Chemical product synthesis system, chemical product synthesis method, and computer program

Abstract

To provide a technique that enables efficient chemical product synthesis in a chemical product synthesis system.SOLUTION: A chemical product synthesis system includes: a first reactor that houses metal oxide and receives hydrogen and carbon dioxide from independent supply sources; a switching unit that can switch between a state of hydrogen being supplied to the first reactor and a state of carbon dioxide being supplied; a control unit that controls the switching unit so that hydrogen and carbon dioxide are alternately supplied to the first reactor, where the control unit generates water by supplying hydrogen to a reaction unit and generates carbon monoxide by supplying carbon dioxide to the reaction part; and a chemical product synthesis unit which receives the gas generated in the first reactor, where the chemical product synthesis unit synthesizes a chemical product using carbon monoxide contained in the generated gas.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a chemical synthesis system, a chemical synthesis method, and a computer program. [Background technology]

[0002] 2. Description of the Related Art Conventionally, chemical product synthesis systems that synthesize chemical products using carbon monoxide have been known (for example, Patent Documents 1 to 3 and Non-Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-118890 A [Patent Document 2] International Publication No. 2019 / 163968 [Patent Document 3] Patent Publication No. 2022-171010 [Non-patent literature]

[0004] [Non-Patent Document 1] J. Makiura, S. Kakihara, T. Higo, N. Ito, Y. Hirano and Y. Sekine, "Efficient CO2 conversion to CO using chemical looping over Co?In oxide" Chemical Communications, 2022, 58, 4837-4840, [Retrieved July 19, 2023], Internet<https: / / pubs.rsc.org / en / content / articlelanding / 2022 / cc / d2cc00208f> Summary of the Invention [Problem to be solved by the invention]

[0005] However, even with the prior art such as Patent Document 1, there is still room for improvement in the technology for efficiently synthesizing chemical products in a chemical product synthesis system.

[0006] The present invention has been made to solve the above-mentioned problems, and has an object to provide a technique capable of efficiently synthesizing chemical products in a chemical product synthesis system. [Means for solving the problem]

[0007] The present invention has been made to solve at least part of the above-mentioned problems, and can be realized in the following forms.

[0008] (1) According to one aspect of the present invention, a chemical synthesis system is provided, which includes a first reactor that contains a metal oxide and to which hydrogen and carbon dioxide are supplied from respective supply sources, a switching unit that can switch between a state in which hydrogen is supplied to the first reactor and a state in which carbon dioxide is supplied to the first reactor, a control unit that controls the switching unit so that hydrogen and carbon dioxide are alternately supplied to the first reactor, the control unit producing water by supplying hydrogen to the first reactor and producing carbon monoxide by supplying carbon dioxide to the first reactor, and a chemical synthesis unit that is supplied with a product gas produced in the first reactor and synthesizes a chemical product using the carbon monoxide contained in the product gas.

[0009] According to this configuration, carbon monoxide, which is the raw material for chemical products, is generated by repeatedly reducing the metal oxide contained in the first reactor with hydrogen and oxidizing it with carbon dioxide, i.e., by the chemical looping method. Carbon monoxide generated by the chemical looping method using metal oxide is generated by oxidizing the metal oxide with carbon dioxide, so moisture is less likely to be contained in the product gas generated in the first reactor. This makes it possible to reduce the energy required to dehumidify the product gas used in the synthesis of chemical products. Therefore, the energy required for the synthesis of chemical products can be reduced, and chemical products can be synthesized efficiently.

[0010] (2) The chemical synthesis system of the above embodiment may further include a flow rate adjustment unit that adjusts the flow rate of at least one of hydrogen and carbon dioxide supplied to the first reactor, and the control unit may adjust the concentration ratio of carbon monoxide to the concentration of carbon dioxide contained in the generated gas supplied to the chemical synthesis unit by controlling the flow rate adjustment unit. According to this configuration, the concentration ratio of carbon monoxide to the concentration of carbon dioxide contained in the generated gas can be adjusted by adjusting the flow rate of at least one of hydrogen and carbon dioxide supplied to the first reactor. As a result, the first reactor can supply generated gas having an optimal concentration ratio of carbon monoxide to the concentration of carbon dioxide for the chemical products synthesized in the chemical synthesis unit, thereby enabling efficient synthesis of the chemical products.

[0011] (3) The chemical synthesis system of the above embodiment may include a flow rate adjustment unit that adjusts the flow rate of at least one of hydrogen and carbon dioxide supplied to the first reactor, and the control unit may adjust the concentration ratio of hydrogen to the sum of the concentrations of carbon monoxide and carbon dioxide contained in the generated gas supplied to the chemical synthesis unit by controlling the flow rate adjustment unit. According to this configuration, the concentration ratio of hydrogen to the sum of the concentrations of carbon monoxide and carbon dioxide contained in the generated gas can be adjusted by adjusting the flow rate of at least one of hydrogen and carbon dioxide supplied to the first reactor. This makes it possible to supply a generated gas with an optimal concentration ratio of hydrogen to the sum of the concentrations of carbon monoxide and carbon dioxide for the chemical products synthesized in the chemical synthesis unit, thereby enabling efficient synthesis of the chemical products.

[0012] (4) The chemical synthesis system of the above embodiment may include a second reactor that contains a metal oxide and is supplied with hydrogen and carbon dioxide from respective supply sources, in addition to the first reactor, and the switching unit may be capable of switching between a state in which hydrogen is supplied to the second reactor and a state in which carbon dioxide is supplied to the second reactor, and the control unit may control the switching unit so that when hydrogen is supplied to one of the first reactor and the second reactor, carbon dioxide is supplied to the other of the first reactor and the second reactor. According to this configuration, the control unit controls the switching unit so that when hydrogen is supplied to one of the first reactor and the second reactor, carbon dioxide is supplied to the other of the first reactor and the second reactor. This allows a gas containing carbon monoxide to be continuously supplied to the chemical synthesis unit, so that chemical products can be continuously synthesized.

[0013] (5) In the above-mentioned chemical synthesis system, the chemical synthesis unit includes a synthesis reactor that contains a catalyst for synthesizing a chemical product, a mixer that mixes carbon dioxide with the product gas generated in the first reactor, and a mixing amount adjustment unit that adjusts the flow rate of carbon dioxide supplied to the mixer. The control unit controls the mixing amount adjustment unit to adjust the concentration ratio of carbon monoxide to the concentration of carbon dioxide contained in the raw gas composed of the carbon dioxide and the product gas mixed in the mixer, and the synthesis reactor may synthesize a chemical product using the raw gas. According to this configuration, the chemical synthesis unit includes a mixer that mixes carbon dioxide with the product gas generated in the first reactor. The control unit controls the flow rate of carbon dioxide to be mixed with the product gas in the mixer to adjust the concentration ratio of carbon monoxide to the concentration of carbon dioxide contained in the raw gas composed of the carbon dioxide and the product gas mixed in the mixer. This makes it possible to supply a gas with an optimal concentration ratio of carbon monoxide to the concentration of carbon dioxide for the chemical product synthesized in the synthesis reactor, thereby enabling efficient synthesis of the chemical product.

[0014] (6) In the above-described chemical synthesis system, the chemical synthesis unit includes a synthesis reactor that contains a catalyst for synthesizing chemicals, a mixer that mixes at least one of hydrogen and carbon dioxide with the product gas generated in the first reactor, and a mixing amount adjustment unit that adjusts the flow rate of at least one of hydrogen and carbon dioxide supplied to the mixer, and the control unit controls the mixing amount adjustment unit to adjust the hydrogen concentration ratio to the sum of the carbon monoxide concentration and the carbon dioxide concentration contained in the raw material gas composed of at least one of hydrogen and carbon dioxide and the product gas mixed in the mixer, and the synthesis reactor may synthesize chemicals using the raw material gas. According to this configuration, the chemical synthesis unit includes a mixer that mixes at least one of hydrogen and carbon dioxide with the product gas generated in the first reactor. The control unit adjusts the concentration ratio of hydrogen to the sum of the concentrations of carbon monoxide and carbon dioxide contained in the raw material gas composed of the product gas and at least one of hydrogen and carbon dioxide mixed in the mixer by controlling the flow rate of at least one of hydrogen and carbon dioxide to be mixed with the product gas in the mixer. This makes it possible to supply a gas having an optimum concentration ratio of hydrogen to the sum of the concentrations of carbon monoxide and carbon dioxide for the chemical products synthesized in the synthesis reactor, thereby enabling the chemical products to be synthesized efficiently.

[0015] (7) In the above-described chemical synthesis system, the chemical synthesis unit may have a catalyst for methanol synthesis, and may synthesize methanol as the chemical product. According to this configuration, the chemical synthesis unit has a catalyst for methanol synthesis, and synthesizes methanol as the chemical product. When synthesizing methanol, the theoretical limit conversion rate derived from thermochemical equilibrium is higher for carbon monoxide as a raw material gas than for carbon dioxide. Thus, by combining a reactor that generates carbon monoxide from carbon dioxide by a chemical looping method with the chemical synthesis unit, the yield of methanol can be improved.

[0016] (8) According to another aspect of the present invention, there is provided a method for synthesizing a chemical product using a chemical synthesis system. The method for synthesizing a chemical product includes a reduction step of producing water by supplying hydrogen to a first reactor containing a metal oxide, an oxidation step of producing carbon monoxide by supplying carbon dioxide to the first reactor, and a synthesis step in which a product gas produced in the first reactor is supplied and a chemical product is synthesized using the carbon monoxide contained in the product gas. According to this configuration, carbon monoxide, which is a raw material for a chemical product, can be produced by a chemical looping method including a reduction step by hydrogen on a metal oxide contained in the first reactor and an oxidation step by carbon dioxide. In the chemical looping method, the product gas is less likely to contain moisture, so that the energy required for dehumidifying the product gas used in the synthesis of the chemical product can be reduced. This reduces the energy required for the synthesis of the chemical product, so that the chemical product can be efficiently synthesized.

[0017] (9) According to yet another aspect of the present invention, there is provided a computer program for causing a computer to execute synthesis of a chemical product using a chemical product synthesis system. The computer program causes the computer to execute a reduction function of producing water by supplying hydrogen to a first reactor containing a metal oxide, an oxidation function of producing carbon monoxide by supplying carbon dioxide to the first reactor, and a synthesis function in which a product gas generated in the first reactor is supplied and a chemical product is synthesized using the carbon monoxide contained in the product gas. According to this configuration, carbon monoxide, which is a raw material for a chemical product, can be generated by a chemical looping method including a reduction function by hydrogen in a metal oxide contained in the first reactor and an oxidation function by carbon dioxide. In the chemical looping method, moisture is less likely to be contained in the product gas, so that the energy required for dehumidifying the product gas used in the synthesis of the chemical product can be reduced. This reduces the energy required for the synthesis of the chemical product, so that the chemical product can be efficiently synthesized.

[0018] The present invention can be realized in various forms, for example, in the form of a control method for a chemical synthesis system, a computer program for synthesizing chemicals using the chemical synthesis system, a server device for distributing the computer program, a non-transitory storage medium on which the computer program is stored, etc. [Brief description of the drawings]

[0019] [Figure 1] 1 is a schematic diagram showing a schematic configuration of a chemical product synthesis system according to a first embodiment. [Diagram 2] FIG. 2 is a diagram illustrating a reduction process in a reactor. [Diagram 3] FIG. 2 is a diagram illustrating the oxidation process in a reactor. [Figure 4] FIG. 1 is a first diagram illustrating the function of a reactor. [Diagram 5] FIG. 2 is a second diagram illustrating the function of the reactor. [Figure 6] FIG. 3 is a third diagram illustrating the function of the reactor. [Figure 7] FIG. 4 is a fourth diagram illustrating the function of the reactor. [Figure 8] FIG. 5 is a fifth diagram illustrating the function of the reactor. [Figure 9] FIG. 6 is a sixth diagram explaining the function of the reactor. [Figure 10] 1 is a flowchart of a chemical product synthesis method according to a first embodiment. [Figure 11] 3 is a flow chart of control in the chemical product synthesis method of the first embodiment. [Figure 12] 10 is a flow chart of control in a chemical product synthesis method according to a second embodiment. [Figure 13] 10 is a flow chart of control in a chemical product synthesis method according to a third embodiment. [Figure 14] 13 is a flow chart of control in a chemical product synthesis method according to a fourth embodiment. [Figure 15] FIG. 13 is a schematic diagram showing a schematic configuration of a chemical product synthesis system according to a fifth embodiment. [Figure 16]13 is a flowchart of a chemical product synthesis method according to a fifth embodiment. [Figure 17] 13 is a flow chart of control in a chemical product synthesis method according to a fifth embodiment. [Figure 18] 13 is a flow chart of control in a chemical product synthesis method according to a sixth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] First Embodiment FIG. 1 is a schematic diagram showing a schematic configuration of a chemical synthesis system of the first embodiment. The chemical synthesis system 1 of this embodiment uses hydrogen (H2) and carbon dioxide (CO2) to produce a chemical product using carbon monoxide (CO) as a raw material. The chemical synthesis system 1 produces a chemical product, for example, a higher alcohol such as methanol (CH3OH), but the chemical product produced by the chemical synthesis system 1 is not limited thereto. The chemical synthesis system 1 of this embodiment produces methanol by utilizing a catalytic reaction involving carbon monoxide and hydrogen. The chemical synthesis system 1 includes a carbon dioxide supply source 6, a hydrogen supply source 7, a carbon monoxide production unit 10, a chemical synthesis unit 20, and a control unit 30.

[0021] The carbon dioxide supply source 6 is, for example, a combustion furnace for fossil fuels or waste, and supplies carbon dioxide contained in the exhaust gas discharged from the combustion furnace. The higher the concentration of carbon dioxide supplied by the carbon dioxide supply source 6, the more preferable it is for improving the synthesis efficiency of chemical products. In this embodiment, the concentration of carbon dioxide supplied by the carbon dioxide supply source 6 is 80% or more, more preferably 95% or more, and most preferably 99% or more. The concentration of carbon dioxide supplied by the carbon dioxide supply source 6 does not necessarily need to be 100%, and even if impurities such as oxygen (O2), nitrogen (N2), and moisture (H2O) are mixed to a certain extent, it is possible to generate carbon monoxide gas in the carbon monoxide generation unit 10 and synthesize methanol in the chemical product synthesis unit 20. The concentration of carbon dioxide supplied by the carbon dioxide supply source 6 may be determined based on the magnitude relationship between the increase in energy required to highly purify carbon dioxide and the increase in the input energy to the chemical product synthesis system 1 due to the decrease in the purity of carbon dioxide. The carbon dioxide supply source 6 is not limited to a combustion furnace for fossil fuels or waste, but may be a device that concentrates and collects carbon dioxide in the atmosphere, or a storage tank that stores carbon dioxide sent from an external device.

[0022] The hydrogen supply source 7 is, for example, a water electrolysis device, and supplies hydrogen generated by electrolysis of water. The higher the concentration of hydrogen supplied by the hydrogen supply source 7, the more preferable it is for improving the synthesis efficiency of chemical products. In this embodiment, the concentration of hydrogen supplied by the hydrogen supply source 7 is 80% or more, more preferably 95% or more, and most preferably 99% or more. The concentration of hydrogen supplied by the hydrogen supply source 7 does not necessarily need to be 100%, and even if impurities such as moisture are mixed in to a certain extent, carbon monoxide gas can be generated in the carbon monoxide generation unit 10 and methanol can be synthesized in the chemical product synthesis unit 20. The concentration of hydrogen supplied by the hydrogen supply source 7 may be determined based on the magnitude relationship between the increase in energy required for dehumidification to reduce the moisture concentration of the gas discharged from the water electrolysis device and increase the purity of hydrogen, and the increase in the amount of energy input to the chemical product synthesis system 1 due to the decrease in the purity of hydrogen. The hydrogen supply source 7 is not limited to a water electrolysis device, and may be a storage tank in which hydrogen sent from an external device is stored.

[0023] The carbon monoxide generation unit 10 generates carbon monoxide using carbon dioxide supplied from the carbon dioxide supply source 6 and hydrogen supplied from the hydrogen supply source 7. The carbon monoxide generation unit 10 includes a reactor 11, two flow rate adjustment units 12 and 13, an upstream switching valve 14, a downstream switching valve 15, a compressor 16, an intermediate storage unit 17, and a gas concentration detection unit 18.

[0024] The reactor 11 accommodates a metal oxide 11a therein. The metal oxide 11a can be reduced by a chemical reaction with hydrogen and oxidized by a chemical reaction with carbon dioxide. In this embodiment, the metal oxide 11a is a metal oxide having a plurality of stable valences, such as iron oxide, cobalt oxide, and indium oxide. The reactor 11 is provided with a gas inlet capable of introducing gas into the internal space filled with the metal oxide 11a, and a gas outlet capable of discharging the gas in the internal space to the outside. As a result, the gas introduced from the gas inlet comes into contact with the metal oxide 11a and is then discharged to the outside of the reactor 11 from the gas outlet. The reactor 11 corresponds to a "first reactor" in the claims.

[0025] 2 is a diagram illustrating the reduction process in the reactor 11. In the reactor 11, when hydrogen is introduced from a gas inlet, the reaction shown in the following formula (1) proceeds, and MO x The metal oxide 11a represented by is reduced (reduction step). MO x +δH2→MO x- δ + δH2O + (1 - δ)H2 (1) As the reaction of formula (1) progresses, mainly moisture and unreacted hydrogen are discharged from the gas outlet of the reactor 11. In the reduction step in the reactor 11, as the reaction of formula (1) progresses, the moisture concentration decreases and the hydrogen concentration increases. In this embodiment, the gas in which moisture and hydrogen are mixed and discharged from the reactor 11 in the reduction step is mainly recovered as a reuse gas and recycled as hydrogen for the reduction step of the reactor 11. In the reduction step, a portion of the gas in which moisture and hydrogen are mixed and discharged from the reactor 11 is stored in the intermediate storage unit 17.

[0026] 3 is a diagram illustrating the oxidation process in the reactor 11. In the reactor 11, when carbon dioxide is introduced from a gas inlet, the reaction shown in the following formula (2) proceeds, and MO x- The metal oxide 11a, represented by δ, is oxidized (oxidation step). MO x- δ+δCO2→MO x +δCO+(1-δ)CO2 (2) As the reaction of formula (2) progresses, mainly carbon monoxide and unreacted carbon dioxide are discharged from the gas outlet of the reactor 11. In the oxidation step in the reactor 11, as the reaction of formula (2) progresses, the concentration of carbon monoxide decreases and the concentration of carbon dioxide increases. In this embodiment, the carbon monoxide and carbon dioxide discharged from the reactor 11 in the oxidation step are stored in the intermediate storage section 17.

[0027] In the reactor 11 of this embodiment, the above-mentioned reduction step and oxidation step are performed alternately. This allows the reactor 11 to generate water in the reduction step and to generate carbon monoxide in the oxidation step.

[0028] 1, the flow rate adjustment unit 12 is provided in a flow path 6a that connects the carbon dioxide supply source 6 and an upstream switching valve 14, which will be described later. The flow rate adjustment unit 12 is, for example, a mass flow controller, and adjusts the flow rate of carbon dioxide flowing through the flow path 6a by changing the flow rate in response to a command from a control unit 30 that is electrically connected to the flow rate adjustment unit 12.

[0029] The flow rate adjustment unit 13 is provided in a flow path 7a that connects the hydrogen supply source 7 and the upstream switching valve 14. The flow rate adjustment unit 13 is, for example, a mass flow controller, and adjusts the flow rate of hydrogen flowing through the flow path 7a by changing the flow rate in response to a command from a control unit 30 that is electrically connected to the flow rate adjustment unit 13.

[0030] The upstream switching valve 14 is connected to a gas inlet of the reactor 11 via a flow path 10a. The upstream switching valve 14 is electrically connected to the control unit 30, and supplies either hydrogen or carbon dioxide to the reactor 11 in response to a command output by the control unit 30.

[0031] The downstream switching valve 15 is connected to the gas outlet of the reactor 11 via the flow path 10b. The downstream switching valve 15 is electrically connected to the control unit 30, and switches the destination of the gas discharged from the reactor 11 in response to a command output from the control unit 30. In this embodiment, the downstream switching valve 15 switches the gas discharged from the reactor 11 between sending it to the compressor 16 or sending it to the hydrogen supply source 7 as a recycle gas.

[0032] The compressor 16 is provided in the flow path 10c that connects the downstream switching valve 15 and the intermediate storage section 17. The compressor 16 compresses the gas discharged from the reactor 11. The compressed gas discharged from the reactor 11 is sent to the intermediate storage section 17.

[0033] The intermediate storage unit 17 stores the gas discharged from the reactor 11 and compressed in the compressor 16. The intermediate storage unit 17 mainly stores carbon monoxide and carbon dioxide discharged in the oxidation step in the reactor 11, as well as a portion of the hydrogen discharged in the reduction step in the reactor 11. In this embodiment, the gas stored in the intermediate storage unit 17 is the product gas. The product gas contains carbon monoxide and hydrogen necessary for producing methanol, as well as hydrogen and moisture discharged in the reduction step, and carbon dioxide discharged in the oxidation step without reacting with the metal oxide 11a. The product gas stored in the intermediate storage unit 17 is sent to the chemical product synthesis unit 20.

[0034] Gas concentration detection unit 18 is provided in intermediate storage unit 17. Gas concentration detection unit 18 detects the concentrations of carbon monoxide, carbon dioxide, and hydrogen in the generated gas stored in intermediate storage unit 17. Data relating to the concentrations of carbon monoxide, carbon dioxide, and hydrogen contained in the generated gas detected by gas concentration detection unit 18 is sent to control unit 30.

[0035] The chemical product synthesis unit 20 synthesizes methanol using the product gas generated by the carbon monoxide production unit 10. The chemical product synthesis unit 20 includes a methanol synthesis reactor 21, three flow rate adjustment units 22, 23, and 24, a mixer 25, a methanol separator 26, a methanol storage unit 27, a gas concentration detection unit 28a, a methanol concentration detection unit 28b, and a compressor 29.

[0036] The methanol synthesis reactor 21 accommodates a methanol synthesis catalyst 21a therein. The methanol synthesis catalyst 21a synthesizes methanol from hydrogen and carbon monoxide. The methanol synthesis reactor 21 is provided with a gas inlet capable of introducing gas into the internal space filled with the methanol synthesis catalyst 21a, and a gas outlet capable of discharging gas in the internal space to the outside. As a result, the gas introduced from the gas inlet comes into contact with the methanol synthesis catalyst 21a, and is then discharged to the outside of the methanol synthesis reactor 21 from the gas outlet.

[0037] The flow rate adjustment unit 22 is provided in a flow path 10d that connects the intermediate storage unit 17 of the carbon monoxide generation unit 10 and a mixer 25 described below. The flow rate adjustment unit 22 is, for example, a mass flow controller, and adjusts the flow rate of the generated gas flowing through the flow path 10d by changing it in response to a command from a control unit 30 that is electrically connected to the flow rate adjustment unit 22.

[0038] The flow rate adjustment unit 23 is provided in a flow path 6b that connects the carbon dioxide supply source 6 and the mixer 25. The flow rate adjustment unit 23 is, for example, a mass flow controller, and adjusts the flow rate of carbon dioxide flowing through the flow path 6b by changing the flow rate in response to a command from a control unit 30 that is electrically connected to the flow rate adjustment unit 23.

[0039] The flow rate adjustment unit 24 is provided in a flow path 7b that connects the hydrogen supply source 7 and the mixer 25. The flow rate adjustment unit 24 is, for example, a mass flow controller, and adjusts the flow rate of hydrogen flowing through the flow path 7b by changing the flow rate in response to a command from a control unit 30 that is electrically connected to the flow rate adjustment unit 24.

[0040] The mixer 25 is connected to a gas inlet of the methanol synthesis reactor 21 via a flow path 20a. The mixer 25 is capable of mixing at least one of carbon dioxide flowing through a flow path 6b and hydrogen flowing through a flow path 7b with the produced gas flowing through the flow path 10d. This allows the raw material gas supplied from the mixer 25 to the methanol synthesis reactor 21 to be a gas obtained by adding carbon dioxide and / or hydrogen to the produced gas.

[0041] The methanol separator 26 is connected to the gas outlet of the methanol synthesis reactor 21 via a flow path 20b. The methanol separator 26 separates methanol from the methanol-containing synthesis gas discharged from the methanol synthesis reactor 21. The methanol separated from the synthesis gas is sent to and stored in a methanol storage section 27. Components other than methanol contained in the synthesis gas, such as carbon monoxide and hydrogen, are sent to a compressor 29, which will be described later.

[0042] Gas concentration detector 28a is provided in flow path 20a. Gas concentration detector 28a detects the concentrations of carbon monoxide, carbon dioxide, and hydrogen contained in the synthesis gas flowing through flow path 20a. Data relating to the concentrations of carbon monoxide, carbon dioxide, and hydrogen contained in the synthesis gas detected by gas concentration detector 28a is sent to controller 30.

[0043] The methanol concentration detector 28b is provided in the flow path 20b and detects the concentration of methanol contained in the synthesis gas flowing through the flow path 20b.

[0044] The compressor 29 compresses components other than methanol separated from the synthesis gas in the methanol separator 26 that can be reused for the synthesis of methanol in the methanol synthesis reactor 21, i.e., carbon monoxide, hydrogen, etc. The compressor 29 is connected to the mixer 25 via a flow path 20c, and adjusts the flow rate of the reuse gas sent from the compressor 29 to the mixer 25 by changing the flow rate adjustment unit 29c provided in the flow path 20c.

[0045] The control unit 30 is a computer including a ROM, a RAM, and a CPU. The control unit 30 executes the functions of various programs, such as the synthesis of chemical products by the chemical product synthesis system 1, by expanding the programs stored in the ROM into the RAM. In this embodiment, the control unit 30 controls the flow rate adjustment units 12 and 13, the upstream switching valve 14, and the downstream switching valve 15 in the carbon monoxide generation unit 10 using data related to the concentration of carbon monoxide contained in the generated gas in the intermediate storage unit 17, which is sent from the gas concentration detection unit 18. The control unit 30 functions as a reduction function, an oxidation function, and a synthesis function.

[0046] Next, a detailed description will be given of the function of the reactor 11. In the reactor 11 of this embodiment, a carbon dioxide supply source 6 and a hydrogen supply source 7 are connected to a gas inlet via an upstream switching valve 14. As a result, the type of generated gas discharged from a gas outlet changes depending on switching of the connection destination by the upstream switching valve 14 and the state of the metal oxide 11a.

[0047] FIG. 4 is the first diagram for explaining the function of the reactor 11. FIG. 4 is a diagram showing the change in the oxidation number of the metal oxide 11a when hydrogen is continuously supplied to the metal oxide 11a with an increased oxidation number without controlling the switching of the upstream switching valve 14, and the type of gas discharged from the gas outlet. x " represents an oxide of metal M, and x is a positive value indicating the number of oxygen atoms bonded to one atom of metal M. In the initial state shown in FIG. 4(a), the metal oxide 11a is x and carbon dioxide is present in the reactor 11. When hydrogen is supplied to the reactor 11, the carbon dioxide in the reactor 11 is discharged from the gas outlet. At this time, the oxidation number of the metal oxide 11a on the gas inlet side, which is likely to come into contact with the introduced hydrogen, decreases, and the oxidation number of the metal oxide 11a becomes MO. x- δ (δ: a positive value smaller than x). Metal oxide 11a is MO x-In the region where δ exists, moisture and hydrogen are present (see FIG. 4(b)). Furthermore, when hydrogen is supplied to the reactor 11, after carbon dioxide is discharged, moisture and hydrogen are discharged from the gas outlet (see FIG. 4(c)). At this time, the metal oxide 11a is in a state of MO with a reduced oxidation number throughout the reactor 11. x- In the reactor 11, hydrogen is present in the region on the gas inlet side, and moisture and hydrogen are present in the region on the gas outlet side (see FIG. 4(c)). Furthermore, when hydrogen is supplied to the reactor 11, the reduction reaction in the metal oxide 11a is completed, so that the inside of the reactor 11 is entirely replaced with hydrogen, and the hydrogen is discharged from the gas outlet (see FIG. 4(d)).

[0048] Fig. 5 is a second diagram illustrating the function of the reactor 11. Fig. 5 is a diagram showing the change in the oxidation number of the metal oxide 11a and the type of gas discharged from the gas outlet when carbon dioxide is continuously supplied to the metal oxide 11a in a state where the oxidation number is reduced without controlling the switching of the upstream switching valve 14. In the initial state shown in Fig. 5(a), the metal oxide 11a is x- δ, and hydrogen is present in the reactor 11. When carbon dioxide is supplied to the reactor 11, the hydrogen in the reactor 11 is discharged from the gas outlet. At this time, the metal oxide 11a on the gas inlet side, which is likely to come into contact with the introduced carbon dioxide, increases in oxidation number and becomes MO x Metal oxide 11a is MO x In the region where the oxidation number is increased, carbon monoxide and carbon dioxide are present (see FIG. 5(b)). Furthermore, when carbon dioxide is supplied to the reactor 11, after hydrogen is discharged, carbon monoxide and carbon dioxide are discharged from the gas outlet (see FIG. 5(c)). At this time, the metal oxide 11a is the MO x In the reactor 11, carbon dioxide is present in the region on the gas inlet side, and carbon monoxide and carbon dioxide are present in the region on the gas outlet side (see FIG. 5(c)). Furthermore, when carbon dioxide is supplied to the reactor 11, the oxidation reaction in the metal oxide 11a is completed, so that the inside of the reactor 11 is entirely replaced with carbon dioxide, and the carbon dioxide is discharged from the gas outlet (see FIG. 5(d)).

[0049] Fig. 6 is a third diagram for explaining the function of the reactor 11. Fig. 6 is a diagram for explaining the effect of switching the downstream switching valve 15 while hydrogen is being supplied to the metal oxide 11a in a state where the oxidation number is increased. x When hydrogen is supplied to the metal oxide 11a indicated by (a) and (b), carbon dioxide is initially discharged from the gas outlet (see Figs. 6(a) and (b)). The carbon dioxide discharged at this time is sent to the intermediate storage section 17. When the oxidation number of the metal oxide 11a decreases in the entire reactor 11, gas containing hydrogen is discharged from the gas outlet. Therefore, at the timing when the gas discharged from the gas outlet changes from carbon dioxide to gas containing hydrogen (the timing when the state shifts from Fig. 6(b) to Fig. 6(c)), the switching of the downstream switching valve 15 is controlled to switch the destination of the gas discharged from the gas outlet from "intermediate storage" to "recycle". As a result, the gas containing hydrogen discharged from the gas outlet is recovered as a recycled gas and can be reused as hydrogen for the reduction step of the reactor 11.

[0050] Fig. 7 is a fourth diagram for explaining the function of the reactor 11. Fig. 7 is a diagram for explaining the effect of switching the downstream switching valve 15 while carbon dioxide is being supplied to the metal oxide 11a in a state where the oxidation number is reduced. x-When carbon dioxide is supplied to the metal oxide 11a indicated by δ, hydrogen is initially discharged from the gas outlet (see Figs. 7(a) and 7(b)). The hydrogen discharged at this time is recovered as a reuse gas. When the oxidation number of the metal oxide 11a increases in the entire reactor 11, a gas containing carbon monoxide and carbon dioxide is discharged from the gas outlet. Therefore, at the timing when the gas discharged from the gas outlet changes from a gas containing hydrogen to a gas containing carbon monoxide and carbon dioxide (the timing when the gas changes from Fig. 7(b) to Fig. 7(c)), the switching of the downstream switching valve 15 is controlled to switch the destination of the gas discharged from the gas outlet from "reuse" to "intermediate storage". As a result, the gas containing carbon monoxide and carbon dioxide discharged from the gas outlet is stored in the intermediate storage unit 17. As a result, the moisture content of the gas containing carbon monoxide and carbon dioxide stored in the intermediate storage unit 17 can be reduced.

[0051] FIG. 8 is a fifth diagram for explaining the function of the reactor 11. FIG. 8 is a diagram for explaining the effect of switching the upstream switching valve 14 and the downstream switching valve 15 on the metal oxide 11a in a state where the oxidation number is increased. As in FIG. 4, x When hydrogen is supplied to the metal oxide 11a indicated by (a), carbon dioxide is initially discharged from the gas outlet (see Figs. 8(a) and (b)). The carbon dioxide discharged at this time is sent to the intermediate storage section 17. In the entire reactor 11, at the timing when the oxidation number of the metal oxide 11a decreases and gas containing hydrogen is discharged from the gas outlet (the timing of transition from Fig. 8(b) to Fig. 8(c)), the switching of the upstream side switching valve 14 is controlled to supply carbon dioxide from the gas inlet, and the switching of the downstream side switching valve 15 is controlled to switch the destination of the gas discharged from the gas outlet to "recycle". This makes it possible to suppress the consumption of hydrogen that is not involved in the reaction in the reduction step, and to reuse the recovered hydrogen.

[0052] Fig. 9 is a sixth diagram for explaining the function of the reactor 11. Fig. 9 is a diagram for explaining the effect of switching the upstream switching valve 14 and the downstream switching valve 15 on the metal oxide 11a in a state where the oxidation number is reduced. x- When carbon dioxide is supplied to the metal oxide 11a indicated by δ, hydrogen is initially discharged from the gas outlet (see Figs. 9(a) and 9(b)). The hydrogen discharged at this time is recovered as a reuse gas. In the entire reactor 11, at the timing when the oxidation number of the metal oxide 11a increases and a gas containing carbon monoxide and carbon dioxide is discharged from the gas outlet (the timing when the state shifts from Fig. 9(b) to Fig. 9(c)), the upstream switching valve 14 is controlled to supply hydrogen from the gas inlet, and the downstream switching valve 15 is controlled to switch the destination of the gas discharged from the gas outlet to "intermediate storage". This makes it possible to suppress excess consumption of carbon dioxide and reduce the moisture contained in the gas containing carbon monoxide and carbon dioxide. In addition, the flow time of hydrogen that is not involved in the reaction in the reduction step is relatively long, and the concentration of moisture contained in the generated gas stored in the intermediate storage unit 17 can be reduced as much as possible, so that the energy required for dehumidification can be reduced.

[0053] In this way, the reactor 11 of the chemical synthesis system 1 of this embodiment can combine switching of the timing of supplying carbon dioxide or hydrogen to the reactor 11 in the upstream switching valve 14 with switching of the destination of the gas discharged from the gas outlet in the downstream switching valve 15. This makes it possible to store the produced gas suitable for the synthesis of methanol in the chemical synthesis section 20 in the intermediate storage section 17, and to reduce the consumption of energy required for dehumidifying the produced gas.

[0054] Next, the chemical synthesis method of the present embodiment will be described in detail. The chemical synthesis method of the present embodiment is executed by a user of the chemical synthesis system 1 operating the control unit 30 and inputting a command to synthesize a chemical in the chemical synthesis system 1.

[0055] FIG. 10 is a flow chart of a chemical synthesis method using the chemical synthesis system 1. In the chemical synthesis method of this embodiment, first, as a "reduction step", the metal oxide 11a accommodated in the reactor 11 is reduced (step S1). In step S1, the control unit 30 controls the flow rate adjustment unit 13 and the upstream switching valve 14 to supply hydrogen from the hydrogen supply source 7 to the reactor 11. As a result, the metal oxide 11a is reduced. Next, as an "oxidation step", a product gas containing carbon monoxide is generated using the reduced metal oxide 11a (step S2). In step S2, the control unit 30 controls the flow rate adjustment unit 12 and the upstream switching valve 14 to supply carbon dioxide from the carbon dioxide supply source 6 to the reactor 11. As a result, the carbon dioxide is reduced by the metal oxide 11a, and carbon monoxide is generated. The generated carbon monoxide passes through the compressor 16 and is stored in the intermediate storage unit 17.

[0056] Next, in the "synthesis step", ethanol is produced using the carbon monoxide produced by the carbon monoxide production unit 10 (step S3). In step S3, the control unit 30 controls the flow rate adjustment unit 22 to supply the produced gas containing carbon monoxide stored in the intermediate storage unit 17 to the methanol synthesis reactor 21. In step S3, the control unit 30 may control the flow rate adjustment units 23 and 24 to mix at least one of the carbon dioxide from the carbon dioxide supply source 6 and the hydrogen from the hydrogen supply source 7 with the produced gas and supply it to the methanol synthesis reactor 21. In the methanol synthesis reactor 21, methanol is synthesized from carbon monoxide and hydrogen in the methanol synthesis catalyst 21a. In this embodiment, steps S1 to S3 are repeatedly performed to intermittently synthesize methanol.

[0057] Fig. 11 is a flow chart of control in the chemical synthesis method of this embodiment. In the chemical synthesis method of this embodiment, it is possible to control the concentration ratio of carbon monoxide to carbon dioxide contained in the generated gas in the reduction step and the oxidation step shown in Fig. 10. Here, a method of controlling the concentration ratio of carbon monoxide to the sum of the concentrations of carbon monoxide and carbon dioxide (hereinafter referred to as "CO / (CO+CO2) in the generated gas") as the concentration ratio of carbon monoxide to the concentration of carbon dioxide contained in the generated gas will be described.

[0058] The method for controlling CO / (CO+CO2) in the product gas of this embodiment starts by setting the hydrogen flow rate FHn, the carbon dioxide flow rate FCn, the hydrogen flow time THn, and the carbon dioxide flow time TCn to predetermined values. The hydrogen flow rate FHn and the carbon dioxide flow rate FCn are each set in a range from 0.01 L / min to 100 L / min, and the hydrogen flow time THn and the carbon dioxide flow time TCn are each set in a range from 1 second to 100 hours.

[0059] After a predetermined time t has elapsed since the start of control (step S11), it is determined whether the absolute value of the difference between the detection ratio and the target ratio regarding the concentration of carbon monoxide contained in the generated gas stored in the intermediate storage unit 17 is equal to or less than a predetermined value (step S12). The predetermined time t ranges from 1 minute to 100 hours. Here, the detection ratio RCn1 regarding the concentration of carbon monoxide contained in the generated gas is a value expressed by the following formula (3). The CO m1 and CO2 m1 indicate the concentrations of carbon monoxide and carbon dioxide detected by the gas concentration detection unit 18, respectively. RCn1=CO m1 / (CO m1 +CO2 m1 ) ···(3)

[0060] The target ratio RCa1 regarding the concentration of carbon monoxide contained in the generated gas is a value expressed by the following formula (4). a1 and CO2a1 indicate the preset target concentrations of carbon monoxide and carbon dioxide, respectively. RCa1=CO a1 / (CO a1 +CO2 a1 ) ···(4)

[0061] In step S12, the control unit 30 judges whether or not the absolute value of the difference between the detection ratio RCn1 and the target ratio RCa1 related to the carbon monoxide concentration is equal to or less than a preset value G1. If it is judged that the absolute value of the difference between the detection ratio RCn1 and the target ratio RCa1 is equal to or less than the preset value G1 (step S12: Yes), the process returns to step S11, and after a predetermined time has elapsed (step S11), the process proceeds to step S12 again. If it is judged that the absolute value of the difference between the detection ratio RCn1 and the target ratio RCa1 is greater than the preset value G1 (step S12: No), the process proceeds to step S13. The preset value G1 is within a range from 0.01 to 10.

[0062] In step S13, it is determined whether the value obtained by subtracting the target ratio from the detection ratio regarding the carbon monoxide concentration is greater than 0 (step S13). If the control unit 30 determines that the value obtained by subtracting the target ratio RCa1 from the detection ratio RCn1 is greater than 0 (step S13: Yes), the process proceeds to step S14. If the control unit 30 determines that the value obtained by subtracting the target ratio RCa1 from the detection ratio RCn1 is less than 0 (step S13: No), the process proceeds to step S15. Note that in step S14, since it was determined in the immediately preceding step S13 that the absolute value of the difference between the detection ratio RCn1 and the target ratio RCa1 is greater than the positive predetermined value G1, the value obtained by subtracting the target ratio RCa1 from the detection ratio RCn1 does not become 0.

[0063] When the control unit 30 determines that the value obtained by subtracting the target ratio RCa1 from the detection ratio RCn1 is greater than 0, it performs at least one of the following operations (step S14): "reduce the flow rate of hydrogen", "increase the flow rate of carbon dioxide", "reduce the flow time of hydrogen", and "increase the flow time of carbon dioxide". In step S14, the control unit 30 performs at least one of the following setting changes: "change the flow rate of hydrogen to a flow rate FHn+1 obtained by subtracting Δr1 from the flow rate FHn", "change the flow rate of carbon dioxide to a flow rate FCn+1 obtained by adding Δr2 to the flow rate FCn", "change the flow time of hydrogen to a flow time THn+1 obtained by subtracting Δt1 from the flow time THn", and "change the flow time of carbon dioxide to a flow time TCn+1 obtained by adding Δt2 to the flow time TCn". Each of Δr1 and Δr2 is within the range of 0.001 L / min to 100 L / min, and each of Δt1 and Δt2 is within the range of 0.1 seconds to 100 hours.

[0064] In step S14, when at least one of the settings of decreasing the flow rate of hydrogen and decreasing the flow time of hydrogen is changed, the degree of reduction of the metal oxide 11a in the reduction step is decreased. As a result, the oxidation reaction of the metal oxide 11a in the oxidation step is less likely to proceed, and the concentration of carbon monoxide in the generated gas is decreased. On the other hand, when at least one of the settings of increasing the flow rate of carbon dioxide and increasing the flow time of carbon dioxide is changed, the amount of carbon dioxide reacting with the metal oxide 11a in the oxidation step is increased, and the degree of oxidation of the metal oxide 11a is increased, and the degree of reduction of the metal oxide 11a in the next reduction step is decreased. As a result, the concentration of carbon monoxide in the generated gas is decreased.

[0065] When the control unit 30 determines from the detection ratio RCn1 that the target ratio RCa1 is smaller than 0, it performs at least one of the following (step S15): "increase the hydrogen flow rate", "decrease the carbon dioxide flow rate", "increase the hydrogen flow time", and "decrease the carbon dioxide flow time". In step S15, the control unit 30 performs at least one of the following setting changes: "change the hydrogen flow rate to flow rate FHn+1 obtained by adding Δr1 to the flow rate FHn", "change the carbon dioxide flow rate to flow rate FCn+1 obtained by subtracting Δr2 from the flow rate FCn", "change the hydrogen flow time to flow time THn+1 by adding Δt1 to the flow time THn", and "change the carbon dioxide flow time to flow time TCn+1 obtained by subtracting Δt2 from the flow time TCn".

[0066] In step S15, if at least one of the settings is changed to increase the flow rate of hydrogen and the flow time of hydrogen, the degree of reduction of the metal oxide 11a in the reduction step increases. This makes it easier for the oxidation reaction of the metal oxide 11a to proceed in the oxidation step, and the concentration of carbon monoxide in the generated gas increases. In addition, if at least one of the settings is changed to increase the flow rate of carbon dioxide and the flow time of carbon dioxide, the amount of carbon dioxide that reacts with the metal oxide 11a in the oxidation step decreases, and the degree of oxidation of the metal oxide 11a decreases, and the degree of reduction of the metal oxide 11a in the next reduction step increases. This increases the concentration of carbon monoxide in the generated gas.

[0067] After a predetermined time u has elapsed since the setting was changed in steps S14 and S15 (step S16), it is determined whether the difference between the detection ratio and the target ratio regarding the concentration of carbon monoxide before and after the setting change has become smaller (step S17). The predetermined time u ranges from 1 minute to 100 hours. In step S17, the control unit 30 determines whether the difference between the detection ratio RCn1 and the target ratio RCa1 after the setting change in steps S14 and S15 has become smaller than the difference between the detection ratio RCn1 and the target ratio RCa1 before the setting change in steps S14 and S15. When the control unit 30 determines that the difference between the detection ratio RCn1 and the target ratio RCa1 after the change has become smaller than the difference between the detection ratio RCn1 and the target ratio RCa1 before the change (step S17: Yes), the process returns to step S11. When the control unit 30 determines that the difference between the changed detection ratio RCn1 and the target ratio RCa1 is not smaller than the difference between the changed detection ratio RCn1 and the target ratio RCa1 (step S17: No), the control unit 30 returns to step S13 and determines whether the value obtained by subtracting the target ratio from the detection ratio related to the carbon monoxide concentration is greater than 0 (step S13). Depending on the determination result of step S13, the setting is changed in step S14 or step S15.

[0068] In this manner, the chemical synthesis system 1 of the present embodiment controls CO / (CO+CO2) in the generated gas stored in the intermediate storage unit 17. Note that, in the chemical synthesis system 1 of the present embodiment, the controllable range of CO / (CO+CO2) in the generated gas is greater than 0 and less than or equal to 1.

[0069] According to the chemical synthesis system 1 of the present embodiment described above, carbon monoxide, which is a raw material of chemical products, is generated by repeating reduction by hydrogen and oxidation by carbon dioxide in the metal oxide 11a contained in the reactor 11, that is, by the chemical looping method. Carbon monoxide generated by the chemical looping method using the metal oxide 11a is generated by oxidation of the metal oxide 11a by carbon dioxide, so that moisture is less likely to be contained in the product gas generated in the reactor 11. This makes it possible to reduce the energy required for dehumidifying the product gas used in the synthesis of chemical products. Therefore, the energy required for the synthesis of chemical products can be reduced, and chemical products can be efficiently synthesized.

[0070] Moreover, according to the chemical product synthesis system 1 of this embodiment, it is possible to adjust the CO / (CO+CO2) in the generated gas by changing the flow rate of at least one of the hydrogen and carbon dioxide supplied to the reactor 11. As a result, the reactor 11 can supply generated gas with an optimal CO / (CO+CO2) for the chemical products synthesized in the chemical product synthesis section, so that the chemical products can be efficiently synthesized.

[0071] According to the chemical synthesis system 1 of this embodiment, the chemical synthesis unit 20 has a methanol synthesis catalyst 21a and synthesizes methanol as a chemical product. When synthesizing methanol, the theoretical limit conversion rate derived from thermochemical equilibrium is higher for carbon monoxide as a raw material gas than for carbon dioxide. Thus, by combining the chemical synthesis unit 20 with the reactor 11 that generates carbon monoxide from carbon dioxide by a chemical looping method, the yield of methanol can be improved.

[0072] Furthermore, according to the chemical synthesis method of this embodiment, carbon monoxide, which is a raw material for chemical products, can be produced by a chemical looping process including a reduction step with hydrogen and an oxidation step with carbon dioxide in the metal oxide 11a contained in the reactor 11. In the chemical looping process, moisture is less likely to be contained in the generated gas, so that the energy required for dehumidifying the generated gas used in the synthesis of chemical products can be reduced. This reduces the energy required for the synthesis of chemical products, and thus chemical products can be synthesized efficiently.

[0073] Furthermore, according to the computer program of this embodiment, carbon monoxide, which is a raw material for chemical products, can be produced by a chemical looping process including a reduction function by hydrogen and an oxidation function by carbon dioxide in the metal oxide 11a contained in the reactor 11. In the chemical looping process, moisture is less likely to be contained in the generated gas, so that the energy required for dehumidifying the generated gas used in the synthesis of chemical products can be reduced. This reduces the energy required for the synthesis of chemical products, and thus chemical products can be synthesized efficiently.

[0074] <Second embodiment> 12 is a flow chart of control in the chemical synthesis method of the second embodiment. The chemical synthesis system of the second embodiment is different from the chemical synthesis system of the first embodiment (FIG. 1) in that the concentration of hydrogen contained in the generated gas can be controlled.

[0075] The chemical synthesis method of the second embodiment is carried out using a chemical synthesis system 1. In the chemical synthesis method of the present embodiment, in the reduction step and the oxidation step in the reactor 11, it is possible to control the concentration ratio of hydrogen to the sum of the concentrations of carbon monoxide and carbon dioxide contained in the generated gas (hereinafter referred to as "H2 / (CO+CO2) in the generated gas").

[0076] The method for controlling H2 / (CO+CO2) in the generated gas of this embodiment starts with the hydrogen flow rate FHn, carbon dioxide flow rate FCn, hydrogen flow time THn, and carbon dioxide flow time TCn set to predetermined values. After a predetermined time t has elapsed since the start of control (step S21), it is determined whether the absolute value of the difference between the detection ratio and the target ratio regarding the hydrogen concentration in the generated gas stored in the intermediate storage unit 17 is equal to or less than a predetermined value (step S22). The detection ratio RHn1 regarding the hydrogen concentration in the generated gas is a value expressed by the following formula (5). Note that the H2 m1 indicates the concentration of hydrogen detected by the gas concentration detection unit 18. RHn1=H2 m1 / (CO m1 +CO2 m1 ) ···(5)

[0077] The target ratio RHa1 regarding the concentration of hydrogen in the generated gas is a value expressed by the following formula (6). a1 indicates a preset target concentration of hydrogen. RHa1=H2 a1 / (CO a1 +CO2 a1 ) ···(6)

[0078] In step S22, the control unit 30 judges whether the absolute value of the difference between the detection ratio RHn1 and the target ratio RHa1 relating to the hydrogen concentration is equal to or less than a preset value G2. If it is judged that the absolute value of the difference between the detection ratio RHn1 and the target ratio RHa1 is equal to or less than the preset value G2 (step S22: Yes), the process returns to step S21, and after a predetermined time has elapsed (step S21), the process proceeds to step S22 again. If it is judged that the absolute value of the difference between the detection ratio RHn1 and the target ratio RHa1 is greater than the preset value G2 (step S22: No), the process proceeds to step S23. The preset value G2 is within a range of 0.01 to 10.

[0079] In step S23, it is determined whether the value obtained by subtracting the target ratio from the detection ratio related to the hydrogen concentration is greater than 0 (step S23). If the control unit 30 determines that the value obtained by subtracting the target ratio RHa1 from the detection ratio RHn1 is greater than 0 (step S23: Yes), the process proceeds to step S24. If the control unit 30 determines that the value obtained by subtracting the target ratio RHa1 from the detection ratio RHn1 is less than 0 (step S23: No), the process proceeds to step S25. Note that in step S24, since it was determined in the immediately preceding step S23 that the absolute value of the difference between the detection ratio RHn1 and the target ratio RHa1 is greater than the positive predetermined value G2, the value obtained by subtracting the detection ratio RHn1 from the target ratio RHa1 will not be 0.

[0080] If the control unit 30 determines that the difference between the detection ratio RHn1 and the target ratio RHa1 is greater than 0, it performs at least one of the following actions (step S24): "decrease the hydrogen flow rate," "increase the carbon dioxide flow rate," "decrease the hydrogen flow time," and "increase the carbon dioxide flow time." In step S24, the control unit 30 performs at least one of the following setting changes: "change the hydrogen flow rate to flow rate FHn+1 obtained by subtracting Δr1 from the flow rate FHn," "change the carbon dioxide flow rate to flow rate FCn+1 obtained by adding Δr2 to the flow rate FCn," "change the hydrogen flow time to flow time THn+1 obtained by subtracting Δt1 from the flow time THn," and "change the carbon dioxide flow time to flow time TCn+1 obtained by adding Δt2 to the flow time TCn."

[0081] If the control unit 30 determines that the difference between the detection ratio RHn1 and the target ratio RHa1 is less than 0, it performs at least one of the following actions (step S25): "increase the hydrogen flow rate", "decrease the carbon dioxide flow rate", "increase the hydrogen flow time", and "decrease the carbon dioxide flow time". In step S25, the control unit 30 performs at least one of the following setting changes: "change the hydrogen flow rate to flow rate FHn+1 by adding Δr1 to the flow rate FHn", "change the carbon dioxide flow rate to flow rate FCn+1 by subtracting Δr2 from the flow rate FCn", "change the hydrogen flow time to flow time THn+1 by adding Δt1 to the flow time THn", and "change the carbon dioxide flow time to flow time TCn+1 by subtracting Δt2 from the flow time TCn".

[0082] After a predetermined time u has elapsed since the settings were changed in steps S24 and S25 (step S26), the control unit 30 determines whether the difference between the detection ratio and the target ratio relating to the hydrogen concentration before and after the setting change has become smaller (step S27). In step S27, the control unit 30 determines whether the difference between the detection ratio RHn1 and the target ratio RHa1 after the setting change in steps S24 and S25 has become smaller than the difference between the detection ratio RHn1 and the target ratio RHa1 before the setting change in steps S24 and S25. If the control unit 30 determines that the difference between the detection ratio RHn1 and the target ratio RHa1 after the change has become smaller than the difference between the detection ratio RHn1 and the target ratio RHa1 before the change (step S27: Yes), the process returns to step S21. When the control unit 30 determines that the difference between the changed detection ratio RHn1 and the target ratio RHa1 is not smaller than the difference between the pre-change detection ratio RHn1 and the target ratio RHa1 (step S27: No), the process returns to step S23, and determines whether the value obtained by subtracting the target ratio from the detection ratio related to the hydrogen concentration is greater than 0 (step S23). Depending on the determination result of step S23, the settings in step S24 or step S25 are changed. In this manner, in this embodiment, H2 / (CO+CO2) in the generated gas stored in the intermediate storage unit 17 is controlled. Note that, in this embodiment, the controllable range of H2 / (CO+CO2) in the generated gas is greater than 0 and equal to or less than 1.

[0083] According to the chemical product synthesis system 1 of the present embodiment described above, it is possible to adjust H2 / (CO+CO2) in the generated gas by changing the flow rate of at least one of hydrogen and carbon dioxide supplied to the reactor 11. This makes it possible to supply a generated gas with an optimal H2 / (CO+CO2) ratio for the chemical products synthesized in the chemical product synthesis section 20, thereby enabling efficient synthesis of the chemical products.

[0084] <Third embodiment> 13 is a flow chart of control in the chemical synthesis method of the third embodiment. The chemical synthesis system of the third embodiment is different from the chemical synthesis system of the first embodiment (FIG. 1) in that the concentration of carbon monoxide in the raw material gas supplied to the methanol synthesis reactor 21 can be controlled.

[0085] The chemical synthesis method of the third embodiment is carried out using a chemical synthesis system 1. In the chemical synthesis method of the present embodiment, the carbon dioxide supplied from the carbon dioxide supply source 6 is mixed with the generated gas stored in the intermediate storage unit 17, making it possible to control the carbon monoxide concentration ratio to the sum of the carbon monoxide concentration and the carbon dioxide concentration contained in the raw material gas supplied to the methanol synthesis reactor 21 (hereinafter referred to as "CO / (CO+CO2) in the raw material gas").

[0086] The method for controlling CO / (CO+CO2) in the raw material gas of this embodiment starts by setting the flow rate FCn of carbon dioxide supplied from the carbon dioxide supply source 6 to the mixer 25 and the flow rate FMn of the generated gas stored in the intermediate storage unit 17 to predetermined set values. After a predetermined time t has elapsed since the start of control (step S31), it is determined whether or not the absolute value of the difference between the detection ratio and the target ratio regarding the carbon monoxide concentration in the raw material gas supplied to the methanol synthesis reactor 21 is equal to or less than a predetermined value (step S32). Here, the detection ratio RCn2 regarding the carbon monoxide concentration in the raw material gas is a value expressed by the following formula (7). Note that the CO m2 and CO2 m2 indicate the concentrations of carbon monoxide and carbon dioxide detected by the gas concentration detection unit 28a, respectively. RCn2=CO m2 / (CO m2 +CO2 m2 ) ···(7)

[0087] The target ratio RCa2 regarding the concentration of carbon monoxide in the raw material gas is a value expressed by the following formula (8). a2 and CO2 a2indicate the preset target concentrations of carbon monoxide and carbon dioxide, respectively. RCa2=CO a2 / (CO a2 +CO2 a2 ) ···(8)

[0088] In step S32, the control unit 30 judges whether or not the absolute value of the difference between the detection ratio RCn2 and the target ratio RCa2 related to the carbon monoxide concentration is equal to or less than a preset value G3. If it is judged that the absolute value of the difference between the detection ratio RCn2 and the target ratio RCa2 is equal to or less than the preset value G3 (step S32: Yes), the process returns to step S31, and after a predetermined time has elapsed (step S31), the process proceeds to step S32 again. If it is judged that the absolute value of the difference between the detection ratio RCn2 and the target ratio RCa2 is greater than the preset value G3 (step S32: No), the process proceeds to step S33. The preset value G3 is within a range from 0.01 to 10.

[0089] In step S33, it is determined whether the value obtained by subtracting the target ratio from the detection ratio related to the carbon monoxide concentration is greater than 0 (step S33). If the control unit 30 determines that the value obtained by subtracting the target ratio RCa2 from the detection ratio RCn2 is greater than 0 (step S33: Yes), the process proceeds to step S34. If the control unit 30 determines that the value obtained by subtracting the target ratio RCa2 from the detection ratio RCn2 is less than 0 (step S33: No), the process proceeds to step S35. Note that in step S34, since it was determined in the immediately preceding step S33 that the absolute value of the difference between the detection ratio RCn2 and the target ratio RCa2 is greater than the positive predetermined value G3, the value obtained by subtracting the target ratio RCa2 from the detection ratio RCn2 does not become 0.

[0090] If the control unit 30 determines that the value obtained by subtracting the target ratio RCa2 from the detection ratio RCn2 is greater than 0, it performs at least one of "increasing the flow rate of carbon dioxide" and "decreasing the flow rate of the generated gas" (step S34). In step S34, the control unit 30 performs at least one of the setting changes of "changing the flow rate of carbon dioxide to flow rate FCn+1 obtained by adding Δr2 to flow rate FCn" and "changing the flow rate of the generated gas to flow rate FMn+1 obtained by subtracting Δr3 from flow rate FMn". Here, Δr3 is within the range of 0.001 L / min to 100 L / min.

[0091] If the control unit 30 determines that the difference between the detection ratio RCn2 and the target ratio RCa2 is less than 0, it performs at least one of "decreasing the flow rate of carbon dioxide" and "increasing the flow rate of the generated gas" (step S35). In step S35, the control unit 30 performs at least one of the setting changes of "changing the flow rate of carbon dioxide to flow rate FCn+1 obtained by subtracting Δr2 from flow rate FCn" and "changing the flow rate of the generated gas to flow rate FMn+1 by adding Δr3 to flow rate FMn".

[0092] After a predetermined time u has elapsed since the setting was changed in steps S34 and S35 (step S36), the control unit 30 determines whether the difference between the detection ratio and the target ratio regarding the carbon monoxide concentration before and after the setting change has become smaller (step S37). In step S37, the control unit 30 determines whether the difference between the detection ratio RCn2 and the target ratio RCa2 after the setting change in steps S34 and S35 has become smaller than the difference between the detection ratio RCn2 and the target ratio RCa2 before the setting change in steps S34 and S35. If the control unit 30 determines that the difference between the detection ratio RCn2 and the target ratio RCa2 after the change has become smaller than the difference between the detection ratio RCn2 and the target ratio RCa2 before the change (step S37: Yes), the process returns to step S31. When the control unit 30 determines that the difference between the changed detection ratio RCn2 and the target ratio RCa2 is not smaller than the difference between the changed detection ratio RCn2 and the target ratio RCa2 (step S37: No), the control unit 30 returns to step S33 and determines whether the value obtained by subtracting the target ratio from the detection ratio related to the carbon monoxide concentration is greater than 0 (step S33). Depending on the determination result of step S33, the settings in step S34 or step S35 are changed. In this manner, in this embodiment, CO / (CO+CO2) in the raw material gas supplied to the methanol synthesis reactor 21 is controlled.

[0093] In the process of methanol synthesis using the product gas stored in the intermediate storage unit 17, it is desirable to be able to control the CO / (CO+CO2) in the methanol synthesis reactor 21 to be 0.5 to 1.0. The reactor 11 of the carbon monoxide production unit 10 is capable of setting the CO / (CO+CO2) to be greater than 0 and equal to or less than 1. Thus, for example, the product gas is produced by the reactor 11 so that the CO / (CO+CO2) in the product gas stored in the intermediate storage unit 17 becomes 1, and by controlling the flow rate of the carbon dioxide mixed in the mixer 25 and the flow rate of the product gas, the CO / (CO+CO2) in the raw material gas can be controlled to a value suitable for methanol synthesis.

[0094] According to the chemical synthesis system 1 of the present embodiment described above, the chemical synthesis unit 20 has a mixer 25 that mixes carbon dioxide with the product gas generated in the reactor 11. The control unit 30 adjusts the CO / (CO+CO2) ratio in the raw material gas by controlling the flow rate of carbon dioxide mixed with the product gas in the mixer 25. This makes it possible to supply gas with an optimal CO / (CO+CO2) ratio for the chemical products synthesized in the synthesis reactor, thereby enabling the chemical products to be efficiently synthesized.

[0095] <Fourth embodiment> 14 is a flow chart of control in the chemical synthesis method of the fourth embodiment. The chemical synthesis system of the fourth embodiment is different from the chemical synthesis system of the first embodiment (FIG. 1) in that the concentration of hydrogen contained in the raw material gas supplied to the methanol synthesis reactor 21 can be controlled.

[0096] The chemical synthesis method of the fourth embodiment is carried out using a chemical synthesis system 1. In the chemical synthesis method of the present embodiment, at least one of carbon dioxide supplied from a carbon dioxide supply source 6 and hydrogen supplied from a hydrogen supply source 7 is mixed with the generated gas stored in the intermediate storage unit 17, and it is possible to control the concentration ratio of hydrogen to the sum of the concentrations of carbon monoxide and carbon dioxide contained in the raw material gas supplied to the methanol synthesis reactor 21 (hereinafter referred to as "H2 / (CO+CO2) in the raw material gas").

[0097] The method for controlling H2 / (CO+CO2) in the raw material gas of this embodiment starts by setting the flow rate FHn of hydrogen supplied from the hydrogen supply source 7 to the mixer 25, the flow rate FCn of carbon dioxide supplied from the carbon dioxide supply source 6 to the mixer 25, and the flow rate FMn of the generated gas stored in the intermediate storage unit 17 to predetermined set values. After a predetermined time t has elapsed since the start of control (step S41), it is determined whether or not the absolute value of the difference between the detection ratio and the target ratio regarding the hydrogen concentration in the raw material gas supplied to the methanol synthesis reactor 21 is equal to or less than a predetermined value (step S42). Here, the detection ratio RHn2 regarding the hydrogen concentration in the raw material gas is a value expressed by the following formula (9). Note that the H2 m2 indicates the concentration of hydrogen detected by gas concentration detector 28a. RHn2=H2 m2 / (CO m2 +CO2 m2 ) ···(9)

[0098] The target ratio RHa2 regarding the hydrogen concentration in the source gas is a value expressed by the following formula (10). a2 indicates a preset target concentration of hydrogen. RHa2=H2 a2 / (CO a1 +CO2 a1 ) ···(10)

[0099] In step S42, the control unit 30 judges whether the absolute value of the difference between the detection ratio RHn2 and the target ratio RHa2 relating to the hydrogen concentration is equal to or less than a preset value G4. If it is judged that the absolute value of the difference between the detection ratio RHn2 and the target ratio RHa2 is equal to or less than the preset value G4 (step S42: Yes), the process returns to step S41, and after a predetermined time has elapsed (step S41), the process proceeds to step S42 again. If it is judged that the absolute value of the difference between the detection ratio RHn2 and the target ratio RHa2 is greater than the preset value G4 (step S42: No), the process proceeds to step S43. The preset value G4 is within a range of 0.01 to 10.

[0100] In step S43, it is determined whether the value obtained by subtracting the target ratio from the detection ratio related to the hydrogen concentration is greater than 0 (step S43). If the control unit 30 determines that the value obtained by subtracting the target ratio RHa2 from the detection ratio RHn2 is greater than 0 (step S43: Yes), the process proceeds to step S44. If the control unit 30 determines that the value obtained by subtracting the target ratio RHa2 from the detection ratio RHn2 is less than 0 (step S43: No), the process proceeds to step S45. Note that in step S44, since it was determined in the immediately preceding step S43 that the absolute value of the difference between the detection ratio RHn2 and the target ratio RHa2 is greater than the positive predetermined value G4, the value obtained by subtracting the detection ratio RHn2 from the target ratio RHa2 will not be 0.

[0101] If the control unit 30 determines that the difference between the detection ratio RHn2 and the target ratio RHa2 is greater than 0, it performs at least one of the following actions (step S44): "decrease the hydrogen flow rate", "increase the carbon dioxide flow rate", and "increase the generated gas flow rate". In step S44, the control unit 30 performs at least one of the following setting changes: "change the hydrogen flow rate to flow rate FHn+1 obtained by subtracting Δr1 from the flow rate FHn", "change the carbon dioxide flow rate to flow rate FCn+1 obtained by adding Δr2 to flow rate FCn", and "change the generated gas flow rate to flow rate FMn+1 obtained by adding Δr3 to flow rate FMn".

[0102] If the control unit 30 determines that the difference between the detection ratio RHn2 and the target ratio RHa2 is less than 0, it performs at least one of the following actions (step S45): "increase the hydrogen flow rate", "decrease the carbon dioxide flow rate", and "decrease the generated gas flow rate". In step S45, the control unit 30 performs at least one of the following setting changes: "change the hydrogen flow rate to flow rate FHn+1 obtained by adding Δr1 to the flow rate FHn", "change the carbon dioxide flow rate to flow rate FCn+1 obtained by subtracting Δr2 from the flow rate FCn", and "change the generated gas flow rate to flow rate FMn+1 obtained by subtracting Δr3 from the flow rate FMn".

[0103] After a predetermined time u has elapsed since the settings were changed in steps S44 and S45 (step S46), the control unit 30 determines whether the difference between the detection ratio and the target ratio relating to the hydrogen concentration before and after the setting change has become smaller (step S47). In step S47, the control unit 30 determines whether the difference between the detection ratio RHn2 and the target ratio RHa2 after the setting change in steps S44 and S45 has become smaller than the difference between the detection ratio RHn2 and the target ratio RHa2 before the setting change in steps S44 and S45. If the control unit 30 determines that the difference between the detection ratio RHn2 and the target ratio RHa2 after the change has become smaller than the difference between the detection ratio RHn2 and the target ratio RHa2 before the change (step S47: Yes), the process returns to step S41. When the control unit 30 determines that the difference between the changed detection ratio RHn2 and the target ratio RHa2 is not smaller than the difference between the changed detection ratio RHn2 and the target ratio RHa2 (step S47: No), the control unit 30 returns to step S43 and determines whether the difference between the detection ratio related to the hydrogen concentration and the target ratio is greater than 0 (step S43). Depending on the determination result of step S43, the settings in step S44 or step S45 are changed. In this manner, in this embodiment, H2 / (CO+CO2) in the raw material gas supplied to the methanol synthesis reactor 21 is controlled.

[0104] In the process of methanol synthesis using the product gas stored in the intermediate storage unit 17, it is desirable to be able to control H2 / (CO+CO2) in the methanol synthesis reactor 21 to a value between 2 and 8. The reactor 11 of the carbon monoxide production unit 10 is capable of changing H2 / (CO+CO2). Thus, for example, the product gas is produced by the reactor 11, and the flow rates of the hydrogen, carbon dioxide, and product gas mixed in the mixer 25 are controlled so that the H2 / (CO+CO2) of the product gas stored in the intermediate storage unit 17 becomes 2, thereby controlling the concentration ratio of H2 / (CO+CO2) suitable for methanol synthesis.

[0105] According to the chemical synthesis system 1 of this embodiment described above, the chemical synthesis unit 20 has a mixer 25 that mixes at least one of hydrogen and carbon dioxide with the product gas generated in the reactor 11. The control unit 30 adjusts the H2 / (CO+CO2) ratio in the raw material gas by controlling the flow rate of at least one of hydrogen and carbon dioxide mixed with the product gas in the mixer 25. This makes it possible to supply a gas with an optimal H2 / (CO+CO2) ratio for the chemical products synthesized in the methanol synthesis reactor 21, thereby enabling the chemical products to be efficiently synthesized.

[0106] <Fifth embodiment> 15 is a schematic diagram showing a schematic configuration of a chemical synthesis system according to a fifth embodiment. The chemical synthesis system according to the fifth embodiment is different from the chemical synthesis system according to the first embodiment (FIG. 1) in that two reactors for generating carbon monoxide are provided.

[0107] The chemical synthesis system 2 of this embodiment includes a carbon dioxide supply source 6, a hydrogen supply source 7, a carbon monoxide generator 40, a chemical synthesis unit 20, and a control unit 30. The chemical synthesis system 2 of this embodiment produces methanol by utilizing a catalytic reaction. However, the chemicals produced by the chemical synthesis system 2 are not limited thereto.

[0108] The carbon monoxide generator 40 generates carbon monoxide using carbon dioxide supplied from a carbon dioxide supply source 6 and hydrogen supplied from a hydrogen supply source 7. The carbon monoxide generator 40 includes a first reactor 41, a second reactor 42, two flow rate adjustment units 12 and 13, an upstream switching valve 44, a downstream switching valve 45, a compressor 16, an intermediate storage unit 17, and a gas concentration detection unit 18.

[0109] Each of the first reactor 41 and the second reactor 42 has the same configuration as the reactor 11 of the first embodiment. That is, the first reactor 41 accommodates therein a metal oxide 41a that can be reduced by a chemical reaction with hydrogen and oxidized by a chemical reaction with carbon dioxide. The second reactor 42 accommodates therein a metal oxide 42a that can be reduced by a chemical reaction with hydrogen and oxidized by a chemical reaction with carbon dioxide, separately from the first reactor 41. In this embodiment, each of the metal oxides 41a and 42a is a metal oxide having a plurality of stable valences, such as iron oxide, cobalt oxide, and indium oxide. In each of the first reactor 41 and the second reactor 42, the reduction step described in formula (1) of the first embodiment and the oxidation step described in formula (2) are alternately performed. As a result, each of the first reactor 41 and the second reactor 42 can separately generate water in the reduction step and generate a product gas containing carbon monoxide in the oxidation step.

[0110] The upstream switching valve 44 is a so-called four-way valve, and is connected to the gas inlet of the first reactor 41 via a flow path 40a, and is connected to the gas inlet of the second reactor 42 via a flow path 40c. The upstream switching valve 44 is electrically connected to the control unit 30, and supplies one of hydrogen or carbon dioxide to one of the first reactor 41 or the second reactor 42, and supplies the other of the hydrogen or carbon dioxide to the other of the first reactor 41 or the second reactor 42, in response to a command output by the control unit 30.

[0111] The downstream switching valve 45 is a so-called four-way valve, and is connected to the gas outlet of the first reactor 41 via the flow path 40b, and is connected to the gas outlet of the second reactor 42 via the flow path 40d. The downstream switching valve 45 is electrically connected to the control unit 30, and switches the destination of the gas discharged from the first reactor 41 and the second reactor 42 in response to a command output by the control unit 30. In this embodiment, when the gas discharged from one of the first reactor 41 or the second reactor 42 is sent to the intermediate storage unit 17 via the compressor 16, the downstream switching valve 45 sends the gas discharged from the other of the first reactor 41 or the second reactor 42 to the hydrogen supply source 7.

[0112] Next, the chemical synthesis method of the present embodiment will be described in detail. The chemical synthesis method of the present embodiment is executed by a user of the chemical synthesis system 2 operating the control unit 30 and inputting a command to synthesize a chemical in the chemical synthesis system 2.

[0113] FIG. 16 is a flowchart of a chemical synthesis method using the chemical synthesis system 2. In the chemical synthesis method of this embodiment, one of the metal oxide 41a in the first reactor 41 or the metal oxide 42a in the second reactor 42 is required to be in a reduced state (a state in which the oxidation number is decreased) as a condition for executing the chemical synthesis method. Therefore, when both the metal oxide 41a and the metal oxide 42a are in an oxidized state (a state in which the oxidation number is increased), one of the metal oxide 41a and the metal oxide 42a is reduced and then the chemical synthesis method is executed. Here, it is assumed that the metal oxide 41a is in a reduced state.

[0114] In the chemical synthesis method of the present embodiment, first, in an "oxidation step", a product gas containing carbon monoxide is generated using the metal oxide 41a (step S1a), while in a "reduction step", the metal oxide 42a in the second reactor 42 is reduced (step S1b). In steps S1a and S1b, the control unit 30 controls the flow rate regulators 12, 13 and the upstream switching valve 44 to supply carbon dioxide from the carbon dioxide supply source 6 to the first reactor 41, and supply hydrogen from the hydrogen supply source 7 to the second reactor 42. As a result, in the first reactor 41, carbon dioxide is reduced by the metal oxide 41a to generate carbon monoxide, while in the second reactor 42, the metal oxide 42a is reduced by hydrogen to generate moisture.

[0115] Next, in the methanol synthesis reactor 21, methanol is synthesized using the raw material gas containing carbon monoxide produced in the first reactor 41 (step S2a: synthesis step). At this time, in the second reactor 42, reduction of the metal oxide 42a with hydrogen is carried out (step S1b).

[0116] Next, in the "reduction step", the metal oxide 41a in the first reactor 41 is reduced (step S3a), while in the "oxidation step", the metal oxide 42a is used to generate a product gas containing carbon monoxide (step S2b). In steps S3a and S2b, the control unit 30 controls the flow rate regulators 12 and 13 and the upstream switching valve 44 to supply carbon dioxide from the carbon dioxide supply source 6 to the second reactor 42, and supply hydrogen from the hydrogen supply source 7 to the first reactor 41.

[0117] Next, in the methanol synthesis reactor 21, methanol is synthesized using the raw material gas containing carbon monoxide generated in the second reactor 42 (step S3b: synthesis step). At this time, in the first reactor 41, reduction of the metal oxide 41a with hydrogen is performed. In the methanol synthesis method of this embodiment, carbon dioxide is supplied to one of the first reactor 41 or the second reactor 42 to generate carbon monoxide, while hydrogen is supplied to the other of the first reactor 41 or the second reactor 42 to reduce the metal oxide. As a result, carbon monoxide for producing methanol can be generated in either the first reactor 41 or the second reactor 42, so that the methanol synthesis reactor 21 can continuously synthesize methanol.

[0118] Fig. 17 is a flow chart of the control in the chemical synthesis method of this embodiment. In the chemical synthesis method of this embodiment, it is possible to control CO / (CO+CO2) in the generated gas in the reduction step and the oxidation step shown in Fig. 16. Here, the method of controlling CO / (CO+CO2) in the generated gas will be described.

[0119] The method for controlling CO / (CO+CO2) in the product gas of this embodiment is started by setting the hydrogen flow rate FHn, the carbon dioxide flow rate FCn, the gas switching span TSn, and the gas switching delay time TDn to predetermined set values. The "gas switching span" refers to the time interval for switching the upstream switching valve 44 and the downstream switching valve 45, that is, the time for the oxidation process and the reduction process. The "gas switching delay time" refers to the delay time from when the upstream switching valve 44 is switched to when the downstream switching valve 45 is switched in the transition from the oxidation process to the reduction process in one reactor, or from the reduction process to the oxidation process, and is a time interval that does not exceed the gas switching span. The setting ranges of the gas switching span TSn and the gas switching delay time TDn are from 1 second to 100 hours.

[0120] After a predetermined time t has elapsed since the start of control (step S51), it is determined whether the absolute value of the difference between the detection ratio and the target ratio for the carbon monoxide concentration in the produced gas stored in intermediate storage unit 17 is equal to or less than a predetermined value (step S52). The detection ratio RCn3 for the carbon monoxide concentration in the produced gas is a value expressed by the following formula (11), and the target ratio RCa3 for the carbon monoxide concentration in the produced gas is a value expressed by the following formula (12). RCn3=CO m1 / (CO m1 +CO2 m1 ) ···(11) RCa1=CO a1 / (CO a1 +CO2 a1 ) ···(12)

[0121] In step S52, the control unit 30 judges whether or not the absolute value of the difference between the detection ratio RCn3 and the target ratio RCa3 related to the concentration of carbon monoxide is equal to or less than a preset value G5. If it is judged that the absolute value of the difference between the detection ratio RCn3 and the target ratio RCa3 is equal to or less than the preset value G5 (step S52: Yes), the process returns to step S51, and after a predetermined time has elapsed (step 51), the process proceeds to step S52 again. If it is judged that the absolute value of the difference between the detection ratio RCn3 and the target ratio RCa3 is greater than the preset value G5 (step S52: No), the process proceeds to step S53. The preset value G5 is within a range from 0.01 to 10.

[0122] In step S53, it is determined whether or not the value obtained by subtracting the target ratio from the detection ratio related to the carbon monoxide concentration is greater than 0 (step S53). If the control unit 30 determines that the value obtained by subtracting the target ratio RCa3 from the detection ratio RCn3 is greater than 0 (step S53: Yes), the process proceeds to step S54. If the control unit 30 determines that the value obtained by subtracting the target ratio RCa3 from the detection ratio RCn3 is less than 0 (step S53: No), the process proceeds to step S55. Note that in step S54, since it was determined in the previous step S53 that the absolute value of the difference between the detection ratio RCn3 and the target ratio RCa3 is greater than the positive predetermined value G5, the value obtained by subtracting the target ratio RCa3 from the detection ratio RCn3 does not become 0.

[0123] If the control unit 30 determines that the value obtained by subtracting the target ratio RCa3 from the detection ratio RCn3 is greater than 0, it performs at least one of the following operations (step S54): "reduce the hydrogen flow rate", "increase the carbon dioxide flow rate", "increase the gas switching span", and "increase the gas switching delay time". In step S54, the control unit 30 performs at least one of the following setting changes: "change the hydrogen flow rate to flow rate FHn+1 obtained by subtracting Δr1 from flow rate FHn", "change the carbon dioxide flow rate to flow rate FCn+1 obtained by adding Δr2 to flow rate FCn", "change the gas switching span to time TCn+1 obtained by adding time TSn to Δt3", and "change the gas switching delay time to time TDn+1 obtained by adding time TDn to Δt4". Each of Δt3 and Δt4 is within the range of 0.1 seconds to 100 hours.

[0124] If the control unit 30 determines that the difference between the detection ratio RCn3 and the target ratio RCa3 is less than 0, it performs at least one of the following actions (step S55): "increase the hydrogen flow rate", "decrease the carbon dioxide flow rate", "decrease the gas switching span", and "decrease the gas switching delay time". In step S55, the control unit 30 performs at least one of the following setting changes: "change the hydrogen flow rate to flow rate FHn+1 obtained by adding Δr1 to the flow rate FHn", "change the carbon dioxide flow rate to flow rate FCn+1 obtained by subtracting Δr2 from the flow rate FCn", "change the gas switching span to time TCn+1 obtained by subtracting Δt3 from time TSn", and "change the gas switching delay time to time TDn+1 obtained by subtracting Δt4 from time TDn".

[0125] After a predetermined time u has elapsed since the setting was changed in steps S54 and S55 (step S56), the control unit 30 determines whether the difference between the detection ratio and the target ratio regarding the carbon monoxide concentration before and after the setting change has become smaller (step S57). In step S57, the control unit 30 determines whether the difference between the detection ratio RCn3 and the target ratio RCa3 after the setting change in steps S54 and S55 has become smaller than the difference between the detection ratio RCn3 and the target ratio RCa3 before the setting change in steps S54 and S55. If the control unit 30 determines that the difference between the detection ratio RCn3 and the target ratio RCa3 after the change has become smaller than the difference between the detection ratio RCn3 and the target ratio RCa3 before the change (step S57: Yes), the process returns to step S51. When the control unit 30 judges that the difference between the changed detection ratio RCn3 and the target ratio RCa3 is not smaller than the difference between the changed detection ratio RCn3 and the target ratio RCa3 (step S57: No), the process returns to step S53 and judges whether the value obtained by subtracting the target ratio from the detection ratio related to the carbon monoxide concentration is greater than 0 (step S53). Depending on the judgment result of step S53, the setting is changed in step S54 or step S55. In this way, the chemical synthesis system 2 of this embodiment controls CO / (CO+CO2) in the generated gas stored in the intermediate storage unit 17. Note that, in the chemical synthesis system 2 of this embodiment, the controllable range of CO / (CO+CO2) in the generated gas is greater than 0 and equal to or less than 1.

[0126] The chemical synthesis system 2 of this embodiment includes two reactors 41 and 42 arranged in parallel with respect to the flow of carbon dioxide that is reduced to carbon monoxide. In the chemical synthesis method using the chemical synthesis system 2, the reduction process and the oxidation process are simultaneously switched between the first reactor 41 and the second reactor 42 by switching the upstream switching valve 44. Therefore, the flow time of hydrogen and the flow time of carbon dioxide are the same, and the time at which the hydrogen is sent to be recovered as a reused gas in the downstream switching valve 45 and the time at which the hydrogen is sent to the intermediate storage section 17 to be stored as a generated gas are also the same. Therefore, by changing at least one of the gas switching span TSn and the gas switching delay time TDn in addition to the hydrogen flow rate FHn and the carbon dioxide flow rate FCn, the CO / (CO+CO2) in the generated gas can be controlled.

[0127] According to the chemical product synthesis system 2 of the present embodiment described above, when hydrogen is supplied to one of the first reactor 41 and the second reactor 42, the control unit 30 controls the upstream switching valve 44 so that carbon dioxide is supplied to the other of the first reactor 41 and the second reactor 42. This allows the gas containing carbon monoxide to be continuously supplied to the chemical product synthesis unit 20, so that chemical products can be continuously synthesized.

[0128] Moreover, according to the chemical product synthesis system 1 of this embodiment, it is possible to adjust the CO / (CO+CO2) in the generated gas by changing the flow rate of at least one of the hydrogen and carbon dioxide supplied to the first reactor 41 and the second reactor 42. As a result, the first reactor 41 and the second reactor 42 can supply generated gas with an optimal CO / (CO+CO2) for the chemical products synthesized in the chemical product synthesis section, so that the chemical products can be efficiently synthesized.

[0129] Sixth embodiment Fig. 18 is a flow chart of control in the chemical synthesis method of the sixth embodiment. The chemical synthesis system of the sixth embodiment is different from the chemical synthesis system of the fifth embodiment (Fig. 15) in that the concentration of hydrogen contained in the generated gas can be controlled.

[0130] The chemical synthesis method of the sixth embodiment is carried out using a chemical synthesis system 2. In the chemical synthesis method of the present embodiment, it is possible to control H2 / (CO+CO2) in the generated gas in the reduction step and the oxidation step in the reactor 11. Here, a method for controlling H2 / (CO+CO2) in the generated gas will be described.

[0131] The method for controlling H2 / (CO+CO2) in the generated gas of this embodiment starts with the hydrogen flow rate FHn, carbon dioxide flow rate FCn, gas switching span TSn, and gas switching delay time TDn set to predetermined values. After a predetermined time t has elapsed since the start of control (step S61), it is determined whether the absolute value of the difference between the detection ratio and the target ratio regarding the hydrogen concentration in the generated gas stored in the intermediate storage unit 17 is equal to or less than a predetermined value (step S62). The detection ratio RHn3 regarding the hydrogen concentration in the generated gas is a value expressed by the following formula (13). The target ratio RHa3 regarding the hydrogen concentration in the generated gas is a value expressed by the following formula (14). RHn3=H2 m1 / (CO m1 +CO2 m1 ) ···(13) RHa3=H2 a1 / (CO a1 +CO2 a1 ) ···(14)

[0132] In step S62, the control unit 30 judges whether the absolute value of the difference between the detection ratio RHn3 and the target ratio RHa3 relating to the hydrogen concentration is equal to or less than a preset value G6. If it is judged that the absolute value of the difference between the detection ratio RHn3 and the target ratio RHa3 is equal to or less than the preset value G6 (step S62: Yes), the process returns to step S61, and after a predetermined time has elapsed (step S61), the process proceeds to step S62 again. If it is judged that the absolute value of the difference between the detection ratio RHn3 and the target ratio RHa3 is greater than the preset value G6 (step S62: No), the process proceeds to step S63. The preset value G6 is within a range of 0.01 to 10.

[0133] In step S63, it is determined whether the value obtained by subtracting the target ratio from the detection ratio related to the hydrogen concentration is greater than 0 (step S63). If the control unit 30 determines that the value obtained by subtracting the target ratio RHa3 from the detection ratio RHn3 is greater than 0 (step S63: Yes), the process proceeds to step S64. If the control unit 30 determines that the value obtained by subtracting the target ratio RHa3 from the detection ratio RHn3 is less than 0 (step S63: No), the process proceeds to step S65. Note that in step S64, since it was determined in the immediately preceding step S63 that the absolute value of the difference between the detection ratio RHn3 and the target ratio RHa3 is greater than the positive predetermined value G6, the value obtained by subtracting the detection ratio RHn3 from the target ratio RHa3 will not be 0.

[0134] If the control unit 30 determines that the difference between the detection ratio RHn3 and the target ratio RHa3 is greater than 0, it performs at least one of the following actions (step S64): "decrease the hydrogen flow rate," "increase the carbon dioxide flow rate," "increase the gas switching span," and "increase the gas switching delay time." In step S64, the control unit 30 performs at least one of the following setting changes: "change the hydrogen flow rate to flow rate FHn+1 obtained by subtracting Δr1 from the flow rate FHn," "change the carbon dioxide flow rate to flow rate FCn+1 obtained by adding Δr2 to flow rate FCn," "change the gas switching span to time TCn+1 obtained by adding Δt3 to time TSn," and "change the gas switching delay time to time TDn+1 obtained by adding Δt4 to time TDn."

[0135] If the control unit 30 determines that the difference between the detection ratio RHn3 and the target ratio RHa3 is less than 0, it performs at least one of the following actions (step S65): "increase the hydrogen flow rate," "decrease the carbon dioxide flow rate," "decrease the gas switching span," and "decrease the gas switching delay time." In step S65, the control unit 30 performs at least one of the following setting changes: "change the hydrogen flow rate to flow rate FHn+1 obtained by adding Δr1 to the flow rate FHn," "change the carbon dioxide flow rate to flow rate FCn+1 obtained by subtracting Δr2 from the flow rate FCn," "change the gas switching span to time TCn+1 obtained by subtracting Δt3 from time TSn," and "change the gas switching delay time to time TDn+1 obtained by subtracting Δt4 from time TDn."

[0136] After a predetermined time u has elapsed since the settings were changed in steps S64 and S65 (step S66), the control unit 30 determines whether the difference between the detection ratio and the target ratio for the hydrogen concentration before and after the setting change has become smaller (step S67). In step S67, the control unit 30 determines whether the difference between the detection ratio RHn3 and the target ratio RHa3 after the setting change in steps S64 and S65 has become smaller than the difference between the detection ratio RHn3 and the target ratio RHa3 before the setting change in steps S64 and S65. If the control unit 30 determines that the difference between the detection ratio RHn3 and the target ratio RHa3 after the change has become smaller than the difference between the detection ratio RHn3 and the target ratio RHa3 before the change (step S67: Yes), the process returns to step S61. When the control unit 30 judges that the difference between the changed detection ratio RHn3 and the target ratio RHa3 is not smaller than the difference between the changed detection ratio RHn3 and the target ratio RHa3 (step S67: No), the process returns to step S63, and judges whether the value obtained by subtracting the target ratio from the detection ratio related to the hydrogen concentration is greater than 0 (step S63). Depending on the judgment result of step S63, the setting is changed in step S64 or step S65. In this way, the chemical synthesis system 2 of this embodiment controls H2 / (CO+CO2) in the generated gas stored in the intermediate storage unit 17. Note that, in the chemical synthesis system 2 of this embodiment, the controllable range of H2 / (CO+CO2) in the generated gas is greater than 0 and equal to or less than 1.

[0137] The chemical synthesis system 2 of this embodiment includes two reactors 41, 42 arranged in parallel with respect to the flow of carbon dioxide, and therefore the reduction process and the oxidation process are switched simultaneously between the first reactor 41 and the second reactor 42 by switching the upstream switching valve 44. This makes it possible to control H2 / (CO+CO2) in the generated gas by changing at least one of the gas switching span TSn and the gas switching delay time TDn in addition to the hydrogen flow rate FHn and the carbon dioxide flow rate FCn.

[0138] According to the chemical product synthesis system 2 of the present embodiment described above, it is possible to adjust H2 / (CO+CO2) in the generated gas by changing the flow rate of at least one of hydrogen and carbon dioxide supplied to the first reactor 41 and the second reactor 42. As a result, the first reactor 41 and the second reactor 42 can supply generated gas with an optimal H2 / (CO+CO2) ratio for the chemical products synthesized in the chemical product synthesis section, so that the chemical products can be efficiently synthesized.

[0139] <Modifications of this embodiment> The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit and scope of the invention. For example, the following modifications are also possible.

[0140] [Variation 1] In the first embodiment, it is possible to control the concentration ratio of carbon monoxide to the concentration of carbon dioxide contained in the generated gas. In the second embodiment, it is possible to control the concentration ratio of hydrogen to the total concentration of carbon monoxide and carbon dioxide contained in the generated gas. It may be possible to simultaneously control the concentration ratio of carbon monoxide to the concentration of carbon dioxide and the concentration ratio of hydrogen to the total concentration of carbon monoxide and carbon dioxide in the generated gas.

[0141] [Variation 2] In the third embodiment, it is possible to control the concentration ratio of carbon monoxide to the concentration of carbon dioxide contained in the raw material gas. In the fourth embodiment, it is possible to control the concentration ratio of hydrogen to the total concentration of carbon monoxide and carbon dioxide contained in the raw material gas. In the raw material gas, it may be possible to simultaneously control the concentration ratio of carbon monoxide to the concentration of carbon dioxide and the concentration ratio of hydrogen to the total concentration of carbon monoxide and carbon dioxide. In addition, for example, it is possible to control the concentration ratio of hydrogen to the total concentration of carbon monoxide and carbon dioxide contained in the raw material gas while controlling the concentration ratio of carbon monoxide to the concentration of carbon dioxide contained in the generated gas.

[0142] [Variation 3] In the first, second, fifth and sixth embodiments, the flow rate regulator 12 for regulating the flow rate of carbon dioxide supplied to the reactor and the flow rate regulator 13 for regulating the flow rate of hydrogen are provided to regulate the carbon monoxide concentration and the hydrogen concentration contained in the generated gas. However, these flow rate regulators are not necessary. It is sufficient if a chemical product can be synthesized using carbon monoxide generated using a metal oxide.

[0143] [Variation 4] In the third and fourth embodiments, a mixer is provided for mixing the product gas with at least one of carbon dioxide and hydrogen. However, the mixer may be omitted. It is sufficient that the product gas is mixed with at least one of carbon dioxide and hydrogen in the methanol synthesis reactor before the synthesis of methanol.

[0144] [Variation 5] In the above embodiment, the chemical synthesis system synthesizes methanol. However, the chemicals synthesized by the chemical synthesis system are not limited to this. In the chemical synthesis system in the above embodiment, the concentration ratio of carbon monoxide and the concentration ratio of hydrogen can be adjusted in the generated gas or the raw material gas, so that the concentration ratio can be adjusted according to the type of chemical product, and the chemical product can be efficiently synthesized.

[0145] Although the present aspect has been described above based on the embodiment and modified examples, the above-mentioned embodiment of the aspect is intended to facilitate understanding of the present aspect and does not limit the present aspect. The present aspect may be modified or improved without departing from the spirit and scope of the claims, and equivalents are included in the present aspect. Furthermore, if a technical feature is not described as essential in this specification, it may be deleted as appropriate.

[0146] <Application example 1> A chemical synthesis system comprising: a first reactor containing a metal oxide and into which hydrogen and carbon dioxide are supplied from respective sources; A switching unit capable of switching between a state in which hydrogen is supplied to the first reactor and a state in which carbon dioxide is supplied to the first reactor; a control unit that controls the switching unit so that hydrogen and carbon dioxide are alternately supplied to the first reactor, the control unit producing water by supplying hydrogen to the first reactor and producing carbon monoxide by supplying carbon dioxide to the first reactor; A chemical product synthesis unit to which the product gas generated in the first reactor is supplied, and which synthesizes a chemical product using carbon monoxide contained in the product gas. Chemical synthesis system. <Application example 2> The chemical synthesis system according to Application Example 1 further comprises: a flow rate adjusting unit that adjusts a flow rate of at least one of hydrogen and carbon dioxide supplied to the first reactor, The control unit controls the flow rate adjustment unit to adjust the ratio of carbon monoxide concentration to carbon dioxide concentration contained in the generated gas supplied to the chemical product synthesis unit. Chemical synthesis system. <Application example 3> The chemical synthesis system according to Application Example 1 or Application Example 2 further comprises: a flow rate adjusting unit that adjusts a flow rate of at least one of hydrogen and carbon dioxide supplied to the first reactor, The control unit controls the flow rate adjustment unit to adjust the hydrogen concentration ratio to the sum of the carbon monoxide concentration and the carbon dioxide concentration contained in the generated gas supplied to the chemical product synthesis unit. Chemical synthesis system. <Application Example 4> The chemical synthesis system according to any one of Application Examples 1 to 3 further comprises: a second reactor containing a metal oxide and supplied with hydrogen and carbon dioxide from respective sources, said second reactor being separate from said first reactor; The switching unit is capable of switching between a state in which hydrogen is supplied to the second reactor and a state in which carbon dioxide is supplied to the second reactor, The control unit controls the switching unit so that, when hydrogen is supplied to one of the first reactor and the second reactor, carbon dioxide is supplied to the other of the first reactor and the second reactor. Chemical synthesis system. <Application example 5> The chemical synthesis system according to any one of Application Examples 1 to 4, The chemical synthesis unit includes: A synthesis reactor containing a catalyst for synthesizing a chemical product; A mixer that mixes carbon dioxide with the product gas generated in the first reactor; A mixing amount adjusting unit that adjusts the flow rate of carbon dioxide supplied to the mixer, the control unit controls the mixing amount adjustment unit to adjust a concentration ratio of carbon monoxide to a concentration of carbon dioxide contained in a raw material gas including the carbon dioxide and the produced gas mixed in the mixer, The synthesis reactor synthesizes a chemical product using the raw material gas. Chemical synthesis system. <Application Example 6> The chemical synthesis system according to any one of Application Examples 1 to 5, The chemical synthesis unit includes: A synthesis reactor containing a catalyst for synthesizing a chemical product; a mixer for mixing at least one of hydrogen and carbon dioxide with the product gas generated in the first reactor; a mixture amount adjusting unit that adjusts a flow rate of at least one of hydrogen and carbon dioxide supplied to the mixer, the control unit controls the mixing amount adjustment unit to adjust a concentration ratio of hydrogen to a sum of a concentration of carbon monoxide and a concentration of carbon dioxide contained in a raw material gas including at least one of hydrogen and carbon dioxide and the generated gas mixed in the mixer; The synthesis reactor synthesizes a chemical product using the raw material gas. Chemical synthesis system. <Application Example 7> The chemical synthesis system according to any one of Application Examples 1 to 6, The chemical synthesis unit includes: It has a catalyst for methanol synthesis, Methanol is synthesized as the chemical product. Chemical synthesis system. <Application Example 8> A chemical synthesis method for synthesizing a chemical product using a chemical synthesis system, comprising: a reduction step of producing water by supplying hydrogen to a first reactor containing a metal oxide; an oxidation step of producing carbon monoxide by supplying carbon dioxide to the first reactor; A synthesis step in which a product gas generated in the first reactor is supplied, and a synthesis step in which a chemical product is synthesized using carbon monoxide contained in the product gas is provided. Chemical product synthesis method. <Application Example 9> A computer program for causing a computer to execute synthesis of a chemical product using a chemical product synthesis system, A reduction function for producing water by supplying hydrogen to a first reactor containing a metal oxide; an oxidation function of generating carbon monoxide by supplying carbon dioxide to the first reactor; a synthesis function to which a product gas generated in the first reactor is supplied, the synthesis function being for synthesizing a chemical product using carbon monoxide contained in the product gas; Computer program. [Explanation of symbols]

[0147] 1,2…Chemical synthesis system 6…Carbon dioxide sources 7. Hydrogen supply source 11...Reactor 11a, 41a, 42a...Metal oxide 12,13,22,23,24,29a...Flow rate adjustment section 14, 44…Upstream switching valve 20...Chemical product synthesis department 21...Methanol synthesis reactor 21a…Methanol synthesis catalyst 25...Mixer 41…First reactor 42...Second reactor

Claims

1. A chemical synthesis system comprising: a first reactor containing a metal oxide and into which hydrogen and carbon dioxide are supplied from respective sources; A switching unit capable of switching between a state in which hydrogen is supplied to the first reactor and a state in which carbon dioxide is supplied to the first reactor; a control unit that controls the switching unit so that hydrogen and carbon dioxide are alternately supplied to the first reactor, the control unit producing water by supplying hydrogen to the first reactor and producing carbon monoxide by supplying carbon dioxide to the first reactor; A chemical product synthesis unit to which the product gas generated in the first reactor is supplied, and which synthesizes a chemical product using carbon monoxide contained in the product gas. Chemical synthesis system.

2. The chemical synthesis system according to claim 1 further comprises: a flow rate adjusting unit that adjusts a flow rate of at least one of hydrogen and carbon dioxide supplied to the first reactor, The control unit controls the flow rate adjustment unit to adjust the ratio of carbon monoxide concentration to carbon dioxide concentration contained in the generated gas supplied to the chemical product synthesis unit. Chemical synthesis system.

3. The chemical synthesis system according to claim 1 further comprises: a flow rate adjusting unit that adjusts a flow rate of at least one of hydrogen and carbon dioxide supplied to the first reactor, The control unit controls the flow rate adjustment unit to adjust the hydrogen concentration ratio to the sum of the carbon monoxide concentration and the carbon dioxide concentration contained in the generated gas supplied to the chemical product synthesis unit. Chemical synthesis system.

4. The chemical synthesis system according to any one of claims 1 to 3 further comprises: a second reactor containing a metal oxide and supplied with hydrogen and carbon dioxide from respective sources, said second reactor being separate from said first reactor; The switching unit is capable of switching between a state in which hydrogen is supplied to the second reactor and a state in which carbon dioxide is supplied to the second reactor, The control unit controls the switching unit so that, when hydrogen is supplied to one of the first reactor and the second reactor, carbon dioxide is supplied to the other of the first reactor and the second reactor. Chemical synthesis system.

5. The chemical synthesis system according to any one of claims 1 to 3, The chemical synthesis unit includes: A synthesis reactor containing a catalyst for synthesizing a chemical product; A mixer that mixes carbon dioxide with the product gas generated in the first reactor; A mixing amount adjusting unit that adjusts the flow rate of carbon dioxide supplied to the mixer, the control unit controls the mixing amount adjustment unit to adjust a concentration ratio of carbon monoxide to a concentration of carbon dioxide contained in a raw material gas including the carbon dioxide and the produced gas mixed in the mixer, The synthesis reactor synthesizes a chemical product using the raw material gas. Chemical synthesis system.

6. The chemical synthesis system according to any one of claims 1 to 3, The chemical synthesis unit includes: A synthesis reactor containing a catalyst for synthesizing a chemical product; a mixer that mixes at least one of hydrogen and carbon dioxide with the product gas generated in the first reactor; a mixture amount adjusting unit that adjusts a flow rate of at least one of hydrogen and carbon dioxide supplied to the mixer, the control unit controls the mixing amount adjustment unit to adjust a concentration ratio of hydrogen to a sum of a concentration of carbon monoxide and a concentration of carbon dioxide contained in a raw material gas including at least one of hydrogen and carbon dioxide and the generated gas mixed in the mixer; The synthesis reactor synthesizes a chemical product using the raw material gas. Chemical synthesis system.

7. The chemical synthesis system according to any one of claims 1 to 3, The chemical synthesis unit includes: It has a catalyst for methanol synthesis, Methanol is synthesized as the chemical product. Chemical synthesis system.

8. A chemical synthesis method for synthesizing a chemical product using a chemical synthesis system, comprising: a reduction step of producing water by supplying hydrogen to a first reactor containing a metal oxide; an oxidation step of producing carbon monoxide by supplying carbon dioxide to the first reactor; A synthesis step in which a product gas generated in the first reactor is supplied, and a synthesis step in which a chemical product is synthesized using carbon monoxide contained in the product gas is provided. Chemical product synthesis method.

9. A computer program for causing a computer to execute synthesis of a chemical product using a chemical product synthesis system, A reduction function for producing water by supplying hydrogen to a first reactor containing a metal oxide; an oxidation function of generating carbon monoxide by supplying carbon dioxide to the first reactor; a synthesis function to which a product gas generated in the first reactor is supplied, the synthesis function synthesizing a chemical product using carbon monoxide contained in the product gas; Computer program.

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