JP2021035909A - Production method for methane and production facility therefor - Google Patents

Abstract

To reduce a feed energy to a system for producing methane by separating and collecting carbon dioxide CO2 in exhaust gas by a solid CO2 adsorbent to react the collected CO2 with H2.SOLUTION: There is provided a methane production system producing methane from carbon dioxide (CO2) collected from an exhaust gas, and hydrogen (H2). The system comprises: a CO2 adsorption process of separating and adsorbing CO2 by feeding the exhaust gas to an adsorption tower filled with a CO2 solid adsorbent; a purge process of discharging the exhaust gas remaining in a void of the adsorption tower by gas substitution; a desorption process of desorbing CO2 from the adsorbent by heating of the adsorption tower and feeding of H2; a cooling process of cooling the adsorbent after the desorption process; a gas pooling process of pooling the gas including CO2 discharged from the desorption process and H2; and a methanation process of generating methane by reacting CO2 with H2 in a catalyst. The gases CO2 and H2 pooled in the gas pooling process are fed to the purge and methanation processes.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for producing methane (CH4) and its equipment.

In recent years, from the viewpoint of preventing global warming, technologies for recovering CO2 have been developed in order to reduce CO2 emissions from coal gasification, steelmaking, thermal power plants, and the like. As an example, in Patent Documents 1 and 2, CO contained in the gas produced from a coal gasification furnace is converted into CO2 by the CO shift reaction shown in [Equation 1] by a shift reactor, and then converted into CO2 by a CO2 capture facility. A method for recovering CO2 in gas is disclosed.

As methods that have been put into practical use as CO2 capture technology up to now, in addition to chemical absorption and physical absorption methods using an absorbent solution, a membrane separation method that selectively permeates CO2 and a liquefaction temperature difference of a mixed gas are used. There is a deep cold separation method, etc. Although each CO2 separation and recovery technology has technical and cost advantages, it is said that the chemical absorption method or physical absorption method using a CO2 absorption liquid is suitable as the CO2 separation and recovery technology from a large-scale plant. ..

However, the CO2 separation and recovery technology using a CO2 absorbing liquid requires a large amount of energy to regenerate the absorbing liquid that has absorbed CO2, and the energy required for the regeneration has been the main cause of the increase in CO2 recovery cost. On the other hand, there is a CO2 recovery method using a solid CO2 adsorbent as a CO2 scavenger. Since the solid adsorbent has a smaller heat capacity than the above-mentioned absorbent liquid, it is considered to be a technology capable of reducing renewable energy, and has been attracting attention in recent years.

An example of a CO2 separation / recovery method using a solid adsorbent is described in Patent Document 3. This patent has an adsorption step of adsorbing CO2 in exhaust gas to an adsorbent and a desorption step of desorbing CO2 adsorbed on the adsorbent, and the desorption step is the CO2 content when adsorbing CO2 to the adsorbent. This is a CO2 separation and recovery method that uses purge gas that exhibits a partial pressure of CO2 that is lower than the pressure, for example, steam extracted during or after the turbine of a thermal power plant.

Further, Patent Document 4 aims at separating and recovering CO2 from boiler exhaust gas, and includes a CO2 adsorption step of capturing CO2 with an adsorbent, a purging step of purging a CO2 adsorption tower with high-purity CO2, and thermal energy such as water vapor. It consists of a CO2 desorption step that desorbs CO2 from the adsorbent and a cooling step that cools the adsorption tower after CO2 desorption with the atmosphere or high-purity CO2.

On the other hand, technologies for liquefying CO2 recovered from various plants and storing it underground or on the seabed have been developed in advance. However, since the existence of storage destinations depends largely on the region and land, it cannot be a general-purpose technology common to the whole world. Therefore, in recent years, the development of technology for converting the recovered CO2 into more valuable secondary energy has been promoted. A typical secondary energy is methane. Methane can be obtained by the reaction shown in [Equation 2] using CO2 and H2 as reactants. However, since CO2 is a stable compound, a catalyst is required to allow [Equation 2] to proceed.

Further, in [Equation 2], H2 is required as a CO2 reactant, and one of the issues is how to produce and supply H2. As an H2 production method, a method of producing from fossil fuel is common. For example, there is a method of producing H2 from the CO shift reaction shown in [Equation 1] by reacting CO in the above-mentioned coal gasification gas with water vapor. However, it is possible to produce methane directly from CO and H2 in coal gasification gas by the reaction of [Equation 3], and it is inefficient to produce H2 through a CO shift reaction and then react with CO2. is there. There is a method of producing H2 from natural gas with the same fossil fuel by, for example, the steam reforming reaction of [Equation 4], but it is extremely inefficient to resynthesize methane from H2 produced by this reaction. As a method for producing hydrogen from sources other than fossil fuels, a method for producing H2 by electrolysis of water using electricity obtained from renewable energy represented by wind power generation and solar power generation has been attracting attention in recent years. In particular, in Europe, where the introduction of renewable energy is rapidly increasing, there is an oversupply of electricity depending on the country, and surplus electricity is generated. Using the surplus electricity, H2 produced by electrolysis of water and CO2 emitted and recovered from thermal power generation, steel industry, and other industrial fields are used to produce methane by [Equation 2] reaction and supplied to the pipeline. Measures are being taken to do so. A typical example is the Power to Gas project, which is being promoted as a national policy of Germany.

Patent Document 5 describes an example of a methane production method using CO2 and H2 as raw materials. It is a system that produces methane by mixing CO2 separated from industrial exhaust gas and H2 generated by electrolysis of water using electricity obtained from renewable energy in a multi-column methane reactor filled with a catalyst.

Japanese Patent No. 2870929 Japanese Patent No. 3149561

As described in Patent Documents 1 and 2 as a method for recovering CO2 from industrial exhaust gas, the purpose has been to recover CO2, so that the final product should be high-purity CO2. Therefore, as described in Patent Documents 1 and 2, as a method for desorbing CO2 adsorbed on the CO2 solid adsorbent, a method using water vapor, which can easily separate the desorbed gas and obtain high-purity CO2, is used. It was mainstream. However, if there is water vapor in the plant where the CO2 recovery equipment is installed, for example, CO2 separation and recovery from a thermal power plant, water vapor can be used as the desorption gas, but some plants cannot use water vapor. In addition, when steam is used in the above thermal power plant, the power generation efficiency is lowered.

On the other hand, there are few inventions on the premise that CO2 after being separated and recovered by a solid adsorbent is used as it is for methane production. By combining the CO2 separation and recovery process with the methane production process, the available utilities and restrictions on the CO2 specifications produced by the CO2 separation and recovery process can be expanded.

As a method for solving the above problems, the present invention relates to a methane production method for producing methane from carbon dioxide (CO2) and hydrogen (H2) recovered from exhaust gas, and supplies exhaust gas to an adsorption tower filled with a solid CO2 adsorbent. A CO2 adsorption process that separates CO2 by gas replacement, a purge process that discharges the exhaust gas remaining in the voids of the adsorption tower by gas replacement, and a desorption step and desorption that desorbs CO2 from the adsorbent by heating the adsorption tower and supplying H2. A cooling step to cool the adsorbent after the step, a gas storage step to store the gas containing CO2 and H2 discharged from the desorption step, and a metanation step to generate methane by reacting CO2 and H2 on a catalyst. The methane production method is characterized in that CO2 + H2 stored in the gas storage step is supplied to the purging step and the methanation step.

Further, the methane production method is provided with an exhaust gas storage process for storing CO2-free gas discharged from the adsorption process, and the cooling gas used in the cooling process is supplied from the exhaust gas storage process and circulated and supplied. is there.

Furthermore, the gas storage process is equipped with a CO2 concentration detection process and the wake of the gas storage process is equipped with an H2 supply process, and the amount of H2 supplied from the H2 supply process is adjusted according to the CO2 concentration in the gas stored in the gas storage process. This is a methane production method characterized by the above.

According to the present invention, H2 supplied by the metanation process can be used as the CO2 desorption gas from the CO2 adsorbent, and the energy required for CO2 desorption can be reduced.

This is the process flow of the present invention shown in Example 1. This is an example of the system configuration diagram of the present invention shown in Example 2. This is an example of the system configuration diagram of the present invention shown in Example 3.

Hereinafter, embodiments of the present invention will be described with reference to examples, but the present invention is not limited to the following embodiments.

In this embodiment, the basic process of the methane production method of the present invention will be described. FIG. 1 shows a conceptual diagram of a methane production method according to the present invention. Here, the positioning of the four steps of adsorption, purging, desorption, and cooling and the gas storage and metanation steps will be described for one adsorption tower filled with a solid CO2 adsorbent.

First, the exhaust gas 1 containing CO2 is supplied to the adsorption tower. When CO2 in the exhaust gas 1 is captured by the adsorbent, the exhaust gas 2 containing no CO2 is discharged from the outlet of the adsorption tower. The temperature of the exhaust gas 1 supplied to the adsorbent depends on the type of adsorbent to be filled. It is considered that the appropriate temperature differs depending on whether the adsorbent captures CO2 by the mechanism of physical adsorption or chemical adsorption. However, when CO2 is captured by adsorption rather than absorption, it is desirable to select an adsorbent that can be adsorbed at as low a temperature as possible in consideration of the energy required for regeneration. As a guide, it is 100 ° C or lower, preferably 50 ° C or lower. When the CO2 adsorption to the adsorbent reaches saturation in the adsorption process, the supply of exhaust gas 1 is stopped. At that time, the exhaust gas 1 containing CO2 remains in the voids in the adsorption tower.

Next, CO2 + H2 is supplied to the adsorption tower in the purging process in order to discharge the exhaust gas 1 remaining in the voids. The CO2 + H2 supplied here is supplied from the CO2 storage process that stores the gas discharged in the desorption process, which is the next process. The purpose of the purging step is to discharge the exhaust gas 1 remaining in the voids from the adsorption tower, and the exhaust gas 1 discharged from the adsorption tower is exhausted to the outside of the system. Therefore, if the amount of CO2 + H2 supplied in the purging process becomes excessive, the amount of CO2 + H2 in the exhaust gas increases, and the CO2 recovery rate of the plant decreases. Therefore, it is desirable that the amount of (CO2 + H2) supplied in the purging step ≈ the amount of voids. In addition, in order to prevent the supplied CO2 and the exhaust gas 1 in the voids from being mixed in the adsorption tower, a rectifying plate such as a mesh plate is installed above the adsorbent in the adsorption tower to make the flow uniform. In addition, it is desirable to control the flow velocity so that the flow becomes a laminar flow. After the completion of the purging process, CO2 is saturated and adsorbed on the adsorbent, and CO2 + H2 is retained in the voids.

Next, in the desorption step, CO2 in the adsorbent is desorbed to regenerate the adsorbent. As a method for desorbing CO2 from an adsorbent, there are a temperature swing method (TSA: Thermal Swing Adsorption) using thermal energy and a pressure swing method (PSA: Pressure Swing Adsorption) using gas compression and expansion as a driving force. , The present invention targets TSA. Further, in the present invention, H2 is used as a medium gas for discharging CO2 desorbed from the adsorbent by heat energy and CO2 staying in the voids from the adsorption tower. The adsorption and purge steps are operated at a low temperature of 100 ° C or less. Therefore, at the time of desorption, the adsorbent is first heated, and after raising the temperature to a predetermined temperature in order to discharge the CO2 desorbed from the adsorbent and the H2 staying in the voids to the outside of the adsorbent during the heating process, the H2 Is supplied from the suction gate. The heating method of the adsorption tower may be either external or internal heating. The heating temperature depends on the characteristics of the adsorbent to be filled in the adsorption tower, but it is 100 ° C to 250 ° C, CO2 desorption characteristics, the regeneration temperature of the chemical absorption method using the above-mentioned absorbent solution, and the adsorbent in the next step (tower tower). ) Considering the time required for cooling, 100 ° C to 200 ° C is desirable. The regenerated gas discharged from the adsorption tower is cooled and then sent to a gas storage process.

Next, the adsorbent (tower) heated in the desorption step is cooled. The preferred cooling gas is exhaust gas 2 that does not contain CO2 and is emitted after CO2 is adsorbed in the adsorption process. If surplus utilities such as nitrogen and oxygen can be used in the plant where the CO2 separation and recovery equipment is installed, these gases may be used. Here, it is assumed that there is no surplus utility mentioned above. The cooling gas needs to be a dry gas, and a gas containing no CO2 is preferable. For example, when cooling using exhaust gas 1 containing CO2, not only CO2 is emitted as exhaust gas under the assumption of cooling, but also CO2 is adsorbed on the adsorbent and the amount of CO2 adsorbed decreases in the subsequent adsorption process. is there. In the cooling process, the exhaust gas 2 is used to cool the adsorbent (tower) to 100 ° C or lower, which is the adsorption temperature in the adsorption process. After cooling to the operating temperature in the adsorption step, the same operation as described above is repeated from the adsorption step again.

Further, a feature of the present invention is to integrate a CO2 separation and recovery system and a metanation system. In the gas storage process described above, a gas containing H2 supplied as desorbed gas and CO2 separated and recovered from the exhaust gas is stored. As shown in [Equation 2], since the reactants of the metanation reaction are CO2 and H2, the gas stored in the gas storage step is supplied to the metanation step as it is, and methane, which is the final product in the metanation step. Is manufactured.

In the methanation step 1, methane is produced with the reaction of [Equation 2] as the target reaction. In [Equation 2], 4 mol of H2 reacts with 1 mol of methane in terms of stoichiometry, so it is sufficient to supply methane: H2 = 1: 4, but equilibrium is achieved by supplying H2 more than the stoichiometric ratio. In addition, since it is considered that the reaction is promoted, it is desirable that the supply amount is H2 / CO2 ≥ 4.

In this embodiment, an example of the system according to the present invention is shown. An example of the system configuration diagram is shown in FIG. The system of FIG. 2 includes an adsorption tower 1 filled with an adsorbent 2, an electric heater 3 for external heating, a gas storage tank 4, an exhaust gas storage tank 5, a methane reactor 6 filled with a methane catalyst 7, and a hydrogen separation facility. It is composed of 8, a pump 9, a cooler 10, a heater 11, and a gas-liquid separator 12. In this embodiment, four fixed layer adsorption towers were used. Here, an example of CO2 adsorption operation in exhaust gas and a methane production operation are shown for the first adsorption tower 1a.

First, the exhaust gas is supplied to the adsorption tower 1a. At that time, the valve V1a installed in the exhaust gas supply pipe 21 and the valve V3a installed in the exhaust gas discharge pipe 24 are opened. During the adsorption operation, a part of the exhaust gas discharged from the adsorption tower is supplied to the exhaust gas storage tank 5 and stored. After the CO2 adsorption to the adsorbent 2a reaches saturation, the valve V1a is closed to stop the exhaust gas to the adsorption tower 1a, and at the same time, the valve V1b is opened to move to the adsorption operation of the adsorption tower 1b. The adsorbent to be filled in the adsorption tower may be any solid substance that adsorbs CO2, such as activated carbon, zeolite, and cerium oxide. However, if the exhaust gas contains water, CO2 is adsorbed on the adsorbent. Since there is a concern about adsorption inhibition, for example, a cerium oxide-based adsorbent that is less affected by water is preferable. Further, the filling method may be any form as long as it can be filled in the fixed layer such as granular, honeycomb-shaped, and plate-shaped. However, when the amount of processing gas is large, a honeycomb-shaped or plate-shaped one in which an adsorbent is coated on the surface is preferable in consideration of pressure loss.

Next, in the adsorption tower 1a, the valve 4a installed in the purge gas supply pipe 22 is opened, CO2 + H2 stored in the gas storage tank 4 is supplied via the pump 9a, and the inside of the adsorption tower is purged with CO2 + H2. To do. In the purging operation, the amount of voids in the adsorption tower is measured in advance, and the exhaust gas remaining in the voids is controlled to be supplied to the minimum amount of CO2 discharged to the outside of the adsorption tower. After the purging operation is completed, the valves 4a and 3a are closed.

Next, a detachment operation is performed. In this embodiment, an external heating type electric heater 3 is installed in each adsorption tower. Any external / internal heating type may be used as long as the adsorption tower and the filled adsorbent can be heated, and the heating method can be any medium other than an electric heater, for example, a medium having heat such as steam. It may be a method. In the desorption operation, the valve V5a installed in the desorption gas discharge pipe 25 is first opened, and then the suction tower is heated to the desorption temperature by an electric heater. In the process of heating, the gas expansion component and CO2 desorbed from the adsorbent are discharged from the desorbed gas discharge pipe together with H2 staying in the voids and sent to the gas storage tank 4. After the temperature of the adsorption tower 1a has risen to a predetermined temperature, the valve V6a installed in the H2 supply pipe 23 is opened, H2 is introduced into the adsorption tower 1a, and CO2 + H2 staying in the voids is discharged to the outside of the adsorption tower. At the same time as the CO2 is discharged, the CO2 desorbed from the adsorbent 2a is discharged to the outside of the tower as the CO2 partial pressure decreases. The desorbed gas is cooled by the cooler 10a and then stored in the gas storage tank 4. After the detachment operation is completed, the valves 5a and 6a are closed and the electric heater 3a is stopped.

Next, a cooling operation is performed. The cooling operation is performed with a gas that is discharged from the adsorption tower during the adsorption operation and contains almost no CO2 stored in the exhaust gas storage tank. First, among the valves installed in the exhaust gas supply pipe 21, V1a and then V2a are opened. Also, open the valve V3a installed in the exhaust gas discharge pipe. After that, the exhaust gas stored in the exhaust gas storage tank 5 is supplied to the adsorption tower 1a via the pump 9b. The gas discharged from the adsorption tower is cooled by the cooler 10b, and then the exhaust gas is circulated and supplied to the adsorption tower again via the exhaust gas storage tank 5 and the pump 9b. When the temperature inside the adsorption tower drops to a predetermined temperature, the valve V2a is closed and the supply of circulating gas is stopped.

In the gas storage tank 4 by the operation so far, a gas containing CO2 separated and recovered from the exhaust gas and H2 supplied as a desorbed gas is stored. The stored gas is heated to a predetermined temperature by the heater 11b and then supplied to the methane reactor 6a filled with the methane catalyst 7a. In the first methane reactor 6a, methane is produced by the reaction of [Equation 2]. Since the methanation reaction is an exothermic reaction, the theoretical conversion rate increases as the temperature decreases, but since CO2 is a stable compound, the reaction does not start unless the inlet temperature is set above a predetermined temperature. As the methanation catalyst, Rh / Mn-based, Rh-based, Ni-based, Pd-based, and Pt-based catalysts using alumina as a carrier are known, and among them, the Rh / Mn-based catalyst has the highest low-temperature activity. For Rh / Mn-based catalysts, the catalyst inlet temperature is preferably 250 ° C. or higher, and for other catalysts, 300 ° C. or higher is required. The Rh / Mn-based catalyst is preferable because it is desirable to start the reaction at a lower temperature in consideration of the heat resistant temperature of the reactor, the heat resistance of the catalyst, and the methane production yield at equilibrium. The gas after metanation by the first reactor 6a is supplied to the cooler 10c, and after the gas is sufficiently cooled, the drain generated by the metanation reaction is removed by the gas-liquid separator 12a. After that, before and after the second and third methane reactors, the steps of heating, reaction, cooling, and drain removal are performed in the same manner as in the first methane reactor, respectively, to finally produce high-purity methane. As the catalyst to be filled in the second and third methane reactors, a Rh / Mn-based catalyst is preferable as in the case of the first reactor 6a. According to [Equation 2], the CO2 metanation reaction is a reaction that consumes 4 mol of H2 for 1 mol of CO2, and theoretically reacts at H2 / CO2 = 4 mol / mol, but at H2 / CO2> 4. The reaction is more balanced and the reaction progress is promoted. If the composition of the gas stored in the gas storage tank 4 is H2 / CO2> 4 mol / mol, methane and H2 are present in the gas after all CO2 is converted to methane. Here, since the methane purity decreases when H2 is present in the final produced gas, it is preferable to install the hydrogen separator 8 at the subsequent stage of the most downstream methane reactor. The methane separated by the hydrogen separator 8 is stored or sent to the destination, and H2 is returned to the H2 supply pipe upstream of the CO2 adsorption process.

In this embodiment, an example of the operation control method of the meta-nation process is shown. An example of the system configuration is shown in FIG. Most of the system configuration in FIG. 3 is the same as in FIG. 2. In FIG. 3, a CO2 analyzer 13 is installed in the gas storage process of the system in FIG. 2, and a pipe supplied from the gas storage process to the metanation reactor. The H2 pipe 14 was connected to the H2 pipe, and a flow rate control valve 15 for controlling the flow rate based on the analysis value of the CO2 analyzer was installed in the H2 pipe. As described in Example 2, it is desirable to supply the CO2 metanation reaction with H2 / CO2 ≥ 4, but in the operation process of the upstream CO2 separation and recovery process, the gas of H2 / CO2 <4 is gas storage tank 4 It may be stored in. In that case, not only the reaction progress of [Equation 2] is suppressed in equilibrium, but also CO2 is mixed in methane, which is the final production gas, leading to a decrease in methane purity. Therefore, a CO2 analyzer 13 that constantly measures the CO2 concentration in the gas stored in the gas storage tank 4 is installed, and if the composition of the stored gas is H2 / CO2 <4, the gas control valve 15 is opened. The degree is adjusted so that the composition of the gas supplied to the methane production process is H2 / CO2 ≥ 4.

According to this embodiment, the purity of methane, which is the final production gas, can be increased.

1 ... Adsorption tower, 2 ... Adsorbent, 3 ... Electric heater, 4 ... Gas storage tank, 5 ... Exhaust gas storage tank, 6 ... Methane reactor, 7 ... Metanation catalyst, 8 ... Hydrogen separation equipment, 9 ... Pump, 10 ... cooler, 11 ... heater, 12 ... gas-liquid separator, 13 ... CO2 analyzer, 14 ... H2 piping, 15 ... flow control valve, 21 ... exhaust gas supply pipe, 22 ... CO2 supply pipe, 23 ... steam supply pipe , 24 ... Exhaust gas discharge pipe, 25 ... Desorption gas discharge pipe, V1-7 ... Valve

Claims (12)

Regarding the methane production method that produces methane from carbon dioxide (CO2) and hydrogen (H2) recovered from exhaust gas, a CO2 adsorption process that separates CO2 and gas replacement by supplying exhaust gas to an adsorption tower filled with a solid CO2 adsorbent. A purging process that discharges the exhaust gas remaining in the voids of the adsorption tower, a desorption step that desorbs CO2 from the adsorbent by heating the adsorption tower and H2 supply, and a cooling step and desorption that cools the adsorbent after the desorption step. A gas storage step for storing gas containing CO2 and H2 discharged from the step and a metanation step for producing methane by reacting CO2 and H2 on a catalyst are provided, and the purging step and the metanation step include the gas. A methane production method characterized by supplying CO2 + H2 stored in a storage process. The methane production method according to claim 1 includes an exhaust gas storage step for storing CO2-free gas discharged from the adsorption step, and the cooling gas used in the cooling step is supplied from the exhaust gas storage step and circulated and supplied. A methane production method characterized by In the methane production method according to claims 1 and 2, the gas storage step is provided with a CO2 concentration detection step, and the wake of the gas storage step is provided with an H2 supply step, depending on the CO2 concentration in the gas stored in the gas storage step. A methane production method characterized by adjusting the amount of H2 supplied from the H2 supply process. After separating CO2 contained in the exhaust gas with an adsorption tower filled with a solid CO2 adsorbent, purge the exhaust gas remaining in the voids of the adsorption tower by gas replacement, and remove CO2 from the adsorbent by heating the adsorption tower and supplying H2. Methane is produced by reacting CO2 separated and recovered in a CO2 separation and recovery facility that has the function of separating and cooling the adsorbent after CO2 desorption and H2 supplied from the outside in a methane reactor filled with a methanation catalyst. Regarding the methane production method with the added function of generating, it has a gas storage rank for storing the gas desorbed from the adsorbent, and for purging and desorbing from the gas storage tank when purging the adsorption tower and desorbing from the adsorbent. A methane production facility characterized by supplying gas. The methane production facility according to claim 4 is provided with an exhaust gas storage tank and a pump for storing CO2-free gas discharged from the adsorption tower, and the cooling gas used for cooling the adsorption tower is supplied from the exhaust gas storage tank. A methane production facility characterized by circulating supply. The methane production facility according to claims 4 and 5 is provided with a CO2 analyzer in the gas storage tank, an H2 supply pipe in the wake of the gas storage tank, and a flow rate control valve in the H2 supply pipe, and CO2 in the gas in the gas storage tank. A methane production facility characterized in that the flow rate control valve is controlled according to the concentration to adjust the H2 supply amount. In the methane production facility according to claims 4 to 6, the CO2 adsorption tower has a fixed layer type multi-tower configuration, and each CO2 adsorption tower inlet is provided with an exhaust gas supply pipe, a purge gas supply pipe, and an H2 supply pipe, and CO2. A methane production facility characterized by having an exhaust gas discharge pipe and a desorption gas discharge pipe at the outlet of the adsorption tower. The methane production facility according to claims 4 to 6, wherein the methane reactor has a multi-column structure, and a cooler and a gas-liquid separator are provided between the reactors. In the methane production facility according to claims 4 to 6, the desorbed gas from the CO2 adsorption tower and H2 supplied to the methane reactor were generated by an electrolysis step of water using electricity obtained from renewable energy. A methane production method characterized by being H2. The methane production facility according to claims 4 to 6, wherein a hydrogen separation facility is provided after the most downstream methane reactor. The methane production facility according to claim 4, wherein the CO2 solid adsorbent is an oxide containing Ce. The methane production method according to claim 4, wherein the metanation catalyst is any one of Rh / Mn-based, Rh-based, Ni-based, Pd-based, and Pt-based using alumina as a carrier.

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