Method for producing ammonia-based compounds and apparatus for producing ammonia-based compounds

Abstract

This provides a new method for producing ammonia-based compounds. [Solution] The disclosed manufacturing method is a method for producing an ammonia-based compound. The manufacturing method includes a step (X) of applying a voltage between an anode 121 and a cathode 122 in a liquid L containing dissolved nitrogen.

Description

[Technical Field]

[0001] The present invention relates to a method for producing ammonia-based compounds and an apparatus for producing ammonia-based compounds. [Background technology]

[0002] The Haber-Bosch process is a well-known method for synthesizing ammonia. However, the Haber-Bosch process requires the use of fossil fuels such as coal and natural gas, and necessitates reactions under high temperature and pressure conditions. Therefore, the Haber-Bosch process has faced challenges due to its high environmental impact and poor production efficiency.

[0003] On the other hand, the synthesis of ammonia by electrolysis has also been proposed. Claim 1 of Patent Document 1 (Patent No. 5127385) states: "An apparatus for electrolytically synthesizing ammonia from water and nitrogen, wherein the apparatus is (1) An apparatus for synthesizing ammonia by supplying atomized water vapor and nitrogen gas to a molten salt which is an electrolytic bath, (2) O produced by the reaction of the water vapor 2- and / or OH - An anode that oxidizes to generate oxygen gas, (3) Reduce nitrogen gas to N 3- A cathode that generates, (4) Means for supplying the atomized water vapor, (5) A means for supplying a gas that generates gas lift to the molten salt, thereby generating an upward flow in the molten salt, and circulating the molten salt within a loop having a supply port for the anode, cathode and water vapor supply means in part, (6) The electrolytic cell is provided with a supply port at or near the bottom for supplying the gas that generates the gas lift, The document describes an ammonia electrolytic synthesis apparatus characterized by the following features. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 5127385 [Overview of the project] [Problems that the invention aims to solve]

[0005] Currently, there is a need for new methods for producing ammonia-based compounds. One of the objectives of this invention is to provide a new method for producing ammonia-based compounds. [Means for solving the problem]

[0006] One aspect of the present invention relates to a method for producing an ammonia-based compound. The method for producing an ammonia-based compound includes a step (X) of applying a voltage between an anode and a cathode in a liquid containing dissolved nitrogen.

[0007] One aspect of the present invention relates to an apparatus for producing ammonia-based compounds. The apparatus for producing ammonia-based compounds includes a tank in which a liquid containing dissolved nitrogen is disposed, and an anode and a cathode disposed in the tank. [Effects of the Invention]

[0008] According to the present invention, ammonia-based compounds can be produced by a novel method. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic diagram showing an example of the configuration of the manufacturing apparatus according to this embodiment. [Figure 2] Figure 2 is a schematic diagram showing the configuration of another example of the manufacturing apparatus of this embodiment. [Figure 3] Figure 3 is a schematic diagram showing the configuration of another example of the manufacturing apparatus of this embodiment. [Figure 4] Figure 4 is a schematic diagram showing the configuration of another example of the manufacturing apparatus of this embodiment. [Figure 5] FIG. 5 is a diagram schematically showing the configuration of another example of the manufacturing apparatus according to the present embodiment. [Figure 6] FIG. 6 is a diagram schematically showing the configuration of another example of the manufacturing apparatus according to the present embodiment. [Figure 7] FIG. 7 is a diagram schematically showing the configuration of another example of the manufacturing apparatus according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments according to the present invention will be described with examples, but the present invention is not limited to the examples described below. In the following description, specific numerical values and materials may be exemplified, but other numerical values and other materials may be applied as long as the effects of the present invention can be obtained. In this specification, the description "numerical value A to numerical value B" includes numerical value A and numerical value B, and can be reinterpreted as "not less than numerical value A and not more than numerical value B". In the following description, when the lower limit and upper limit of numerical values for specific physical properties, conditions, or the like are exemplified, any of the exemplified lower limits and any of the exemplified upper limits can be arbitrarily combined as long as the lower limit does not exceed the upper limit. In the following description, when examples of constituent elements and examples of methods are listed, unless otherwise specified, only one of the listed examples may be used, or a plurality of the listed examples may be used in combination.

[0011] (Method for Producing Ammonia-based Compound) Hereinafter, the production method according to the present embodiment may be referred to as production method (M). Production method (M) is a method for producing an ammonia-based compound. Production method (M) includes step (X) of applying a voltage between an anode and a cathode in a liquid containing dissolved nitrogen. Hereinafter, the liquid may be referred to as "liquid (L)".

[0012] In step (X), electrolysis occurs by applying a voltage between the anode and the cathode. The reaction caused by the electrolysis in step (X) is not clear at present. However, a reduction reaction of dissolved nitrogen can occur at the cathode. Specifically, dissolved nitrogen in liquid (L) is electrolyzed to form nitride ions (N 3- ), which may be generated as shown in the following formula. The generated nitride ions can react with water to produce ammonia. N2+6e - →2N 3-

[0013] N generated by the above reaction 3- is considered to react with hydrogen ions (H + ) in liquid (L) or water molecules to form ammonia or ammonium ions. The reaction at the anode depends on the type of liquid (L) and the anode. When the anode is an electrode containing activated carbon, an electrolysis reaction (oxidation reaction) and / or adsorption of anions may occur at the anode. When the anode is a metal electrode, an electrolysis reaction (oxidation reaction) occurs at the anode, and for example, oxygen gas can be generated.

[0014] Liquid (L) may be a liquid containing water. The content of water in liquid (L) may be 50 mass% or more, 80 mass% or more, or 90 mass% or more. The content of water in the solvent in liquid (L) may be 50 mass% or more, 80 mass% or more, or 90 mass% or more, and 100 mass% or less. The solvent of liquid (L) may be water. That is, liquid (L) may be an aqueous solution. The solvent of liquid (L) may be a mixed solution of water and another liquid (for example, an organic solvent) as long as it does not inhibit the generation of ammonia compounds.

[0015] Liquid (L) may be an acidic aqueous solution. The pH of liquid (L) may be 6 or less, 4 or less, or 3 or less. The pH of liquid (L) may be 1 or more, or 2 or more. The pH of liquid (L) may be in the range of 1.04 to 4 (for example, in the range of 2 to 3). The low pH of liquid (L) suppresses the generation of hydrogen at the cathode, so that nitride ions (N 3-This can increase the generation speed of ).

[0016] Examples of acidic aqueous solutions include water in which an acid is dissolved. As the acid, an acid containing anions that are difficult to decompose at the anode may be used. Examples of anions that are difficult to decompose at the anode include sulfate ions, phosphate ions, and organic acid ions (such as acetate ions). Chloride ions (Cl) can also be used as anions. - Acids containing ) may be used. Examples of acids dissolved in liquid (L) include hydrogen chloride, phosphoric acid compounds, sulfuric acid, and acetic acid. Examples of phosphoric acid compounds include phosphoric acid, potassium hydrogen phosphate, and sodium hydrogen phosphate. Liquid (L) may be hydrochloric acid (an aqueous solution of hydrogen chloride). Liquid (L) may contain only one of these acids, or several of these acids. In addition to the above acids, liquid (L) may contain other solutes (e.g., salts).

[0017] The manufacturing method (M) may include a step (a) of dissolving a gas containing nitrogen gas in a liquid (L). In step (X), a voltage is applied between an anode and a cathode in the liquid (L) prepared in step (a). Step (X) can be performed after step (a). However, when producing ammonia-based compounds continuously, steps (a) and (X) can be performed simultaneously.

[0018] The method for dissolving nitrogen-containing gas (gas containing nitrogen gas) in a liquid is not particularly limited, and known methods may be used. Examples of methods for dissolving nitrogen-containing gas in a liquid include bubbling the nitrogen-containing gas, stirring the liquid in an atmosphere where nitrogen-containing gas is present, and passing the liquid through an atmosphere where nitrogen-containing gas is present. These methods may be used in combination. For example, a liquid being bubbled with nitrogen-containing gas may be stirred.

[0019] Examples of liquids that dissolve nitrogen-containing gases include the liquids mentioned above (e.g., acidic aqueous solutions). The nitrogen-containing gas may be nitrogen gas itself, or a mixture of nitrogen gas and other gases. For example, the nitrogen-containing gas may be air. Air is preferred because it is readily available everywhere and reduces manufacturing costs.

[0020] In this specification, examples of electrodes (anodes, cathodes) having any substance A (element or compound) on their surface include electrodes whose surface is coated with substance A, and electrodes made of substance A. The substrate coated with substance A is not particularly limited, and conductive materials such as metals (e.g., titanium, copper, iron, and their alloys) can be used.

[0021] The cathode is not particularly limited as long as it can produce ammonia-based compounds. Preferably, the cathode is an electrode with a high hydrogen overpotential. By using a cathode with a high hydrogen overpotential, the voltage applied between the anode and cathode can be increased, and as a result, the rate of ammonia-based compound production can be increased.

[0022] The cathode may have a surface material (metal, compound, or elemental element other than a metal) having a hydrogen overpotential greater than that of copper. Examples of metals having a hydrogen overpotential greater than that of copper include copper, palladium, tin, lead, zinc, mercury, and tantalum. Lead (Pb), tin (Sn), and zinc (Zn) are preferred because they have high hydrogen overpotentials. The cathode may have a surface material on which at least one of the group consisting of activated carbon, lead, tin, and copper, or an alloy thereof, is selected. The cathode may have a surface material on which at least one of the group consisting of lead and tin is selected. The cathode may be an electrode with lead or an alloy thereof on its surface, or an electrode with tin or an alloy thereof on its surface, or an electrode with copper or an alloy thereof on its surface. However, it is preferable to use a material that is not easily dissolved in liquid (L) for the surface of the cathode.

[0023] The cathode may be an electrode made of activated carbon. Electrodes made of activated carbon are preferred because they have a large surface area. The cathode may also include a sheet containing activated carbon. Examples of sheets containing activated carbon include nonwoven fabrics made of activated carbon fibers and porous sheets supporting activated carbon. The cathode may also be an activated carbon sheet used in energy storage devices such as capacitors. The cathode may include an activated carbon sheet and a current collector in contact with the sheet. The current collector is not particularly limited, and a current collector made of metal can be used. It is preferable to use a metal that does not easily dissolve in liquid (L) (for example, titanium) for the current collector.

[0024] The activated carbon may be activated carbon that has been heat-treated at a high temperature (e.g., 900°C or higher). The BET specific surface area of ​​the activated carbon before heat treatment is 1000 m². 2 / g or more, 1500m 2 / g or more, or 2000m 2 It may be more than / g. There is no particular upper limit to the BET specific surface area of ​​activated carbon, for example, 3000m 2 It may be less than / g.

[0025] The anode is not particularly limited as long as it can produce ammonia-based compounds. Preferably, the anode is an electrode with a low oxygen overpotential. Using an anode with a low oxygen overpotential allows for a lower anode potential, thereby suppressing unwanted electrolysis reactions (e.g., oxidation of chloride ions).

[0026] An example of an anode with low oxygen overpotential is an anode having iridium oxide on its surface. Another example of an anode is an electrode coated with iridium oxide. For example, a metal coated with iridium oxide (e.g., titanium, niobium, tantalum, etc.) may be used as an anode. Other examples of anodes include electrodes with high electrical double-layer capacitance. The anode may also be an activated carbon electrode. An example of an activated carbon electrode is the activated carbon electrode described as an example of a cathode. In an activated carbon anode, electrolysis (oxidation) and / or anion adsorption may occur. An activated carbon anode can also be used as an electrode for removing dissolved oxygen from liquid (L).

[0027] The combination of the anode and cathode may be any of the following combinations (1) to (3). (1) Anode: An anode made of activated carbon. Cathode: A cathode made of activated carbon. (2) Anode: An anode having iridium oxide on its surface. Cathode: A cathode using activated carbon. (3) Anode: An anode having iridium oxide on its surface. Cathode: A cathode having a metal with a high hydrogen overpotential on its surface.

[0028] In step (X), a voltage (DC voltage) is applied between the anode and cathode while they are immersed in solution (S). The voltage applied between the anode and cathode is the voltage necessary for the electrolysis of dissolved nitrogen. The magnitude of the applied voltage is affected by the liquid (L), the oxygen overpotential of the anode, and the hydrogen overpotential of the cathode. Therefore, the magnitude of the applied voltage should be selected according to the liquid (L), anode, and cathode. For example, the voltage should be applied so that the potential of the cathode is below the potential at which dissolved nitrogen is reduced. More specifically, the voltage should be applied so that the potential of the cathode is below the potential at which dissolved nitrogen is reduced, and the potential of the anode is above the oxygen evolution potential. The potential of the electrodes may be controlled using a potentiostat.

[0029] When using a cathode containing activated carbon and an anode having iridium oxide on its surface, the applied voltage may be in the range of 1.6V to 2.0V per cell. When using a cathode having tin (Sn) on its surface and an anode having iridium oxide (IrO2) on its surface, the applied voltage may be in the range of 2.1V to 2.5V per cell.

[0030] When using an activated carbon anode, charge may accumulate on the surface of the activated carbon anode during electrolysis at the cathode. Therefore, after a certain amount of step (X), a step may be performed to release the charge accumulated on the surface of the activated carbon. For example, after performing step (X), a step may be performed in which current is passed through the anode in step (X) (an activated carbon anode) as the cathode. For example, a step (Z) may be performed in which a voltage is applied in the opposite direction to the voltage applied in step (X). That is, in step (Z), current may be passed between the two such that the anode in step (X) (an activated carbon anode) becomes the cathode and the cathode in step (X) becomes the anode. The activated carbon can be regenerated by step (Z).

[0031] Alternatively, instead of applying a voltage between the anode and cathode used in process (X), the activated carbon may be regenerated using a regeneration electrode. For example, a voltage (DC voltage) may be applied between the regeneration electrode and the anode (activated carbon electrode) in process (X) such that the regeneration electrode becomes the anode and the activated carbon electrode becomes the cathode. The regeneration electrode is not particularly limited, but it is desirable that it be an electrode with low oxygen overpotential and that does not dissolve at the oxygen evolution potential, such as an iridium oxide electrode. An electrode with platinum on its surface may also be used as the regeneration electrode.

[0032] The cathode may have voids through which liquid (L) flows. The process (X) may then be carried out with liquid (L) flowing through the voids of the cathode. This configuration can increase the rate of ammonia-based compound formation. Examples of cathodes with voids include porous cathodes and cathodes with through-holes. One example of a cathode with voids is a sheet containing activated carbon (e.g., a nonwoven fabric containing activated carbon). Another example of a cathode with voids is a metal electrode with voids. Examples of metal electrodes with voids include electrodes made of foamed metal, electrodes made of perforated metal, electrodes made of expanded metal, and electrodes composed of linear electrodes. The cathode may include at least one sheet-like electrode with voids. The cathode may also include a laminate in which multiple sheet-like electrodes with voids are stacked. As described above, these electrodes may have a material with a high hydrogen overpotential on their surface. For example, these electrodes may have a metal with a high hydrogen overpotential (e.g., lead, tin, tantalum) on their surface.

[0033] The shape of the anode is not particularly limited and may be the shape exemplified for the cathode, or it may be plate-shaped. The anode and cathode may each have a flat shape as a whole. The flat electrodes (anode, cathode) may be arranged parallel or nearly parallel to the surface of the liquid (L), or perpendicular or nearly perpendicular to the surface of the liquid (L). When the electrodes are considered as flat plate-shaped electrodes, the angle between the main surface of the electrode and the surface of the liquid (L) may be in the range of 60 to 90° (e.g., 75 to 90°) or in the range of 0 to 30° (e.g., 0 to 15°).

[0034] Ammonia-based compounds can be produced by step (X). Examples of ammonia-based compounds include ammonia and compounds derived from ammonia. Examples of compounds derived from ammonia include ammonium salts. The ammonia-based compound may be at least one selected from the group consisting of ammonia and ammonium salts. Examples of ammonium salts include ammonium chloride (NH4Cl), ammonium sulfate ((NH4)2SO4), ammonium phosphate ((NH4)3PO4), etc. The compound derived from ammonia may be a compound produced by the reaction of the ammonia generated by step (X) with a component in liquid (L).

[0035] The ammonia produced in process (X) is converted into ions (e.g., NH) in liquid (L). 4+ It may exist in the state of ). Therefore, manufacturing method (M) can also be considered as a method for manufacturing ammonia-based atomic groups. In this specification, ammonia-based compounds may be read as ammonia-based atomic groups. Examples of ammonia-based atomic groups include ammonia-based compounds and ions derived from ammonia. Examples of ions derived from ammonia include ammonium ions (NH₄). 4+ ) is included. The ammonia-based compound may be at least one selected from the group consisting of ammonia and ammonium chloride.

[0036] The liquid (L) containing the ammonia-based compound obtained in step (X) may be used as is for a predetermined purpose. Alternatively, the manufacturing method (M) may include a step (Z) for separating the ammonia-based compound produced in step (X) from the liquid (L). Step (Z) is selected according to the type of ammonia-based compound produced in step (X) and the type of liquid (L). For example, ammonia may be selectively extracted by heating the liquid (L) containing the ammonia-based compound.

[0037] If an ammonia-based compound is in an equilibrium state in a liquid (L) that changes with the pH of the liquid (L), the concentration of the ammonia-based compound may be increased or the ammonia-based compound may be made easier to separate from the liquid (L) by changing the pH of the liquid (L). For example, if the liquid (L) contains ammonium ions, making the liquid (L) alkaline can replace some of the ammonium ions with ammonia, allowing it to be separated from the liquid (L) as ammonia gas. In this case, the liquid (L) may be heated as needed. The ammonia separated from the liquid (L) can be made into a liquid by pressurizing it.

[0038] Dissolved oxygen present in the liquid (L) is electrolyzed at the cathode to form hydroxide ions (OH) - This can cause a loss. Therefore, if dissolved oxygen is present in the liquid (L), the power input may be consumed in the electrolysis of the dissolved oxygen. To reduce such losses, the manufacturing method (M) may include a step (b) to reduce the dissolved oxygen concentration in the liquid (L). Step (b) may be performed before step (a) to dissolve the nitrogen-containing gas in the liquid (L), or after step (a). In a preferred example, step (b) is performed after step (a).

[0039] In manufacturing method (M), nitrogen may be separated from air and used as a nitrogen gas-containing gas. The method and apparatus for separating nitrogen from air are not particularly limited. For example, a nitrogen gas separator using polyimide hollow fibers (manufactured by UBE Corporation) may be used.

[0040] Step (b) may be carried out by applying a DC voltage between the electrodes for dissolved oxygen removal at a voltage within a range in which ammonia-based compounds are not generated. Activated carbon may be used as the cathode for dissolved oxygen removal, and the anode for dissolved oxygen removal may be one of the anodes exemplified as ammonia-based compounds.

[0041] When using an activated carbon anode, dissolved oxygen may be electrolyzed at the anode during process (X). In that case, there is no power loss due to dissolved oxygen.

[0042] To increase the dissolved nitrogen concentration in the liquid (L), the nitrogen gas-containing gas (the nitrogen gas-containing gas dissolved in the liquid (L)) may be dissolved in the liquid (L) under pressurized conditions. For example, the entire system containing the liquid (L) may be pressurized. Alternatively, when dissolving the nitrogen gas-containing gas in the liquid (L), a high-pressure nitrogen gas-containing gas may be dissolved. For the high-pressure nitrogen gas-containing gas, a high-pressure nitrogen gas-containing gas contained in a gas cylinder or the like may be used.

[0043] When dissolving a high-pressure nitrogen gas-containing gas in a liquid (L), the tank in which process (X) is performed and the separation unit for separating ammonia-based compounds may be separated and connected via a pressure regulating valve.

[0044] In the manufacturing method (M), multiple electrolytic cells (cells) in which process (X) is carried out may be used. The multiple electrolytic cells may be connected in series or in parallel. One or more electrode sets consisting of an anode and a cathode may be placed in one cell. The multiple electrode sets may be connected in series or in parallel.

[0045] In addition, in the electrolysis of process (X), the cathode potential may be the potential at which hydrogen gas is generated at the cathode. By setting the cathode potential to the potential at which hydrogen gas is generated, it may be possible to increase the power used for the electrolysis of dissolved nitrogen. Let current In be the current used for the electrolysis of dissolved nitrogen at the cathode, and current Ih be the current used for the generation of hydrogen gas at the cathode. In this case, the cathode potential in process (X) may be set to a potential such that the ratio Ih / In of current Ih to current In is 0.01 or greater (for example, 0.03 or greater). The cathode potential in process (X) may be set to a potential such that the ratio Ih / In is 0.20 or less, or 0.10 or less.

[0046] (Equipment for manufacturing ammonia-based compounds) The manufacturing apparatus according to this embodiment may be referred to as "manufacturing apparatus (D)" below. Manufacturing apparatus (D) is an apparatus for manufacturing ammonia-based compounds. Manufacturing method (M) can be easily carried out using manufacturing apparatus (D). Manufacturing method (M) may also be carried out using apparatus other than manufacturing apparatus (D). Matters described regarding manufacturing method (M) can also be applied to manufacturing apparatus (D), so redundant explanations may be omitted. Matters described regarding manufacturing apparatus (D) may also be applied to manufacturing method (M).

[0047] The manufacturing apparatus (D) includes a tank in which a liquid (L) containing dissolved nitrogen is placed, and an anode and a cathode placed inside the tank. Since the liquid (L), anode, and cathode have been described above, redundant explanations are omitted.

[0048] The power supply for carrying out process (X) may be prepared separately from the manufacturing apparatus (D). Alternatively, the manufacturing apparatus (D) may include a power supply (DC power supply) for applying a voltage (DC voltage) between the anode and cathode. This power supply may be a solar cell or a secondary battery. Alternatively, this power supply may be an AC-DC converter that converts an externally supplied alternating current into direct current. The power supply provides the power necessary to cause electrolysis in process (X). The manufacturing apparatus (D) may include a potentiostat for controlling the potential of the electrodes (anode, cathode).

[0049] The tank in which the liquid (L) is placed is not particularly limited; any tank capable of stably holding the liquid (L) is acceptable. The tank may not be open to the atmosphere.

[0050] The manufacturing apparatus (D) may further include a gas dissolving section for dissolving a nitrogen gas-containing gas in a liquid (L). The gas dissolving section includes equipment for carrying out the above-described method as a method for dissolving a nitrogen gas-containing gas in a liquid. For example, the gas dissolving section may include equipment for bubbling the nitrogen gas-containing gas, equipment for stirring the liquid, and equipment for spraying the liquid in the nitrogen gas-containing gas. The nitrogen gas-containing gas may be air or nitrogen gas.

[0051] As described above, the cathode may have a void through which liquid (L) flows. In that case, the manufacturing apparatus (D) may further include a liquid delivery mechanism for delivering liquid (L) so that it flows through the void of the cathode. The liquid delivery mechanism is not particularly limited, and known liquid delivery mechanisms may be used. Examples of liquid delivery mechanisms include screw-type liquid delivery mechanisms and pumps.

[0052] The manufacturing apparatus (D) may include a dissolved oxygen removal unit for carrying out the process (b) described above. The dissolved oxygen removal unit includes a cathode and an anode for dissolved oxygen removal, and optionally includes a power supply for applying voltage to them. The power supply is not particularly limited and may be one of the power supplies exemplified as a power supply for carrying out the process (X).

[0053] If the liquid (L) and / or a nitrogen gas-containing gas are pressurized to increase the dissolved nitrogen concentration in the liquid (L), the manufacturing apparatus (D) may include a pressurization mechanism for that purpose. The pressurization mechanism is not particularly limited and may include a pump or the like.

[0054] When dissolving a high-pressure nitrogen gas-containing gas in a liquid (L), the manufacturing apparatus (D) may include a tank (electrolytic cell) for performing process (X) and a separation unit (e.g., a separation tank) for separating ammonia-based compounds. The electrolytic cell and the separation unit may be connected via a pressure regulating valve.

[0055] In the manufacturing apparatus (D), nitrogen may be separated from the air and used as a nitrogen-containing gas. In this case, the manufacturing apparatus (D) may include a device for separating nitrogen from the air. The device for separating nitrogen is not limited, and a nitrogen gas separator using polyimide hollow fibers (manufactured by UBE Corporation) may be used.

[0056] The manufacturing apparatus (D) may include multiple cells (electrolytic cells) in which process (X) is carried out. The multiple electrolytic cells may be connected in series or in parallel. One cell may contain one or more electrode sets consisting of an anode and a cathode. The multiple electrode sets may be connected in series or in parallel.

[0057] Hereinafter, examples of embodiments relating to this disclosure will be specifically described with reference to the drawings. The above description may be applied to the embodiments described below, and the embodiments described below may be modified based on the above description. Among the components of the embodiments described below, components that are not essential to the manufacturing method and manufacturing apparatus relating to this disclosure and can be omitted may be omitted. Furthermore, the matters described below may be applied to the above embodiments.

[0058] (Embodiment 1) Embodiment 1 describes examples of a manufacturing method (M) and a manufacturing apparatus (D). The configuration of the manufacturing apparatus 100 of Embodiment 1 is schematically shown in Figure 1. The ammonia-based compound manufacturing apparatus 100 includes a tank 110, an anode 121 and a cathode 122 placed inside the tank 110, and a power supply (DC power supply) 130. A liquid L containing dissolved nitrogen is placed inside the tank 110. The power supply 130 applies a predetermined DC voltage between the anode 121 and the cathode 122. This causes an electric current to flow between the anode 121 and the cathode 122, resulting in electrolysis. As a result, an ammonia-based compound is produced in the liquid L.

[0059] The manufacturing apparatus 100 may further include a gas dissolution section for dissolving nitrogen gas-containing gas in liquid L. Figure 2 schematically shows the configuration of an example of a manufacturing apparatus (D) including such a gas dissolution section. The manufacturing apparatus 100 shown in Figure 2 includes a gas dissolution section 140. The gas dissolution section 140 includes a gas dissolution tank 141, a gas dissolution mechanism 142 located inside the gas dissolution tank 141, a first flow path 143, a second flow path 144, and a pump 145.

[0060] Figure 2 shows an example in which the pump 145 is placed in the first flow path 143, but the pump 145 may also be placed in the second flow path 144. In Figure 2, the direction of flow of the liquid L is indicated by arrows. The liquid L in the gas dissolution tank 141 is sent from the gas dissolution tank 141 to the tank 110 by the pump 145 through the first flow path 143. The liquid L in the tank 110 is sent to the gas dissolution tank 141 through the second flow path 144. In other words, the liquid L in the tank 110 circulates in a circulation path that includes the tank 110 and the gas dissolution tank 141.

[0061] Figure 2 shows an example where a bubbler is used as the gas dissolution mechanism 142 to bubble a nitrogen gas-containing gas (e.g., air). A flow path (not shown) for supplying the nitrogen gas-dissolved gas is connected to the gas dissolution mechanism 142. Of the bubbling nitrogen gas-containing gas, the gas that does not dissolve in liquid L is released from the gas outlet 141a at the top of the gas dissolution tank 141. The gas dissolution mechanism 142 may also be a stirring device that stirs liquid L in the presence of the nitrogen gas-containing gas. The nitrogen gas dissolves in liquid L by the gas dissolution mechanism 142, becoming dissolved nitrogen. The dissolved nitrogen concentration in liquid L in the gas dissolution tank 141 increases due to the gas dissolution mechanism 142. On the other hand, the dissolved nitrogen concentration in liquid L in tank 110 decreases due to electrolysis.

[0062] As described above, the cathode 122 may have a void through which the liquid L flows. An example configuration of the manufacturing apparatus (D) in this case is schematically shown in Figure 3. In Figure 3, the direction of flow of the liquid L is indicated by an arrow. In the manufacturing apparatus 100 shown in Figure 3, the first flow path 143 and the second flow path 144 are arranged so that the liquid L in the tank 110 passes through the void in the cathode 122. Specifically, the inlet 143a through which the liquid L from the gas dissolution tank 141 flows into the tank 110 and the outlet 144a through which the liquid L flows out of the tank 110 toward the gas dissolution tank 141 are arranged so as to sandwich the cathode 122. The cathode 122 is positioned to partition the tank 110.

[0063] As described above, the manufacturing apparatus (D) may include a dissolved oxygen removal unit for removing dissolved oxygen. The manufacturing apparatus (D) may also include a mechanism for pressurizing liquid L and / or nitrogen gas-containing gas.

[0064] An example of a manufacturing apparatus (D) including a pump for pressurizing liquid L and nitrogen gas-containing gas is shown in Figure 4, and another example is shown in Figure 5. The manufacturing apparatus 100 in Figures 4 and 5 includes a pump 151 for pressurizing the nitrogen gas-containing gas and sending it to the tank 110. In the manufacturing apparatus 100 in Figures 4 and 5, the nitrogen gas-containing gas is pressurized and sent to the tank 110. Therefore, the dissolved nitrogen concentration in liquid L can be increased, and the rate of ammonia-based compound formation can be increased.

[0065] The manufacturing apparatus in Figure 5 is a modified version of the manufacturing apparatus in Figure 3, so redundant explanations will be omitted. In the manufacturing apparatus 100 in Figure 5, bubbling is performed using pressurized nitrogen gas-containing gas. The manufacturing apparatus 100 in Figure 5 includes a gas outlet 141a for releasing gas from the gas dissolution tank 141, and a pressure regulating valve 152 located in the flow path between the gas outlet 141a and the gas dissolution tank 141. The pressure regulating valve 152 is a valve for maintaining the pressure in the gas dissolution tank 141.

[0066] Another example of a manufacturing apparatus (D) including a pump for pressurizing liquid L and nitrogen gas-containing gas is shown in Figure 6. Note that the power supply is not shown in Figures 6 and 7. The manufacturing apparatus 100 in Figure 6 includes a pump 151 for pressurizing the nitrogen gas-containing gas and sending it to the tank 110. In the manufacturing apparatus 100 in Figure 6, the nitrogen gas-containing gas is pressurized and sent to the tank 110. Therefore, the dissolved nitrogen concentration in liquid L can be increased, and the rate of ammonia-based compound production can be increased.

[0067] The manufacturing apparatus 100 in Figure 6 includes a separation tank 161 as a separation unit for separating ammonia-based compounds. The separation tank 161 and the tank 110 are connected by flow paths 162 and 163. A pump 164 is located in flow path 162. A pressure regulating valve (pressure reducing valve) 165 is located in flow path 163. The pump 164 circulates liquid L in the direction of the arrow through a circulation path consisting of the tank 110, flow path 163, separation tank 161, and flow path 162. In the manufacturing apparatus in Figure 6, the flow path 162 downstream of the pump 164, the tank 110, and the flow path 163 upstream of the pressure regulating valve 165 are in a high-pressure region. On the other hand, the flow path 163 downstream of the pressure regulating valve 165, the separation tank 161, and the flow path 162 upstream of the pump 164 can be at a low pressure (e.g., around atmospheric pressure).

[0068] In the separation tank 161, ammonia-based compounds are separated. The separation of ammonia-based compounds may be performed by adjusting the pH, or by utilizing the difference in physical properties between the ammonia-based compounds and liquid L (for example, the difference in vapor pressure or boiling point). When utilizing the difference between the boiling point of the ammonia-based compounds and the boiling point of liquid L, the liquid L in the separation tank 161 may be heated. The separation tank 161 is provided with an outlet for removing the ammonia-based compounds, if necessary.

[0069] In the apparatus shown in Figures 4 and 6, a flat cathode is positioned approximately parallel to the surface of liquid L. In this case, the cathode 122 may be positioned near the surface of liquid L. For example, a portion of the cathode 122 may be exposed from the surface of liquid L. Alternatively, the cathode 122 may be positioned such that the distance between the surface of liquid L and the cathode 122 immersed in liquid L is within 1 cm. By positioning the cathode 122 near the surface of liquid L, dissolved nitrogen dissolved in liquid L can be rapidly electrolyzed.

[0070] As shown in Figure 5, in the manufacturing apparatus (D), bubbling may be performed using a high-pressure nitrogen gas-containing gas. Figure 7 shows an example of bubbling using a high-pressure nitrogen gas-containing gas in the apparatus of Figure 6. The manufacturing apparatus 100 in Figure 7 includes a gas dissolution mechanism 142 and a pump 151. The pump 151 sends the high-pressure nitrogen gas-containing gas to the gas dissolution mechanism 142. In the gas dissolution mechanism 142, the nitrogen gas-containing gas is released into the liquid L in the form of bubbles. The manufacturing apparatus 100 in Figure 7 may also include a gas outlet for releasing the gas in the tank 110 and a pressure regulating valve located in the flow path between the gas outlet and the tank 110.

[0071] Furthermore, apparatuses other than those shown in Figure 6 may also include a separation unit for separating ammonia-based compounds, similar to those shown in Figure 6.

[0072] The above description discloses the following manufacturing apparatus and manufacturing method. (1) A method for producing ammonia-based compounds, A method for producing an ammonia-based compound, comprising the step (X) of applying a voltage between an anode and a cathode in a liquid containing dissolved nitrogen. (2) The method of production described in (1), wherein the liquid is an acidic aqueous solution. (3) The manufacturing method according to (1) or (2), comprising the step (a) of dissolving a gas containing nitrogen gas in the liquid. (4) The manufacturing method described in (3), wherein the gas is air. (5) The manufacturing method according to any one of (1) to (4), wherein the anode has iridium oxide on its surface. (6) The manufacturing method according to any one of (1) to (5), wherein the cathode has at least one material selected from the group consisting of activated carbon, lead, tin, and tantalum on its surface. (7) The method of production according to any one of (1) to (6), wherein the ammonia-based compound is selected from the group consisting of ammonia and ammonium salts, at least one. (8) Apparatus for producing ammonia-based compounds, A tank in which a liquid containing dissolved nitrogen is placed, An apparatus for producing ammonia-based compounds, comprising an anode and a cathode arranged in the tank. (9) The manufacturing apparatus according to (8), wherein the liquid is an acidic aqueous solution. (10) The manufacturing apparatus according to (8) or (9), further comprising a gas dissolving section for dissolving a gas containing nitrogen gas in the liquid. (11) The manufacturing apparatus according to (10), wherein the gas is air. (12) The manufacturing apparatus according to any one of (8) to (11), wherein the anode has iridium oxide on its surface. (13) The manufacturing apparatus according to any one of (8) to (12), wherein the cathode has at least one material selected from the group consisting of activated carbon, lead, tin, and tantalum on its surface. (14) The manufacturing apparatus according to any one of (8) to (13), wherein the ammonia-based compound is selected from the group consisting of ammonia and ammonium salts, at least one. [Examples]

[0073] The manufacturing apparatus and manufacturing method relating to this disclosure will be described in more detail by reference to examples.

[0074] (Experiment 1) Experiment 1 describes an example of the production of ammonia-based compounds. An IrO2 electrode was used as the anode. An activated carbon cloth was used as the cathode. The activated carbon cloth used was heat-treated at 900°C. A pH 2 hydrochloric acid aqueous solution was used as the liquid (L). The dissolved nitrogen concentration in the liquid (L) was increased by bubbling air through it.

[0075] While continuously bubbling air, a DC voltage of 1.8V was applied between the anode and cathode immersed in liquid (L) for approximately 3 minutes to induce a current flow between them. Subsequently, Nessler's reagent was used to check whether ammonia was being generated in liquid (L). The results confirmed that ammonia was being generated in liquid (L).

[0076] The results of performing process (X) using the apparatus shown in Figure 2 and the apparatus shown in Figure 3 were compared. The results showed that when using the apparatus shown in Figure 3, the current flowing between the anode and cathode increased 30 times compared to when using the apparatus shown in Figure 2. From these results, it is considered that ammonia-based compounds can be efficiently produced by using the apparatus shown in Figure 3. [Industrial applicability]

[0077] The present invention can be used in a method for producing ammonia-based compounds and in an apparatus for producing ammonia-based compounds. [Explanation of symbols]

[0078] 100: Manufacturing equipment 110: Tank 121: Anode 122: Cathode 130: Power supply 140: Gas dissolution section 141: Gas dissolution tank 141a: Gas discharge port 142: Gas dissolution mechanism 143: First channel 144: Second channel 145, : pump L liquid

Claims

1. A method for producing ammonia-based compounds, A method for producing an ammonia-based compound, comprising the step (X) of applying a voltage between an anode and a cathode in a liquid containing dissolved nitrogen.

2. The manufacturing method according to claim 1, wherein the liquid is an acidic aqueous solution.

3. The manufacturing method according to claim 1 or 2, comprising the step (a) of dissolving a gas containing nitrogen gas in the liquid.

4. The manufacturing method according to claim 3, wherein the gas is air.

5. The manufacturing method according to claim 1 or 2, wherein the anode has iridium oxide on its surface.

6. The manufacturing method according to claim 1 or 2, wherein the cathode has at least one material selected from the group consisting of activated carbon, lead, tin, and tantalum on its surface.

7. The method for producing aquatic compounds according to claim 1 or 2, wherein the ammonia-based compound is selected from the group consisting of ammonia and ammonium salts, to the same extent as described in claim 1 or 2.

8. A apparatus for producing ammonia-based compounds, A tank in which a liquid containing dissolved nitrogen is placed, An apparatus for producing ammonia-based compounds, comprising an anode and a cathode arranged in the tank.

9. The manufacturing apparatus according to claim 8, wherein the liquid is an acidic aqueous solution.

10. The manufacturing apparatus according to claim 8 or 9, further comprising a gas dissolving unit for dissolving a gas containing nitrogen gas in the liquid.

11. The manufacturing apparatus according to claim 10, wherein the gas is air.

12. The manufacturing apparatus according to claim 8 or 9, wherein the anode has iridium oxide on its surface.

13. The manufacturing apparatus according to claim 8 or 9, wherein the cathode has at least one material selected from the group consisting of activated carbon, lead, tin, and tantalum on its surface.

14. The manufacturing apparatus according to claim 8 or 9, wherein the ammonia-based compound is at least one selected from the group consisting of ammonia and ammonium salts.

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