Method for producing ammonia

Abstract

The present disclosure relates to a method for producing ammonia, the method including a step for obtaining ammonia by reacting a substrate containing an amine compound in the presence of water and at least one selected from the group consisting of divalent metal ions and trivalent metal ions.

Description

Ammonia production method

[0001] This disclosure relates to a method for producing ammonia.

[0002] Ammonia is an essential compound for fertilizers and chemical raw materials, and is currently produced from hydrogen and nitrogen using the Haber-Bosch process. However, the hydrogen used in the Haber-Bosch process is gray hydrogen derived from underground resources, resulting in gray ammonia. Therefore, the development of green ammonia production technology is necessary to realize a carbon-neutral society.

[0003] Regarding ammonia production technology, Non-Patent Document 1 describes a method for synthesizing ammonia using a specific electride supported with ruthenium. Non-Patent Document 2 describes a method for synthesizing ammonia using samarium(II) iodide and alcohol or water with a molybdenum catalyst.

[0004] M. Kitano, et al., “Electride support boosts nitrogen dissociation over ruthenium catalyst and shifts the bottleneck in ammonia synthesis” Nat. Commun., 2015, 6,6731. Y. Nishibayashi, et al., “Molybdenum-catalysed ammonia production with samarium diiodide and alcohols or water” Nature, 2019, 568, 536.

[0005] Methods for producing ammonia using amine compounds containing nitrogen atoms as substrates are useful. However, no simple method for producing ammonia using such amine compounds is known, and a new method for producing ammonia was needed.

[0006] This disclosure aims to provide a new method for producing ammonia.

[0007] This disclosure includes the following embodiments: [1] A method for producing ammonia, comprising the step of obtaining ammonia by a reaction of a substrate containing an amine compound in the presence of water and at least one selected from the group consisting of divalent metal ions and trivalent metal ions. [2] The method for producing ammonia according to [1], wherein the reaction is a thermal reaction or a photoreaction. [3] The method for producing ammonia according to [1] or [2], wherein the amine compound is an amino sugar. [4] The method for producing ammonia according to any one of [1] to [3], wherein the amine compound is a primary amine compound or a secondary amine compound. [5] The method for producing ammonia according to any one of [1] to [4], wherein the substrate is nitrogen-containing biomass. [6] The method for producing ammonia according to any one of [1] to [5], wherein the substrate is a biomass containing chitin, or a biomass containing protein or amino acids. [7] The method for producing ammonia according to any one of [1] to [6], wherein the substrate contains at least one selected from the group consisting of crustaceans, mollusks, mushrooms and insects. [8] The method for producing ammonia according to any one of [1] to [6], wherein the at least one selected from the group consisting of divalent metal ions and trivalent metal ions is Cu ２＋ Mn ２＋ and Zn ２＋ A method for producing ammonia according to any one of [1] to [7], wherein at least one selected from the group consisting of divalent metal ions and trivalent metal ions is Cu ２＋ A method for producing ammonia according to any one of [1] to [8].

[10] A method for producing ammonia according to any one of [1] to [9], wherein the reaction is a thermal reaction and the reaction temperature is 40°C or higher.

[11] A method for producing ammonia according to any one of [1] to

[10] , wherein the reaction is carried out in the presence of hydroxide ions.

[0008] This disclosure provides a novel method for producing ammonia.

[0009] Hereinafter, embodiments of the present disclosure will be described. However, the following embodiments are examples for describing the present disclosure, and are not intended to limit the present disclosure to the following content. A numerical range exemplified by "a to b" is a numerical range including a as the lower limit and b as the upper limit, and includes both a and b. The present disclosure also includes embodiments in which the upper or lower limit of any numerical range is replaced with a numerical value from any of the examples. When a plurality of materials are exemplified, one of them may be used alone, or two or more thereof may be used in combination.

[0010] The method for producing ammonia of the present embodiment includes a step (reaction step) of obtaining ammonia by reacting a substrate containing an amine compound in the presence of at least one selected from the group consisting of divalent metal ions and trivalent metal ions (hereinafter also simply referred to as "metal ions") and water.

[0011] <Substrate Containing Amine Compound> The "amine compound" in the present specification is a compound having a group containing a nitrogen atom. Examples of the nitrogen atom-containing group include an unsubstituted amino group (-NH ２ ), a primary amino group, a secondary amino group, a tertiary amino group, and an acylamino group.

[0012] The amine compound may have one or more amino groups in the molecule. Examples of the amine compound include primary amine compounds (-NH ２ compounds having a group), secondary amine compounds (compounds having an -NHR group), tertiary amine compounds (-NR ２ compounds having a group), and amide compounds (-CO-NH ２ , -CO-NHR, or -CO-NR ２ compounds having the above group). R herein represents a substituted or unsubstituted hydrocarbon group.

[0013] Examples of the amine compound include aliphatic amines (e.g., aliphatic diamines such as ethylenediamine), aliphatic amides (e.g., acetamide), amino sugars, amino acids, and the like. The amine compound may be, for example, a polymer having, as a monomer unit, a compound having the above nitrogen atom-containing group. Examples of such polymer include polysaccharides containing an amino sugar as a constituent sugar, and proteins.

[0014] The amine compound may be a sugar in which a nitrogen atom is directly bonded to at least some of the carbon atoms constituting the ring. That is, the amine compound may be, for example, an amino sugar. In an amino sugar, some of the hydroxyl groups (-OH) of the sugar molecule are replaced with amino groups (-NH). ２ These are compounds substituted with (and their derivatives, e.g., acetylated compounds). Examples of amino sugars include glucosamine, galactosamine, mannosamine, neuraminic acid, etc. ２ Amino sugars having a -NH-CO- group; examples include amino sugars having an -NH-CO- group such as N-acetylglucosamine, N-acetylgalactosamine, N-acetylmannosamine, N-acetylmuramic acid, and N-acetylneuraminic acid. The amino sugar may be DL, D, or L form.

[0015] Amino acids are compounds having an amino group and a carboxyl group. Examples of amino acids include glycine, arginine, alanine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, and valine. Amino acids may be DL, D, or L forms.

[0016] Examples of polysaccharides containing amino sugars as constituent sugars include chitin (a polymer of N-acetylglucosamine), chitosan (a polymer of glucosamine), hyaluronic acid, chitobiose, and chitotriose.

[0017] The substrate is not particularly limited as long as it contains an amine compound. The substrate may include at least one selected from the group consisting of crustaceans, mollusks, fungi, and insects.

[0018] Crustaceans are also called the subphylum Crustacea. Examples of crustaceans include crabs, shrimp, hermit crabs, and mantis shrimp (Oratosquilla oratoria). Crabs are crustaceans classified in the suborder Brachyura of the order Decapoda. Hermit crabs are crustaceans classified in the suborder Anomura. Shrimp are crustaceans belonging to the order Decapoda (shrimp), excluding those in the suborders Brachyura and Anomura.

[0019] "Mollusks" are animals belonging to the phylum Mollusca. Examples of mollusks include shellfish and cephalopods. "Shellfish" are mollusks (Mollusca) that have shells. The term shellfish encompasses the classes Bivalvia, Gastropoda (snails), Scaphopoda (horn snails), and Polyplacophora (chitons). Examples of shellfish include bivalves (Bivalvia), such as oysters (Crassostrea gigas). Cephalopods are mollusks belonging to the class Cephalopoda.

[0020] The term "mushroom" is a concept that encompasses organisms belonging to the kingdom Fungi, specifically those classified under the phyla Basidiomycota and Ascomycota. Examples of mushrooms include shiitake (Lentinula edodes), enokitake (Flammulina velutipes), buna-shimeji (Hypsygius marmoreus), maitake (Griffola frondosa), oyster mushroom (Pleurotus ostreatus), button mushroom (Agaricus bisporus), matsutake (Tricholoma matsutake), morel (Morchella esculenta), and fly agaric (Amanita muscaria).

[0021] "Insects" are arthropods belonging to the class Insecta, which is part of the subphylum Hexapoda. Examples of insects include beetles (such as the rhinoceros beetle (Trypoxylus dichotomus)) and other insects of the order Coleoptera, such as those belonging to the subfamily Dynastinae, family Lucanidae, and family Coccinellidae; and the cabbage white butterfly (Pieris). The order Lepidoptera includes insects classified as butterflies and moths such as rapae; the order Hymenoptera includes insects classified as formicidae, Apidae, Apis, and Vespinae; and the suborders Muscomorpha and Culicidae. Insects of the order Diptera, such as those classified as icidae and Chironomidae; insects of the order Orthoptera, such as those classified as grasshoppers, tettigonidae, and crickets; cockroaches (Periplaneta) Examples include cockroach insects of the order Blattodea, such as *Fuliginosa* and the American cockroach (Periplaneta americana); dragonflies (Odonata); mayflies (Ephemeroptera); and Neuroptera insects, such as those of the family Myrmeleontidae. The insects may be in larval or adult forms. For example, the insects may be caterpillars, which are the larvae of lepidoptera insects; maggots, which are the larvae of flies classified under the suborder Diptera; and antlions, which are the larvae of insects of the family Myrmeleontidae.

[0022] The substrate may include amine-containing parts in crustaceans, mollusks, mushrooms, and insects. Examples of amine-containing parts in crustaceans, mollusks, and insects include the exoskeleton. Examples of amine-containing parts in mushrooms include the cell wall.

[0023] The substrate may be nitrogen-containing biomass containing amine compounds. The method of this disclosure can utilize nitrogen-containing biomass, thus enabling the effective utilization of waste. Examples of nitrogen-containing biomass include biomass containing chitin, and biomass containing proteins or amino acids. Examples of chitin-containing biomass include the shells of crustaceans such as crab shells, shrimp shells, mantis shrimp shells, and hermit crab shells, as well as the shells of mollusks such as oyster shells. In this specification, "crab shell" is not limited to the shells of crustaceans belonging to the Brachyura suborder of the Decapoda, but also includes the shells of crustaceans belonging to the Anomura suborder, such as king crabs. Examples of protein-containing biomass include food processing residues (including, but not limited to, processing residues of meat such as pork, soybeans, fish and shellfish, wheat, and dairy products), food factory wastewater sludge, sewage sludge, livestock excrement, feathers and hair, blood meal, methane fermentation residues, plankton biomass, and microbial biomass (including yeast, bacteria, microbial residues, and fermentation residues).

[0024] The substrate may contain components other than amine compounds. Examples of components other than amine compounds include calcium carbonate. For example, crab shells contain 20-30% chitin, 30% protein, and 40% calcium carbonate. Even when the substrate contains components other than amine compounds, the method of this disclosure can produce ammonia from the amine compound in the substrate.

[0025] The amount of substrate is appropriately selected depending on the type of substrate, etc. For example, the amount of substrate may be 0.01 mg or more, or 1 mg or more, and 1000 mg or less, or 10 mg or less, per 0.01 mmol of metal ions. For example, the amount of substrate may be 0.01 mg to 1000 mg, 0.01 mg to 10 mg, 1 mg to 1000 mg, or 1 mg to 10 mg per 0.01 mmol of metal ions.

[0026] The substrate concentration may be 0.1 mM or higher, 1 mM or higher, or 10 mM or higher, and may be 1000 mM or lower, or 100 mM or lower. The substrate concentration may be 0.1 mM to 1000 mM, 0.1 mM to 100 mM, 1 mM to 1000 mM, 1 mM to 1000 mM, 10 mM to 1000 mM, or 10 mM to 100 mM. The substrate concentration refers to the number of moles of substrate per 1 mL of aqueous solvent.

[0027] <Metal Ions> Divalent metal ions may be divalent cations derived from alkaline earth metal elements or transition metal elements. Examples of divalent metal ions include Mg ２＋ Ca ２＋ Ba ２＋ , Sr ２＋ Ions of alkaline earth metal elements such as Fe ２＋ ,Cd ２＋ , Zn ２＋ Ni ２＋ Co ２＋ Mn ２＋ , Sc ２＋ Ti ２＋ , V ２＋ , Cr ２＋ Examples include ions of transition metal elements such as the following.

[0028] Metal ions with high complex formation stability tend to have better conversion efficiency to ammonia. Therefore, Cu, which has a high stability constant in the Irving-Williams series of stability constants for complexes formed by divalent cations, is a good choice. ２＋ This is a suitable metal ion because it has superior conversion efficiency to ammonia.

[0029] The trivalent metal ion may be a trivalent cation derived from a transition metal element or a typical metal element. Examples of trivalent metal ions include Fe. ３＋ , Sc ３＋ Ti ３＋ , V ３＋ , Cr ３＋ Mn ３＋ Co ３＋ Ni ３＋ ,Cd ３＋ Ions of transition metal elements such as Al ３＋ Ga ３＋ In ３＋Examples include ions of typical metallic elements.

[0030] The metal ions may be divalent metal ions, such as Cu, as this further improves the conversion efficiency to ammonia. ２＋ Mn ２＋ , Zn ２＋ Fe ２＋ Co ２＋ and Ni ２＋ It may be at least one selected from the group consisting of Cu ２＋ Mn ２＋ and Zn ２＋ It may be at least one selected from the group consisting of the following. The metal ion is Cu ２＋ In this case, the conversion efficiency to ammonia is particularly improved.

[0031] Metal ions can be obtained by dissolving a metal compound containing the above-mentioned metal ions in an aqueous solvent. In this specification, "metal compound" means a compound containing the above-mentioned metal ions. The metal compound may be, for example, a metal salt or a metal oxide. In this specification, "aqueous solvent" means a solvent containing water. The aqueous solvent may further contain an organic solvent that is miscible with water. Examples of organic solvents include alcohols such as methanol, ethanol, 1-propanol, and 2-propanol. The water content may be 90 to 100% by mass or 95 to 100% by mass, or 100% by mass, based on the total amount of the aqueous solvent.

[0032] Examples of anions that make up metal compounds include sulfate ions (SO4). ４ ２－ ), halide ions (Cl － , Br － , I － (etc.), nitrate ions (NO ３ － ), acetate ion (CH ３ COO － ), carbonate ions (CO ３ ２－ ), phosphate ion (PO ４ ３－ ) and oxide ions (O ２－ ) are examples. The anion is sulfate ion (SO ４２－ ), chloride ion (Cl － ), and oxide ion (O ２－ ) may be at least one selected from the group consisting of.

[0033] Examples of the metal compound include Cu ＩＩ SO ４ , Cu ＩＩ Cl ２ , Cu ＩＩ (NO ３ ) ２ , Cu ＩＩ (CH ３ COO) ２ , Cu ＩＩ CO ３ and other copper salts; Mg ＩＩ Cl ２ and other magnesium salts; Mn ＩＩ SO ４ , Mn ＩＩ Cl ２ and other manganese salts; Fe ＩＩ SO ４ , Fe ＩＩ Cl ２ , Fe ＩＩＩ Cl ３ and other iron salts; Co ＩＩ SO ４ , Co ＩＩ Cl ２ and other cobalt salts; Ni ＩＩ SO ４ , Ni ＩＩ Cl ２ and other nickel salts; Zn ＩＩ SO ４ , Zn ＩＩ Cl ２ and other zinc salts; and metal oxides such as Cu ＩＩ O. The metal compound may be an anhydride or a solvate such as a hydrate.

[0034] Since the conversion efficiency to ammonia is further improved, the metal compound may be at least one selected from the group consisting of copper salts and copper oxides, and may be Cu ＩＩ SO ４ , Cu ＩＩ Cl ２ and Cu ＩＩIt may be at least one selected from the group consisting of O. From the viewpoint of cost reduction and availability, the metal compound is Cu ＩＩ SO ４ That's fine.

[0035] The concentration of metal ions (or metal compounds) may be 0.1 mM or higher, 0.5 mM or higher, 1 mM or higher, 2 mM or higher, 4 mM or higher, 6 mM or higher, 8 mM or higher, 10 mM or higher, 30 mM or higher, 50 mM or higher, or 100 mM or higher, and may be 1000 mM or lower, 100 mM or lower, 50 mM or lower, 30 mM or lower, 20 mM or lower, or 10 mM or lower. The concentration of metal ions (or metal compounds) may be, for example, 0.1 mM to 100 mM, 0.5 mM to 50 mM, 1 mM to 20 mM, or 1 mM to 10 mM. In this specification, the concentration of metal ions (or metal compounds) means the number of moles of metal ions per 1 mL of aqueous solvent, or the number of moles of metal compounds per 1 mL of aqueous solvent.

[0036] The amount of metal ions (or metal compounds) may be 0.0001 mmol or more, or 0.001 mmol or more, and 0.1 mmol or less, or 0.01 mmol or less, per 1 mg of substrate. The amount of metal ions (or metal compounds) may be 0.0001 mmol to 0.1 mmol, 0.0001 mmol to 0.01 mmol, 0.001 mmol to 0.1 mmol, or 0.001 mmol to 0.01 mmol, per 1 mg of substrate.

[0037] <Water> The reaction is carried out in the presence of water. The amount of water used can be appropriately set according to the reaction conditions, the type and amount of substrate, the type and amount of metal ions (or metal compounds), etc. The amount of water may be, for example, an amount that results in the substrate concentration and / or metal ion (or metal compound) concentration being within the range described above.

[0038] <Hydroxide Ions> The reaction may be carried out in the presence of hydroxide ions, as this further improves the efficiency of conversion to ammonia. The method for obtaining hydroxide ions is not particularly limited as long as it is a method of generating hydroxide ions in an aqueous solvent. Examples include a method of obtaining hydroxide ions by dissolving metal hydroxides in an aqueous solvent, or a method of obtaining hydroxide ions together with the metal ions by using a metal salt containing the above-mentioned metal ions and hydroxide ions as constituent ions.

[0039] Examples of metal hydroxides include alkali metal hydroxides and alkaline earth metal hydroxides.

[0040] Examples of alkali metal hydroxides include sodium hydroxide, lithium hydroxide, and potassium hydroxide.

[0041] The amount of hydroxide ions may be 0.0001 mmol or more, 0.001 mmol or more, or 0.036 mmol or more per 1 mg of substrate, and may be 1 mmol or less, or 0.1 mmol or less. The amount of hydroxide ions may be 0.0001 mmol to 1 mmol, 0.0001 mmol to 0.1 mmol, 0.001 mmol to 1 mmol, 0.001 mmol to 0.1 mmol, 0.001 mmol to 0.1 mmol, 0.036 mmol to 1 mmol, or 0.036 mmol to 0.1 mmol per 1 mg of substrate.

[0042] The amount of hydroxide ions may be 0.1 mmol or more, 1 mmol or more, or 15 mmol or more per 1 mmol of metal ions, and may be 1000 mmol or less, or 100 mmol or less. The amount of hydroxide ions may be 0.1 mmol to 1000 mmol, 0.1 mmol to 100 mmol, 1 mmol to 1000 mmol, 1 mmol to 1000 mmol, 1 mmol to 100 mmol, 15 mmol to 1000 mmol, or 15 mmol to 100 mmol per 1 mmol of metal ions.

[0043] <Reaction Conditions> The reaction can be carried out in a reaction solution containing a substrate, a metal compound containing the above-mentioned metal ions, a metal hydroxide, and an aqueous solvent. The reaction solution can be obtained by mixing the substrate, the metal compound, and the metal hydroxide. The mixing order is not particularly limited, but one method is to mix the substrate, the metal compound, and the aqueous solvent, and then add an aqueous solution of the metal hydroxide.

[0044] The reaction may be a thermal reaction or a photoreaction. A thermal reaction can be carried out by heating the reaction solution with a heating device. The heating temperature (reaction temperature) in a thermal reaction may be 40°C or higher, 60°C or higher, 80°C or higher, 100°C or higher, 120°C or higher, or 140°C or higher, and may be 180°C or lower, 170°C or lower, or 160°C or lower. The reaction temperature may be 40°C to 180°C, 40°C to 170°C, 40°C to 160°C, 60°C to 180°C, 60°C to 170°C, 60°C to 160°C, 80°C to 180°C, 80°C to 170°C, 80°C to 160°C, 100°C to 180°C, 100°C to 170°C, 100°C to 160°C, 120°C to 180°C, 120°C to 170°C, 120°C to 160°C, 140°C to 180°C, 140°C to 170°C, or 140°C to 160°C. The heating temperature may be the set temperature of the heating device. The reaction time during the thermal reaction may be 1 hour or more, 2 hours or more, 3 hours or more, or 4 hours or more, and may be 10 hours or less, 8 hours or less, or 6 hours or less. The reaction time for the thermal reaction may be 1 to 10 hours, 1 to 8 hours, 1 to 6 hours, 2 to 10 hours, 2 to 8 hours, 2 to 6 hours, 3 to 10 hours, 3 to 8 hours, 3 to 6 hours, 4 to 10 hours, 4 to 8 hours, or 4 to 6 hours.

[0045] The photoreaction can be carried out by irradiating the reaction solution with ultraviolet light. The ultraviolet light used for irradiation may be ultraviolet light with a peak wavelength in the range of 250 to 385 nm. Xenon lamps, high-pressure mercury lamps, metal halide lamps, and low-pressure mercury lamps can be used as ultraviolet light sources. The ultraviolet light intensity should be 5 to 100 mW / cm². ２ , 10-70mW / cm ２ , or 15-50 mW / cm² ２The temperature during the photoreaction may be room temperature, 0°C to 50°C, 10°C to 30°C, or 15°C to 25°C. The reaction time during the photoreaction may be, for example, 1 hour or more, 5 hours or more, 10 hours or more, 15 hours or more, or 18 hours or more, and may be 30 hours or less, 25 hours or less, or 20 hours or less.

[0046] During the reaction process, the reaction mixture may be stirred. Stirring can be carried out using equipment with stirring capabilities, such as a stirrer, stirring blades, or an in-line mixer.

[0047] The reaction may be carried out under an air atmosphere or an inert gas atmosphere. Examples of inert gases include nitrogen and argon.

[0048] The reaction is preferably carried out in a sealable reaction vessel. If the reaction is carried out under pressure, it is preferable to use a reaction vessel that is also pressure-resistant.

[0049] According to the method disclosed herein, ammonia can be produced using nitrogen-containing biomass such as crab shells, which were previously discarded, as a substrate, thereby enabling the effective utilization of biomass resources.

[0050] The contents of this disclosure will be explained in more detail below with reference to examples and comparative examples. However, this disclosure is not limited to the examples described below.

[0051] <Experimental Procedure> Photoreaction Experiment Procedure: Chitin (substrate) 44.2 mg and Cu ＩＩ SO ４ ・5H ２ 5.0 mg of O (metal compound) was added to 2.5 mL of water (solvent), and the resulting reaction solution was irradiated with ultraviolet light (250-385 nm, 30 mW, Asahi Spectrometer MAX-303) for 19 hours while stirring. The ammonia contained in the aqueous solution after the reaction was quantified by the indophenol blue method.

[0052] Thermal reaction experimental procedure 1 (without addition of sodium hydroxide) Chitin (substrate) 30.5 mg and Cu ＩＩ SO ４ ・5H ２3.0 mg of O (metal compound) was added to 1.5 mL of water (solvent), and the resulting reaction solution was heated in a sealed container with stirring at 150°C for 4 hours. The ammonia contained in the aqueous solution after the reaction was quantified by the indophenol blue method.

[0053] Thermal reaction experimental procedure 2 (with sodium hydroxide addition) Chitin (substrate) 5 mg and Cu ＩＩ SO ４ ・5H ２ 3.0 mg of O (metal compound) was added to 1.5 mL of water (solvent), then 40 μL of NaOH aqueous solution (0.75 M) was added, and the resulting reaction mixture was heated at 150°C for 5 hours while stirring in a sealed container. The ammonia contained in the aqueous solution after the reaction was quantified by the indophenol blue method. The results are shown in entries 3-4.

[0054] The experiment was carried out in the same manner as any of the above experimental procedures, except that the type and amount of substrate, the type and amount of metal compound, the presence or absence and amount of sodium hydroxide added, and the reaction time were changed.

[0055] The "conversion rate" in the table was calculated using the following formula. ａ） Conversion rate (%) = NH in the reaction solution after the reaction is complete ３ moles (mol) of N atoms in the substrate / moles (mol) of N atoms in the substrate × 100

[0056] For the conversion rate when the substrate is chitin, the conversion rate is defined as 100% when 1 mol of ammonia molecules are produced from 1 mol of nitrogen atoms contained in chitin. For example, when 44.3 mg of chitin is used as the substrate, since chitin is a polymer of N-acetylglucosamine (M.W. = 203.2), the amount of nitrogen atoms contained in 44.3 mg of chitin can be calculated as 0.0443 / 203.2 = 0.000218 mol = 0.218 mmol. If 0.000042 g of ammonia is produced, the amount of ammonia produced can be calculated as 0.000042 g / 17.03 = 0.00000247 mol = 0.00247 mmol (molecular weight of ammonia: 17.03). Based on the above results, the conversion rate can be calculated as 0.00247 / 0.218 × 100 = 1.1%. When 3.72 mg of ammonia is produced from 44.2 mg of chitin, the conversion rate is 100%.

[0057] For ammonia detection, the indophenol blue method using UV-vis spectroscopy was employed. The indophenol blue method is an ammonia detection method that utilizes the reaction in which ammonium ions react with phenol in the presence of hypochlorite ions to produce indophenol. In the indophenol blue method, ammonium ions can be quantified by measuring the absorption of indophenol, which is produced in the presence of ammonia, around 630 nm. The aqueous solution after the reaction was subjected to the indophenol blue method, and the amount of ammonia was quantified by measuring the UV-vis spectrum after 30 minutes.

[0058] <Test Example 1: Ammonia Production by Thermal Reaction Using Acetamide or Ethylenediamine as a Substrate> Table 1 shows the test results when acetamide was used as the substrate, and Table 2 shows the test results when ethylenediamine was used as the substrate. In the experiments shown in Tables 1 and 2, the amount of water (solvent) used was 1.5 mL, and the sodium hydroxide concentration was 3 M.

[0059]

[0060]

[0061] Cu ２＋Ammonia was produced by the reaction of the substrate (acetamide or ethylenediamine) in a reaction solution containing water (entries 1-1, 1-2, 1-5). The conversion rate to ammonia was particularly significant when hydroxide ions were present in the reaction solution compared to when hydroxide ions were absent (comparison of entry 1-2 and entry 1-1).

[0062] <Test Example 2: Ammonia Production by Thermal Reaction Using GlcNAc, Chitosan, and D-Glu as Substrates> Table 3 shows the test results when N-acetylglucosamine (GlcNAc), chitosan, or D-glucosamine (D-Glu) was used as the substrate. In the experiments shown in Table 3, the amount of water (solvent) used was 1.5 mL, and the sodium hydroxide concentration was 3 M.

[0063]

[0064] Even when N-acetylglucosamine (GlcNAc), chitosan, and D-glucosamine (D-Glu) are used as substrates, NH ３ I confirmed that it generates.

[0065] <Test Example 3: Ammonia Production by Thermal Reaction Using Chitin as a Substrate 1> Tables 4-7 show the test results when chitin is used as the substrate. In the experiments shown in Tables 4-7, the amount of water (solvent) used was 1.5 mL. In the experiment shown in Table 4, no sodium hydroxide was added; in the experiments shown in Tables 5-6, the sodium hydroxide concentrations shown in the table were used; and in the experiment shown in Table 7, the sodium hydroxide concentration was 3 M. ｂ） The substrate concentrations for chitin substrate amounts of 30.5 mg, 10.0 mg, 5.0 mg, and 1.0 mg were converted to 100 mM, 32.8 mM, 16.4 mM, and 3.28 mM, respectively.

[0066]

[0067] As shown in Table 4, even when chitin is used as a substrate, NH ３ I confirmed that it generates.

[0068]

[0069] As shown in Table 5, the higher the base concentration, the higher the NH ３The amount produced tended to increase. In the absence of copper sulfate, NH ３ The amount produced decreased.

[0070]

[0071] As shown in Table 7, the metal ions are Cu ２＋ It was confirmed that a significant amount of ammonia could be generated in this case.

[0072] <Test Example 4: Ammonia Production by Thermal Reaction Using Chitin as a Substrate 2> Table 8 shows the results of investigating the type of metal catalyst used with chitin as the substrate. 5 mg of chitin and a metal catalyst were added to 1.5 mL of solvent (water) to obtain a reaction solution. The substrate (chitin) concentration was 16.4 mM. The concentrations of the metal catalyst (metal compound) were as shown in Table 8. The obtained reaction solution was heated at 150°C for 3 hours. After the reaction was complete, the amount of ammonia contained in the reaction solution was quantified. The conversion rate was calculated by the method described above. The turnover number (TON) was calculated using the following formula: TON = NH ３ Amount (mM) / Catalyst concentration (mM)

[0073] It was confirmed that ammonia can be produced even when various sulfates of different metal species are used.

[0074] Table 9 shows the results of an investigation into the types of metal catalysts used with chitin as a substrate. 5 mg of chitin and a metal catalyst were added to 1.5 mL of solvent (water) to obtain a reaction solution. The substrate (chitin) concentration was 16.4 mM. The concentrations of the metal catalyst (metal compound) were as shown in Table 9. An aqueous NaOH solution (NaOH concentration: 0.67 M) was added to the reaction solution, and the resulting reaction solution was heated at 150°C for 3 hours while stirring. The ammonia content in the reaction solution was quantified after the reaction. The conversion rate and TON were calculated using the same method as in the experiment shown in Table 8.

[0075] In reactions in the presence of hydroxide ions, the conversion rate was particularly high when copper sulfate was used.

[0076] Table 10 shows the results of investigating NaOH concentration using chitin as a substrate. 5 mg of chitin and Cu ＩＩ SO ４The reaction solution was prepared by adding to 1.5 mL of solvent (water). The substrate (chitin) concentration was 16.4 mM, and Cu ＩＩ SO ４ The concentration was 8 mM. NaOH aqueous solution was added to the reaction mixture to achieve the NaOH concentration shown in Table 10, and the resulting reaction mixture was heated at 150°C for 3 hours while stirring. After the reaction, the amount of ammonia contained in the reaction mixture was quantified. The conversion rate and TON were calculated using the same method as in the experiment shown in Table 8.

[0077] Table 11 shows the results of temperature studies using chitin as a substrate. 5 mg of chitin and Cu ＩＩ SO ４ The reaction solution was prepared by adding to 1.5 mL of solvent (water). The substrate (chitin) concentration was 16.4 mM, and Cu ＩＩ SO ４ The concentration was 8 mM. An aqueous NaOH solution (NaOH concentration: 0.67 M) was added to the reaction solution, and the resulting reaction solution was heated while stirring under the conditions shown in Table 11 at the temperature and for 3 hours. After the reaction, the amount of ammonia in the reaction solution was quantified. The conversion rate and TON were calculated using the same method as in the experiment shown in Table 8.

[0078] Table 12 shows the results of investigating catalyst concentrations using chitin as a substrate. Chitin 5 mg and Cu ＩＩ SO ４ The reaction solution was prepared by adding to 1.5 mL of solvent (water). The concentration of the substrate (chitin) was 16.4 mM. Cu ＩＩ SO ４ The concentrations were as shown in Table 12. An aqueous NaOH solution (NaOH concentration 0.67 M) was added to the reaction solution, and the resulting reaction solution was heated at 150°C for 3 hours while stirring. After the reaction, the ammonia content in the reaction solution was quantified. The conversion rate and TON were calculated using the same method as in the experiment shown in Table 8.

[0079] Table 13 shows the results of examining the amount of chitin used as a substrate. Chitin and Cu ＩＩ SO ４ The reaction solution was prepared by adding to 1.5 mL of solvent (water). The amount of substrate (chitin) is shown in Table 13. Cu ＩＩ SO４ The concentration was 8 mM. An aqueous NaOH solution (NaOH concentration 0.67 M) was added to the reaction solution, and the resulting reaction solution was heated at 150°C for 3 hours while stirring. After the reaction, the ammonia content in the reaction solution was quantified. The conversion rate and TON were calculated using the same method as in the experiment shown in Table 8.

[0080] Table 14 shows the results of investigating the counterions constituting the metal catalyst using chitin as the substrate. A reaction solution was prepared by adding 5 mg of chitin and the metal catalyst to 1.5 mL of solvent (water). The substrate (chitin) concentration was 16.4 mM, and the metal catalyst concentration was 8 mM. An aqueous NaOH solution (NaOH concentration 0.67 M) was added to the reaction solution, and the resulting reaction solution was heated at 150°C for 3 hours while stirring. The ammonia content in the reaction solution was quantified after the reaction. The conversion rate and TON were calculated using the same method as in the experiment shown in Table 8.

[0081] <Test Example 5: Ammonia Production by Thermal Reaction Using Crab Shells as a Substrate> Table 15 shows the test results when crab shells were used as a substrate. In the experiment shown in Table 15, the amount of water (solvent) used was 1.5 mL, and the sodium hydroxide concentration was 3 M. Crab shells are waste products of crustaceans and contain approximately 40% calcium carbonate, approximately 30% chitin, and approximately 30% protein.

[0082]

[0083] As shown in Table 15, NH can also be converted from crab shells at a high rate. ３ We confirmed that it is produced. The reason why the conversion rate exceeds 100% in entries 5-2 and 5-4 is thought to be because not only chitin but also proteins are used as substrates.

[0084] <Test Example 6: Ammonia Production by Thermal Reaction Using Amino Acids as Substrates> Table 16 shows the test results when DL-serine or DL-threonine was used as the substrate. In the experiments shown in Table 16, the amount of water (solvent) used was 1.5 mL, and the sodium hydroxide concentration was 3 M.

[0085]

[0086] As shown in Table 16, ammonia production from amino acids was also confirmed. The method disclosed herein is expected to have applications in reducing food waste.

[0087] <Test Example 7: Ammonia Production by Photoreaction Using Chitin as a Substrate> Table 17 shows the evaluation results of ammonia production by photoreaction using chitin as a substrate. In the experiment shown in Table 17, the amount of water (solvent) used was 2.5 mL, the UV irradiation intensity was 30 mW, and the visible light irradiation intensity was 150 mW. ｃ） When the chitin substrate amount was 44.2 mg, the substrate concentration was calculated to be 83.4 mM. In Table 17, "DARK" indicates no light irradiation.

[0088] Cu ２＋ , when the substrate (chitin) and ultraviolet light coexist, NH ３ I confirmed that it generates.

[0089] <Test Example 8: Ammonia Production by Photoreaction Using D-Glucosamine as a Substrate> Table 18 shows the evaluation results of ammonia production by photoreaction using D-glucosamine as a substrate. In the experiment shown in Table 18, the amount of water (solvent) used was 2.5 mL, the UV irradiation intensity was 30 mW, and the visible light irradiation intensity was 150 mW. In Table 18, "DARK" indicates no light irradiation.

[0090] Cu ２＋ , when the substrate (D-Glu) and ultraviolet light coexist, NH ３ I confirmed that it generates.

[0091] <Test Example 9: Ammonia Production by Thermal Reaction Using Various Biomass Substrates> The biomass substances shown in Table 19 were used. 5 mg of biomass substance and Cu ＩＩ SO ４ The reaction solution was prepared by adding to 1.5 mL of solvent (water). Cu ＩＩ SO ４ The concentration was 1 mM. An aqueous NaOH solution (NaOH concentration: 0.4 M) was added to the reaction mixture and heated at 150°C for 3 hours. After the reaction, the ammonia content in the reaction mixture was quantified. TON was calculated using the same method as in the experiment shown in Table 8.

[0092]

Claims

1. A method for producing ammonia, comprising the step of obtaining ammonia by the reaction of a substrate containing an amine compound with at least one selected from the group consisting of divalent and trivalent metal ions in the presence of water.

2. The method for producing ammonia according to claim 1, wherein the reaction is a thermal reaction or a photoreaction.

3. The method for producing ammonia according to claim 1 or 2, wherein the amine compound is an amino sugar.

4. The method for producing ammonia according to claim 1 or 2, wherein the amine compound is a primary amine compound or a secondary amine compound.

5. The method for producing ammonia according to claim 1 or 2, wherein the substrate is nitrogen-containing biomass.

6. The method for producing ammonia according to claim 1 or 2, wherein the substrate is biomass containing chitin, or biomass containing protein or amino acids.

7. The method for producing ammonia according to claim 1 or 2, wherein the substrate comprises at least one selected from the group consisting of crustaceans, mollusks, fungi, and insects.

8. At least one selected from the group consisting of divalent and trivalent metal ions is Cu ２＋ Mn ２＋ and Zn ２＋ A method for producing ammonia according to claim 1 or 2, wherein the at least one selected from the group consisting of the above.

9. At least one selected from the group consisting of divalent and trivalent metal ions is Cu ２＋ The method for producing ammonia according to claim 1 or 2.

10. The method for producing ammonia according to claim 1 or 2, wherein the reaction is a thermal reaction and the reaction temperature is 40°C or higher.

11. The method for producing ammonia according to claim 1 or 2, wherein the reaction is carried out in the presence of hydroxide ions.

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