Method for producing basic chemicals and system for producing basic chemicals

Abstract

To provide a method for producing basic chemicals that employs chemosynthetic bacteria and enables basic chemicals to be produced from hydrogen and carbon dioxide by a more simplified basic chemical production system, and also to provide a system for producing the basic chemicals.SOLUTION: A method for producing basic chemicals includes supplying carbon dioxide and hydrogen to a bioreactor and causing a reaction, where the bioreactor includes chemosynthetic bacteria, and the supply of the hydrogen is performed by supplying a hydrogen-dissolved liquid to the bioreactor.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a basic chemical product and a system for producing a basic chemical product. [Background technology]

[0002] Carbon dioxide, methane, nitrous oxide, chlorofluorocarbons, etc. are known as greenhouse gases. Carbon dioxide accounts for the majority of greenhouse gas emissions. Currently, most of the carbon dioxide emitted is due to industrial activities. Reducing carbon dioxide emissions into the atmosphere is necessary to prevent the progression of global warming.

[0003] Methods for converting carbon dioxide into useful basic chemicals are currently being widely investigated. However, carbon dioxide is an extremely stable compound and is difficult to react with. One method for solving this problem is fermentation using chemosynthetic bacteria.

[0004] Patent Document 1 discloses chemosynthetic bacteria that produce ethanol, a basic chemical, by fermenting hydrogen and carbon dioxide. The fermentation by chemosynthetic bacteria described in Patent Document 1 can produce ethanol at a high yield with less energy consumption than chemical processes that use industrial catalysts, etc. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2013-521807 Summary of the Invention [Problem to be solved by the invention]

[0006] When using chemosynthetic bacteria to produce basic chemicals such as ethanol from hydrogen and carbon dioxide, the hydrogen and carbon dioxide must be dissolved in a water-based medium in a bioreactor. The hydrogen dissolved in the medium then reacts with the carbon dioxide to produce the basic chemical. Compared to carbon dioxide, hydrogen has a lower solubility in water. For example, the saturated solubility of hydrogen in water at 1 atmosphere and 20°C is approximately 1 / 50 of that of carbon dioxide. Therefore, hydrogen that does not dissolve in the medium remains within the bioreactor or is discharged from the bioreactor. Therefore, the bioreactor-based equipment in the production system must be adapted to handle hydrogen-containing gases, which creates the challenge of making the production system more complex.

[0007] The present invention has been made in consideration of the above circumstances, and aims to provide a method for producing basic chemicals that can produce basic chemicals from hydrogen and carbon dioxide using chemosynthetic bacteria and a simpler basic chemical production system, as well as the basic chemical production system. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention has the following aspects. [1] A method for producing basic chemicals, comprising supplying carbon dioxide and hydrogen to a bioreactor and reacting them, wherein the bioreactor is equipped with chemosynthetic bacteria, and the hydrogen is supplied by supplying a hydrogen solution to the bioreactor. [2] The method for producing a basic chemical product according to [1], wherein the carbon dioxide is supplied by supplying a first gas containing carbon dioxide to the bioreactor. [3] The method for producing a basic chemical product according to [2], wherein the carbon dioxide content in the first gas is less than 100% by volume. [4] The method for producing basic chemicals according to any one of [1] to [3], wherein the hydrogen concentration in the hydrogen-dissolved solution is 1 ppm by mass or more. [5] The method for producing a basic chemical product according to any one of [1] to [4], wherein the hydrogen solution is a solution in which hydrogen in a second gas containing hydrogen is dissolved in a solvent, and the hydrogen content in the second gas is less than 100% by volume. [6] The method for producing a basic chemical product according to [5], wherein the solvent is a culture medium for the chemosynthetic bacteria. [7] The method for producing basic chemicals according to any one of [2] to [6], wherein the first gas is a by-product gas from a factory. [8] The method for producing a basic chemical according to any one of [3] to [7], wherein the content of carbon dioxide in the first gas is 10% by volume or less. [9] The method for producing a basic chemical product according to any one of [5] to [8], wherein the second gas is a by-product gas from a factory.

[10] The method for producing a basic chemical according to any one of [5] to [9], wherein the content of hydrogen in the second gas is 20% by volume or less.

[11] The method for producing a basic chemical product according to any one of [1] to

[10] , wherein the carbon dioxide is supplied by supplying a carbon dioxide solution to the bioreactor.

[12] The method for producing a basic chemical according to any one of [1] to

[11] , wherein the basic chemical contains an alcohol.

[13] The method for producing a basic chemical product according to

[12] , wherein the alcohol includes ethanol.

[0009]

[14] A basic chemical manufacturing system comprising a tank for producing a hydrogen-dissolved solution and a bioreactor, the bioreactor containing chemosynthetic bacteria, and supplying a first gas containing carbon dioxide and the hydrogen-dissolved solution produced in the tank for producing a hydrogen-dissolved solution to the bioreactor.

[15] The system for producing basic chemicals according to

[14] , wherein the tank for producing hydrogen-dissolved liquid is equipped with a hydrogen concentration meter.

[16] A system for producing basic chemicals according to

[14] or

[15] , comprising two or more of the bioreactors.

[17] The system for producing basic chemicals according to any one of

[14] to

[16] , further comprising a tank for producing a carbon dioxide solution. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a method for producing basic chemicals that can produce basic chemicals from hydrogen and carbon dioxide using chemosynthetic bacteria and a simpler basic chemical production system, as well as the basic chemical production system. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a configuration diagram showing the configuration of a basic chemical manufacturing system according to one embodiment of the present invention. [Figure 2] FIG. 10 is a configuration diagram illustrating the configuration of a basic chemical manufacturing system according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] The following describes in detail the embodiments of the present invention. However, the following description is an example of an embodiment of the present invention, and the present invention is not limited to these contents and can be modified and implemented within the scope of its gist.

[0013] <Basic chemical manufacturing system> The system for producing basic chemicals of this embodiment includes a tank for producing a hydrogen-dissolved solution and a bioreactor. The bioreactor contains chemosynthetic bacteria. A first gas containing carbon dioxide and the hydrogen-dissolved solution produced in the tank for producing a hydrogen-dissolved solution are supplied to the bioreactor.

[0014] FIG. 1 is a diagram illustrating the configuration of a basic chemical production system according to one embodiment of the present invention. The basic chemical production system 100 of this embodiment includes a hydrogen-dissolved solution production tank 10, a bioreactor 20, and pipes L01, L11, L12, L02, and L29. The basic chemical production system 100 of this embodiment may further include a solid-liquid separation device 30, a concentrator 40, a dehydrator 50, a wastewater treatment device 60, pipes L23, L32, L34, L41, L45, L51, L59, and L69, and valves V10 and V11. The solid-liquid separation device 30, the concentrator 40, the dehydrator 50, and the wastewater treatment device 60 are primarily purification equipment used to purify basic chemicals synthesized by chemosynthetic bacteria; the above is merely exemplary. The purification equipment can be selected appropriately depending on the chemosynthetic bacteria used and the type and amount of basic chemicals to be produced.

[0015] 2 is a configuration diagram showing the configuration of a basic chemical production system according to another embodiment of the present invention. In addition to the basic chemical production system 100 described above, the basic chemical production system 200 of this embodiment includes a bioreactor 20A and pipes L12A, L02A, and L29A. The basic chemical production system 200 of this embodiment may further include a solid-liquid separator 30A and pipes L23A, L32A, and L34A.

[0016] 1 and 2 do not show pumps for delivering liquids such as culture media, pressure regulating valves for adjusting gas pressure, mass controllers for controlling the flow rates of liquids and gases, etc., but these can be installed and used as needed. Also, while FIGS. 1 and 2 do not show all of the valves in the piping between each device, it is preferable that valves be installed in the piping between each device. Furthermore, while FIGS. 1 and 2 do not show heating and cooling devices for heating and cooling each device and the piping between each device, these can also be installed and used as needed.

[0017] <Hydrogen solution production tank> In the hydrogen-dissolved solution production tank 10, hydrogen in the second gas containing hydrogen is dissolved in a solvent to produce a hydrogen-dissolved solution. As shown in Fig. 1, the hydrogen-dissolved solution production tank 10 and the bioreactor 20 are connected via a pipe L12. A second gas supply source containing hydrogen is connected to the hydrogen-dissolved solution production tank 10 via a pipe L01. As shown in Fig. 2, the pipe L12 and the bioreactor 20A are connected via a pipe L12A. That is, the hydrogen-dissolved solution production tank 10 and the bioreactor 20A are connected via pipes L12 and L12A.

[0018] 1 and 2, the hydrogen-dissolved liquid production tank 10 is connected to the atmosphere via a pipe L11. The pipe L11 branches at a branch 11 and is connected back to the hydrogen-dissolved liquid production tank 10. A valve V11 is provided between the branch 11 of the pipe L11 and the junction of the pipe L11 with the pipe L01. A valve V10 is provided between the branch 11 of the pipe L11 and the atmosphere. The hydrogen-dissolved solution production tank 10 is provided with a solvent. The solvent is preferably a culture medium for chemosynthetic bacteria. The hydrogen-dissolved solution production tank 10 is preferably provided with a stirrer, a heating / cooling device, a solids separator, a pressure gauge, a thermometer, a pH meter, a COD meter, a hydrogen concentration meter, etc. The number of hydrogen-dissolved solution production tanks 10 may be one or two or more. When there are two or more, they may be installed in series or in parallel, with parallel installation being preferred. The ratio of the number of hydrogen-dissolved solution production tanks 10 to the number of bioreactors 20 may be less than 1, 1, or 2 or more.

[0019] <Bioreactor> The bioreactor 20 contains chemosynthetic bacteria and synthesizes basic chemicals by the reaction (fermentation) of hydrogen and carbon dioxide. The bioreactor 20 also has the function of culturing the chemosynthetic bacteria. As shown in FIG. 1, the bioreactor 20 and the solid-liquid separator 30 are connected via a pipe L23. The bioreactor 20 and the solid-liquid separator 30 are also connected via a pipe L32. The bioreactor 20 is connected to a first gas supply source containing carbon dioxide via a pipe L02. The bioreactor 20 is connected to the atmosphere via a pipe L29. As shown in FIG. 2, the bioreactor 20A and the solid-liquid separator 30A are connected via a pipe L23A. The bioreactor 20A and the solid-liquid separator 30A are also connected via a pipe L32A. The pipe L02 and the bioreactor 20A are connected via a pipe L02A. That is, the first gas supply source containing carbon dioxide and the bioreactor 20A are connected via pipes L02 and L02A. The bioreactor 20A is connected to the atmosphere via a pipe L29A. The bioreactors 20 and 20A contain chemosynthetic bacteria. Preferably, the bioreactors 20 and 20A contain a culture medium. Any bioreactor known in the art can be used. Examples of bioreactors include, but are not limited to, stirred tank reactors, column fermenters containing immobilized or suspended chemosynthetic bacteria, continuous flow reactors, and high-pressure reactors. The bioreactor 20 is preferably equipped with a stirrer, a heating / cooling device, a pressure gauge, a thermometer, a pH meter, a COD meter, a hydrogen concentration meter, a carbon dioxide concentration meter, and the like. The number of bioreactors 20, 20A may be one as shown in Figure 1, or two or more as shown in Figure 2. When there are two or more bioreactors, they may be installed in series or in parallel as shown in Figure 2. Of these, installation in parallel is preferred.

[0020] (Chemosynthetic bacteria) The chemosynthetic bacteria are not particularly limited as long as they can synthesize basic chemicals by fermenting hydrogen and carbon dioxide as raw materials. The chemosynthetic bacteria may be aerobic or anaerobic bacteria. Aerobic bacteria are preferred. When the chemosynthetic bacteria are aerobic bacteria, the basic chemical production systems 100 and 200 preferably have a pipe for supplying an oxygen-containing gas connected to the bioreactors 20 and 20A. For example, air can be used as the oxygen-containing gas. The chemosynthetic bacteria may be chemosynthetic bacteria that synthesize basic chemicals while growing (hereinafter also referred to as "chemosynthetic bacteria A"), or chemosynthetic bacteria that can switch between growth and synthesis of basic chemicals (hereinafter also referred to as "chemosynthetic bacteria B"), with chemosynthetic bacteria B being preferred. The switch between growth and synthesis of basic chemicals can be achieved by adding a specific additive (hereinafter also referred to as "switching additive"). In the case of such chemosynthetic bacteria B, growth initially takes precedence. Once a certain level of growth has been achieved, a switching additive is added. After the addition of the switching additive, synthesis of basic chemicals takes precedence over proliferation.

[0021] Examples of chemosynthetic bacteria include the genera Clostridium and Mooreella, which synthesize ethanol; the genera Acetobacterium and Mooreella, which synthesize acetic acid; the genus Acetonema, which synthesizes propionic acid; the genus Acetobacterium, which synthesizes acetone; the genus Hydrogenophilus, which synthesizes butanol; the genera Eubacterium and Clostridium, which synthesize butyric acid; the genus Hydrogenovibrio, which produces proteins and amino acids; the genus Hydrogenophilus, which produces lipids; and the genus Cupriavidus, which produces polymers.

[0022] An example of the genus Clostridium is the mesophilic bacterium Clostridium ljungdahlii. An example of the genus Moorella is the thermophilic bacterium Moorella sp. HUC22-1. An example of the genus Acetobacterium is the mesophilic bacterium Acetobacterium woodii. An example of the genus Moorella is the thermophilic bacterium Moorella thermoacetica. An example of the genus Acetonema is Acetonema longum. An example of the genus Acetobacterium is Acetobacterium woodii (genetically recombinant). An example of the genus Hydrogenophilus is Hydrogenophilus bacterium (genetically recombinant). An example of the genus Eubacterium is Eubacterium limosum. An example of the genus Clostridium is a co-culture system of Clostridium autoethanogenum and Clostridium beijerinckii. An example of the genus Hydrogenovibrio is Hydrogenovibrio marinus MH110. An example of the genus Hydrogenophilus is Hydrogenophilus thermoluteolus. An example of the genus Cupriavidus is Cupriavidus necator (genetically recombinant). The above chemosynthetic bacteria are merely examples and are not intended to be limiting.

[0023] <Solid-liquid separator> In the solid-liquid separator 30, the chemosynthetic bacteria are separated from the crude product containing the chemosynthetic bacteria, basic chemicals, and culture medium after the reaction in the bioreactor. As shown in Fig. 1, the solid-liquid separator 30 and the concentrator 40 are connected via a pipe L34. As shown in Fig. 2, the solid-liquid separator 30A and the pipe L34 are connected via a pipe L34A. That is, the solid-liquid separator 30A and the concentrator 40 are connected via pipes L34 and L34A. A solid-liquid separator known in the art can be used as the solid-liquid separators 30 and 30A, including, but not limited to, a low-pressure separator, a high-pressure separator, and a centrifugal separator. The number of solid-liquid separators 30 may be one or two or more. When two or more solid-liquid separators are used, they may be installed in series or in parallel. Of these, installation in parallel is preferred.

[0024] <Concentrator> In the concentrator 40, the medium is removed from the mixture of the medium and the basic chemicals separated in the solid-liquid separators 30, 30A, and the concentration of the basic chemicals is increased. 1 and 2, the concentrator 40 and the dehydrator 50 are connected via a pipe L45. A pipe L41 is connected to the concentrator 40. The pipe L41 merges with a pipe L51. The pipe after the merger of the pipes L41 and L51 is designated as a pipe L69. Any concentrator known in the art can be used as the concentrator 40. Examples of concentrators include, but are not limited to, a distillation apparatus and a solvent extraction apparatus. The number of concentrators 40 may be one or two or more. When there are two or more concentrators, they may be installed in series or in parallel.

[0025] <Dehydration equipment> In the dehydration device 50, the water that could not be removed in the concentrator 40 is removed from the water-containing basic chemicals whose concentration has been increased in the concentrator 40, and the basic chemicals are refined into finished products. 1 and 2, a pipe L59 is connected to the dehydration device 50. A pipe L51 is connected to the dehydration device 50. The pipe L51 merges with the pipe L41. The pipe L69, which is the pipe after the merging of the pipes L41 and L51, branches at a branch 66, one end of which is connected to the hydrogen-dissolved liquid production tank 10 and the other end of which is connected to the wastewater treatment facility 60. Any dehydration device known in the art can be used as the dehydration device 50. Examples of the dehydration device include, but are not limited to, a dehydration device filled with a dehydrating agent and a dehydration device equipped with a separation membrane. The number of dehydration devices 50 may be one or two or more. When there are two or more, they may be installed in series or in parallel.

[0026] <Wastewater treatment equipment> The wastewater treatment device 60 treats the culture medium separated in the concentrator 40 and the water separated in the dehydrator 50 . As the wastewater treatment device 60, any wastewater treatment device known in the art can be used. The number of wastewater treatment devices 60 may be one or two or more. When there are two or more devices, they may be installed in series or in parallel.

[0027] <Other facilities> The basic chemical manufacturing systems 100 and 200 of the present embodiment may include other equipment in addition to those described above. Examples of such other equipment include an inert treatment device and a carbon dioxide dissolved liquid manufacturing tank.

[0028] The inactivation treatment device is a device that inactivates chemosynthetic bacteria whose activity has decreased. If the chemosynthetic bacteria are, for example, genetically modified bacteria, they are inactivated and then discarded. An example of an inactivation method is treating the chemosynthetic bacteria at high temperature and / or high pressure. When the basic chemical production system 100, 200 is equipped with an inactivation treatment device, the inactivation treatment device is preferably connected to the solid-liquid separation device 30, 30A via piping.

[0029] In the carbon dioxide solution production tank, carbon dioxide in a first gas containing carbon dioxide is dissolved in a solvent to produce a carbon dioxide solution. That is, in the basic chemical production systems 100, 200 described above, carbon dioxide is supplied as a gas to the bioreactors 20, 20A from a first gas source containing carbon dioxide, but instead of or in addition to this supply, carbon dioxide may be supplied as a carbon dioxide solution to the bioreactors 20, 20A. The configurations of the carbon dioxide solution production tank and the piping connected to the carbon dioxide solution production tank, as well as the valves on the piping, can be similar to those of the hydrogen solution production tank 10.

[0030] The carbon dioxide solution production tank may be installed in place of the first gas supply source containing carbon dioxide. In this case, the hydrogen solution is supplied from the hydrogen solution production tank 10 to the bioreactors 20 and 20A, and the carbon dioxide solution is supplied from the carbon dioxide solution production tank to the bioreactors 20 and 20A. The carbon dioxide solution production tank may also be installed in series with the hydrogen solution production tank 10. Specifically, the carbon dioxide solution production tank may be installed upstream or downstream of the hydrogen solution production tank 10. For example, when the carbon dioxide solution production tank is installed downstream of the hydrogen solution production tank 10, the hydrogen solution discharged from the hydrogen solution production tank 10 is supplied to the carbon dioxide solution production tank. A first gas containing carbon dioxide is supplied to the hydrogen solution supplied to the carbon dioxide solution production tank to produce the carbon dioxide solution. The resulting solution contains dissolved hydrogen and carbon dioxide. The resulting solution is then supplied to the bioreactors 20 and 20A.

[0031] <Basic chemical manufacturing methods> In the method for producing basic chemicals of this embodiment, carbon dioxide and hydrogen are supplied to a bioreactor and reacted (basic chemical production step). The bioreactor is equipped with chemosynthetic bacteria. Hydrogen is supplied by supplying a hydrogen-dissolved solution to the bioreactor. The method for producing basic chemicals may include a culturing step for culturing the chemosynthetic bacteria, a hydrogen-dissolved solution production step for dissolving hydrogen in a second gas containing hydrogen in a solvent to produce the hydrogen-dissolved solution, and a purification step for purifying a crude product containing the basic chemical produced in the basic chemical production step. The hydrogen-dissolved solution production process, the culturing process, the basic chemical production process, and the refining process will be described below with reference to FIGS.

[0032] <Hydrogen solution manufacturing process> In the hydrogen-dissolved solution production process, hydrogen contained in a hydrogen-containing second gas is dissolved in a solvent to produce a hydrogen-dissolved solution. In the basic chemical production systems 100 and 200 shown in Figures 1 and 2, a solvent is charged into a hydrogen-dissolved solution production tank 10, and a hydrogen-containing second gas is supplied from a hydrogen-containing second gas supply source through a pipe L01 to the solvent in the hydrogen-dissolved solution production tank 10, thereby dissolving hydrogen in the solvent. A culture medium for chemosynthetic bacteria is preferred as the solvent.

[0033] The hydrogen content in the second gas may be 100% by volume. In order to increase the amount of hydrogen dissolved in the solvent, it is preferable that the hydrogen content in the second gas is high. Examples of gases with high hydrogen contents include gases produced by hydrogen production. Methods for producing hydrogen include reforming reactions of liquefied natural gas, reforming reactions of liquefied petroleum gas, electrolysis of water, and catalytic reforming reactions of naphtha. Gases with low hydrogen contents may also be concentrated to produce gases with high hydrogen contents.

[0034] In the basic chemical production method of this embodiment, not only high-hydrogen gas produced by the above-described hydrogen production method but also low-hydrogen by-product gases generated in industrial processes may be used. Such by-product gases are primarily used as heat source gases. The use of such by-product gases is preferable in terms of effective utilization, as the hydrogen content of the by-product gas is not necessarily high. However, such gases are also suitable for use in the basic chemical production method of this embodiment. Examples of the by-product gases include by-product gases containing unreacted hydrogen from industrial processes that use hydrogen as a raw material and by-product gases containing hydrogen from industrial processes that do not use hydrogen. Examples of the former include by-product gases discharged from hydrodesulfurization units in oil refineries. Examples of the latter include by-product gases discharged from coke ovens in steelmaking, by-product gases discharged by naphtha thermal cracking in ethylene plants, and by-product gases discharged from fluidized catalytic cracking units in oil refineries.

[0035] The hydrogen content in the second gas is preferably less than 100% by volume. The hydrogen content in the second gas may be 90% by volume or less, 80% by volume or less, 70% by volume or less, 60% by volume or less, 50% by volume or less, 40% by volume or less, 30% by volume or less, or 20% by volume or less. The hydrogen content in the second gas is preferably 1% by volume or more, more preferably 5% by volume or more, and even more preferably 10% by volume or more. When the hydrogen content in the second gas is less than (or equal to) the upper limit, a process such as concentrating hydrogen is often unnecessary. A concentration process to increase the hydrogen content requires a very large amount of energy. According to the method for producing basic chemicals of this embodiment, a second gas having a hydrogen content less than (or equal to) the upper limit can be used, thereby improving energy efficiency. When the hydrogen content in the second gas is equal to or greater than the lower limit, the amount of hydrogen dissolved in the solvent can be increased.

[0036] Examples of gases other than hydrogen contained in the second gas include methane, ethane, ethylene, propylene, carbon dioxide, hydrogen sulfide, etc. When the chemosynthetic bacteria are anaerobic bacteria, it is preferable that the second gas does not contain oxygen.

[0037] From the viewpoint of increasing the rate of dissolution of hydrogen into the solvent, it is preferable to increase the contact area between the second gas containing hydrogen and the solvent. As a method for increasing the contact area, for example, it is preferable to contact the second gas containing hydrogen with the solvent by bubbling. It is also preferable to reduce the size of the bubbles.

[0038] The temperature inside the hydrogen-dissolved liquid production tank 10 is preferably 30 to 70°C, more preferably 40 to 60°C, and even more preferably 50 to 55°C. When the temperature is equal to or higher than the lower limit, it is easy to adjust the temperature when supplying the obtained hydrogen-dissolved solution directly to the bioreactors 20 and 20A. When the temperature is equal to or lower than the upper limit, it is possible to increase the amount of hydrogen dissolved in the solvent.

[0039] The pressure inside the hydrogen-dissolved solution production tank 10 is preferably 0.1 to 2 MPa, more preferably 0.3 to 1.5 MPa, and even more preferably 0.5 to 0.9 MPa. If the pressure is equal to or higher than the lower limit, the partial pressure of hydrogen in the hydrogen-containing second gas increases, allowing for an increased amount of hydrogen to be dissolved in the solvent. If the pressure is equal to or lower than the lower limit, pressure reduction is not required when supplying the resulting hydrogen-dissolved solution to bioreactor 20, making it easier to maintain the hydrogen concentration of the hydrogen-dissolved solution.

[0040] The amount of hydrogen dissolved in the hydrogen solution is preferably the saturated dissolution amount under the conditions (temperature, hydrogen partial pressure) for producing the hydrogen solution. The hydrogen concentration (hydrogen content) relative to the total mass of the hydrogen-dissolved solution is preferably 1 mass ppm or more, more preferably 3 mass ppm or more, and even more preferably 5 mass ppm or more.

[0041] The hydrogen-containing second gas that has not dissolved in the solvent is discharged from the hydrogen-dissolved solution production tank 10 through the pipe L11. If the hydrogen concentration in the discharged hydrogen-containing second gas is low, the valve V10 in FIG. 1 may be opened and the valve V11 closed, and the hydrogen-containing second gas may be released to the atmosphere. If the hydrogen concentration in the discharged hydrogen-containing second gas is high, the valve V11 in FIG. 1 may be opened and the valve V10 closed, and the hydrogen-containing second gas may be resupplied to the hydrogen-dissolved solution production tank 10. When resupplying the second gas, the supply of the hydrogen-containing second gas from the hydrogen-containing second gas supply source may be continued or stopped.

[0042] <Culture process, basic chemical manufacturing process> In the culturing step, a first gas containing carbon dioxide and a hydrogen solution are supplied to a bioreactor 20 containing chemosynthetic bacteria, and the chemosynthetic bacteria are cultured. In the basic chemical production process, a first gas containing carbon dioxide and a hydrogen solution are supplied to a bioreactor 20 containing chemosynthetic bacteria, and reacted to produce basic chemicals. When the chemosynthetic bacterium is the above-mentioned chemosynthetic bacterium A, the culturing step and the basic chemical production step may be carried out simultaneously. When the chemosynthetic bacterium is the above-mentioned chemosynthetic bacterium B, the chemosynthetic bacterium is first grown in the culturing step, and the basic chemical is produced in the basic chemical production step while suppressing growth by adding a switching additive.

[0043] A hydrogen-dissolved solution is supplied to the bioreactor 20 from the hydrogen-dissolved solution production tank 10 through a pipe L12. A first gas containing carbon dioxide is supplied to the bioreactor 20 from a first gas supply source containing carbon dioxide through a pipe L02. If the basic chemical production system 100 has a carbon dioxide-dissolved solution production tank, carbon dioxide may be supplied to the bioreactor 20 as a carbon dioxide-dissolved solution instead of or in addition to the first gas. If the chemosynthetic bacteria are aerobic bacteria, an oxygen-containing gas is supplied to the bioreactor 20.

[0044] The basic chemical production process may be carried out continuously or batchwise, but is preferably carried out continuously. When carried out batchwise, first, the hydrogen-dissolved solution is supplied from the hydrogen-dissolved solution production tank 10 to the bioreactor 20 through pipe L12. Then, the valves on pipes L12 and L23 are closed. When carried out continuously, the valves on pipes L12 and L23 are opened. Then, the reaction is carried out by continuously supplying the first gas containing carbon dioxide from the first gas supply source containing carbon dioxide through pipe L02 to the bioreactor 20. After the reaction, the first gas containing carbon dioxide is discharged to the atmosphere through pipe L29. Note that if the carbon dioxide concentration in the first gas containing carbon dioxide after the reaction is high, it may be resupplied to the bioreactor 20 (piping not shown). For example, if the carbon dioxide content in the first gas containing carbon dioxide after the reaction is 1% by volume or more, it is preferable to resupply it to the bioreactor 20.

[0045] From the viewpoint of increasing the dissolution rate of carbon dioxide in the hydrogen solution, it is preferable to increase the contact area between the first gas containing carbon dioxide and the hydrogen solution. A method for increasing the contact area is, for example, to contact the first gas containing carbon dioxide with the hydrogen solution by bubbling. It is also preferable to reduce the size of the bubbles.

[0046] The carbon dioxide content in the first gas may be 100% by volume. In order to increase the amount of carbon dioxide dissolved in the culture medium, it is preferable that the carbon dioxide content in the first gas is high. An example of a gas with a high carbon dioxide content is a gas produced by concentrating a gas with a low carbon dioxide content. On the other hand, concentration processing has disadvantages such as being time-consuming, requiring energy, and increasing costs.

[0047] In the basic chemical production method of this embodiment, not only the gases with a high carbon dioxide content as described above, but also by-product gases with a low carbon dioxide content generated in industrial processes may be used. Such by-product gases are exhaust gases generated in factories. Although the carbon dioxide content of the by-product gases is not necessarily high, such gases are also suitable for use in the basic chemical production method of this embodiment. Examples of the by-product gases include by-product gases discharged from manufacturing equipment when producing various industrial products, and by-product gases discharged from heating furnaces, boilers, incinerators, power plants, etc. Note that industrial products include not only products provided to consumers, but also parts of such products, materials for such parts such as resins, and raw materials for such materials such as monomers used to produce such resins. In other words, industrial products also include chemical products produced in oil refineries and chemical factories. In addition to the above, atmospheric air may be used as the first gas containing carbon dioxide.

[0048] The carbon dioxide content in the first gas is preferably less than 100% by volume. The carbon dioxide content in the first gas may be 90% by volume or less, 80% by volume or less, 70% by volume or less, 60% by volume or less, 50% by volume or less, 40% by volume or less, 30% by volume or less, or 20% by volume or less. The carbon dioxide content in the first gas is preferably 0.03% by volume or more, more preferably 1% by volume or more, and even more preferably 5% by volume or more. When the carbon dioxide content in the first gas is less than (or equal to or less than) the upper limit, there are many cases where a process such as concentrating carbon dioxide is not required. When the carbon dioxide content in the first gas is equal to or greater than the lower limit, the amount of carbon dioxide dissolved in the solvent can be increased.

[0049] Examples of gases contained in the first gas other than carbon dioxide include nitrogen, oxygen, SOx, and NOx. The first gas preferably does not contain hydrogen. When the chemosynthetic bacteria are anaerobic bacteria, the first gas preferably does not contain oxygen.

[0050] The reaction temperature may be set depending on the type of chemosynthetic bacteria used, and is preferably 30 to 70°C, more preferably 40 to 60°C, and even more preferably 50 to 55°C. When the reaction temperature is within the above range, the production of basic chemicals by the chemosynthetic bacteria proceeds efficiently. Furthermore, when the reaction temperature is equal to or lower than the above upper limit, the amount of carbon dioxide dissolved in the solvent can be increased.

[0051] The reaction pressure may be set depending on the type of chemosynthetic bacteria used, and is, for example, preferably 0.1 to 2 MPa, more preferably 0.3 to 1.5 MPa, and even more preferably 0.5 to 0.9 MPa. When the reaction pressure is within the above range, the production of basic chemicals by the chemosynthetic bacteria proceeds efficiently. When the reaction pressure is equal to or higher than the above lower limit, the amount of carbon dioxide dissolved in the solvent can be increased.

[0052] As the reaction progresses, the hydrogen dissolved in the hydrogen-dissolved solution is consumed. The reaction solution after the reaction is discharged to the solid-liquid separator 30 through pipe L23, as described below. Depending on the amount discharged, the hydrogen-dissolved solution is supplied from the hydrogen-dissolved solution production tank 10 to the bioreactor 20 through pipe L12. Furthermore, as described below, the chemosynthetic bacteria separated in the solid-liquid separator 30 may be resupplied to the bioreactor 20 through pipe L32. It is preferable to continuously supply the hydrogen-dissolved solution to the bioreactor 20, discharge the reaction solution to the solid-liquid separator 30, and supply the chemosynthetic bacteria from the solid-liquid separator 30 to the bioreactor 20. When performing the reaction in a batch process, after the reaction is completed, the valves on pipes L12 and L23 are opened to discharge the reaction solution to the solid-liquid separator 30, and then the hydrogen-dissolved solution is supplied to the bioreactor 20. At this time, the chemosynthetic bacteria separated in the solid-liquid separator 30 may be resupplied to the bioreactor 20 through pipe L32, as described below.

[0053] <Purification process> In the purification step, the basic chemicals are purified from the mixture of the chemosynthetic bacteria, the basic chemicals, and the culture medium after the reaction in the bioreactor 20 .

[0054] After the reaction in bioreactor 20, the crude product containing the chemosynthetic bacteria, basic chemicals, and culture medium is supplied to solid-liquid separator 30 via pipe L23. In solid-liquid separator 30, the chemosynthetic bacteria, which is a solid, and the culture medium and basic chemicals, which are liquid, are separated. The chemosynthetic bacteria after solid-liquid separation are sent to bioreactor 20 via pipe L32 and may be reused. If the activity of the chemosynthetic bacteria has decreased, they are discarded without being sent to bioreactor 20. If the chemosynthetic bacteria are, for example, genetically modified, they are inactivated in an inactivation treatment device and then discarded. The culture medium and basic chemicals after solid-liquid separation are supplied to concentrator 40 via pipe L34.

[0055] The medium and basic chemicals supplied to the concentrator 40 are concentrated by the concentrator 40. For example, if the concentrator 40 is a distillation apparatus and the basic chemical is ethanol, the ethanol is evaporated by distillation and supplied from the distillation apparatus to the dehydration apparatus 50 through a pipe L45. The medium, including water that was not evaporated by distillation, is discharged from a pipe L41.

[0056] The water-containing basic chemicals supplied to the dehydrator 50 are dehydrated by the dehydrator 50. The basic chemicals dehydrated by the dehydrator 50 are discharged from the pipe L59 and become products. The water dehydrated by the dehydrator 50 is discharged from the pipe L51.

[0057] The culture medium discharged from pipe L41 and the water discharged from pipe L51 are mixed at the junction of pipes L41 and L51 to form a mixed liquid, which is then recycled to hydrogen-dissolved solution production tank 10 via pipe L69. Note that the mixed liquid may be treated as wastewater in wastewater treatment device 60 instead of being recycled to hydrogen-dissolved solution production tank 10.

[0058] <Modification> In the basic chemical production system 100 of Figure 1 described above, when basic chemicals are produced using chemosynthetic bacteria B, the basic chemicals cannot be produced or only small amounts can be produced during cultivation. Therefore, when basic chemicals are produced using chemosynthetic bacteria B, it is preferable to employ the basic chemical production system 200 of Figure 2. The hydrogen-dissolved solution production process and purification process can be carried out as described for the basic chemical production system 100 of Figure 1.

[0059] For example, while chemosynthetic bacteria B is being cultured in bioreactor 20A of the basic chemical production system 200 of FIG. 2, basic chemicals are produced in bioreactor 20. When the activity of chemosynthetic bacteria B in bioreactor 20 decreases and the chemosynthetic bacteria B is to be discarded, a switching additive is added to bioreactor 20A. As a result, the chemosynthetic bacteria B in bioreactor 20A prioritizes the production of basic chemicals over proliferation. In other words, basic chemicals can be produced in bioreactor 20A. Meanwhile, new chemosynthetic bacteria B are added to bioreactor 20, and cultivation begins. In this modified example, when cultivation is essentially being carried out in one of bioreactors 20 and 20A, the other is always essentially producing basic chemicals, allowing for more efficient basic chemical production. In this modified example, a substantially constant amount of basic chemicals can always be produced, resulting in greater efficiency.

[0060] <Basic chemicals> The basic chemicals produced by the basic chemical production method of this embodiment are determined by the type of chemosynthetic bacteria. Examples of basic chemicals include alcohols, carboxylic acids, ketones, amino acids, proteins, lipids, polymers, methane, etc. Examples of alcohols include ethanol, isobutanol, and n-butanol. Examples of carboxylic acids include acetic acid, propionic acid, and butyric acid. Examples of ketones include acetone. Among these, alcohols are preferred, with ethanol and isobutanol being more preferred.

[0061] <Mechanism of action> As described above, the basic chemical production method of the present invention allows basic chemicals to be produced without supplying hydrogen in gaseous form to the bioreactor. Therefore, the equipment, centered around the bioreactor, in the basic chemical production system does not need to be equipment compatible with hydrogen-containing gas, making the basic chemical production system simpler.

[0062] Furthermore, the method for producing basic chemicals of the present invention is believed to have the following effects. As mentioned above, hydrogen has a lower solubility in water than carbon dioxide. Furthermore, due to its low solubility, the rate at which hydrogen dissolves in water is also slow. In other words, even when highly active chemosynthetic bacteria are used, there is a problem in that the dissolution of hydrogen into the culture medium is rate-limiting. On the other hand, in the method for producing basic chemicals of the present invention, a hydrogen solution is prepared in advance by dissolving hydrogen in the culture medium, and this hydrogen solution is used. Therefore, there is no need to dissolve hydrogen in the bioreactor. For example, if an excess amount of hydrogen solution is prepared in advance relative to the volume of the bioreactor, the dissolution of hydrogen into the culture medium will not be rate-limiting in the basic chemical production process, and basic chemicals can be produced more efficiently than conventional methods.

[0063] When producing a hydrogen-dissolved solution, solid impurities contained in the hydrogen-containing gas are also trapped in the hydrogen-dissolved solution. If the hydrogen-dissolved solution production tank is equipped with a solids separation device, there is an advantage in that the hydrogen-dissolved solution can be supplied to the bioreactor after removing solid impurities. Furthermore, when producing a hydrogen-dissolved solution, undissolved gas components in the hydrogen-containing second gas are not supplied to the bioreactor, which is thought to have the effect of essentially purifying the hydrogen-containing second gas.

[0064] Furthermore, in conventional methods for producing basic chemicals, the unreacted gas that did not react in the bioreactor contains both hydrogen and carbon dioxide, which makes it difficult to control the recycle, such as adjusting the concentrations of hydrogen and carbon dioxide, when recycling the unreacted gas. On the other hand, in the method for producing basic chemicals of this embodiment, the undissolved gas that did not dissolve in the hydrogen solution essentially contains hydrogen but does not contain carbon dioxide. Therefore, by recycling the undissolved gas back into the hydrogen solution, a hydrogen solution can be produced, making it easy to control the recycle. Furthermore, the unreacted gas that did not react in the bioreactor essentially contains carbon dioxide but does not contain hydrogen. Therefore, by recycling the unreacted gas back into the bioreactor, basic chemicals can be produced, making it easy to control the recycle.

[0065] Furthermore, in the basic chemical production of the present invention, hydrogen is not supplied to the bioreactor in a gaseous state, but carbon dioxide is supplied to the bioreactor in a gaseous state. As mentioned above, carbon dioxide may also be supplied as a carbon dioxide solution. Therefore, when adjusting the carbon dioxide / hydrogen ratio and pH in the culture medium to control the reaction, it is easy to control the carbon dioxide concentration and supply amount of the carbon dioxide-containing gas or carbon dioxide solution, since this is essentially all that is required. Furthermore, if the carbon dioxide concentration in the unreacted gas that did not react in the bioreactor is low, it may be released into the atmosphere. In this case, the unreacted gas does not contain hydrogen, which can reduce hydrogen loss throughout the entire production process. [Explanation of symbols]

[0066] 10...hydrogen solution production tank, 11...branch, 20, 20A...bioreactor, 30, 30A...solid-liquid separation device, 40...concentration device, 50...dehydration device, 60...wastewater treatment device, 66...branch, 100, 200...basic chemicals production system, L01, L02, L02A, L11, L12, L12A, L23, L23A, L29, L29A, L32, L32A, L34, L34A, L41, L45, L51, L59, L69...piping, V10, V11...valve

Claims

1. A method for producing a basic chemical product, comprising supplying carbon dioxide and hydrogen to a bioreactor and reacting them, the bioreactor comprises chemosynthetic bacteria; The method for producing basic chemicals, wherein the hydrogen is supplied by supplying a hydrogen solution to the bioreactor.

2. 2. The method for producing a basic chemical product according to claim 1, wherein the carbon dioxide is supplied by supplying a first gas containing carbon dioxide to the bioreactor.

3. 3. The method for producing basic chemicals according to claim 2, wherein the carbon dioxide content in the first gas is less than 100% by volume.

4. 2. The method for producing basic chemicals according to claim 1, wherein the hydrogen concentration in the hydrogen-dissolved solution is 1 ppm by mass or more.

5. 2. The method for producing basic chemicals according to claim 1, wherein the hydrogen solution is a solution in which hydrogen contained in a second gas is dissolved in a solvent, and the hydrogen content of the second gas is less than 100% by volume.

6. The method for producing basic chemicals according to claim 5, wherein the solvent is a culture medium for the chemosynthetic bacteria.

7. The method for producing basic chemicals according to claim 2 , wherein the first gas is a by-product gas from a factory.

8. 4. The method for producing basic chemicals according to claim 3, wherein the carbon dioxide content in the first gas is 10% by volume or less.

9. The method for producing basic chemicals according to claim 5 , wherein the second gas is a by-product gas from a factory.

10. 6. The method for producing basic chemicals according to claim 5, wherein the second gas has a hydrogen content of 20% by volume or less.

11. The method for producing basic chemicals according to claim 1 , wherein the carbon dioxide is supplied by supplying a carbon dioxide solution to the bioreactor.

12. The method for producing a basic chemical according to any one of claims 1 to 11, wherein the basic chemical includes an alcohol.

13. The method for producing a basic chemical according to claim 12 , wherein the alcohol comprises ethanol.

14. A basic chemical manufacturing system comprising: an apparatus for manufacturing a basic chemical product, the apparatus comprising: a tank for producing a hydrogen-dissolved solution; and a bioreactor, the bioreactor containing chemosynthetic bacteria; and a first gas containing carbon dioxide and the hydrogen-dissolved solution produced in the tank for producing a hydrogen-dissolved solution being supplied to the bioreactor.

15. 15. The system for producing basic chemicals according to claim 14, wherein the hydrogen-dissolved solution producing tank is equipped with a hydrogen concentration meter.

16. The system for producing a basic chemical product according to claim 14 or 15, comprising two or more bioreactors.

17. The system for producing basic chemicals according to claim 14 or 15, further comprising a tank for producing a carbon dioxide solution.

Images