction temperature in the first reactors 4a, 4b (first reaction section 4). In this case, the reaction heat in the first reactors 4a, 4b can be effectively utilized in the second reactor 5. Specifically, the second reaction temperature is preferably 850°C or lower, more preferably 800°C or lower, and even more preferably 750°C or lower. This improves the carbon material production efficiency while also increasing the heat utilization efficiency. The lower limit of the second reaction temperature is usually 600°C or higher.

[0098] A gas line GL5 is connected to the outlet port of the second reactor 5. A product gas supply unit 60 is connected to the end of the gas line GL5 opposite the second reactor 5. This product gas supply unit 60 is configured to supply the product gas (carbon material) to ore, which is the raw material for smelting, via a gas line GL70. The ore mixed with the carbon material (i.e., the ore together with the carbon material) is then supplied to a blast furnace (melting furnace) 101 for smelting. That is, in this embodiment, the blast furnace 101 used for smelting and the blast furnace 101 for recovering the exhaust gas are the same. With this configuration, carbon dioxide can be used for smelting without being released into the external environment, which can contribute to the realization of a circular economy (a material-recycling society).

[0099] Next, a method of using the carbon circulation system 1000 (carbon circulation method) will be described.

[21] First, a step similar to the above step [1] is performed.

[22] Next, a step similar to the above step [2] is performed.

[0100] The temperature (first reaction temperature) of the first reactor 4a (exhaust gas, reducing agent 4R) in the step

[22] is preferably set in the same manner as in the step [2]. The pressure (first reaction pressure) of the first reactor 4a (exhaust gas, reducing agent 4R) is also preferably set in the same manner as in the step [2].

[0101]

[23] A step similar to the step [3] above is carried out.

[24] A step similar to the step [4] above is carried out.

[0102] The temperature (reaction temperature) of the first reactor 4b (reducing gas, reducing agent 4R) in the step

[24] is preferably set in the same manner as in the step [4]. The pressure (first reaction pressure) of the first reactor 4b (reducing gas, reducing agent 4R) is also preferably set in the same manner as in the step [4].

[0103]

[25] Next, a step similar to the above step [5] is carried out.

[0104]

[26] Next, a step similar to the step [6] above is performed.

[27] Next, a step similar to the step [7] above is performed. In this embodiment, the produced gas (mixed gas) containing the carbon material is discharged to the produced gas supply unit 60 via the gas line GL5.

[0105]

[28] Next, the product gas containing the carbon material is supplied from the product gas supply unit 60 via the gas line GL70 to the ore and mixed therewith. As a result, the carbon material is supported on the ore.

[29] Next, in this state, the ore is supplied to the blast furnace 101, together with coke and the like as necessary. As a result, the target metal is separated and recovered from the ore in the blast furnace 101. At this time, exhaust gas containing carbon dioxide is also generated. This step

[29] constitutes a smelting step in which ore is supplied together with the carbon material and smelted. This exhaust gas passes through the above steps

[21] to

[27] , and the carbon material is again generated.

[0106] <<Second Embodiment>> Next, a second embodiment of the carbon circulation system of the present invention will be described. Fig. 10 is a schematic diagram showing the configuration of the second embodiment of the carbon circulation system of the present invention. A carbon circulation system 1000 of the second embodiment will be described below, focusing on differences from the carbon circulation system 1000 of the first embodiment, and a description of similar points will be omitted.

[0107] In the second embodiment, gas lines GL6a and GL6b branch off from gas lines GL4a and GL4b and join at a gas junction J1 to form a gas line GL6. A switching valve is provided at the branch point between the gas lines GL4a and GL4b and the gas lines GL6a and GL6b. The exhaust gas discharged from the first reactors 4a and 4b passes through gas lines GL4a, GL4b, and GL4 and is supplied to the second reactor 5. The reducing gas discharged from the first reactors 4a and 4b passes through gas lines GL6a, GL6b, and GL6, and is returned to the reducing gas supply unit 2 after, for example, water is removed.

[0108] That is, in this embodiment, the exhaust gas after passing through the first reactors 4a, 4b is separated from the reducing gas after passing through the first reactors 4a, 4b. The exhaust gas after passing through the first reactors 4a, 4b is supplied to the second reactor 5 without being merged with the reducing gas after passing through the first reactors 4a, 4b. With this configuration, exhaust gas with reduced water contamination can be supplied to the second reactor 5. Therefore, it is possible to prevent or suppress a decrease in the efficiency of conversion of carbon monoxide to carbon materials and further increase the amount of carbon monoxide produced.

[0109] <<Third Embodiment>> Next, a third embodiment of the carbon circulation system of the present invention will be described. Fig. 11 is a schematic diagram showing the configuration of the third embodiment of the carbon circulation system of the present invention. A carbon circulation system 1000 of the third embodiment will be described below, focusing on differences from the carbon circulation system 1000 of the first embodiment, and a description of similar points will be omitted. The carbon circulation system 1000 of the third embodiment includes a recovery unit 9 instead of the generated gas supply unit 60.

[0110] The recovery section 9 recovers the carbon material from the gas (product gas) produced in the second reactor 5. This recovery section 9 can be configured, for example, by combining one or more of an elutriation apparatus, a centrifugal separator, an electrostatic precipitator, and a filter apparatus. The recovery section 9 is connected to the gas line GL1 via the return gas line GL8. As described above, in the second reactor 5, a product gas containing carbon dioxide in addition to the carbon material is produced from carbon monoxide. Therefore, the product gas is separated into the carbon material and the product gas containing carbon dioxide by passing through the recovery section 9.

[0111] The produced gas after the carbon material has been recovered in the recovery section 9 is returned to the first reactors 4a, 4b via the gas line GL70 and the gas line GL1. With this configuration, the produced gas after passing through the recovery section 9 can be effectively utilized without being discarded. In particular, since the produced gas after passing through the recovery section 9 has a sufficiently high concentration of carbon dioxide, even if the produced gas is mixed with exhaust gas, a decrease in the efficiency of conversion of carbon dioxide to carbon monoxide in the first reactors 4a, 4b can be suitably prevented.

[0112] The carbon circulation system 1000 of the third embodiment further includes a compression unit 12 that compresses the carbon material recovered in the recovery unit 9. By compressing the carbon material, a compressed material is formed, and this compressed material is supplied to the blast furnace 101 together with the ore. In other words, the compressed material can be used as a substitute for coke. The carbon material obtained as described above has a low impurity content, and therefore can be used to smelt high-quality metals. The compression unit 12 can be configured, for example, as a pelletizing device (tabletting device) or the like.

[0113] The shape of the compressed material is preferably, for example, spherical or polyhedral. The use of a compressed material having such a shape can promote the flow of gas and molten ore in the blast furnace 101. From this perspective, the maximum length (e.g., diameter) between two points on the cross section of the compressed material is preferably 10 mm or more and 100 mm or less, and more preferably 20 mm or more and 80 mm or less. When forming the compressed material, a mixture of a carbon material with fine ore, limestone, or the like may be used.

[0114] <<Fourth Embodiment>> Next, a fourth embodiment of the carbon circulation system of the present invention will be described. Fig. 12 is a schematic diagram showing the configuration of the fourth embodiment of the carbon circulation system of the present invention. A carbon circulation system 1000 of the fourth embodiment will be described below, focusing on differences from the carbon circulation system 1000 of the first embodiment, and a description of similarities will be omitted. The carbon circulation system 1000 of the fourth embodiment includes a separation section 11 that separates carbon dioxide from the exhaust gas, located midway along the gas line GL1 (upstream of the first reaction section 4).

[0115] By passing the exhaust gas through the separation section 11, the concentration of carbon dioxide in the exhaust gas can be increased. This can further improve the efficiency of converting carbon dioxide to carbon monoxide in the first reactors 4a, 4b. Methods for separating carbon dioxide from exhaust gas include, for example, a low-temperature separation (cryogenic) separator, a pressure swing adsorption (PSA) separator, a membrane separation separator, a temperature swing adsorption (TSA) separator, an amine absorption separator, and an amine adsorption separator, and these can be used alone or in combination of two or more.

[0116] In the first to fourth embodiments described above, in the first reactors 4a and 4b, when exhaust gas comes into contact with the reducing agent 4R, carbon monoxide is generated by a reduction reaction of carbon dioxide, and at least a portion of the oxygen element released from the carbon dioxide is captured by the reducing agent 4R. Thereafter, when a reducing gas comes into contact with the reducing agent 4R, the captured oxygen is transferred to hydrogen (a reducing substance), and water (an oxide of the reducing substance) is generated. That is, in the first reactors 4a and 4b, at least a portion of the oxygen element can be separated within the carbon dioxide reduction reaction system (reaction field). A reactor capable of separating at least a portion of the oxygen element within such a carbon dioxide reduction reaction system may have the configuration shown in FIG. 5.

[0117] The carbon material production apparatus, carbon material production method, and carbon material production system described above can efficiently produce carbon materials from carbon dioxide. In particular, by using a chemical looping method to generate carbon monoxide from carbon dioxide, the conversion efficiency (conversion rate) to carbon monoxide can be increased, and the carbon monoxide production efficiency, and therefore the carbon material production efficiency, can be sufficiently increased. Furthermore, when the pressure of the gas supplied upstream of the second reaction section is increased, the carbon material production efficiency can be sufficiently increased. Furthermore, the carbon material production apparatus, carbon material production system, and carbon material production method described above can produce carbon materials with an extremely low solid impurity content. In particular, the produced carbon materials have a low solid impurity content and can be used for a variety of applications.

[0118] According to the carbon circulation system and carbon circulation method described above, it is possible to efficiently produce target metals using carbon materials produced from exhaust gas. In particular, the produced carbon materials have a low impurity content, which can improve the quality of the smelted metals.

[0119] Furthermore, it may be provided in the following aspects.

[0120] (1A) An apparatus for producing a carbon material, comprising: a first reaction section that produces carbon monoxide from carbon dioxide; a second reaction section that produces the carbon material from the carbon monoxide; and a gas line that connects the first reaction section and the second reaction section, wherein the first reaction section has at least one reactor that stores a reducing agent, and the reducing agent reduces the carbon dioxide to the carbon monoxide upon contact with a raw material gas containing the carbon dioxide and is oxidized, and the reducing agent in the oxidized state is reduced upon contact with a reducing gas that contains a reducing substance.

[0121] (2A) In the carbon material manufacturing apparatus described in (1A) above, the first reaction section has a plurality of the reactors, and the raw material gas and the reducing gas are alternately supplied to each of the reactors.

[0122] (3A) The carbon material production apparatus according to (2A) above, wherein the carbon material production apparatus is configured to separate the raw material gas after passing through the reactor and the reducing gas after passing through the reactor.

[0123] (4A) The carbon material production apparatus according to (3A) above, wherein the raw material gas after passing through the reactor is supplied to the second reaction section.

[0124] (5A) The carbon material production apparatus according to any one of (1A) to (4A) above, further comprising a recovery section that recovers the carbon material from the gas generated in the second reaction section.

[0125] (6A) In the carbon material production apparatus described in (5A) above, the second reaction section produces carbon dioxide in addition to the carbon material from the carbon monoxide, and further includes a return gas line that connects the recovery section and the first reaction section and returns the gas remaining after the carbon material has been recovered in the recovery section to the first reaction section.

[0126] (7A) The carbon material manufacturing apparatus according to any one of (1A) to (6A) above, further comprising a pressure adjusting unit provided midway along the gas line to increase the pressure of the gas passing through the gas line.

[0127] (8A) The carbon material manufacturing apparatus according to (7A) above, wherein the pressure of the gas after pressurization by the pressure adjusting unit is 0.1 MPaG or more.

[0128] (9A) The carbon material production apparatus according to (7A) or (8A) above, wherein the second reaction temperature in the second reaction section is lower than the first reaction temperature in the first reaction section.

[0129] (10A) The carbon material production apparatus according to (9A) above, wherein the second reaction temperature is 850°C or lower.

[0130] (11A) A carbon material production system comprising: the carbon material production apparatus according to any one of (1A) to (10A) above; and a gas supply unit connected to the carbon material production apparatus, which supplies a raw material gas containing carbon dioxide.

[0131] (12A) A carbon circulation system comprising: the carbon material manufacturing apparatus according to any one of (1A) to (10A) above; and a melting furnace for supplying ore together with the carbon material and smelting the ore, wherein the first reaction section is configured to generate the carbon monoxide from the carbon dioxide contained in the exhaust gas.

[0132] (13A) The carbon circulation system according to (12A) above, wherein the carbon material is supplied to the melting furnace in a state supported on the ore.

[0133] (14A) The carbon circulation system according to (12A) or (13A) above, further comprising a compression section that compresses the carbon material to obtain a compressed material, and the compressed material is supplied to the melting furnace together with the ore.

[0134] (15A) The carbon circulation system according to any one of (12A) to (14A) above, further comprising a separation section provided upstream of the first reaction section and separating the carbon dioxide from the exhaust gas.

[0135] (16A) A carbon circulation system according to any one of (12A) to (15A) above, wherein the exhaust gas is a gas discharged from the same melting furnace as the melting furnace.

[0136] (17A) A method for producing a carbon material, comprising: a first production step of producing carbon monoxide from carbon dioxide; and a second production step of producing the carbon material from the carbon monoxide, wherein the first production step comprises contacting a raw material gas containing the carbon dioxide with a reducing agent to reduce the carbon dioxide and convert it to the carbon monoxide while oxidizing the reducing agent, and contacting a reducing gas containing a reducing substance with the reducing agent in an oxidized state to reduce the carbon dioxide.

[0137] (18A) The method for producing a carbon material according to (17A) above, further comprising a pressure adjustment step of increasing the pressure of the gas generated in the first production step prior to the second production step.

[0138] (19A) A carbon circulation method comprising the method for producing a carbon material described in (17A) above, and a smelting process in which ore is supplied together with the carbon material produced in the second production process and smelted.

[0139] (1B) An apparatus for producing a carbon material, comprising: a first reaction section that produces carbon monoxide from carbon dioxide; a second reaction section that produces the carbon material from the carbon monoxide; a gas line that connects the first reaction section and the second reaction section; and a pressure adjustment section that is provided midway along the gas line and that increases the pressure of a gas passing through the gas line.

[0140] (2B) In the carbon material manufacturing apparatus described in (1B) above, the pressure of the gas after pressurization by the pressure adjusting unit is 0.1 MPaG or more.

[0141] (3B) In the carbon material production apparatus described in (1B) or (2B) above, the second reaction temperature in the second reaction section is lower than the first reaction temperature in the first reaction section.

[0142] (4B) The carbon material production apparatus according to (3B) above, wherein the second reaction temperature is 850°C or lower.

[0143] (5B) In the carbon material production apparatus described in any one of (1B) to (4B) above, the first reaction section contains a reductant that is generated by contact with a raw material gas containing the carbon dioxide and converts the carbon dioxide into the carbon monoxide through a reduction reaction, and has at least one reactor that can separate at least a portion of the oxygen element released from the carbon dioxide within the reduction reaction system.

[0144] (6B) In the carbon material production apparatus described in (5B) above, the reductant is a reducing agent that reduces the carbon dioxide to convert it into carbon monoxide upon contact with the raw material gas and is also oxidized, and the reducing agent in the oxidized state is a reducing agent that is reduced upon contact with a reducing gas containing a reducing substance.

[0145] (7B) In the carbon material manufacturing apparatus described in (6B) above, the first reaction section has a plurality of the reactors, and the raw material gas and the reducing gas are alternately supplied to each of the reactors.

[0146] (8B) The carbon material production apparatus according to (7B) above, wherein the carbon material production apparatus is configured to separate the raw material gas after passing through the reactor and the reducing gas after passing through the reactor.

[0147] (9B) In the apparatus for producing a carbon material according to (8B) above, the raw material gas after passing through the reactor is supplied to the second reaction section.

[0148] (10B) The carbon material production apparatus according to any one of (1B) to (9B) above, further comprising a recovery section that recovers the carbon material from the gas generated in the second reaction section.

[0149] (11B) In the carbon material production apparatus described in (10B) above, the second reaction section produces carbon dioxide from the carbon monoxide in addition to the carbon material, and further includes a return gas line that connects the recovery section and the first reaction section and returns the gas remaining after the carbon material has been recovered in the recovery section to the first reaction section.

[0150] (12B) A carbon material production system comprising: the carbon material production apparatus according to any one of (1B) to (11B) above; and a gas supply unit connected to the carbon material production apparatus, which supplies a raw material gas containing carbon dioxide.

[0151] (13B) A method for producing a carbon material, comprising: a first production step of producing carbon monoxide from carbon dioxide; a second production step of producing the carbon material from the carbon monoxide; and a pressure adjustment step of increasing the pressure of the gas produced in the first production step prior to the second production step.

[0152] (1C) An apparatus for producing a carbon material, comprising a first reaction section that produces carbon monoxide from carbon dioxide and a second reaction section that produces a carbon material from the carbon monoxide, wherein the content of solid impurities in the carbon material is 1 mass% or less.

[0153] (2C) In the carbon material production apparatus described in (1C) above, the first reaction section contains a reductant that is generated by contact with a raw material gas containing the carbon dioxide and converts the carbon dioxide into the carbon monoxide through a reduction reaction, and has at least one reactor that is capable of separating at least a portion of the oxygen element released from the carbon dioxide within the reduction reaction system.

[0154] (3C) In the apparatus for producing a carbon material described in (2C) above, the reductant is a reducing agent that reduces the carbon dioxide to convert it into carbon monoxide upon contact with the raw material gas and is also oxidized, and the reducing agent in the oxidized state is a reducing agent that is reduced upon contact with a reducing gas containing a reducing substance.

[0155] (4C) In the carbon material manufacturing apparatus described in (3C) above, the first reaction section has a plurality of the reactors, and the raw material gas and the reducing gas are alternately supplied to each of the reactors.

[0156] (5C) The carbon material production apparatus according to (4C) above, wherein the carbon material production apparatus is configured to separate the raw material gas after passing through the reactor and the reducing gas after passing through the reactor.

[0157] (6C) The carbon material production apparatus according to (5C) above, wherein the raw material gas after passing through the reactor is supplied to the second reaction section.

[0158] (7C) The carbon material production apparatus according to any one of (1C) to (6C) above, further comprising a recovery section that recovers the carbon material from the gas generated in the second reaction section.

[0159] (8C) In the carbon material production apparatus described in (7C) above, the second reaction section is configured to produce carbon dioxide in addition to the carbon material from the carbon monoxide, and to return the gas remaining after the carbon material has been recovered in the recovery section to the first reaction section via a return gas line connecting the recovery section and the first reaction section.

[0160] (9C) The carbon material manufacturing apparatus according to any one of (1C) to (8C) above, wherein the carbon material is used for at least one of a secondary battery material, a tire filler, a colorant for a resin material or a rubber material, a UV protection / absorbing material, a fuel cell electrode material, and a heat dissipation agent.

[0161] (10C) A carbon material production system comprising: the carbon material production apparatus according to any one of (1C) to (9C) above; and a gas supply unit connected to the carbon material production apparatus, which supplies a raw material gas containing carbon dioxide.

[0162] (11C) The carbon material production system according to (10C) above, further comprising a separation unit provided between the gas supply unit and the first reaction unit, which separates the carbon dioxide from the raw material gas.

[0163] (12C) The carbon material production system according to (11C) above, wherein the gas supply unit is a furnace associated with a smelter.

[0164] (13C) In the carbon material production system described in (12C) above, the furnace associated with the smelter is a blast furnace.

[0165] (14C) A method for producing a carbon material, comprising a first production step of producing carbon monoxide from carbon dioxide and a second production step of producing the carbon material from the carbon monoxide, wherein the content of solid impurities in the carbon material is 1 mass% or less.

[0166] (1D) A carbon circulation system comprising: a first reaction unit that produces carbon monoxide from carbon dioxide contained in exhaust gas; a second reaction unit that produces a carbon material from the carbon monoxide; and a smelting furnace to which ore is supplied together with the carbon material and smelted, wherein the first reaction unit contains a reductant that converts the carbon dioxide to the carbon monoxide through a reduction reaction of the carbon dioxide produced by contact with the exhaust gas, and has at least one reactor that is capable of separating at least a portion of the oxygen element released from the carbon dioxide within the reduction reaction system, wherein the reductant is a reducing agent that reduces the carbon dioxide to the carbon monoxide by contact with the exhaust gas and is also oxidized, and the reducing agent in the oxidized state is a reducing agent that is reduced by contact with a reducing gas containing a reducing substance.

[0167] (2D) In ​​the carbon circulation system described in (1D) above, the carbon material is supplied to the melting furnace in a state supported on the ore.

[0168] (3D) The carbon circulation system according to (1D) or (2D) above, further comprising a compression section that compresses the carbon material to obtain a compressed product, and the compressed product is supplied to the smelting furnace together with the ore.

[0169] (4D) The carbon circulation system according to any one of (1D) to (3D) above, further comprising a separation section provided upstream of the first reaction section and separating the carbon dioxide from the exhaust gas.

[0170] (5D) In ​​the carbon circulation system described in any one of (1D) to (4D) above, the exhaust gas is a gas discharged from the same melting furnace as the melting furnace.

[0171] (6D) In ​​the carbon circulation system described in any one of (1D) to (5D) above, the first reaction section has a plurality of the reactors, and the exhaust gas and the reducing gas are alternately supplied to each of the reactors.

[0172] (7D) A carbon circulation system according to (6D) above, configured to separate the exhaust gas after passing through the reactor and the reducing gas after passing through the reactor.

[0173] (8D) In ​​the carbon circulation system described in (7D) above, the exhaust gas after passing through the reactor is supplied to the second reaction section.

[0174] (9D) The carbon circulation system according to any one of (1D) to (8D) above, further comprising a recovery section that recovers the carbon material from the gas generated in the second reaction section.

[0175] (10D) In ​​the carbon circulation system described in (9D) above, the second reaction section produces carbon dioxide in addition to the carbon material from the carbon monoxide, and further includes a return gas line that connects the recovery section and the first reaction section and returns the gas remaining after the carbon material has been recovered in the recovery section to the first reaction section.

[0176] (11D) A carbon circulation method comprising: a first generation step of generating carbon monoxide from carbon dioxide contained in exhaust gas; a second generation step of generating the carbon material from the carbon monoxide; and a smelting step of supplying ore together with the carbon material and smelting the ore, wherein the first generation step is carried out using at least one reactor that contains a reductant that converts the carbon dioxide generated by contact with the exhaust gas into carbon monoxide through a reduction reaction and is capable of separating at least a portion of the oxygen element released from the carbon dioxide within the reduction reaction system, the reductant being a reducing agent that reduces the carbon dioxide to carbon monoxide and is oxidized by contact with the exhaust gas, and the oxidized reducing agent is a reducing agent that is reduced by contact with a reducing gas containing a reducing substance. Of course, this is not limited to this.

[0177] As described above, various embodiments of the present invention have been described, but these are presented as examples and do not limit the scope of the invention in any way. The novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Such embodiments and their modifications are intended to be included within the scope and spirit of the invention, as well as within the scope of the inventions and their equivalents as set forth in the claims.

[0178] For example, the carbon material production apparatus, carbon material production system, and carbon circulation system may each have any additional configuration compared to the above embodiments, may be replaced with any configuration that exhibits a similar function, or some of the configurations may be omitted. Furthermore, the carbon material production method and carbon circulation method of the present invention may each have any additional steps compared to the above embodiments, may be replaced with any step that exhibits a similar function, or some of the steps may be omitted. In the above embodiments, a gas containing hydrogen has been described as a representative reducing gas, but a gas containing at least one selected from hydrocarbons (e.g., methane, ethane, acetylene, etc.) and ammonia as a reducing substance can also be used as the reducing gas instead of or in addition to hydrogen.

[0179] Furthermore, the first reactor in the present invention may be a reactor configured such that at least a portion of the oxygen element released from carbon dioxide by the reduction reaction is not separated within the reduction reaction system. Examples of such reactors include a device utilizing the reverse water-gas shift reaction (RWGR), in which carbon dioxide and hydrogen are simultaneously contacted with a reducing agent 4R to convert carbon dioxide to carbon monoxide and hydrogen (the reduced substance) to water. In this reactor, at least a portion of the oxygen element released from carbon dioxide reacts with hydrogen to produce water without being separated from the reduction reaction system (reaction field). However, if a reactor such as that described above is used that can separate at least a portion of the oxygen element released from carbon dioxide within the reduction reaction system (reaction field), it becomes difficult for the reaction products carbon monoxide and water to coexist within the system, thereby preventing or suppressing a decrease in the conversion efficiency of carbon dioxide to carbon monoxide due to constraints of chemical equilibrium.

[0180] Furthermore, the carbon material production system 10 (carbon material production apparatus 100) may be configured by combining any of the configurations of the first to seventh embodiments. For example, the first reaction section 4 may be configured by an electrochemical cell as shown in Figure 5, and the second reaction section 5 may be configured by a reactor that performs the reaction of formula 5 above.

[0181] Furthermore, the carbon circulation system 1000 may be configured by combining any of the configurations of the first to fourth embodiments described above with an electrochemical cell such as that shown in Fig. 5. For example, the first reaction section 4 may be configured with an electrochemical cell such as that shown in Fig. 5, and the second reaction section 5 may be configured with a reactor that performs the reaction of formula 5 described above.

[0182] 10: Carbon material manufacturing system 100: Carbon material manufacturing apparatus 1000: Carbon circulation system 1: Exhaust gas supply section 101: Blast furnace (gas supply section) 2: Reducing gas supply section 3: Gas switching section 4: First reaction section 4a: First reactor 4b: First reactor 41: Tube body 42: Housing 421a: Cathode side inlet port 421b: Cathode side outlet port 422a: Anode side inlet port 422b: Anode side outlet port 43: Internal space 45: Cathode 46: Anode 47: Solid electrolyte layer 48: Power source 4R: Reducing agent 5: Second reactor (second reaction section) 6: Produced gas discharge section 60: Produced gas supply section 8: Pressure adjustment section 9 : Recovery section 11 : Separation section 12 : Compression section GL1 : Gas line GL2 : Gas line GL3a : Gas line GL3b : Gas line GL4 : Gas line GL4a : Gas line GL4b : Gas line GL5 : Gas line GL6 : Gas line GL6a : Gas line GL6b : Gas line GL7 : Return gas line GL8 : Return gas line GL70 : Gas line J : Gas junction J1 : Gas junction

Claims

1. An apparatus for producing a carbon material, comprising: a first reaction section that produces carbon monoxide from carbon dioxide; a second reaction section that produces the carbon material from the carbon monoxide; a gas line connecting the first reaction section and the second reaction section; the first reaction section has at least one reactor containing a reducing agent; The reducing agent reduces the carbon dioxide upon contact with a raw material gas containing the carbon dioxide, converting the carbon dioxide into carbon monoxide and being oxidized, and the reducing agent in the oxidized state is reduced upon contact with a reducing gas containing a reducing substance.

2. The carbon material production apparatus according to claim 1, the first reaction section has a plurality of the reactors, The carbon material manufacturing apparatus, wherein the raw material gas and the reducing gas are alternately supplied to each of the reactors.

3. 3. The carbon material manufacturing apparatus according to claim 2, The carbon material production apparatus is configured to separate the raw material gas after passing through the reactor and the reducing gas after passing through the reactor.

4. The carbon material manufacturing apparatus according to claim 3, The raw material gas after passing through the reactor is supplied to the second reaction section.

5. The carbon material production apparatus according to claim 1, The carbon material production apparatus further comprises a recovery section that recovers the carbon material from the gas generated in the second reaction section.

6. 6. The carbon material manufacturing apparatus according to claim 5, the second reaction section produces carbon dioxide from the carbon monoxide in addition to the carbon material; The carbon material manufacturing apparatus further comprises a return gas line connecting the recovery section and the first reaction section, for returning the gas obtained after the carbon material has been recovered in the recovery section to the first reaction section.

7. The carbon material production apparatus according to claim 1, The carbon material manufacturing apparatus further comprises a pressure adjusting unit provided midway along the gas line for increasing the pressure of the gas passing through the gas line.

8. The carbon material manufacturing apparatus according to claim 7, The apparatus for producing a carbon material, wherein the pressure of the gas after pressurization by the pressure adjusting unit is 0.1 MPaG or more.

9. The carbon material manufacturing apparatus according to claim 7, A carbon material production apparatus, wherein a second reaction temperature in the second reaction section is lower than a first reaction temperature in the first reaction section.

10. The carbon material manufacturing apparatus according to claim 9, The carbon material manufacturing apparatus, wherein the second reaction temperature is 850°C or less.

11. A system for producing a carbon material, comprising: The carbon material production apparatus according to any one of claims 1 to 10, a gas supply unit connected to the carbon material production apparatus and supplying a raw material gas containing carbon dioxide;

12. A carbon cycle system, comprising: The carbon material production apparatus according to any one of claims 1 to 10, a melting furnace for supplying ore together with the carbon material and smelting the ore, A carbon circulation system, wherein the first reaction section is configured to produce the carbon monoxide from the carbon dioxide contained in the exhaust gas.

13. The carbon circulation system according to claim 12, The carbon material is supplied to the melting furnace in a state supported on the ore.

14. The carbon circulation system according to claim 12, Further, a compression unit is provided for compressing the carbon material to obtain a compressed product, A carbon circulation system in which the compact is fed to the smelting furnace together with the ore.

15. The carbon circulation system according to claim 12, The carbon circulation system further comprises a separation unit provided upstream of the first reaction unit and configured to separate the carbon dioxide from the exhaust gas.

16. The carbon circulation system according to claim 12, A carbon circulation system, wherein the exhaust gas is a gas discharged from the same melting furnace as the melting furnace.

17. A method for producing a carbon material, comprising: a first generation step of generating carbon monoxide from carbon dioxide; a second production step of producing the carbon material from the carbon monoxide, the first production step includes bringing a raw material gas containing the carbon dioxide into contact with a reducing agent, thereby reducing the carbon dioxide to convert it into carbon monoxide and oxidizing the reducing agent, and bringing a reducing gas containing a reducing substance into contact with the reducing agent in the oxidized state, thereby reducing the carbon dioxide.

18. The method for producing a carbon material according to claim 17, The method for producing a carbon material further comprises a pressure adjustment step of increasing the pressure of the gas produced in the first production step prior to the second production step.

19. A carbon cycle method comprising: The method for producing a carbon material according to claim 17; a smelting step of supplying ore together with the carbon material produced in the second production step and smelting the ore.