A method for synthesizing an aqueous methanol solution, and an apparatus for producing an aqueous methanol solution.

Abstract

This invention provides a method for synthesizing an aqueous methanol solution from a mixed gas containing carbon dioxide and hydrogen under low pressure conditions of less than 1 MPa. [Solution] A method for synthesizing an aqueous methanol solution from a mixed gas containing hydrogen and CO2, wherein methanol and water vapor are generated from a raw material gas containing CO2 and hydrogen by a catalytic reaction in a first reactor, and then the separation layer is M n [Al n Si 96-n O 192 ](2

Description

[Technical Field]

[0001] This invention relates to a method for synthesizing an aqueous methanol solution from a mixed gas containing carbon dioxide (CO2) and hydrogen under low pressure conditions of less than 1 MPa, and to an apparatus for producing the aqueous methanol solution therefor. [Background technology]

[0002] With the aim of achieving carbon neutrality by 2050, investment in green technology development toward carbon neutrality has accelerated globally since 2020, and the business environment has been drastically changed in almost all fields, from automobiles to chemicals, environment, and energy. There is an urgent need to develop and improve new synthesis methods for chemicals and fuels that use renewable biomass or recovered CO2 as raw materials, rather than fossil resources such as natural gas and coal, to achieve carbon neutrality. Methanol is an extremely important compound in industry as a raw material for the manufacture of various chemicals and fuels, and as shown in the reaction below, conventional synthesis using fossil resource-derived raw materials has mainly involved synthesis via synthesis gas, a mixed gas of CO and hydrogen (Equation 1). Furthermore, when CO2 is included as a raw material, it is necessary to consider Equations 2 and 3 in particular. CO + 2H2 ⇔ MeOH (exothermic reaction) ... (Equation 1) CO2 + 2H2 ⇔ CO + H2O (endothermic reaction) ... (Equation 2) CO2 + 3H2 ⇔ MeOH + H2O (exothermic reaction) ... (Equation 3) Equations 1-3 represent equilibrium reactions, and the equilibrium composition that yields high methanol yield is more favorable at lower temperatures and higher pressures. However, industrially, from the perspective of reaction kinetics, synthesis processes are generally carried out under temperature ranges of 200-300°C and high pressure conditions of 5-10 MPa.

[0003] To overcome the equilibrium constraints in methanol synthesis, a method called a membrane reactor, which integrates a solid catalyst and a separation membrane, has been proposed. For example, Patent Document 1 reports that by using a type A zeolite membrane or a type T zeolite membrane capable of selectively permeating and separating water vapor from a raw material gas containing hydrogen and CO2 at reaction conditions of 200°C and 3 MPa, 97.5 wt% methanol could be synthesized with a methanol conversion rate of 53.5%, exceeding the equilibrium conversion rate (23.6%).

[0004] Furthermore, Patent Document 2 proposes a method in which a portion of the methanol produced using a membrane reactor is converted to dimethyl ether, thereby achieving a high yield of 90% or more in the combined yield of methanol and dimethyl ether under conditions of 250°C and 5MPa.

[0005] On the other hand, when reaction conditions exceed 1 MPa, the gas becomes subject to regulations as a high-pressure gas. To ensure safety and durability, the use of high-strength materials, rigorous design and manufacturing processes, strict safety inspections and quality control, the addition of complex valves and safety devices, compliance with legal regulations, and the establishment of a safe environment and operating costs result in costs 3 to 5 times higher than those of typical low-pressure equipment. Therefore, the sites where economic viability can be achieved in small-scale, decentralized methanol synthesis facilities are extremely limited.

[0006] Although the methanol synthesis process temperature at which practical reaction rates can be obtained is 200°C or higher, the methanol synthesis methods proposed so far have the problem that, under low pressure conditions of less than 1 MPa, equilibrium constraints result in almost no methanol being obtained.

[0007] Furthermore, high concentrations of methanol are highly toxic and extremely flammable, making them difficult for the general public to handle without chemistry expertise. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-55970 [Patent Document 2] Japanese Patent No. 7190774 [Summary of the Invention] [Problems to be Solved by the Invention]

[0009] Since much of the demand for methanol synthesis from renewable biomass that is carbon neutral or recovered CO2 as a raw material is small-scale and decentralized, a methanol synthesis system that can operate at less than 1 MPa is desirable for economic reasons. Further, it is easier to transport and store in a small-scale decentralized site when produced in the state of an aqueous methanol solution with improved safety rather than in the state of dangerous high-concentration methanol.

[0010] An object of the present invention is to provide a method for efficiently obtaining an aqueous methanol solution from a mixed gas containing hydrogen and CO2 under low-pressure conditions of less than 1 MPa. [Means for Solving the Problems]

[0011] In order to achieve the above object, a first aspect is a method for synthesizing an aqueous methanol solution from a mixed gas containing hydrogen and CO2, wherein a raw material gas containing CO2 and hydrogen is subjected to a catalytic reaction in a first reactor to generate methanol and water vapor, and then in a second reactor provided with a plurality of porous ceramic separation membranes containing a membrane body of an MFI-type zeolite having a composition of M n [Al n Si 96-n O 192 (2 < n < 8, M: metal cation), both components of the generated methanol and water vapor are permeated through the membrane side by 90% or more, and the permeated methanol and water vapor are cooled and condensed to obtain an aqueous methanol solution of 50 to 90 wt% on the membrane permeation side.

[0012] The second form is characterized in that the reaction temperature of the second reactor is in the range of 210 to 240 °C, and the membrane permeation side pressure of the porous ceramic separation membrane is in the range of 0.001 to 0.01 MPa in absolute pressure indication. Further, the third form is characterized in that M: the metal cation is sodium.

[0013] Furthermore, in a methanol aqueous solution production apparatus for synthesizing a methanol aqueous solution from a mixed gas containing hydrogen and CO2, a first reactor for generating methanol and steam by a catalytic reaction from a raw material gas containing CO2 and hydrogen, a second reactor provided with a plurality of porous ceramic separation membranes including a membrane body of MFI-type zeolite having a separation layer of the composition of Mn[AlnSi96-nO192] (2 < n < 8, M: metal cation), and a heat exchanger for cooling and condensing the permeated methanol and steam are provided. Both components of methanol and steam generated in the first reactor permeate to the membrane permeation side of the second reactor by 90% or more, and a 50 to 90 wt% methanol aqueous solution is generated on the membrane permeation side by cooling and condensing the permeated methanol and steam in the heat exchanger.

Effect of the Invention

[0014] According to the first form, there is provided a method for synthesizing a methanol aqueous solution from a mixed gas containing hydrogen and CO2. Methanol and steam are generated by a catalytic reaction from a raw material gas containing CO2 and hydrogen in a first reactor, and then the separation layer is M n [Al n Si 96-n O 192In a second reactor equipped with a plurality of porous ceramic separation membranes containing a membrane body of MFI-type zeolite having a composition of (2 < n < 8, M: metal cation), both components of methanol and water vapor are permeated through the membrane side by 90% or more, and the methanol and water vapor permeated through the membrane are cooled and condensed to obtain a methanol aqueous solution of 50 to 90 wt% on the membrane permeation side. It is characterized in that a metal cation that selectively adsorbs methanol and water vapor with respect to CO2 and hydrogen is fixed to the exchange cation site of Al in the MFI zeolite framework, and methanol and water vapor can be selectively permeated through the membrane from a mixed gas containing CO2 and hydrogen at approximately equimolar amounts from a reaction system at 200 to 300 °C, and it has the effect of achieving high membrane durability. Furthermore, by operating under low-pressure conditions of less than 1 MPa, the safety is greatly improved, and it has the effect of obtaining a methanol aqueous solution of 50 to 90 wt% that is easy to transport and store on the membrane permeation side. Also, a methanol aqueous solution production apparatus having such a configuration has the same effect.

[0015] According to the second embodiment, the reaction temperature of the second reactor is in the range of 210 to 240 °C, and the pressure on the membrane permeation side of the separation membrane is 0.001 to 0.01 MPa in absolute pressure indication. Even under low-pressure conditions of less than 1 MPa, it has the effect of obtaining a methanol aqueous solution with a high efficiency of 75 to 95% methanol conversion rate per pass. Also, a methanol aqueous solution production apparatus having such a configuration has the same effect.

[0016] According to the third embodiment, M: the metal cation is sodium, and methanol and water can be selectively permeated through the membrane from a mixed gas containing CO2 and hydrogen at approximately equimolar amounts from a reaction system at 200 to 300 °C, and it has the effect of suppressing side reactions other than the methanol synthesis reaction, which is the target product derived from the metal cation. Also, a methanol aqueous solution production apparatus having such a configuration has the same effect.

Brief Description of the Drawings

[0017] [Figure 1]This is a flow sheet showing a method and apparatus configuration for synthesizing an aqueous methanol solution from a mixed gas containing carbon dioxide (CO2) and hydrogen under low pressure conditions of less than 1 MPa in the embodiment. [Figure 2] This is a schematic diagram showing the second reactor (membrane reactor) of the embodiment. [Figure 3] This is a schematic diagram showing a porous ceramic separation membrane according to an embodiment. [Modes for carrying out the invention]

[0018] Next, embodiments will be described based on the drawings, but the embodiments of the present invention are not limited to these.

[0019] Referring to Figure 1, the method for synthesizing an aqueous methanol solution under low pressure in the methanol aqueous solution production apparatus of the embodiment involves pressurizing the raw material gas 1 (a mixed gas of H2 / CO2 / CO) in a compressor 2 to 0.6 to 1 MPa, not exceeding 1 MPa, adjusting the pressure and flow rate to a predetermined level using a gas pressure and flow rate control valve 3, adjusting the raw material gas temperature to a predetermined level in the range of 200 to 250°C, preferably 210 to 240°C, in a heat exchanger (heater) 4, and generating methanol and water vapor near the equilibrium composition through a catalytic reaction by a packed solid catalyst 6 in the first reactor 5. Next, the generated mixed gas (H2 / CO2 / CO / methanol / water vapor) 7 is introduced into a second reactor (membrane reactor) 8 at a predetermined temperature in the range of 200-250°C, preferably 210-240°C. Simultaneously with the catalytic reaction by the packed solid catalyst 6, both methanol and water vapor components generated are permeated through the porous ceramic separation membrane 9 by 90% or more, preferably 99% or more. The permeated methanol and water vapor 10 are cooled and condensed by a heat exchanger (cooler / condenser) 11 to obtain a 50-90 wt% methanol aqueous solution in a collection tank 12 for the membrane-permeated methanol aqueous solution.

[0020] The pressure of the methanol and water vapor 10 that have permeated the membrane is adjusted by a depressurizing pump 13 so that it is in the range of 0.001 to 0.03 MPa, preferably 0.001 to 0.01 MPa, in absolute pressure. The non-permeable side of the separation membrane in the second reactor (membrane reactor) 8 may be closed, but if it is open, the methanol and water vapor are cooled and condensed by a heat exchanger (cooler / condenser) 11 and collected in a non-permeable methanol aqueous solution collection tank 14. For continuous operation, multiple methanol aqueous solution collection tanks can be installed so that when a predetermined amount of methanol aqueous solution is accumulated, the collection tank can be switched and used, enabling continuous operation. The unreacted gas 15 consisting of H2 / CO2 / CO discharged from the permeable and non-permeable sides of the membrane may be recycled by recirculating it to the compressor 2 as needed. However, since there is energy loss due to repressurization, it is desirable to keep the recycling ratio as small as possible.

[0021] Here, known catalysts such as copper-zinc catalysts can be used as the solid catalyst 6 for methanol synthesis. As for the catalyst shape, granular or pellet-like catalysts in the range of 1 to 10 mm are preferred over powder, as they reduce pressure loss and are easier to handle.

[0022] For the second reactor (membrane reactor) 8, since the operating pressure is less than 1 MPa, it is possible to mount multiple tubular porous ceramic separation membranes 9 by using the multi-tube membrane module shape shown in Figure 2. Depending on the processing rate of the raw material gas, multiple second reactors (membrane reactors) 8 may be used by connecting them directly or in parallel, considering them as multi-tube membrane modules as shown in Figure 2. Since the methanol synthesis reaction is an exothermic reaction, it is common to install jackets to flow a heat transfer medium to the multi-tube membrane module to remove heat and equalize the reaction temperature, or to divide the multi-tube membrane module into multiple units and install heat exchangers between each multi-tube membrane module to control the temperature, depending on the processing rate and heat generation of the raw material gas.

[0023] When the porous ceramic separation membrane 9 is tubular, it is common practice to attach a sealing plug to one side of the porous support and a connecting member to the other side, and then mount it on the module. As a method for attaching and sealing the porous ceramic separation membrane 9 to the second reactor (membrane reactor) 8, the use of a fluororesin-based heat-shrinkable tube or sealing tape such as Teflon (registered trademark) is common. From the perspective of continuous operation, operation at 260°C or lower, preferably 230°C or lower, is preferred. In FIG. 1, the first reactor 5 and the first reactor 8 are shown separately, but they may be integrated.

[0024] Regarding the porous ceramic separation membrane 9, as shown in FIG. 3, it is composed of a separation layer 16 and a porous support 17. The separation layer 16 is generally formed on a porous support 17 having an average pore diameter of 0.1 to 5 μm. As the separation layer 16 of the porous ceramic separation membrane 9 used in the present invention, the separation layer 16 is M n [Al n Si 96-n O 192 (2 < n < 8, M: metal cation), and it is an essential requirement to include a membrane body of MFI-type zeolite. Metal cations such as Li, Na, and K that selectively adsorb methanol and water vapor with respect to CO2 and hydrogen need to be fixed at the exchange cation sites of Al in the zeolite framework. If the Si / Al ratio is too low, the membrane durability is poor. If the Si / Al ratio is too high, the separation selectivity for methanol and water with respect to CO2 and hydrogen does not appear. Also, when metal cations are not fixed at the exchange cation sites of Al in the zeolite framework, the separation selectivity for methanol and water with respect to CO2 and hydrogen does not appear. As the separation selectivity for methanol and water with respect to CO2 and hydrogen, those of 100 or more, preferably 400 or more, are preferred. If the separation selectivity is lower than that, the leakage of CO2 and hydrogen, which are the source gases, becomes too large, and it becomes difficult to obtain a predetermined effect.

[0025] In addition, the type A zeolite membrane used in Patent Document 1 is not suitable as the separation membrane used in the embodiments because it allows water to permeate and hardly allows methanol to permeate through the membrane, and its membrane durability is not sufficient. For example, by fixing Na cations to the exchange cation sites of Al in the zeolite framework, Na n [Al n Si 96-n O 192 (2 < n < 8), the MFI-type zeolite membrane has a separation selectivity of methanol with respect to CO2 and hydrogen of 100 or more under conditions of 1 MPa or less even at 200 °C or higher, and a permeability of methanol and water of 2 × 10 -7 [mol / (m2·s·Pa)] or more can be obtained.

[0026] Regarding the porous support 17, for example, ceramic supports made of alumina (α-Al2O3 (alpha-alumina), γ-Al2O3 (gamma-alumina)), mullite, zirconia, titania, or composites thereof can be mentioned, and a porous α-alumina support with an average pore diameter of 0.1 to 3 μm and a porosity of 25 to 55% is preferred. When the porosity is less than 25%, the mechanical strength is excellent, but the membrane permeability decreases more than necessary. On the other hand, when the porosity is greater than 55%, there is a concern that the pressure resistance decreases and the porous ceramic separation membrane 9 may be damaged due to the pressure difference across the membrane. Also, the shape of the porous support 17 can be any of flat plate, tubular, or monolithic, but generally, the tubular shape is common for the support, and from the viewpoints of durability and economy, those in the range of a diameter of 1 to 1.6 cm and a length of 40 to 120 cm are preferred.

[0027] Next, examples will be described together with comparative examples, but the embodiments of the present invention are not limited to these examples.

Examples

[0028] The recovery rates of MeOH and H2O on the membrane permeate side, the methanol concentration of the membrane-permeated methanol aqueous solution, and the MeOH yield were calculated by process simulation by varying the membrane permeability (H2, CO2, CO, H2O, MeOH), reaction temperature, and operating conditions (absolute pressure on the non-permeable side of the porous ceramic separation membrane 9). In the process simulation, the target separation process was divided into 10,000 to 10 billion cells, and the reaction amount and membrane permeability in each divided cell were calculated sequentially. As a prerequisite for analysis, the analysis was performed under isothermal and isobaric conditions relative to the flow direction in order to expedite (simplify) the analysis process. The reaction rate constants of the solid catalyst 6 packed into the first reactor 5 and the second reactor (membrane reactor) 8 were calculated using the reaction rate constants of commercially available copper-zinc catalysts.

[0029] As a model case, 0.6 kg of solid catalyst 6 is packed into the first reactor 5, 6.0 kg of solid catalyst 6 is packed into the second reactor (membrane reactor) 8, and the total effective surface area of ​​the porous ceramic separation membrane 9 in the second reactor is 0.4 m². 2 The analysis was performed with 30 tubular separation membranes (each with a diameter of 1.2 cm and an effective length of 40 cm (effective length of 35 cm)) fixed in place. The absolute pressure on the non-permeable side of the porous ceramic separation membrane 9 in the first and second reactors was fixed at 0.98 MPa for comparison. The system and operating conditions, such as membrane permeability (H2, CO2, CO, H2O, MeOH), reaction temperature, and absolute pressure on the membrane permeation side, along with the analysis results for the permeability of MeOH and H2O to the membrane permeation side, the methanol concentration of the permeated methanol aqueous solution, and the methanol yield, are summarized in Tables 1 and 2. Table 1 summarizes the results when the supply gas flow rates were H2: 3 NL / min and CO2: 1 NL / min, and Table 2 summarizes the results when the supply gas flow rates were H2: 2.5 NL / min, CO2: 0.5 NL / min, and CO: 0.5 NL / min.

[0030] [Table 1]

[0031] [Table 2]

[0032] Regarding the results in Table 1 for the mixed gas with a supply gas flow rate of H2: 3 NL / min and CO2: 1 NL / min, Examples 1 to 12 are in the embodiments of the method for synthesizing an aqueous methanol solution of the present invention shown in FIG. 1, where the separation layer is Na n [Al n Si 96-n O 192 (2 < n < 8), which is the result of analysis of the typical membrane permeability of a porous ceramic separation membrane characterized by including a membrane body of MFI-type zeolite. The influence of the reaction temperature was analyzed in Examples 1 to 7, and the influence of the absolute pressure on the membrane permeation side was analyzed in Examples 8 to 12. Particularly, the reaction temperature of the second reactor equipped with the separation membrane showed a significantly high methanol yield in the range of 210 to 240 °C. Also, the pressure on the membrane permeation side of the separation membrane showed a significantly high methanol yield in the range of 0.001 to 0.01 MPa in absolute pressure indication.

[0033] In Comparative Examples 1 to 3, the pressure on the membrane permeation side of the separation membrane was operated in the range of 0.04 to 0.1 MPa in absolute pressure indication in Example 3. Although it was the methanol yield when the permeation rate of both generated methanol and water vapor to the membrane permeation side was less than 90%, the methanol yield could only be obtained up to 24.5%. Comparative Examples 4 to 6 are the results of analysis of the typical membrane permeability by the A-type zeolite membrane proposed in Patent Document 1. Comparative Examples 7 to 9 are the results of analysis of the typical membrane permeability by the T-type zeolite membrane and the CHA-type zeolite membrane. Comparative Examples 10 to 12 compared the analysis results when almost no methanol or water vapor permeated through the membrane. Despite the reaction temperature and the absolute pressure on the membrane permeation side being the same as in the examples, the results obtained in Examples 1 to 12 showed a significantly higher methanol yield compared to the results obtained in Comparative Examples 4 to 12.

[0034] Regarding the results in Table 2 for the mixed gas with a supply gas flow rate of H2: 2.5 NL / min, CO2: 0.5 NL / min, and CO: 0.5 NL / min, Examples 13 to 24 are in the embodiments of the method for synthesizing an aqueous methanol solution of the present invention shown in FIG. 1, where the separation layer is Na n [Al n Si 96-n O192 This is the result of analysis of the typical membrane permeability of a porous ceramic separation membrane characterized by including a membrane body of an MFI-type zeolite having a composition of (2 < n < 8). The influence of the reaction temperature was analyzed in Examples 13 to 19, and the results of analyzing the influence of the absolute pressure on the membrane permeation side in Examples 20 to 24 were shown. In particular, the reaction temperature of the second reactor equipped with the separation membrane showed a significantly high methanol yield in the range of 210 to 240 °C. Also, the membrane permeation side pressure of the separation membrane showed a significantly high methanol yield in the range of 0.001 to 0.01 MPa in absolute pressure display.

[0035] Comparative Examples 13 to 15 are the methanol yields when the membrane permeation side pressure of the separation membrane was operated in the range of 0.04 to 0.1 MPa in absolute pressure display in Example 15, and the permeation rates of both the produced methanol and water vapor components to the membrane permeation side were less than 90%. However, the methanol yield could only be obtained up to 42.0%. Comparative Examples 16 to 18 are the results of analysis of the typical membrane permeability by the A-type zeolite membrane proposed in Patent Document 1. Comparative Examples 19 to 21 are the results of analysis of the typical membrane permeability by the T-type zeolite membrane and the CHA-type zeolite membrane. Comparative Examples 22 to 24 compared the analysis results when almost no methanol or water vapor permeated through the membrane. Despite the reaction temperature and the absolute pressure on the membrane permeation side being the same as in the examples, the results obtained in Examples 13 to 24 showed a significantly higher methanol yield compared to the results obtained in Comparative Examples 16 to 24. From the above, the usefulness of the embodiment of synthesizing an aqueous methanol solution under low-pressure conditions of less than 1 MPa of the present invention was confirmed.

Industrial Applicability

[0036] The examples demonstrate that it is possible to efficiently produce methanol aqueous solution from a mixed gas containing carbon dioxide and hydrogen under low pressure conditions of less than 1 MPa. The produced methanol aqueous solution can be used industrially, for example, directly as a fuel such as direct methanol fuel (DMFC), or as a transport medium to safely transport methanol raw materials to various chemical manufacturing sites. In particular, since much of the demand for methanol synthesis using renewable biomass or recovered CO2 as raw materials, which is carbon neutral, is small-scale and decentralized, it can be used industrially as an on-site process. [Explanation of symbols]

[0037] 1. Source gas (H2 / CO2 / CO) 2 Compressors 3. Gas pressure and flow control valve 4 Heat exchanger (heater) 5. First Reactor 6. Solid catalysts 7. Mixed gas (H2 / CO2 / CO / methanol / water vapor) 8. Second reactor (membrane reactor) 9. Porous ceramic separation membrane 10. Methanol and water vapor permeated through the membrane. 11. Heat exchangers (coolers / condensers) 12 Membrane-permeated methanol aqueous solution collection tank 13. Pressure Reducing Pump 14. Membrane-impermeable methanol aqueous solution collection tank 15 Unreacted gas (H2 / CO2 / CO) 16 separation layer 17 Porous support

Claims

1. Hydrogen and CO ２ A method for synthesizing an aqueous methanol solution from a mixed gas containing, CO2 is produced in the first reactor. ２ From a raw material gas containing hydrogen, methanol and water vapor are produced by a catalytic reaction. Next, the separation layer M ｎ [Al ｎ Si ９６－ｎ O １９２ In a second reactor equipped with multiple porous ceramic separation membranes containing a membrane body of MFI-type zeolite having the composition (2 < n < 8, M: metal cation), both the generated methanol and water vapor components are permeated to the membrane permeation side by 90% or more. By cooling and condensing the methanol and water vapor that have permeated the membrane, a 50-90 wt% methanol aqueous solution is obtained on the membrane permeate side. A method for synthesizing an aqueous methanol solution, characterized by the following features.

2. The method for synthesizing an aqueous methanol solution according to claim 1, wherein the reaction temperature of the second reactor is in the range of 210 to 240°C, and the membrane permeation pressure of the porous ceramic separation membrane is in the range of 0.001 to 0.01 MPa in absolute pressure.

3. The method for synthesizing an aqueous methanol solution according to claim 1 or 2, wherein the metal cation M is sodium.

4. Hydrogen and CO ２ A methanol aqueous solution production apparatus for synthesizing a methanol aqueous solution from a mixed gas containing the following: CO ２ A first reactor that generates methanol and water vapor from a hydrogen-containing raw material gas through a catalytic reaction, The separation layer is M ｎ [Al ｎ Si ９６－ｎ O １９２ (2 < n < 8, M: metal cation), and a second reactor including a plurality of porous ceramic separation membranes including a film body of MFI-type zeolite having a composition of It comprises a heat exchanger that cools and condenses methanol and water vapor that have permeated the membrane, More than 90% of the methanol and water vapor components generated in the first reactor permeate to the membrane permeate side of the second reactor. The methanol and water vapor that permeate the membrane are cooled and condensed by the heat exchanger, and a 50-90 wt% methanol aqueous solution is produced on the membrane permeate side. A methanol aqueous solution production apparatus characterized by the following features.

5. The methanol aqueous solution production apparatus according to claim 4, wherein the reaction temperature of the second reactor is in the range of 210 to 240°C, and the membrane permeation pressure of the porous ceramic separation membrane is in the range of 0.001 to 0.01 MPa in absolute pressure.

6. The methanol aqueous solution production apparatus according to claim 4 or 5, wherein the M: metal cation is sodium.

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