Method for producing carbon monoxide or synthesis gas, and method for producing chemical product, methane or propane

Abstract

Provided are: a novel method for producing CO or a synthesis gas in which there is little concern that water is produced; and a method in which an external supply of hydrogen is not required in order to recycle CO2 produced in a hydrocarbon oxidation reaction by applying the method.　Provided is: a method for producing CO or a synthesis gas by sequentially carrying out a reaction represented by formula (1) (CH4→C+2H2) using a catalyst having a structure having catalytic activity for a methane pyrolysis reaction and a reaction represented by formula (2) (C+CO2→2CO) in the same vessel in a substantially anhydrous environment. Also provided is a method for producing methane, the method comprising: (S1) producing CO2 by means of a methane oxidation reaction; (S2) producing hydrogen from separately prepared methane using the reaction of formula (1); (S3) producing CO by means of the reaction of formula (2); and (S4) producing methane by reacting hydrogen and CO. Steps (S2) and (S3) are carried out sequentially in a substantially anhydrous environment in the same vessel, which houses a catalyst having a structure having catalytic activity for a methane pyrolysis reaction.

Description

Method for producing carbon monoxide or synthesis gas and method for producing chemicals, methane or propane

[0001] The present invention relates to a novel method for synthesizing carbon monoxide with little risk of generating water, a method for producing chemical products by applying the method or by using an apparatus for realizing the method, and a method for synthesizing CO generated by town gas oxidation, etc. ２ The present invention relates to a method for producing methane or propane by recycling the above-mentioned wastewater.

[0002] Synthetic gas, which is mainly composed of carbon monoxide and hydrogen produced by natural gas reforming, is used as a raw material to make various synthetic compounds such as fuels, synthetic resins, and pharmaceuticals. Many reactions for producing synthetic gas have been proposed, but the H ２ The suitable application is determined by the / CO ratio.

[0003] The steam reforming method (SRM) is the most practical method for producing synthetic gas. On the other hand, the H2O of synthetic gas is used for the production of synthetic fuels and methanol. ２ / CO ratio is too high, so it is necessary to combine it with other methods to ２ It is necessary to reduce the CO / CO ratio. Another problem is that the equipment becomes larger.

[0004] The catalytic partial oxidation process (D-CPOX process) and the non-catalytic partial oxidation process (POX process) are exothermic reactions and are considered to be ideal synthesis gas production processes from the viewpoint of input energy. However, they have problems such as difficulty in reaction control, low thermal efficiency, deposition of heavy hydrocarbons and carbon, and difficulty in continuous operation.

[0005] Recently, dry reforming of methane has been attracting attention as an environmentally green reforming method using methane and carbon dioxide, which are greenhouse gases, as raw materials (Non-Patent Document 1, etc.).

[0006] The traditional dry reforming reaction (Equation (3)) for producing synthesis gas from methane and carbon dioxide is carried out at high temperatures, and therefore the supported catalysts used have problems such as a tendency for catalytic activity to decrease due to aggregation of catalyst particles on the support surface and carbon deposition, making it difficult to maintain catalytic activity (Patent Document 1, Non-Patent Document 2, Non-Patent Document 3). ２ In many cases of reactions in chemical manufacturing using CH as a raw material, water is generated as a by-product along with the target product. The main cause is the reverse water gas shift reaction (Equation (4)), in which the product hydrogen is oxidized to water. ４ +CO ２ → 2CO + 2H ２ ... (3) CO ２ +H ２ → CO + H ２ O (4) The by-product water causes 1) a decrease in the equilibrium conversion rate due to the progression of a reverse reaction, and 2) deactivation of the catalyst (catalyst poisoning) due to a reaction between the catalyst and water, thereby hindering the efficient progress of the reaction (Non-Patent Document 4).

[0007] Methanol synthesis and synthesis of polycarbonate raw materials are typical examples where the by-production of water is an issue. Therefore, the development of a reaction system that can efficiently remove the by-product water from the reaction system is essential for CO ２ This is considered to be one of the fundamental technological developments for the production of useful chemicals using these as raw materials (Non-Patent Document 4).

[0008] Incidentally, methanation is positioned as a "next-generation thermal energy industry" in the "Green Growth Strategy for Carbon Neutrality by 2050," formulated in June 2021, and is considered an important field expected to grow, with development of basic technologies being promoted.

[0009] In France in 2018 and in Japan in 2021, CO generated by the following formula (a) on the premises of a factory that oxidizes city gas was ２ Some manufacturers have begun demonstrating systems that recycle CH using the conventional methanation reaction represented by the following formula (b) (Non-Patent Documents 5 and 6). ４ +20 ２ →CO ２ +2H ２O (a) 4H ２ +CO ２ →CH ４ +2H ２ However, as is clear from the above formula (b), in the conventional methanation reaction, ３ It would take 4 Nm to produce and use methane in a carbon-neutral way. ３ This hydrogen needs to be produced on-site or supplied from an external source (Patent Document 2).

[0010] When hydrogen is produced on-site, renewable energy equipment such as solar power generation, water electrolysis hydrogen production equipment, storage equipment, piping, etc. are required (Patent Documents 3, 4, 5, 6, and 7). However, CO generated on-site is usually ２ The amount is enormous and cannot possibly meet the demand for hydrogen. Therefore, hydrogen will be produced off-site and received, but in that case, transportation vehicles, compression equipment, storage equipment, and drivers will be required on the supply side, and storage equipment will be required on the receiving side. All of these will increase the initial cost.

[0011] The initial cost is ultimately reflected in the running cost, and the cost of hydrogen itself is ３ The CIF price of hydrogen is expected to be 30 yen in 2030 and 20 yen in 2050. Therefore, in the conventional methanation reaction, the cost of hydrogen utilization (120 yen / Nm in 2030) ３ ・CH ４ , 80 yen / Nm in 2050 ３ ・CH ４ ) will be added to the price of using methane simply by oxidation, and the high running costs of hydrogen will be an issue even in the future (Non-Patent Document 7).

[0012] JP 2012-188321 A JP 2023-66417 A JP 2022-060640 A JP 2023-527415 A JP 2015-196619 A JP 2005-60137 A International Publication No. 2018 / 099709

[0013] Ogawa et al., "Catalysts for Methane, Carbon Dioxide, and Hydrogen," Chemistry and Education, Vol. 66, No. 2, 2018 (URL: https: / / www.jstage.jst.go.jp / article / kakyoshi / 66 / 2 / 66_68 / _pdf). Cabinet Office, "Comprehensive Survey on Technical Issues of Promising Technologies in the Energy and Environmental Fields," Report, March 2018 (URL: https: / / www8.cao.go.jp / cstp / stmain / houkokusho.pdf). Fukuhara et al., "Ni-Based Structured Catalytic Reaction System Combining a CH4 Dry Reforming Site and a Carbon Capture Site," Program of the 66th Research Presentation Meeting of the Japan Petroleum Institute, May 2017 (URL: https: / / www.jstage.jst.go.jp / article / sekiyu / 2017 / 0 / 2017_5 / _pdf). Cabinet Office, "CO2 "Bottleneck Issues in Utilization and Directions for Research and Development," p. 18, February 2018 (URL: https: / / www8.cao.go.jp / cstp / stmain / 20180221bottleneck.html); Takagi, "Trends in Methanation Technology," Document 8 of the 1st Methanation Promotion Public-Private Council, June 2021 (URL: https: / / www.meti.go.jp / shingikai / energy_environment / methanation_suishin / pdf / 001_08_00.pdf); DENSO website, "DENSO Begins Demonstration Experiment of CO2 Recirculation Plant at Anjo Plant Electric Power Development Center," April 7, 2021 (URL: https: / / www.denso.com / jp / ja / news / newsroom / 2021 / 20210407-01 / ); Agency for Natural Resources and Energy, "Basic Hydrogen Strategy," pp. 12-13, June 2023 (URL: https: / / www.meti.go.jp / shingikai / enecho / shoene_shinene / suiso_seisaku / pdf / 20230606_2.pdf#page=12) Agency for Natural Resources and Energy, "Status of Action Toward Achieving the Strategic Roadmap for Hydrogen and Fuel Cells (2019)," p. 3, June 25, 2019 (URL: https: / / www.meti.go.jp / shingikai / energy_environment / suiso_nenryo / roadmap_hyoka_wg / pdf / 001_03_00.pdf#page=3) Agency for Natural Resources and Energy, "Explanation of Standard Calorific Values ​​and Carbon Emission Factors by Energy Source (Revised in 2018)," p. 75 (URL: https: / / www.enecho.meti.go.jp / statistics / total_energy / pdf / stte_028.pdf#page=82) INPEX website (URL: https: / / www.inpex.co.jp / ir / unit.html).

[0014] If a carbon-neutral methanation process can be developed using cheaper raw materials rather than hydrogen, it is believed that this will also lead to the promotion of methanation itself.

[0015] In view of the above-mentioned current situation, the present invention provides a novel method for producing CO or synthesis gas with little risk of water generation, and also provides a method for producing CO generated through an oxidation reaction of hydrocarbons by applying the method or by using an apparatus for realizing the method. ２ The present invention provides a carbon-neutral methanation process that does not require an external hydrogen supply for recycling.

[0016] The present inventors have noticed that the methane dry-forming reaction of formula (3) can be divided into formulas (1) and (2). CH4 + CO2 → 2CO + 2H2 ... (3) CH4 → C + 2H2 ... (1) C + CO2 ⇔ 2CO ... (2) Formula (1) is the thermal decomposition of methane, and the present inventors have previously revealed that the reaction is promoted at a high conversion rate by radiant heating of a nickel-based structure catalyst with a copper intermediate layer (for example, WO 2021 / 079660 pamphlet, WO 2023 / 013182 pamphlet). Formula (2) is known to be a reversible reaction commonly referred to as the Boudouard reaction.

[0017] Here, if the reactions of the formulas (1) and (2) can be smoothly advanced to the right, it is expected that the methane dry-forming reaction of the formula (3) can be substantially advanced while avoiding the progress of the reaction of the formula (4) that produces water.

[0018] One aspect of the present invention made to achieve the above object is a method for producing carbon monoxide or carbon monoxide and hydrogen, which comprises sequentially carrying out the reactions represented by the above formulas (1) and (2) in the same vessel in a substantially anhydrous environment, and in which the reaction of formula (1) is carried out using a structural catalyst having catalytic activity for a methane thermal decomposition reaction. According to this method (Sequential Dry Reforming of Methane (SDRM)), the reactions of (1) and (2) are carried out sequentially in a substantially anhydrous environment, and therefore H is produced from the reaction system without producing water as a by-product due to a reverse water gas shift reaction or the like. ２ In addition to being able to produce CO and HCl separately, because each reaction is carried out in the same vessel, the heat used to advance one reaction can be effectively used for the other reaction, and there is an advantage in that the same catalyst can be used without the hassle of replacing it.

[0019] In the above method, carbon dioxide (CO ２ ) stored CO using carbon capture and storage (CCS) technology ２ Currently, the large amount of CO captured by CCS is ２ The use of high-concentration CO2 obtained without separation and purification has been an issue (Non-Patent Document 4). ２ In addition, the CO produced is CO ２ This is because it is the only compound that can be industrially used to reduce the compound (Non-Patent Document 2, p. 95).

[0020] In the above method, the reaction of formula (2) can be carried out in the presence of the carbon produced in the reaction of formula (1), which allows the produced carbon to be effectively consumed and utilized as a raw material for CO when not being recovered.

[0021] Another aspect of the present invention is a method for producing a synthesis gas or a chemical product using the same, which comprises mixing the hydrogen and carbon monoxide obtained by the above method at a fixed ratio by adjusting the molar flow rates. Also, the method for producing the synthesis gas or a chemical product using the same further comprises adding hydrogen derived from renewable energy to produce H ２ This may include adjusting the H / CO ratio. ２ The / CO ratio can be adjusted from around 1 obtained by the SDRM method to any level exceeding 2.

[0022] Another aspect of the present invention is a reactor including a reactor containing a structural catalyst that catalyzes the pyrolysis of methane, and a CO detector in a flow path connected to the gas outlet of the reactor. This configuration provides a compact device suitable for implementing the SDRM method, which generates carbon monoxide by utilizing carbon generated by the catalytic action of the pyrolysis of methane. Furthermore, the use of a structural catalyst reduces the amount of carbon (filamentous carbon, carbon nanotubes, etc.) temporarily stored in the reactor, which can lead to clogging of the reactor, as occurs with supported catalysts. This also reduces the risk of increased energy required to deliver reaction gases, etc.

[0023] In the above-mentioned reaction apparatus, it is preferable that the reaction furnace is provided with one gas supply port and one gas exhaust port, and further provided with a supply-side three-way valve for switching the supply path to the gas supply port and a discharge-side three-way valve for switching the discharge path from the gas exhaust port. With such a configuration, the number of pipes directly connected to the apparatus is reduced, and the supply-side three-way valve can be used to ４ The supply side three-way valve is open and the discharge side three-way valve is H ２ When the valve is open in the direction of CO ２ The supply side three-way valve is closed in the supply direction of CO and the discharge direction of CO. ２ When the three-way valve on the discharge side is open in the CO supply direction and the three-way valve on the discharge side is open in the CO discharge direction, ４ Supply direction and H ２ This allows the device to be operated by alternately switching the direction of discharge so that the outlet is closed in the opposite direction, making the device even more suitable for carrying out the SDRM method.

[0024] The above-mentioned reaction apparatus preferably includes a discharge-side valve for controlling the discharge of hydrogen and / or CO from the reactor, and a main valve capable of releasing gas remaining in the reactor into the atmosphere, or a main valve capable of releasing gas remaining in the reactor into a flow path separate from the flow paths for hydrogen or CO, located closer to the gas outlet of the reactor than the discharge-side valve. The presence of such a main valve makes it possible to improve the purity of the product gas controlled by the discharge-side valve located downstream of the main valve by purging the main valve using the raw material gas.

[0025] One aspect of the present invention, which has been made to achieve the above object, is to provide a method for producing CO produced through an oxidation reaction of hydrocarbons. ２ a method for producing methane or propane by recycling the hydrocarbons, ２ This method for producing methane or propane includes step (1) of producing methane or propane from hydrocarbons, step (2) of producing carbon and hydrogen by thermal decomposition of hydrocarbons, and step (4) of reacting the hydrogen produced in step (1) and / or step (2) with the CO produced in step (3) to produce methane or propane, and further satisfies the following condition (I) or (II): the reaction in step (2) and the reaction in step (3) are carried out sequentially in a substantially anhydrous environment in a vessel containing a structural catalyst that has catalytic activity for the methane thermal decomposition reaction. This method does not require the supply of renewable energy hydrogen throughout the methanation / propanation process, and only hydrocarbons are required as raw materials to produce methane or propane for use in a carbon-neutral manner. Furthermore, selling a portion of the carbon monoxide and / or carbon produced can reduce hydrocarbon costs. Furthermore, by preventing the reverse water gas shift reaction (formula (c) below), in which the product hydrogen is oxidized to water, catalyst deactivation (catalyst poisoning) due to the reaction between the catalyst and water can be prevented, and the hydrogen required for the methanation process can be supplied with high efficiency. Furthermore, after the produced carbon is discharged, the carbon remaining in the reactor can be gasified (CO) for cleanup, and it can be used not only for methanation but also when CO or hydrogen is desired to be output, so this method can be said to be superior to the case where only methane thermal decomposition is performed. ２ +H２ → CO + H ２ O...(c)

[0026] The above-mentioned method for producing methane or propane preferably further satisfies the following condition (I) or (II): (I) It further comprises step (5A) of using the methane or propane produced in step (4) as the hydrocarbon in step (1); or (II) It further comprises step (5B) of using the unreacted hydrocarbon used in step (2) in step (1). In either case, the amount of hydrocarbon supplied can be reduced.

[0027] In the method for producing methane or propane, the step (2) is ２ Preferably, the step involves producing carbon and hydrogen by thermal decomposition of 1.5 times or more methane or 5 / 6 times or more propane in a molar ratio relative to the carbon monoxide produced. This method does not require the supply of renewable hydrogen throughout the methanation process, and only methane or propane is needed as a raw material to produce methane or propane and use it in a carbon-neutral manner. Furthermore, selling a portion of the carbon monoxide and / or carbon produced can reduce methane costs.

[0028] In the method for producing methane or propane, instead of the step (4), the CO generated in the step (1) is ２ and the hydrogen generated in the step (1) and / or the step (2) to produce methane or propane. According to this method, the amount of methane or propane to be thermally decomposed is proportional to the amount of CO2 to be recycled. ２ In terms of molar ratio, 2 times and 2.5 times the amount of CO are sufficient. ２ Since the step (3) of converting CO into CO is not necessary, the apparatus configuration is simpler than when conversion is performed.

[0029] In the method for producing methane or propane, when methane is thermally decomposed in the step (2), CO ２In this method, the amount of methane produced in step (4) is three times or more by molar ratio relative to the amount of methane consumed through the oxidation reaction, and the excess amount of methane produced in step (4) is used in step (2). ３ of methane produced and used in a carbon-neutral manner, with a molar ratio of twice the amount (minimum 2 Nm ３ ), but for simplicity, if we consider LNG as methane, ３ The CIF price of LNG is 13.3 yen / Nm ３ ・H ２ Assuming that (Non-Patent Document 8), 45.2 yen / Nm ３ ・CH ４ (Non-Patent Documents 9 and 10; the calorific values ​​of LNG and hydrogen are calculated using the lower heating value (LHV)). From the viewpoint of methane cost, methane is 2 Nm ３ Since it is necessary, 45.2 x 2 = 90.4 yen / 2 Nm ３ This is the hydrogen required for the conventional method of supplying hydrogen to methanation: 4 Nm ３ Cost 4 x 30 yen = 120 yen / 4 Nm ３ This represents a significant cost reduction compared to the 2030 level. In addition, since procuring hydrogen from outside the facility would require the cost of transporting the hydrogen overland and the cost of receiving facilities, this system maintains an economic advantage in terms of running costs. Furthermore, if part of the carbon produced is sold, the cost of hydrogen equivalent to the calorific value of LNG can be reduced to 24 yen / Nm ３ ・H ２ When it is assumed that methane 1 Nm ３ CIF price (81.6 yen / Nm ３ ・CH ４ ; The calorific value of LNG and hydrogen is the lower heating value (LHV), but methane 2Nm ３ Cost: 81.6 x 2 = 163.2 yen / 2 Nm ３ can be compressed to 11 m3, which is the 4 Nm3 required for conventional methods of supplying hydrogen for methanation. ３ The cost is 4 x 20 yen = 80 yen / 4 Nm ３ Even assuming a future (2050), Japan will still be able to maintain its economic advantage.

[0030] In the method for producing methane or propane, the reaction in step (3) is preferably carried out in the presence of the carbon produced in the reaction in step (2), which allows the produced carbon to be effectively consumed and utilized as a raw material for CO when not being recovered.

[0031] According to the method for producing CO or synthesis gas of the present invention, H is produced without producing water as a by-product from the reaction system. ２ Since CO and H are produced separately, they can be used separately. When producing synthesis gas, H and CO can be used separately depending on the target product. ２ The cost recovery of the methane thermal decomposition reaction is being considered through the effective use of the "solid carbon" that is produced as a by-product in addition to hydrogen gas. However, if the reactor according to the present invention is used, when the market price of fixed carbon is low, it is possible to ２ By capturing carbon dioxide and causing a Boudouard reaction, the methane or propane produced by the methane or propane production method of the present invention can be used flexibly for CO synthesis. The methane or propane production method of the present invention requires only hydrocarbons as raw materials to produce methane or propane through a methanation / propanation process and utilize it in a carbon-neutral manner. Furthermore, selling a portion of the carbon produced can reduce hydrocarbon costs.

[0032] (a) Vertical cross-sectional view and (b) A-A cross-sectional view of the reactor of Experimental Example 1. Graph showing the time course of hydrogen concentration in Experimental Example 1. SEM image of catalyst with product attached and EDS measurement results. Furnace temperature and CO and CO ２ Graph showing the relationship between the equilibrium concentration level of N ２ CO from gas ２ CO and CO after switching to ２ A graph showing the change in concentration level over time. ２ The overall configuration of one embodiment of the recycling system is shown, and a schematic diagram showing the substances that enter and exit each module when the produced methane is used as a raw material for the SDRM module (a) and (b) is not used. ２ A schematic diagram showing the overall configuration of an embodiment of a recycling system. ２Another embodiment of the recycling system is a schematic diagram showing the materials that enter and exit each module when produced methane is used as a feedstock for the SDRM module and hydrogen derived from renewable energy is also introduced. ２ Another embodiment of the recycling system is a schematic diagram showing the mass balance of each module when hydrogen is produced by the methane decomposition module. ２ 1 is a schematic diagram showing the mass balance of each module in another embodiment of the circulatory utilization system in which propane is combusted and recycled. ２ 1 is a schematic diagram showing the mass balance of each module in another embodiment of the circulatory utilization system when propane is used for combustion and methane is regenerated and recycled. ２ Schematic diagram showing the material balance of each module in the recycling system.

[0033] The terms used in this specification are defined below. In this specification, "hydrocarbon" refers to linear or branched saturated hydrocarbons having 1 to 12 carbon atoms, such as methane, ethane, propane, and octane, and linear or branched unsaturated hydrocarbons having 1 to 12 carbon atoms, such as ethylene, propylene, and acetylene. In this specification, "in a substantially anhydrous environment" refers to an environment in which water or water vapor (steam) is not artificially introduced into or added to the raw materials for the purpose of inducing reaction. Therefore, while the accidental or unavoidable introduction of water due to reactions between the raw materials and impurities, or reactions between multiple impurities, is permitted in a "substantially anhydrous environment," it is preferable to reduce the moisture and humidity of the raw materials by contacting them with a desiccant, for example. In this specification, "promoting reactions sequentially" refers to the progression of multiple reactions in order and / or alternately, without allowing them to proceed simultaneously, and in the desired direction in the case of reversible reactions. In this specification, a "structure catalyst" refers to a catalyst in which the structure itself functions as a catalyst, or a catalyst based on the structure. A structure-based catalyst generally refers to one obtained by impregnating a substrate having a shape such as a honeycomb in a slurry containing a catalyst component, but it may also be one in which an unsupported catalyst layer (plated layer, sprayed layer) exposed by thermal spraying, plating, or the like is formed on a structure. In this specification, the term "structure" refers to an object having a certain shape even if there is no mold to maintain the shape. The shape of the structure is not particularly limited, and examples include plates (not only flat plates but also flat plates that have been subjected to any processing such as bending, folding, punching, notching, embossing, etc.), rods, cylinders, porous bodies, honeycombs (monolith type), felt, mesh, fabric, and expanded metal. In this specification, "carbon dioxide capture and storage (CCS) technology" refers to a technology for capturing and storing carbon dioxide emitted from power plants, chemical plants, etc. ２This refers to a technology that captures CO2 before it is emitted into the atmosphere or from the atmosphere, storing it or effectively utilizing it as a resource. In this specification, "renewable energy" refers to non-fossil energy sources that are recognized as sustainable energy sources (Article 2, Paragraph 3 of the Act on Promotion of Environmentally Compatible Use of Energy Sources and Effective Use of Fossil Energy Materials by Energy Suppliers). Examples include seven types of renewable energy: (a) solar power, (b) wind power, (c) hydropower, (d) geothermal power, (e) solar heat, (f) atmospheric heat and other heat present in nature, and (g) biomass (organic matter derived from plants and animals) (Article 4 of the Enforcement Order of the Act). In this specification, "chemical products" refers to any product manufactured in the chemical industry using synthetic gas. Examples include industrial chemicals such as methacrylic acid, methanol, acetic acid, and aldehydes; synthetic fuels; chemical fertilizers; synthetic fibers; rubber; synthetic resins such as polycarbonate and urethane; pharmaceuticals; dyes; soap; and cosmetics.

[0034] One embodiment of the present invention is a method for producing carbon monoxide or carbon monoxide and hydrogen, which comprises sequentially carrying out reactions represented by the following formulas (1) and (2) in a substantially anhydrous environment: ４ →C+2H ２ ...(1) C+CO ２ →2CO (2) Unless otherwise specified, specific conditions and catalyst configurations for the reactions represented by the above formulas (1) and (2) are the same as those described below for step (2) and step (3) of the method for producing methane or propane according to one embodiment of the present invention, and therefore will be omitted. Specific examples of the device configuration are the same as those of the SDRM reaction module 11 shown in Figure 7, which will be described later, and will therefore be omitted.

[0035] When the present invention is considered as a method for producing carbon monoxide, there is no restriction on how the carbon and hydrogen produced in the above formula (1) are handled. That is, they may or may not be used in a subsequent reaction involving carbon monoxide, and they may be used alone or discarded.

[0036] When the present invention is considered as a method for producing carbon monoxide, the carbon monoxide may contain hydrogen, methane, and other impurities. Whether or not it is necessary to remove the hydrogen and methane remaining in the first stage (reaction (1)) when proceeding with the second stage (reaction (2)) of the present production method depends on the purity of the CO produced, which depends on the application. However, the reactions represented by the above formulas (1) and (2) are carried out in a substantially oxygen-free environment (O ２ It is preferable to carry out the reaction in a sequential manner under an environment free of

[0037] When the present invention is considered as a method for producing carbon monoxide and hydrogen, it is not limited to a method for producing a synthesis gas consisting of carbon monoxide and hydrogen, and the present invention also includes cases where the uses of carbon monoxide and hydrogen are completely different. Uses of carbon monoxide other than synthesis gas include a reducing agent for metal oxides, and uses of hydrogen other than synthesis gas include a fuel for promoting the reaction of the above formula (1) or (2), a mixture with city gas, turbine fuel, a raw material for fuel cells, etc.

[0038] Methane (CH ４ Preferably, the natural gas is derived from methane (CH ４ ), and city gas, which is in abundant supply and also derived from natural gas, can easily become a source of high concentrations of methane if it is passed through a desulfurizer. Examples of natural gas include city gas, non-associated gas produced from gas fields, associated gas produced together with crude oil from oil fields, shale gas, methane hydrate, etc. In light of the global trend toward carbon negativity, biogas-derived CO ２ Methane obtained by separating CO2 from coal gas may be used, but there is a limit to the amount of methane that can be supplied. Methane derived from coal gas may also be used, but coal gas is essentially a mixed gas, and methane and CO2 ２ However, there is a drawback in that the two cannot be supplied separately.

[0039] The carbon dioxide (CO ２ ) stored CO using carbon capture and storage (CCS) technology ２ The CO stored by the carbon dioxide capture and storage (CCS) technology here is preferably２ The CO2 may be CO2 that has already been stored or injected deep underground, CO2 that has been temporarily stored above ground in preparation for storage or injection, or CO2 that has just been separated from other gases. ２ Although it may be used, there is a limit to the supply.

[0040] Another embodiment of the present invention is a method for producing a synthesis gas or a chemical product using the synthesis gas, which includes mixing hydrogen and carbon monoxide obtained by the above method at a constant ratio by adjusting the molar flow rates. The molar flow rate adjustment refers to adjusting the flow rates based on the molar ratio of carbon monoxide to hydrogen, taking into account the stoichiometric ratio of hydrogen to carbon monoxide in a subsequent reaction using the synthesis gas, which is a mixed gas of hydrogen and carbon monoxide. The constant ratio here does not have to be strictly equal to the stoichiometric ratio; it can be higher or lower than the stoichiometric ratio based on established or future knowledge about subsequent reactions using synthesis gas, operating conditions, the ratio of carbon to carbon monoxide as by-products of hydrogen, and the like. The constant ratio can be set, for example, to ±50%, ±20%, ±5%, or the like, relative to the stoichiometric ratio of the subsequent reaction.

[0041] In the method for producing the synthesis gas or a chemical product using the synthesis gas, hydrogen derived from renewable energy is further added to produce H ２ The hydrogen derived from renewable energy is not particularly limited, but examples thereof include hydrogen generated by water electrolysis using surplus electricity from solar power generation or wind power generation.

[0042] In one embodiment of the present invention, a method for producing methane or propane is carried out by using CO produced through an oxidation reaction of hydrocarbons. ２ This is a method for producing methane or propane by recycling CO ２ "Recycling" means that the CO generated ２This means that an equimolar amount of methane or 1 / 3 molar amount of propane can ultimately be produced and secured. Therefore, in order to call it cyclical use, it is not necessary to combust and reuse the produced methane or propane at the plant, reuse it as a raw material for the SDRM reaction module or methane oxidation module, or use it in combustion as a heat source for the SDRM reaction module or methane oxidation module. Supplying the produced methane or propane to city gas pipelines or cylinders and using it for other purposes also falls under the category of cyclical use.

[0043] A method for producing methane or propane according to one embodiment of the present invention includes the steps of: oxidizing hydrocarbons to produce CO ２ In this specification, "via an oxidation reaction of hydrocarbons" means via any one-stage or multiple-stage reaction including a reaction in which hydrocarbons can be regarded as a reducing agent and one or more other chemical substances as oxidizing agents. Such reactions are not limited to the hydrocarbon combustion reactions represented by the following formulas (d), (e), and (f), but also include hydrocarbon steam reforming reactions represented by the following formulas (g) and (h). C ｎ H 2ｎ＋2 +((3n+1) / 2)O ２ →nCO ２ +(n+1)H ２ O...(d) C ｎ H ２ｎ +(3n / 2)O ２ →nCO ２ +nH ２ O...(e) C ｎ H ２ｎ-2 +((3n-1) / 2)O ２ →nCO ２ +(n-1)H ２ O...(f) CH ４ +H ２ O → CO + 3H ２ ...(g) CO+H ２ O → CO ２ +H ２ ...(h)

[0044] The oxidation reaction of hydrocarbons may be an exothermic (combustion) reaction or an endothermic reaction, and depending on the reaction, a catalyst may or may not be required. The combustion reactions of the above formulas (d), (e), and (f) do not require the use of a catalyst, but examples of catalysts that can be used to completely combust the remaining methane contained in the exhaust gas include Pt / SnO ２ Pt-Ir / SnO catalyst ２ Examples of catalysts that can be used in the steam reforming reaction of the above formula (g) include catalysts in which a catalytically active component containing nickel, cobalt, molybdenum, rhodium, ruthenium, aluminum, zirconium, magnesium, or an oxide thereof is supported on a porous support. Ru / Al catalysts in which ruthenium is supported on an alumina support are also suitable. ２ O ３ Ni / Al catalysts, in which nickel is supported on an alumina support ２ O ３ A catalyst or the like can be used. When a catalyst is used, the reaction temperature of the above formulas (g) and (h) is usually set to 500 to 900°C.

[0045] The source of the hydrocarbon to be oxidized is preferably derived from an oil field, crude oil, natural gas, city gas, or biogas. When the hydrocarbon is methane, the source is preferably derived from natural gas, city gas, or biogas. City gas is methane (CH ４ ) in high concentrations, can be easily obtained from existing pipelines, and can easily become a source of high concentrations of methane if passed through a desulfurizer. In light of the global trend toward carbon negativity, carbon-neutralized natural gas or biogas, i.e., biogas can be used to remove CO ２ methane or CO ２ Methane containing

[0046] Possible oxidizers for combustion include air, pure oxygen, and oxygenated air (air with oxygen added). Pure oxygen can be purchased as industrial gas, or it can be one of the pure hydrogen and pure oxygen produced by water electrolysis using renewable energy such as solar power generation (installed in the factory). Alternatively, renewable energy can be purchased from the grid, and pure hydrogen and pure oxygen can be produced by a water electrolysis device (installed in the factory), and the pure oxygen produced can be used. The pure hydrogen produced by the water electrolysis device can be used as fuel for the heating device 35 for pyrolysis, which will be described later.

[0047] A method for producing methane or propane according to one embodiment of the present invention includes step (2) of producing carbon and hydrogen by thermally decomposing methane or propane, which is prepared separately from the hydrocarbon to be oxidized, in a substantially anhydrous environment to cause a methane thermal decomposition reaction represented by the following formula (i) or a propane thermal decomposition reaction represented by the following formula (j): ４ →C+2H ２ ....(i) C ３ H ８ →3C+4H ２ ...(j)

[0048] The reaction temperature of the above formula (i) or (j) requires a high temperature of usually 1000° C. to 1200° C. when no catalyst is used, but when a catalyst is used, it is usually set to 600° C. to 800° C. or higher. The reaction temperature in this specification is a value obtained by measurement using a thermocouple.

[0049] The reaction represented by the above formula (i) or (j) may or may not require the use of a catalyst, but when the reaction is carried out at the above reaction temperature, it is preferable to use a catalyst.

[0050] The reaction of formula (i) or (j) above is typically carried out using a catalyst capable of catalyzing the thermal decomposition of methane. A catalyst "capable of catalyzing the thermal decomposition of methane" preferably comprises an exposed nickel-containing layer approximately 1 μm to 200 μm thick and a support layer approximately 0.5 mm to 10 mm thick made of iron, copper, nickel, steel, cast iron, an iron-nickel alloy, or a copper alloy. A more preferred catalyst comprises an intermediate layer containing copper approximately 1 to 1,000 μm thick between the support layer and the nickel-containing layer. The support layer may be the structure itself before the nickel-containing layer is laminated, or it may be a layer laminated on the structure. Here, "exposed" means that methane molecules can come into contact with the nickel-containing layer, and is not limited to being visually exposed. The nickel-containing layer may also be an unsupported nickel-containing layer. "Unsupported" means that the nickel-containing component as a catalytic component is present in an organized state, rather than dispersed as particles, on a porous support such as activated carbon or a porous oxide. The term "organized" may mean that particles are fused together in some regions, that particles are fused together in all regions, or that particles are melted as a whole and then cooled and solidified. Note that the catalyst having catalytic activity for the methane pyrolysis reaction is not limited to a structure catalyst, and may be a powder catalyst that cannot maintain a fixed shape without a mold to maintain the shape.

[0051] Methane (CH) was prepared separately from the hydrocarbon to be oxidized in the above formula (i) or (j). ４ ) is preferably derived from city gas. City gas is methane (CH ４ ) in high concentrations, can be easily obtained from existing pipelines, and can easily become a source of high concentrations of methane if passed through a desulfurizer. In light of the global trend toward carbon negativity, biogas-derived CO ２ Methane obtained by separating CO2 from coal gas may be used, but there is a limit to the amount of methane that can be supplied. Methane derived from coal gas may also be used, but coal gas is essentially a mixed gas, and methane and CO2 ２ However, there is a drawback in that the two cannot be supplied separately.

[0052] The amount of methane that is thermally decomposed is２ The molar ratio is usually 1.5 times or more relative to the amount of propane to be recycled, but strictly speaking, the lower limit of 1.5 times can be increased or decreased based on the knowledge that has been established or will be established in the future regarding subsequent reactions using synthesis gas, the operating conditions, the ratio of carbon to carbon monoxide as by-products of hydrogen, etc. Preferred lower limits of the molar ratio are 1.8 times, 2 times, 2.5 times, and 3 times. The amount of propane to be thermally decomposed is determined based on the amount of CO to be recycled. ２ Typically, the molar ratio is 5 / 6 or more times the amount of the synthesis gas, but strictly speaking, the lower limit of 5 / 6 times the amount of the synthesis gas can be increased or decreased based on established or future knowledge regarding subsequent reactions using synthesis gas, whether propane or methane is produced in the subsequent reaction (the lower limit of the molar ratio when methane is produced is 1 stoichiometrically as shown in Figure 12), operating conditions, the ratio of carbon to carbon monoxide as by-products of hydrogen, and other factors. Preferred lower limits of the molar ratio are 1, 2, 2.5, and 3. The molar ratio can be set, for example, within ±50%, ±20%, or ±5% of the lower limit.

[0053] In one embodiment of the present invention, a method for producing methane or propane is carried out by oxidizing a hydrocarbon to produce CO 2 . ２ The reaction may include step (3) of reacting the carbon produced in step (2) with the Boudouard reaction represented by the following formula (k) in a substantially anhydrous environment to produce carbon monoxide: ２ →2CO・・・(k)

[0054] When a catalyst is used, the reaction temperature of the above formula (k) is usually set to 400°C or higher. However, in order to allow the reaction to proceed so that the CO production side is dominant, the reaction temperature is preferably 650°C or higher, more preferably over 650°C, and even more preferably 800°C or higher.

[0055] The reaction represented by the above formula (k) may or may not require the use of a catalyst, but when the reaction is carried out at the above reaction temperature, it is preferable to use a catalyst.

[0056] The reaction of formula (k) above is usually carried out in the presence of carbon produced in the reaction of formula (i) or (j). It is sufficient for some of the produced carbon to remain, and some of it may be removed. The carbon produced here tends to be primarily observed as nanofibers (tip-growth forms with nickel nanoparticles attached to the tips, which appear as white dots at the tips, as shown in the SEM image of Figure 3). These produced carbons containing catalyst fine particles may not only function as raw materials but also have catalytic properties. However, regardless of the form or role they have, their presence is sufficient for carrying out the production method of the present invention. In other words, what has catalytic properties does not in any way limit the technical scope of the production method of the present invention.

[0057] Of the carbon produced in step (2), the surplus that was not used in step (3) can be made valuable and sold, reducing methane costs. The shape of the carbon produced (spherical, fibrous) varies depending on the type of structural catalyst and reaction conditions, so it is difficult to generalize. However, in cases where spherical graphite with different particle sizes was produced, the electrical conductivity of the produced carbon was comparable to that of Ketjenblack, and it is possible to sell it as carbon black, either as is or after removing metal particles (the price of carbon black is 142 yen / kg (2020 = 76 yen / Nm ３ ・CH ４ ), Source URL: https: / / www.meti.go.jp / statistics / tyo / seidou / result / gaiyo / resourceData / 02_kagaku / nenpo / h2dbb2020k.pdf#page=13. It is also possible to mix the resulting carbon with the thermoplastic resin PPS and sell it as a highly thermally conductive resin, or to sell it as a recarburizer in the casting process, but there are no particular limitations on its uses.

[0058] Of the carbon monoxide produced in step (3), any surplus that is not used in the subsequent step (4) can be appropriately used for casting, acrylic acid production, gas fuel, reduction of metal oxides, calcium oxide, calcium phosphate, or silicon dioxide, etc.

[0059] In another embodiment of the method for producing methane / propane according to the present invention, the CO produced in step (1) is used without carrying out step (3). ２ can be used in step (4). Whether or not to perform step (3) can be determined depending on the conditions of the methane thermal decomposition reaction, etc.

[0060] In one embodiment of the present invention, a method for producing methane or propane involves carrying out a Fischer-Tropsch reaction, represented by the following formula (l), in which the hydrogen produced in the step (2) and the CO produced in the step (3) are reacted to produce methane, or, if step (3) is not carried out, a Fischer-Tropsch reaction, represented by the following formula (m), in which the hydrogen produced in the step (1) or step (2) and the CO produced in the step (1) are reacted to produce methane. ２ and (4) producing methane by reaction with ２ +CO→CH ４ +H ２ O...(l) 4H ２ +CO ２ →CH ４ +2H ２ O... (m)

[0061] When a catalyst is used, the reaction temperature of the above formulas (l) and (m) is usually set at 100 to 300°C. However, while low temperature and high pressure are advantageous for avoiding runaway reactions and promoting reactions in a way that favors methane production, elevated temperatures are necessary to develop catalytic activity and increase the CO conversion rate. For this reason, the upper limit is preferably 260°C, more preferably 250°C. The lower limit is preferably 130°C, more preferably 170°C. In setting the reaction temperature to the above range, excess waste heat generated when heating to promote the reactions of formulas (l) and (m) can be utilized.

[0062] The reactions represented by the above formulas (l) and (m) may or may not require the use of a catalyst, but when the reactions are carried out at the above reaction temperatures, it is preferable to use a catalyst. Usable catalysts include Al ２ O ３ , ZrO ２ , TiO ２, SiC, SiO ２ , ZnO, oxides of Group IIA metals, oxides of transition metals of Group IIIB, IVB, VB, and VIB, oxides of rare earth metals, aluminosilicates, zeolites, MOFs (metal-organic frameworks), and mixtures thereof, on which at least one element selected from the group consisting of iron, ruthenium, rhodium, nickel, and cobalt is supported as an active component, and catalysts having catalytic activity for the above-mentioned methane thermal decomposition reaction, etc. Commercially available catalysts include the N110 series (manufactured by JGC Catalysts and Chemicals Co., Ltd.) and the core-shell catalyst (manufactured by IHI Corporation) in which Ni particles are dispersed in a porous matrix as described in Japanese Patent No. 6203375, as well as conventionally known catalysts that have been used for the removal of carbon monoxide by methanation, such as the core-shell catalyst (manufactured by Mitsui Mining & Smelting Co., Ltd.) described in International Publication No. 2022 / 065468 containing nickel in the core and zirconium in the shell.

[0063] As a hydrogen supply source, the hydrogen generated in step (1) or (2) above is usually used, but if there is a shortage, hydrogen generated by water electrolysis using renewable energy may be used.

[0064] A specific example of a system configuration in which methane is used as the hydrocarbon will be described below. ２ The recycling system 1 is a system that is primarily intended to be installed on the premises of city gas consumers or biogas producers, and it uses a methane oxidation module 3 and CO emitted from the methane oxidation module 3. ２ and H ２ H from a gas mixture of O ２ a dehydrator 7 for removing O; and CO discharged from the dehydrator 7. ２ and the SDRM reaction module 11 that receives methane supplied from the city gas 8, and H discharged from the SDRM reaction module 11. ２ and CO are supplied as raw materials. ４ and H ２ Methanation module 15, CH ４ and H ２ H from a gas mixture of O２ and a dehydrator 17 for removing O.

[0065] The methane oxidation module 3 oxidizes methane and CO ２ Examples of the methane oxidation module 3 include conventionally known gas turbine generators, combined cycle generators, diesel generators, biogas generators, pump-driving gas turbines, boilers, chillers, absorption chiller-heaters, solid oxide fuel cells (ENE-FARM), and steam reformers.

[0066] The dehydrator 7 removes water when water is produced through the oxidation reaction of methane in the methane oxidation module 3 (for example, when oxygen is used as an oxidant) or when water is used as an oxidant for methane, thereby preventing catalyst poisoning due to water contamination in the downstream SDRM reaction module 11. The dehydrator 17 removes water produced simultaneously with the production of methane in the methanation module 15, thereby preventing a decrease in thermal efficiency due to water contamination in the downstream methane oxidation module 3 and catalyst poisoning due to water contamination in the SDRM reaction module 11. The dehydrators 7 and 17 can be implemented using a cooling condensation method, a separation method using a membrane such as a polyimide membrane, a ceramic membrane, or a zeolite membrane, or a method using an adsorbent such as silica gel, molecular sieve, zeolite, or activated carbon. Note that the dehydrators 7 and 17 may be omitted when a decrease in oxidation efficiency or conversion rate is acceptable or when an improved catalyst is used.

[0067] The methanation module 15 is a condenser of H2O exhausted from the SDRM reaction module 11. ２ and CO are supplied to CH ４ and H ２ The methanation module 15 is a device or component thereof that discharges O. As an example of the methanation module 15, a methane synthesis unit or the like that is located downstream of the SOEC methanation can also be used.

[0068] The SDRM reaction module 11 shown in FIG. 7 has a methane gas supply port 42 and a CO ２The reactor 33 has a supply port 44, a hydrogen gas outlet 46, and a CO gas outlet 48, a heating device 35 inserted into the reactor 33 from the top and fixed therein, a structural catalyst 37 having a catalytic effect for the methane thermal decomposition reaction, which is arranged in the reactor 33 so as to surround the heating device 35, and a CH ４ CH from the supply source 47 to the methane gas supply port 42 ４ a first on-off valve 39 for controlling the supply of CO ２ CO from source 49 ２ CO to supply port 44 ２ The system is equipped with a second on-off valve 41 that controls the supply of hydrogen, a third on-off valve 43 that controls the discharge of hydrogen from a hydrogen gas discharge port 46, and a fourth on-off valve 45 that controls the discharge of CO from a CO gas discharge port 48.

[0069] The heating device 35 is an internal heating type that is inserted into the reactor 33 and heats from the inside. Specifically, a recuperative burner that uses hydrogen as fuel is used, but biogas may be used as fuel instead. It is also possible to use a heater that heats the reactor 33 from the outside (external heating type).

[0070] The structural catalyst 37, which has catalytic activity for the methane thermal decomposition reaction, is formed by electrolytically plating a copper layer as a copper-containing intermediate layer and a nickel layer as a nickel-containing layer in this order on a nickel plate catalyst as a support layer (structure).

[0071] The first to fourth on-off valves 9, 41, 43, and 45 are gate valves that can be switched between fully open and fully closed, but any other valves such as ball valves can be used instead. When flow rate adjustment is particularly required, butterfly valves or globe valves can also be used. Note that the on-off valves are switched manually, but they may also be switched automatically using solenoid valves or the like.

[0072] CH ４ A desulfurizer 54 for removing trace amounts of sulfur compounds contained in the city gas is provided between the supply source 47 and the first on-off valve 39. A conventionally known solid catalyst or adsorbent can be used as the desulfurizer 54.

[0073] H ２The purification device 36 employs a pressure swing adsorption (PSA) method, but alternatively, a purification method using a zeolite membrane, a DDR membrane, or a palladium alloy membrane permeation may be employed.

[0074] The CO purification device 38 is a CO purification device in which an amine is supported on a porous support. ２ In place of this, a liquid absorbent, a membrane separation method, or a PSA method can also be used. Note that if the required purity is low, the purification devices 36 and 38 do not have to be provided.

[0075] A CO detector (not shown) is provided on the flow path connecting the gas outlet of the reactor and the fourth on-off valve 45, or on the flow path connecting the fourth on-off valve 45 and the CO purification device 38. The CO detector is an instrument that can specifically detect carbon monoxide concentration or an indicator that reflects its change (for example, a change in potential or a change in absorbance). In this embodiment, an NDIR gas sensor is used as the CO detector, but the measurement method is not particularly limited. A detector that can simultaneously measure the concentration of gases other than carbon monoxide may also be used.

[0076] Compressors 40a and 40b are provided downstream of the refining devices 36 and 38, respectively.

[0077] In actual operation, when the first on-off valve 39 and the third on-off valve 43 are open, the second on-off valve 41 and the fourth on-off valve 45 are closed, and when the second on-off valve 41 and the fourth on-off valve 45 are closed, the first on-off valve 39 and the third on-off valve 43 are closed. The procedure for opening and closing each valve is as follows: close the second on-off valve 41 → close the fourth on-off valve 45 → open the first on-off valve 39 → open the third on-off valve 43 to perform the methane thermal decomposition reaction shown in formula (i) or the propane thermal decomposition reaction shown in formula (j), and close the first on-off valve 39 → close the third on-off valve 43 → open the second on-off valve 41 → open the fourth on-off valve 45 to perform the CO ２ Carry out a reduction reaction.

[0078] The CO having the above configuration ２ According to the recycling system 1, instead of requiring the SDRM reaction module 11, CO is generated in the methanation process. ２and / or solid oxide electrolysis cell devices required for water reduction, renewable energy power generation devices such as solar power generation, and CO2 reduction devices in methanation processes. ２ And / or, when metals are used to reduce water, there is no need for a reduction device for the generated metal oxide, a water electrolysis hydrogen production device when generating hydrogen from water in a methanation process, hydrogen storage equipment, hydrogen piping, etc. Furthermore, when hydrogen is produced and received off-site, there is no need for transport vehicles, compression equipment, storage equipment, drivers, and storage equipment required on the supply side, and there is no need for storage equipment on the receiving side.

[0079] CO shown in FIG. ２ The recycling system 101 is an off-site installation system that is primarily intended to be installed at locations such as the city gas supplier's site 102 and the city gas consumer's site 104. The system includes a methane oxidation module 103 installed on the city gas consumer's site 104 and a CO 2 emission control module 105. ２ and H ２ H from a gas mixture of O ２ A dehydrator 107 for removing O and CO discharged from the dehydrator 107 ２ into the site 102 of the city gas supplier, and CO supplied from the transportation means 106, which is installed within the site 102 of the city gas supplier. ２ and an SDRM reaction module 111 that receives methane supplied from a city gas pipeline 108, and H discharged from the SDRM reaction module 111. ２ and CO are supplied as raw materials. ４ and H ２ a methanation module 115 that discharges O; ４ and H ２ H from a gas mixture of O ２ and a dehydrator 117 for removing O.

[0080] The CO having the above configuration ２ According to the recycling system 101, CO ２ Compressor / liquefier 109, CO ２ Shipping equipment (not shown), CO ２ Receiving facility (not shown), CO ２ Storage facility 110, CO２ Although a transport tanker 106 and a driver (not shown) are required, the on-site CO ２ The same advantages as those of the recycling system 1 can be obtained.

[0081] CO shown in FIG. ２ The CO ２ The difference from the circulating utilization system 1 is that the H discharged from the SDRM reaction module 11 is fed to the methanation module 15. ２ In addition, hydrogen derived from renewable energy sources will be added from outside.

[0082] The CO having the above configuration ２ According to the recycling system 121, the CO ２ Compared to the circulating utilization system 1, the hydrogen supplied from renewable energy sources can be halved from 4 unit volumes to 2 unit volumes, and the cost is 30 yen / Nm ３ (2030)×4Nm ３ = 120 yen to 60 yen, 20 yen / Nm ３ (2050)×4Nm ３ The advantages include the price being reduced from 80 yen to 40 yen, the amount of natural gas (city gas, methane) supplied from outside being halved from 2 unit volumes to 1 unit volume, the amount of carbon generated being halved, and it being easier to develop a market for and monetize the carbon generated.

[0083] CO shown in FIG. ２ The CO ２ The difference from the circulating utilization system 1 is that a methane pyrolysis module 41 is used instead of the SDRM reaction module 11, the generated hydrogen is supplied to the methanation module 65, and the CO 2 emitted from the dehydrator 7 is ２is supplied as is to the methanation module 65. Note that in the methane pyrolysis module 41, the structural catalyst 37 having catalytic activity for the methane pyrolysis reaction used in the SDRM reaction module 11 can be reused. In addition, in the methanation module 65, a core-shell catalyst (manufactured by Mitsui Mining & Smelting Co., Ltd.) containing nickel in the core portion and zirconium in the shell portion, as described in International Publication No. 2022 / 065468, can be used.

[0084] The CO having the above configuration ２ According to the recycling system 131, the CO ２ Compared with the recycling system 1, the amount of methane that is thermally decomposed is ２ In terms of molar ratio, two times the amount of CO is sufficient. ２ Since conversion from CO to CO is not necessary, ２ The second on-off valve 41 and the CO ２ This eliminates the need to provide the supply port 44, the CO gas discharge port 48 in the CO discharge system, the fourth on-off valve 45, the refining device 38, and the compressor 40b, which has the advantage of simplifying the device configuration compared to the case of conversion.

[0085] CO shown in FIG. ２ The CO ２ The differences from the circulatory utilization system 131 are that the supply of methane from the pipeline 8 to the methane pyrolysis module 41 has been abolished and instead propane is supplied from the propane cylinder 18 to the propane pyrolysis module 31, that a propanation module 55 is used instead of the methanation module 65, and that the propane from the propane cylinder 18 and the propane derived from the propane propanation module 55 are used in the propane oxidation module 53. Note that the propane oxidation module 53, the propane pyrolysis module 31, and the propanation module 55 can basically have the same configurations as the methane oxidation module 3, the methane pyrolysis module 41, and the methanation module 65.

[0086] The CO having the above configuration ２According to the recycling system 141, the CO ２ Compared with the recycling system 131, the CO generated by propane combustion in a factory located in the suburbs where there is no city gas pipeline is ２ This configuration is suitable for producing propane by recycling the waste heat.

[0087] CO shown in FIG. ２ The CO ２ The difference from the circulating utilization system 141 is that a methanation module 65 is used instead of the propanation module 55 to circulate methane and use it by combustion in the methane oxidation module 3.

[0088] The CO having the above configuration ２ According to the recycling system 151, the CO ２ Compared with the case where the recycling system 141 is used, the amount of recycled CO ２ Although a relatively large amount of propane is required in terms of molar ratio (the former is 5 / 6 times or more, while the latter is 1 time or more), the CO generated by combustion is lower than that of propane because methane is recycled. ２ Low emissions, CO ２ It is excellent from an emissions perspective.

[0089] CO shown in FIG. ２ The CO ２ The difference from the recycling system 131 is that the methane pyrolysis module 41 is installed between the pipeline 8 and the methane oxidation module 3 rather than after the methane oxidation module 3, the supply to the methanation module 65 is still maintained, and the recycled methane is returned to the methane pyrolysis module 41.

[0090] The CO having the above configuration ２ According to the circulatory utilization system 161, when the methane decomposition rate is 1, hydrogen mono-combustion is performed, and when the methane decomposition rate is less than 1, hydrogen co-combustion is performed. ２Compared to the circulating utilization system 131, an excessive amount of methane-hydrogen mixed gas is required to obtain the same amount of heat as that of conventional methane combustion (heat value (LHV) of methane = 35,900 kJ / Nm ３ , calorific value of hydrogen (LHV) = 10780 kJ / Nm ３ ) However, since separation and purification of unreacted methane is not required, the apparatus can be simplified.

[0091] Experimental Example 1—Fabrication of an SDRM Reaction Module and Methane Pyrolysis. The SDRM reaction module 21 shown in FIG. 1 was constructed by electrolytically plating both sides of a Ni plate with Cu to a thickness of approximately 1 μm, followed by electrolytic plating of Ni to a thickness of approximately 10 μm. The resulting metal plate catalyst 27 (size: width 30 mm × length 300 mm × thickness 0.6 mm) was placed in a reactor 23 (capacity Φ30 × 300 mm, 0.2 L) suspended from a catalyst suspension stay 24. Room-temperature methane was flowed from a methane supply port 32 located at the top of the peripheral wall of the furnace 23 from top to bottom at a rate of 10 mL / min. The furnace 23 was heated with a heater (not shown) located on the periphery until the temperature inside the furnace reached 800°C. This was maintained for eight hours a day, and the transition in the hydrogen concentration discharged from the hydrogen gas outlet 36 was observed. For safety reasons, the reactor core was cooled after eight hours of continuous operation each day, and the reactor was heated again from room temperature to 800°C the following day. Figure 2 shows the time course of hydrogen concentration, and Figure 3 shows SEM images and EDS measurement results of the catalyst with the product attached. Furnace temperature was measured using a thermocouple 25 inserted through the furnace top cover and reaching the center. Hydrogen concentration was measured using a Wheatstone bridge-type gas thermal conductivity gas analyzer (zero gas: city gas 13A, span gas: 100% hydrogen, gas flow rate: 0.2 L / min, manufactured by Chino Corporation) attached to the product gas exhaust pipe at the bottom of the furnace peripheral wall, which was used for atmospheric release. SEM images and EDS were obtained by secondary electron detection using a scanning electron microscope (product number: JCM-7000, manufactured by JEOL Ltd.) (incident voltage 15.0 kV, WD 12.5 mm, magnification ×5,000, probe current mode Std.-PC, vacuum mode HighVac). As can be seen from Figure 2, the hydrogen concentration (conversion rate) due to the thermal decomposition reaction of methane continued to increase from the first day to the second day, reaching the theoretical equilibrium concentration of 80% at the end of the second day, and then remaining stable at around 80% from the sixth day onwards. Figure 3 shows that the product was fibrous and consisted mainly of C and Ni. Furthermore, a separate elemental mapping study revealed that the white dots visible at the tip or midway of the fiber were fine particles of Ni.

[0092] (Experimental Example 2 - Demonstration of Boudouard reaction with residual carbon produced and investigation of implementation temperature) After the experiment of Example 1, the supply of methane was stopped and the weight of the carbon produced in the reactor was measured. After measuring the weight of the carbon produced, the metal catalyst plate with the carbon produced again attached and the carbon produced were returned to the reactor. At this time, in order to remove the air that had entered the reactor, room temperature nitrogen gas was filled into the reactor at a flow rate of 0.4 L / min for 30 minutes, and the air remaining in the reactor was purged. Next, instead of stopping the supply of nitrogen gas, room temperature CO ２ While supplying CO at a flow rate of 0.4 L / min, the furnace was heated until the temperature inside the furnace reached a constant heater temperature. ２ The concentration levels were measured until equilibrium was reached. ２ The relationship between the equilibrium concentration levels of CO and CO is shown in Figure 4. ２ The CO concentration was measured by sampling the generated gas from an exhaust pipe at the bottom of the furnace peripheral wall, which was used to release the gas into the atmosphere, using an NDIR gas sensor (gas flow rate: 0.5 L / min, manufactured by AWIT). As can be seen from Figure 4, as the heater temperature increased from 400°C to 800°C, the CO concentration increased from 0% to nearly 85%, while the CO ２ The equilibrium concentration at 800 °C was C + CO ２ ⇔ Theoretical concentration is 87% assuming 2CO (RTlnK = -ΔG°, ΔG° = -17.5 kJ mol －１ Calculated from 800°C, data source: Central Research Institute of Electric Power Industry Report M19002 Basic characteristics of molten carbonate direct carbon fuel cells using cylindrical cells), and the carbon produced and CO attached to the catalyst ２ This suggests that the Boudouard reaction occurs, in which CO reacts with HCl to produce CO.

[0093] (Experimental Example 3 - Changes in Boudouard Reaction Over Time) In Example 1, the supply of methane was stopped, and room temperature nitrogen gas was introduced into the reactor with the metal catalyst plate with the carbon deposits still installed at a flow rate of 0.4 L / min for 30 minutes to purge the methane and hydrogen remaining in the reactor. Next, the supply of nitrogen gas was stopped, and at the same time, room temperature CO ２ was supplied into the furnace at a flow rate of 0.4 L / min. ２The moment the switch is made to 0 seconds, and the CO and CO ２ The change in concentration level over time was observed in seconds. The results are shown in Figure 5. As can be seen from Figure 5, the change in concentration level from nitrogen to CO ２ The reduction started 22 seconds after switching to CO 2 , and the CO 2 concentration stabilized at 83% after 1 minute and 41 seconds. ２ Although there is a temperature drop at the beginning of the introduction of CO, the temperature inside the furnace soon returns to around 800°C, and CO reduction progresses rapidly. ２ It is thought that the CO concentration was converted to CO with almost no increase. ２ It was thought that there was still enough carbon produced in the furnace to reduce the

[0094] It should be noted that the present invention is not limited to the above-described embodiments, and not all of the configurations described in the above-described embodiments are necessarily essential requirements of the present invention. The present invention may be modified in various ways within the scope of the technical concept thereof.

[0095] CO ２ In an alternative embodiment of the recycling system 1, CO 2 is introduced between the dehydrator 7 and the SDRM reaction module 11. ２ A reservoir may be provided. ２ By providing a storage tank, methane is stored when demand is high and released when demand is low, so that the amount of CO supplied to the methanation module 15 can be adjusted so that it does not become too much or too little by 33% compared to the amount of hydrogen produced.

[0096] CO ２ In an alternative embodiment of the recycling system 1, it is assumed that air is used as an oxidant for combustion in the methane oxidation module 3, and CO contained in the combustion gas is supplied to the downstream of the methane oxidation module 3. ２ , nitrogen, nitrogen oxides, etc. to CO ２ A device for separating the

[0097] In an alternative embodiment of the SDRM reaction module 11, a pipe is provided between the purifier 36 and the compressor 40a to return the methane, which is the raw gas separated in the purifier 36, to the reactor 33 or the methane supply port 42, and a pipe is provided between the purifier 38 and the compressor 40b to return the CO, which is the raw gas separated in the purifier 38, to the reactor 33 or the methane supply port 42. ２ reactor 33 or CO ２ A return pipe may be provided to the supply port 44 .

[0098] In an alternative embodiment of the SDRM reaction module 11, a compressor may also be provided upstream of the purification devices 36, 38 (closer to the gas outlet).

[0099] In an alternative embodiment of the SDRM reaction module 11, a main valve capable of releasing gas remaining in the reactor to the atmosphere or a main valve for releasing gas to a flow path separate from each flow path of the generated gas may be provided at a position closer to the gas outlet of the reactor than the third and fourth on-off valves. Purging the main valve using the raw material gas can improve the purity of the generated gas managed by the third and fourth on-off valves located downstream of the main valves.

[0100] In another alternative embodiment of the SDRM reaction module 11, the number of gas supply ports and gas exhaust ports may be reduced to one each, and the flow paths from the gas supply ports to the supply sources of each raw material gas and the flow paths from the gas exhaust port to the third and fourth on-off valves may be unified partway through. A configuration may also be adopted in which one supply-side three-way valve is used at each branch point instead of the first and second on-off valves, and one exhaust-side three-way valve is used instead of the third and fourth on-off valves.

[0101] In an alternative embodiment of the SDRM reaction module 11, multiple units of the apparatus shown in Figure 7 (for example, two units, apparatus A and apparatus B) are prepared, and first, reaction (i) or (j) is carried out temporarily in apparatus A, and reaction (k) is carried out temporarily in apparatus B. When solid carbon accumulates in apparatus A, the apparatuses are switched so that reaction (k) is carried out in apparatus A and reaction (i) or (j) is carried out in apparatus B. Such an apparatus and method can produce carbon monoxide and hydrogen simultaneously and continuously. Furthermore, by preparing at least three apparatuses, operation shutdowns can be prevented even if one of the apparatuses has some kind of equipment or piping trouble.

[0102] The method for producing carbon monoxide or carbon monoxide and hydrogen according to the present invention is less likely to produce water in the carbon monoxide or synthesis gas production process, and CO ２ It has great industrial applicability because it is suitable for the production of useful chemicals using acetic acid (CH ３ COOH), acrylic acid (C ３ H ４ O ２ ) and benzoic acid (C ７ H ６ O ２ ), polycarbonate (C １６ H １４ O ３ ) ｎ The present invention can also be suitably applied to the synthesis of oxygen-containing compounds such as carbon monoxide, which is highly toxic, on-site production and supply, and the synthesis of CO2, which is surplus in large quantities in CCS. ２ The method for producing methane or propane by recycling CO2 according to the present invention can be suitably applied to the utilization of CO2 generated by using natural gas, city gas, and biogas both domestically and internationally. ２ The consumer collects and recycles the ２ Whether the system is installed on the factory premises of a manufacturer that generates CO2 or on the premises of an LNG-fired power plant, or whether it is installed off-site by an energy supplier (for example, on the premises of a city gas plant), there is no need to purchase hydrogen, and the cost of increasing methane can be reduced by converting carbon into a value and selling it, making it a method with lower running costs. Furthermore, for energy suppliers in particular, this system not only avoids the reduction or loss of city gas sales volume that was unavoidable with conventional methanation systems that use hydrogen, but also has the advantage of being able to increase city gas sales volume by 1.5 to 3 times, making it highly applicable industrially. Furthermore, CO2 ２ In particular, when the users who collect and recycle gas are cement factories and the like, they are often located in suburban areas where there are no city gas pipelines, so this method, which can use propane cylinders, has great potential for use.

[0103] 1, 101, 121, 131, 141, 151, 161 CO ２Recycling system 3, 103 Methane oxidation module 53 Propane oxidation module 7, 17, 107, 117 Dehydrator 8, 108 Pipeline 11, 21, 111 SDRM reaction module 31 Propane pyrolysis module 41 Methane pyrolysis module 15, 65, 115 Methanation module 55 Propanation module 18 Propane cylinder 24 Catalyst hanging stay 25 Thermocouple 33, 23 Reactor 54 Desulfurizer 35 Heating device 36 H ２ Purification device 37, 27 Structure catalyst 38 CO purification device 39 First on-off valve 40a, 40b Compressor 41 Second on-off valve 42 Methane supply port 43 Third on-off valve 44 CO ２ Supply port 45 Fourth opening / closing valve 46 Hydrogen gas outlet 47 CH ４ Supply source 48 CO gas outlet 49 CO ２ Supply source 102 City gas supplier's premises 104 City gas consumer's premises 106 Transportation means 109 CO ２ Compressor / liquefier 110 CO ２ Storage facilities

Claims

1. A method for producing carbon monoxide or carbon monoxide and hydrogen, comprising sequentially carrying out the reactions represented by the following formulas (1) and (2) in the same vessel in a substantially anhydrous environment, in which the reaction of the following formula (1) is carried out using a structure catalyst having a catalytic effect in the thermal decomposition reaction of methane. ４ →C+2H ２ ...(1) C+CO ２ →2CO...(2) 2. Carbon Dioxide (CO ２ ) using carbon dioxide capture and storage (CCS) technology ２ The method according to claim 1, wherein 3. The method according to claim 1, wherein the reaction of formula (2) is carried out in the presence of carbon produced in the reaction of formula (1).

4. A method for producing a synthesis gas or a chemical product using the same, which comprises mixing the hydrogen obtained by the method according to claim 1 and carbon monoxide in a fixed ratio by adjusting the molar flow rates.

5. Hydrogen derived from renewable energy is added to produce H ２ The method for producing a synthesis gas or a chemical product using the same according to claim 4, further comprising adjusting the ratio of H2O to CO.

6. A reaction apparatus comprising a reactor housing a structural catalyst having catalytic activity for the thermal decomposition of methane and a CO detector on a flow path connected to the gas exhaust port of the reactor.

7. The apparatus according to claim 6, wherein the reactor is provided with one gas supply inlet and one gas exhaust outlet, and further provided with a supply-side three-way valve for switching the supply path to the gas supply inlet, and a exhaust-side three-way valve for switching the exhaust path from the gas exhaust outlet.

8. The apparatus according to claim 6, further comprising a discharge side valve for controlling the discharge of hydrogen and / or CO from the reactor, and a main valve capable of releasing gas remaining in the reactor into the atmosphere, or a main valve capable of releasing the gas into a flow path separate from the respective flow paths for hydrogen and CO, provided at a position closer to the gas exhaust port of the reactor than the discharge side valve.

9. CO produced through the oxidation reaction of hydrocarbons ２ A method for producing methane or propane by recycling the above-mentioned mixture, comprising the steps of: ２ (1) producing carbon and hydrogen by pyrolysis of hydrocarbons; (2) producing CO produced in (1); ２ with the carbon produced in step (2) to produce CO; and step (4) of producing methane or propane by reacting the hydrogen produced in step (1) and / or step (2) with the CO produced in step (3), wherein the reaction in step (2) and the reaction in step (3) are carried out successively in a substantially anhydrous environment in a vessel containing a structured catalyst having a catalytic effect on the thermal decomposition of methane.

10. The method for producing methane or propane according to claim 9, further satisfying the following condition (I) or (II): (I) the method further comprises step (5A) of using the methane or propane produced in step (4) as the hydrocarbon in step (1), and (II) the method further comprises step (5B) of using the unreacted hydrocarbon used in step (2) in step (1).

11. The step (2) recycles CO ２ 10. The method for producing methane or propane according to claim 9, further comprising the step of producing carbon and hydrogen by pyrolysis of 1.5 times or more methane or 5 / 6 times or more propane in a molar ratio relative to the amount of methane or propane.

12. When methane is thermally decomposed in the above step (2), the CO ２ The method for producing methane or propane according to claim 9, wherein the amount of methane produced in step (4) is three times or more by molar ratio relative to the amount of methane produced in step (2), and an excess amount of methane produced in step (4) is used in step (2).

13. The method for producing methane or propane according to claim 9, wherein the reaction in step (3) is carried out in the presence of carbon produced in the reaction in step (2).

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