Carbonate generating system

Abstract

To provide a carbonate generating system capable of efficiently converting carbon dioxide into carbonate.SOLUTION: A carbonate generating system 100 according to the present invention comprises a generating unit 11 that generates carbonate from a basic compound and carbon dioxide. The generating unit 11 has a separation membrane, and a first space and a second space separated by the separation membrane. During operation of the carbonate generating system 100, carbon dioxide is supplied to the first space, a liquid containing a basic compound is supplied to the second space, the carbon dioxide permeates from the first space to the second space through the separation membrane, and the first space is pressurized.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a carbonate production system. [Background technology]

[0002] As a means of solving the problems of global warming and fossil fuel depletion, there is a need to develop technology that can convert carbon dioxide into useful compounds and fix them.

[0003] For example, Patent Document 1 describes a carbon dioxide fixation device that fixes carbon dioxide by precipitating carbonate after adsorbing carbon dioxide in an alkaline solution. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-96975 Summary of the Invention [Problem to be solved by the invention]

[0005] The most common method for producing carbonates is the aeration method, in which carbon dioxide is blown directly into a basic solution to produce carbonates. However, the aeration method does not efficiently convert carbon dioxide into carbonates, and much of the supplied carbon dioxide is discharged and wasted. Therefore, in conventional carbonate production systems, there is a need for technology that can efficiently convert carbon dioxide and suppress carbon dioxide emissions.

[0006] The present invention provides a carbonate production system that can efficiently convert carbon dioxide into carbonate. [Means for solving the problem]

[0007] The present invention relates to A carbonate generation system including a generation unit that generates carbonate from a basic compound and carbon dioxide, The generation unit has a separation membrane, and a first space and a second space separated by the separation membrane. During the operation of the carbonate generation system, carbon dioxide is supplied to the first space, a liquid containing the basic compound is supplied to the second space, the carbon dioxide permeates the separation membrane from the first space to the second space, and provides a carbonate generation system in which the first space is pressurized.

Advantages of the Invention

[0008] According to the present invention, a carbonate generation system capable of efficiently converting carbon dioxide into carbonate can be provided.

Brief Description of the Drawings

[0009] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of the carbonate generation system according to the present embodiment. [Figure 2A] FIG. 2A is a cross-sectional view schematically showing a hollow fiber membrane module including a hollow fiber membrane, which is an example of the generation unit in the carbonate generation system according to the present embodiment. [Figure 2B] FIG. 2B is a cross-sectional view schematically showing a flat membrane module including a flat membrane, which is another example of the generation unit in the carbonate generation system according to the present embodiment. [Figure 3] FIG. 3 is a schematic diagram showing an example of the carbonate generation system shown in FIG. 1. [Figure 4] FIG. 4 is a schematic diagram showing the configuration of a modified carbonate generation system 300 according to the present embodiment. [Figure 5] FIG. 5 is a schematic diagram showing the configuration of the evaluation system used in Example 1. [Figure 6] FIG. 6 is a schematic diagram showing the configuration of the evaluation system used in Example 2. [Figure 7] FIG. 7 is a schematic diagram showing the configuration of the evaluation system used in Reference Example 1. [Figure 8]FIG. 8 is a schematic diagram showing the configuration of the evaluation system used in Reference Example 2.

Mode for Carrying Out the Invention

[0010] The carbonate generation system according to the first aspect of the present invention is a carbonate generation system including a generation unit that generates carbonate from a basic compound and carbon dioxide, wherein the generation unit has a separation membrane, and a first space and a second space separated by the separation membrane, during operation of the carbonate generation system, the carbon dioxide is supplied to the first space, a liquid containing the basic compound is supplied to the second space, the carbon dioxide permeates the separation membrane from the first space to the second space, and the first space is pressurized.

[0011] In the second aspect of the present invention, for example, the carbonate generation system according to the first aspect further includes a carbonate storage tank.

[0012] In the third aspect of the present invention, for example, the carbonate generation system according to the second aspect further includes a first flow path for supplying the liquid containing the carbonate generated in the generation unit to the carbonate storage tank.

[0013] In the fourth aspect of the present invention, for example, the carbonate generation system according to the third aspect further includes a second flow path for supplying the liquid discharged from the carbonate storage tank to the generation unit.

[0014] In the fifth aspect of the present invention, for example, the carbonate generation system according to the fourth aspect further includes a liquid feeding device that supplies the liquid discharged from the carbonate storage tank to the generation unit through the second flow path.

[0015] In the sixth aspect of the present invention, for example, in the carbonate generation system according to any one of the first to fifth aspects, the separation membrane is a hollow fiber membrane or a flat membrane.

[0016] In a seventh aspect of the present invention, for example, in the carbonate generation system according to any one of the first to sixth aspects, the basic compound contains a hydroxide.

[0017] In an eighth aspect of the present invention, for example, in the carbonate generation system according to the seventh aspect, the hydroxide is at least one selected from the group consisting of potassium hydroxide, sodium hydroxide, magnesium hydroxide, and calcium hydroxide.

[0018] In a ninth aspect of the present invention, for example, in the carbonate generation system according to any one of the first to eighth aspects, the liquid contains water.

[0019] In a tenth aspect of the present invention, for example, the carbonate generation system according to any one of the first to ninth aspects generates a bicarbonate.

[0020] Hereinafter, the details of the present invention will be described, but the following description is not intended to limit the present invention to specific embodiments.

[0021] <Carbonate generation system> The carbonate generation system according to the present embodiment includes a generation unit that generates a carbonate from a basic compound and carbon dioxide. The generation unit has a separation membrane and a first space and a second space separated by the separation membrane. During the operation of the carbonate generation system according to the present embodiment, carbon dioxide is supplied to the first space, a liquid containing a basic compound is supplied to the second space, carbon dioxide permeates through the separation membrane from the first space to the second space, and the first space is pressurized.

[0022] The separation membrane is typically a separation membrane that permeates carbon dioxide and suppresses the permeation of the above liquid.

[0023] In the carbonate generation system according to this embodiment, since the generation unit includes the separation membrane, the contact area between the liquid and the gas increases, promoting gas-liquid mixing. Further, in the carbonate generation system according to this embodiment, when the system is in operation, the first space is pressurized, so that carbon dioxide necessary for carbonate generation can be efficiently supplied to the liquid, reducing the amount of carbon dioxide used. Therefore, the carbonate generation system according to this embodiment can efficiently convert carbon dioxide into carbonate. Further, according to the carbonate generation system according to this embodiment, the carbonate generation rate can be improved. Also, the carbonate generation system according to this embodiment can reduce the carbon dioxide wasted and discharged outside the system, so it is excellent from the perspective of global environmental protection.

[0024] In this specification, "carbonate" means a salt formed by substituting at least a part of the hydrogen atoms of carbonic acid (H2CO3) with a metal. That is, in this specification, "carbonate" includes bicarbonate. The carbonate generation system according to this embodiment may generate bicarbonate. According to the carbonate generation system according to this embodiment, the yield of bicarbonate can be improved.

[0025] The carbonate generation system according to this embodiment may further include a carbonate storage tank. The carbonate storage tank stores the carbonate generated by the generation unit. For example, the liquid containing the carbonate generated by the generation unit is supplied to the carbonate storage tank.

[0026] FIG. 1 is a schematic diagram showing the configuration of a carbonate generation system 100 according to this embodiment. The carbonate generation system 100 includes a generation unit 11 that generates carbonate from a basic compound and carbon dioxide, and a carbonate storage tank 12.

[0027] As shown in FIG. 1, the generation unit 11 and the carbonate storage tank 12 may be arranged separately from each other, or may be provided integrally. When the generation unit 11 and the carbonate storage tank 12 are arranged separately from each other, the carbonate generation system 100 may further include a first flow path 13a for supplying the liquid containing the carbonate generated in the generation unit 11 to the carbonate storage tank 12. With this configuration, the liquid containing the carbonate generated in the generation unit 11 is supplied to the carbonate storage tank 12 through the first flow path 13a. The carbonate generation system 100 may further include a second flow path 13b for supplying the liquid discharged from the carbonate storage tank 12 to the generation unit 11. The carbonate generation system 100 may further include a liquid feeding device 14 for feeding the liquid discharged from the carbonate storage tank 12 to the generation unit 11 through the second flow path 13b. As the liquid feeding device 14, for example, a liquid feeding pump can be used.

[0028] The generation unit 11 and the carbonate storage tank 12 may be connected to each other by a circulation flow path, for example, as shown in FIG. 1. In the carbonate generation system 100 shown in FIG. 1, the first flow path 13a and the second flow path 13b constitute a circulation flow path. By providing such a circulation flow path, the liquid discharged from the carbonate storage tank 12 returns to the generation unit 11 through the second flow path 13b, and more carbonate can be generated by supplying carbon dioxide in the generation unit 11. By circulating the liquid in this way, it is possible to efficiently generate carbonate while reducing the use or discharge of a basic compound and carbon dioxide without permission. For example, the production yield of carbonate can be improved.

[0029] In the carbonate generation system 100, carbon dioxide is supplied to the liquid containing the basic compound. The basic compound preferably contains a hydroxide. The hydroxide may be a metal hydroxide, may be an alkali metal hydroxide or an alkaline earth metal hydroxide, and may be at least one selected from the group consisting of potassium hydroxide, sodium hydroxide, magnesium hydroxide, and calcium hydroxide. The hydroxide may be an alkali metal hydroxide. The hydroxide is preferably potassium hydroxide.

[0030] The liquid preferably contains water, i.e., the liquid is preferably an aqueous solution of hydroxide, more preferably an aqueous solution containing at least one selected from the group consisting of potassium hydroxide, sodium hydroxide, magnesium hydroxide, and calcium hydroxide, and even more preferably an aqueous solution containing potassium hydroxide.

[0031] The carbonate production system 100 does not have to include the carbonate storage tank 12. In this case, for example, the carbonate production system 100 may include a production unit 11, a circulation flow path, and a liquid delivery device 14. The circulation flow path is a flow path for returning the liquid discharged from the production unit 11 to the production unit 11. The liquid delivery device 14 supplies the liquid containing the carbonate produced in the production unit 11 to the production unit 11 through the circulation flow path. The carbonate production system 100 does not have to include the circulation flow path.

[0032] The generation unit 11 will be described in more detail below.

[0033] (Generation part) The production unit 11 produces carbonate from a basic compound and carbon dioxide. Specifically, carbon dioxide is supplied to a liquid L containing a basic compound to produce carbonate. The production unit 11 has a separation membrane and a first space and a second space separated by the separation membrane. When the carbonate production system 100 is in operation, carbon dioxide is supplied to the first space, and liquid L is supplied to the second space. When the carbonate production system 100 is in operation, the first space is pressurized. By flowing a gas G containing carbon dioxide into the first space and flowing liquid L into the second space, the carbon dioxide can permeate the separation membrane and be supplied to the liquid L.

[0034] The production unit 11 is typically a membrane module. The production unit 11 includes a liquid supply port 11a for supplying the liquid L into the second space of the membrane module and a liquid discharge port 11b for discharging the liquid to which carbon dioxide has been supplied to the outside of the membrane module. The production unit 11 includes a gas supply port 11c for supplying the gas G into the first space of the membrane module.

[0035] The content rate of carbon dioxide in the gas G is, for example, 50 wt% or more, preferably 70 wt% or more, more preferably 90 wt% or more, and even more preferably 95 wt% or more. The content rate of carbon dioxide in the gas G is, for example, 100 wt% or less. The gas G is preferably carbon dioxide itself.

[0036] The liquid supplied with carbon dioxide may contain a carbonate. The liquid discharged from the liquid discharge port 11b may contain a carbonate and may further contain the basic compound.

[0037] The generation unit 11 is pressurized, for example, by the gas G in the first space of the generation unit 11 (membrane module). Specifically, the generation unit 11 may have a configuration in which the gas G taken into the membrane module is difficult to be discharged to the outside of the membrane module, for example, a configuration in which it is not discharged. When the generation unit 11 has such a configuration, the gas G supplied into the generation unit 11 (membrane module) is sealed inside the membrane module, the inside of the apparatus is pressurized by the gas, and the first space is pressurized. Such a configuration can be realized, for example, by suppressing the gas discharge amount in the generation unit 11 to a low level. In the generation unit 11, for example, the gas discharge port may be in a closed state, or the gas discharge port may not be provided. Specifically, in the generation unit 11 (membrane module), the discharge port through which the gas G supplied from the gas supply port 11c to the first space is discharged to the outside of the membrane module may be closed, or the discharge port may not be provided. Thus, since the generation unit 11 does not have a gas discharge port, the gas G supplied into the membrane module is not discharged to the outside of the membrane module, and the gas G is sealed inside the membrane module. Therefore, the inside of the membrane module is pressurized by the gas G. According to the above configuration, in the generation unit 11, the first space is pressurized. Also, the waste discharge of carbon dioxide outside the generation unit 11 (membrane module) can be suppressed.

[0038] The pressure in the first space is greater than the atmospheric pressure of the surrounding environment of the generating unit 11. The atmospheric pressure of the surrounding environment is, for example, 0.1 MPa. The upper limit value of the pressure in the first space is, for example, 0.50 MPa or less. The pressure in the first space is preferably 0.12 MPa or more and 0.30 MPa or less, more preferably 0.15 MPa or more and 0.28 MPa or less, and even more preferably 0.18 MPa or more and 0.25 MPa or less. In this specification, unless otherwise specified, "pressure" means absolute pressure.

[0039] The flow rate of the liquid L in the second space is, for example, 500 mL / min or more and 1500 mL / min or less, preferably 650 mL / min or more and 1200 mL / min or less, and more preferably 750 mL / min or more and 1000 mL / min or less.

[0040] The flow rate of carbon dioxide permeating through the separation membrane is, for example, 100 mL / min or more and 1500 mL / min or less, preferably 200 mL / min or more and 1300 mL / min or less, and more preferably 300 mL / min or more and 1000 mL / min or less.

[0041] Note that the generating unit 11 is not limited to a configuration in which the first space is pressurized by the gas G taken in for supplying the liquid L, and may have a configuration in which the first space is pressurized by other means.

[0042] The separation membrane may be a hollow fiber membrane or a flat membrane. For example, a hollow fiber membrane module or a flat membrane module may be used as the generating unit 11.

[0043] The separation membrane includes a separation functional layer. The separation functional layer contains, for example, a resin. Examples of the resin include silicone resin, polyether block amide resin, polyamide resin, polyether resin, polyimide resin, cellulose acetate resin, and fluororesin. The separation functional layer preferably contains silicone resin.

[0044] The thickness of the separation functional layer is, for example, 0.1 μm or more and 100 μm or less, preferably 10 μm or more and 50 μm or less, and more preferably 20 μm or more and 50 μm or less. The thickness of the separation functional layer may, in some cases, be 0.1 μm or less or 100 μm or more.

[0045] In some cases, the separation membrane may further include a porous support. Examples of the porous support include non-woven fabric; porous polytetrafluoroethylene; aromatic polyamide fiber; porous metal; sintered metal; porous ceramic; porous polyester; porous nylon; activated carbon fiber; latex; silicone; silicone rubber; at least one selected from the group consisting of polyvinyl fluoride, polyvinylidene fluoride, polyurethane, polypropylene, polyethylene, polystyrene, polycarbonate, polysulfone, polyetheretherketone, polyacrylonitrile, polyimide, and polyphenylene oxide; a metal foam having continuous or closed cells; a polymer foam having continuous or closed cells; silica; porous glass; a mesh screen, etc. The porous support may be a combination of two or more of these.

[0046] The porous support has an average pore diameter of, for example, 0.01 to 0.4 μm. The thickness of the porous support is not particularly limited and is, for example, 10 μm or more, preferably 20 μm or more, and more preferably 50 μm or more. The thickness of the porous support is, for example, 300 μm or less, preferably 200 μm or less, and more preferably 150 μm or less.

[0047] FIG. 2A is a cross-sectional view schematically showing a hollow fiber membrane module 21 including a hollow fiber membrane, which is an example of the generation unit 11 in the carbonate generation system 100 according to the present embodiment. FIG. 2B is a cross-sectional view schematically showing a flat membrane module 22 including a flat membrane, which is another example of the generation unit 11 in the carbonate generation system 100 according to the present embodiment.

[0048] 2A, hollow fiber membrane module 21 has a liquid supply port 21a for supplying liquid L to the inside, a liquid discharge port 21b for discharging the liquid to which carbon dioxide has been supplied to the outside, and a gas supply port 21c for supplying carbon dioxide to the inside to be supplied to liquid L. Hollow fiber membrane module 21 is provided with a plurality of hollow fiber membranes 21d as separation membranes.

[0049] Liquid L supplied from liquid supply port 21a is sent to the interior (second space) of hollow fiber membrane 21d, passes through the interior of hollow fiber membrane 21d, and is discharged from liquid discharge port 21b. Gas G containing carbon dioxide supplied from gas supply port 21c is supplied to the outside (first space) of hollow fiber membrane 21d. Hollow fiber membrane module 21 has a configuration such that the supplied gas G is not discharged to the outside. Therefore, the supplied gas G pressurizes the interior of hollow fiber membrane module 21, thereby pressurizing the first space.

[0050] 2B, the flat membrane module 22 includes a liquid supply port 22a for supplying the liquid L to the inside, a liquid discharge port 22b for discharging the liquid to which carbon dioxide has been supplied to the outside, and a gas supply port 22c for supplying the carbon dioxide to the inside to be supplied to the liquid L. The flat membrane module 22 is provided with a flat membrane 22d as a separation membrane. The flat membrane 22d divides the internal space of the flat membrane module 22 into two spaces: a first space A and a second space B.

[0051] Liquid L supplied from the liquid supply port 22a passes through a second space B of the internal space partitioned by the flat membrane 22d and is discharged from the liquid discharge port 22b. Gas G containing carbon dioxide supplied from the gas supply port 22c is supplied to a first space A of the internal space partitioned by the flat membrane 22d. The flat membrane module 22 has a configuration in which the supplied gas G is not discharged to the outside, for example. Therefore, the first space A is pressurized by the supplied gas G.

[0052] In the hollow fiber membrane module 21 and the flat membrane module 22, the amount of carbon dioxide supplied to the liquid L can be adjusted by, for example, adjusting the flow rate of the liquid within the module.

[0053] (carbonate reservoir) Fig. 3 is a schematic diagram showing an example of the carbonate production system 100 shown in Fig. 1. In the carbonate production system 200 shown in Fig. 3, the carbonate storage tank 12 has a liquid supply port 12a for supplying a liquid containing carbonate produced in the production unit 11 to the inside, and a liquid discharge port 12b for discharging the liquid from the inside of the carbonate storage tank 12. The carbonate storage tank 12 may be a sealed container whose internal space can be closed, or may be an open container whose internal space is connected to the outside. When the carbonate storage tank 12 is a sealed container, for example, a tank can be used as the carbonate storage tank 12.

[0054] The carbonate storage tank 12 may further include a collection port 12c for collecting carbonate. The collection port 12c is provided separately from the liquid discharge port 12b for discharging the liquid to the second flow path 13b, for example. The collection port 12c is, for example, a sampling cock.

[0055] (others) The carbonate production systems 100 and 200 shown in Figures 1 and 3 described above have a configuration in which the production unit 11 and the carbonate storage tank 12 are installed separately. However, when the carbonate production system according to this embodiment includes a carbonate storage tank, the production unit and the carbonate storage tank may be integrally provided. For example, the production unit may include the carbonate storage tank.

[0056] FIG. 4 is a schematic diagram showing the configuration of a carbonate generation system 300 according to a modified example of the present embodiment.

[0057] The carbonate production system 300 includes a production section 31 including a membrane module 33 and a carbonate storage tank 32. The membrane module 33 includes a liquid supply port 33a for supplying a liquid to be supplied with carbon dioxide into the interior of the membrane module 33, and a liquid discharge port 33b for discharging the liquid to the outside of the membrane module. The membrane module 33 includes a gas supply port 33c for supplying a gas containing carbon dioxide to be supplied to the liquid into the membrane module. The membrane module 33 is installed inside the carbonate storage tank 32, for example.

[0058] The membrane module 33 takes in, for example, a liquid L contained in the carbonate storage tank 32 through a liquid supply port 33a into the interior (second space) of the membrane module 33. The membrane module 33 also takes in a gas G through a gas supply port 33c into the interior (first space) of the membrane module 33. Carbon dioxide is supplied to the liquid L via a separation membrane, and the liquid is discharged from a liquid discharge port 33b into the carbonate storage tank 32. The liquid discharged from the liquid discharge port 33b into the carbonate storage tank 32 contains carbonate. The liquid discharged from the liquid discharge port 33b into the carbonate storage tank 32 may contain carbonate and a basic compound.

[0059] The membrane module 33 does not have a gas outlet. Therefore, the gas G supplied to the inside of the membrane module 33 is not discharged to the outside of the membrane module 33, and the gas is sealed inside the membrane module 33. Therefore, the inside of the membrane module 33 is pressurized by the supplied gas G, and thereby the first space is pressurized.

[0060] As shown in FIG. 4, the generation unit 31 may further include a stirrer 35 for stirring and mixing the content 34 stored in the carbonate storage tank 32. The content 34 may be, for example, a liquid containing carbonate, or may be a liquid containing carbonate and a basic compound. The stirrer 35 includes, for example, a stirring motor 35a and a stirring shaft 35b. Further, as shown in FIG. 4, the membrane module 33 may be provided integrally with the stirrer 35 and installed so as to function as part or all of the stirring blades. When the carbonate generation system 300 has such a configuration, the amount of carbon dioxide supplied to the liquid L can be adjusted by adjusting the stirring speed of the stirrer 35.

[0061] The carbonate generated by the carbonate generation system according to the present embodiment can be used in various applications. The carbonate generated by the carbonate generation system according to the present embodiment may be used, for example, in the production of formate. For example, the carbonate recovered from the carbonate storage tank may be reacted using a catalyst.

[0062] <Method for Producing Carbonate> The method for producing carbonate according to the present embodiment includes supplying carbon dioxide to the liquid L under a pressurized state to generate carbonate. Here, the supply of carbon dioxide to the liquid L is performed using a separation membrane that permeates carbon dioxide and suppresses the permeation of the liquid. In the method for producing carbonate according to the present embodiment, a gas G containing carbon dioxide may be passed through the first space in the first space and the second space separated by the separation membrane, the liquid L may be passed through the second space, and the first space may be pressurized.

[0063] The method for producing carbonate according to the present embodiment may further include supplying the liquid to which carbon dioxide has been supplied to a carbonate storage tank. The liquid supplied to the carbonate storage tank may contain carbonate.

[0064] In the method for producing carbonate according to the present embodiment, the liquid L may be the liquid discharged from the carbonate storage tank.

[0065] The carbonate production method according to this embodiment can be carried out, for example, using the carbonate production system according to this embodiment. The descriptions of the basic compound, liquid L, gas G, separation membrane, first space, second space, and carbonate storage tank in the carbonate production method according to this embodiment are the same as the descriptions of the basic compound, liquid L, gas G, separation membrane, first space, second space, and carbonate storage tank described above for the carbonate production system. [Example]

[0066] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0067] Example 1 [Preparing the generation section] A hollow fiber membrane module (Nagasep M-30B, manufactured by Nagayanagi Industries Co., Ltd.) was prepared as the generation section.

[0068] [Preparation of liquid containing basic compound] An aqueous solution of potassium hydroxide was prepared as a liquid containing a basic compound by dissolving 2.806 g of potassium hydroxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in 500 mL of tap water.

[0069] [Evaluation method] (Preparing the evaluation system) An evaluation system for Example 1 was prepared. FIG. 5 is a schematic diagram showing the configuration of the evaluation system 400 used in Example 1. The evaluation system 400 includes: A hollow fiber membrane module 41 prepared as a generation section, CO2 gas cylinder 43 (liquefied carbon dioxide gas cylinder 7 kg (Yoshida Sangyo)), Diaphragm type liquid transfer pump 44 (1300 mL / min NF100TT.18RC (KNF)), and 42. 1L Erlenmeyer flask as carbonate reservoir; The hollow fiber membrane module 41, the diaphragm-type liquid-transfer pump 44, and the Erlenmeyer flask 42 were connected to each other by a silicone tube that formed a liquid circulation channel.

[0070] (Carbonate generation test) The evaluation system shown in FIG. 5 was operated under the system operating conditions shown in Table 1. The gas outlet of the hollow fiber membrane module 41 was closed, and the hollow fiber membrane module 41 was pressurized by the supplied carbon dioxide. The pressure in the first space (the space to which CO2 was supplied) during system operation was 0.2 MPa. The test time was 30 minutes. 30 minutes after the start of system operation, the system was stopped and the test was terminated. The pH of the liquid in the Erlenmeyer flask 42 was confirmed with pH test paper. The pH was approximately 7 to 8, confirming that potassium hydroxide had been completely consumed. NMR measurements were performed on the liquid in the Erlenmeyer flask 42 as described below, and the production yield of bicarbonate (potassium bicarbonate in Examples 1-2 and Reference Examples 1-2 below) was calculated from the results. The CO2 consumption was calculated by integrating the flow rate (CO2 supply flow rate) of a gas flow meter (not shown) connected to the CO2 gas cylinder 43 over the test time. The CO2 supply flow rate was 300 mL / min. The evaluation results are shown in Table 3.

[0071] [Table 1]

[0072] (NMR measurement) A calibration curve was prepared as follows. The amounts of potassium bicarbonate (Fujifilm Wako Pure Chemical Industries, Ltd.) and potassium carbonate (Fujifilm Wako Pure Chemical Industries, Ltd.) shown in Nos. 1 to 5 in Table 2 were placed in an agate mortar (manufactured by AS ONE) and mixed. The amounts of the powders added shown in Nos. 1 to 5 in Table 2 were taken from the mixed powders, and these powders, 1 mL of DO (Fujifilm Wako Pure Chemical Industries, Ltd.), and 50 μL of CHCN (Fujifilm Wako Pure Chemical Industries, Ltd.) were mixed to prepare NMR samples for obtaining calibration curves Nos. 1 to 5. The prepared NMR samples for obtaining calibration curves were analyzed using an NMR instrument (Bruker Biospin, AV300). 13C-NMR measurements were performed. A calibration curve was created by plotting the mole fraction of potassium bicarbonate on the vertical axis and the NMR chemical shift value at approximately 160 ppm on the horizontal axis from the measurement results.

[0073] [Table 2]

[0074] After the test, 900 μL of the liquid collected from Erlenmeyer flask 42, 100 μL of DO (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 50 μL of CHCN (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were mixed to prepare an NMR sample for yield calculation. The prepared NMR sample for yield calculation was analyzed using an NMR device (manufactured by Bruker Biospin, AV300 model). 13 C-NMR measurement was performed. The production yield of hydrogen carbonate (potassium hydrogen carbonate) was calculated from the NMR chemical shift value of about 160 ppm in the measurement results and the calibration curve.

[0075] <Example 2> [Preparing the generation section] As a generation section, a flat membrane module having the configuration shown in Fig. 2B was prepared. Specifically, a flat membrane test cell "C-10T" manufactured by Nitto Denko Corporation was used, and a non-porous silicone-coated membrane (50 μm PDMS coating, RS50-S8) manufactured by Nitto Denko Corporation was used as the flat membrane 22d, which is a separation membrane, to assemble a flat membrane module having the configuration shown in Fig. 2B.

[0076] [Preparation of liquid containing basic compound] An aqueous potassium hydroxide solution similar to that in Example 1 was prepared.

[0077] [Evaluation method] (Preparing the evaluation system) An evaluation system was prepared for Example 2. Fig. 6 is a schematic diagram showing the configuration of an evaluation system 500 used in Example 2. The evaluation system 500 was constructed by replacing the hollow fiber membrane module 41 in the evaluation system 400 of Example 1 with a flat membrane module 51 assembled as the generation section of Example 2.

[0078] (Carbonate generation test) The system operating conditions were the same as in Example 1. The gas outlet of the "C-10T" cell was plugged to pressurize the cell. The pressure in the first space during system operation was 0.2 MPa. After the test, the pH of the liquid in the Erlenmeyer flask 42 was checked with pH test paper. The pH was approximately 7 to 8, confirming that potassium hydroxide had been completely consumed. The production yield of bicarbonate and the amount of CO2 consumed were calculated in the same manner as in Example 1. The CO2 supply flow rate was 400 mL / min. The evaluation results are shown in Table 3.

[0079] <Reference example 1> [Preparing the generation section] As the generation section, a hollow fiber membrane module similar to that in Example 1 (manufactured by Nagayanagi Industries Co., Ltd., "Nagasep M-30B") was prepared.

[0080] [Preparation of liquid containing basic compound] An aqueous potassium hydroxide solution similar to that in Example 1 was prepared.

[0081] [Evaluation method] (Preparing the evaluation system) An evaluation system for Reference Example 1 was prepared. FIG. 7 is a schematic diagram showing the configuration of an evaluation system 600 used in Reference Example 1. To confirm the effect of pressurizing the first space in the system of Example 1, in the evaluation system 600, the gas outlet port of the hollow fiber membrane module 41 in the evaluation system 400 of Example 1 was opened. This prevented the first space in the hollow fiber membrane module 41 from being pressurized. Apart from this change, the evaluation system 600 for Reference Example 1 was the same as the evaluation system 400 for Example 1.

[0082] (Carbonate generation test) The system operation conditions were the same as those in Example 1. The pressure in the first space during system operation was normal pressure (0.1 MPa). After the test, when the pH of the liquid in the Erlenmeyer flask 42 was checked with pH test paper, it was confirmed that potassium hydroxide had been completely consumed since the pH was about 7 to 8. The production yield of bicarbonate and the CO2 consumption were calculated in the same manner as in Example 1. The evaluation results are shown in Table 3.

[0083] <Reference Example 2> [Preparation of the production unit] As the production unit, a flat membrane module similar to that in Example 2 was prepared.

[0084] [Preparation of the liquid containing the basic compound] An aqueous potassium hydroxide solution similar to that in Example 1 was prepared.

[0085] [Evaluation method] (Preparation of the evaluation system) The evaluation system of Reference Example 2 was prepared. Fig. 8 is a schematic diagram showing the configuration of the evaluation system 700 used in Reference Example 2. In order to confirm the effect of pressurizing the first space in the system of Example 2, in the evaluation system 700, in the evaluation system 500 of Example 2, the gas Out part of the flat membrane module 51 was left open. As a result, the first space in the flat membrane module 51 was not pressurized. Except for this change point, the evaluation system 700 of Reference Example 2 was the same as the evaluation system 500 of Example 2.

[0086] (Carbonate production test) The system operation conditions were the same as those in Example 1. The pressure in the first space during system operation was normal pressure (0.1 MPa). After the test, when the pH of the liquid in the Erlenmeyer flask 42 was checked with pH test paper, it was confirmed that potassium hydroxide had been completely consumed since the pH was about 7 to 8. The production yield of bicarbonate and the CO2 consumption were calculated in the same manner as in Example 1. The evaluation results are shown in Table 3.

[0087] [Table 3]

[0088] In Examples 1 and 2, in which carbon dioxide was supplied to the potassium hydroxide aqueous solution while the first space in the membrane module was pressurized, CO consumption was lower than in Reference Examples 1 and 2, in which carbon dioxide was supplied to the potassium hydroxide aqueous solution while the first space was not pressurized. Specifically, the system of Example 1 consumed 40% less CO than the system of Reference Example 1, which used the same hollow fiber membrane. The system of Example 2 consumed 20% less CO than the system of Reference Example 2, which used the same flat membrane. Furthermore, the systems of Examples 1 and 2 were able to produce bicarbonate at yields equal to or higher than those of the systems of Reference Examples 1 and 2, even with a lower CO supply amount than the systems of Reference Examples 1 and 2. This is presumably because the production rate in Examples 1 and 2 was higher than that of Reference Examples 1 and 2. Furthermore, the carbonate production systems of Examples 1 and 2 are configured not to discharge carbon dioxide to the outside, thereby reducing unnecessary carbon dioxide emissions.

[0089] From the above results, the carbonate production system of the present invention is capable of supplying the necessary amount of carbon dioxide while suppressing the emission of unnecessary carbon dioxide, thereby enabling efficient conversion of carbon dioxide into carbonate. [Industrial Applicability]

[0090] The carbonate production system of the present invention can efficiently convert carbon dioxide into carbonate, and is therefore suitable for use in large-scale carbonate production systems, such as large-scale bicarbonate production systems. [Explanation of symbols]

[0091] 11, 31 Generation part 12, 32 Carbonate reservoir 13a First flow path 13b Second flow path 14 Liquid delivery device 35 Mixer 21 Hollow fiber membrane module 22 Flat membrane module 33 Membrane Module 100, 200, 300 Carbonate Generation System

Claims

1. A carbonate generation system comprising a generation unit that generates a carbonate from a basic compound and carbon dioxide, wherein the generation unit has a separation membrane and a first space and a second space separated by the separation membrane, during operation of the carbonate generation system, the carbon dioxide is supplied to the first space, a liquid containing the basic compound is supplied to the second space, the carbon dioxide permeates the separation membrane from the first space to the second space, and the first space is pressurized. A carbonate generation system.

2. The carbonate generation system according to claim 1, further comprising a carbonate storage tank.

3. The carbonate generation system according to claim 2, further comprising a first flow path for supplying the liquid containing the carbonate generated in the generation unit to the carbonate storage tank.

4. The carbonate generation system according to claim 3, further comprising a second flow path for supplying the liquid discharged from the carbonate storage tank to the generation unit.

5. The carbonate generation system according to claim 4, further comprising a liquid feeding device for supplying the liquid discharged from the carbonate storage tank to the generation unit through the second flow path.

6. The carbonate generation system according to claim 1, wherein the separation membrane is a hollow fiber membrane or a flat membrane.

7. The carbonate generation system according to claim 1, wherein the basic compound contains a hydroxide.

8. The carbonate generation system according to claim 7, wherein the hydroxide is at least one selected from the group consisting of potassium hydroxide, sodium hydroxide, magnesium hydroxide, and calcium hydroxide.

9. The carbonate generation system according to claim 1, wherein the liquid contains water.

10. The carbonate generation system according to claim 1, which generates a bicarbonate.

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