Mixture, ammonia production system, and ammonia production method

Abstract

This mixture contains Azotobacter, a compound semiconductor, and water.

Description

Mixture, ammonia production system and ammonia production method

[0001] The present disclosure relates to a mixture, an ammonia production system, and an ammonia production method.

[0002] As a current industrial production method for ammonia, the Haber-Bosch process, in which ammonia is synthesized from hydrogen and nitrogen using an iron-based catalyst, is mainstream. In the Haber-Bosch process, hydrogen and nitrogen are reacted under high temperature and high pressure conditions (400 to 500°C, 100 to 300 atmospheres). For this reason, methods applying biological nitrogen fixation have attracted attention as methods for producing ammonia under milder conditions. For example, Non-Patent Document 1 describes that ammonia is produced when a mixture containing cyanobacteria having nitrogen fixation ability, a photocatalyst (titanium oxide), and water is irradiated with light in the presence of nitrogen.

[0003] Non-Patent Document 1: Applied Catalysis B: Environmental Volume 342 (2024) 123431

[0004] Biological nitrogen fixation is a process in which an enzyme (e.g., nitrogenase) possessed by certain microorganisms converts nitrogen molecules in the atmosphere into nitrogen compounds such as ammonia. Since biological nitrogen fixation proceeds at normal temperature and pressure, it is promising as a method for producing ammonia with a lower environmental load than conventional chemical production methods. However, as a result of studies by the inventors, there were cases where the method described in Non-Patent Document 1 still had room for improvement in ammonia production efficiency. In view of the above circumstances, an object of the present disclosure is to provide a mixture excellent in ammonia production efficiency, an ammonia production system, and an ammonia production method.

[0005] This disclosure includes the following embodiments: <1> A mixture comprising azotobacter, a compound semiconductor, and water. <2> The mixture according to <1>, further comprising a compound having a cyclic group containing a heteroatom and a functional group selected from the group consisting of a carboxyl group, a phosphate group, and a sulfone group. <3> The mixture according to <1> or <2>, further comprising an alcohol compound. <4> The mixture according to any one of <1> to <3>, further comprising a nitrate. <5> The mixture according to <2>, wherein the compound comprises a compound represented by the following general formula (1). [In general formula (1), R is a monovalent group that does not contain a hydrogen atom or a functional group selected from the group consisting of a carboxyl group, a phosphate group and a sulfone group, X is a functional group selected from the group consisting of a carboxyl group, a phosphate group and a sulfone group, Y is a cyclic group containing a heteroatom, Z is an oxygen atom or a sulfur atom, and n and m are integers from 1 to 3, independently of each other.] <6> The mixture according to <5>, wherein in general formula (1), Y is a cyclic group represented by the following general formula (2). [In general formula (2), R is a monovalent group that does not contain a hydrogen atom or a functional group selected from the group consisting of a carboxyl group, a phosphate group, and a sulfone group, independently of each other.] <7> The compound semiconductor is a mixture according to any one of <1> to <6>. <8> The mixture is a mixture according to any one of <1> to <7>, further comprising an electron mediator. <9> The Mo content of the azotobacter is 0.30 μmol / g cell mass or more, the mixture according to any one of <1> to <8>. <10> The compound content in the mixture is 10 mmol / L or more, the mixture according to <2>. <11> The alcohol compound is a trivalent alcohol, the mixture according to <3>. <12> The ratio of the mass of the compound semiconductor to the mass of the azotobacter in the mixture (compound semiconductor / azotobacter) is 0.01 to 0.25, the mixture according to any one of <1> to <11>. <13> The mixture according to <2>, wherein the ratio of the mass of the compound to the mass of the azotobacter in the mixture (compound / azotobacter) is 0.1 to 10.0. <14> The mixture according to any one of <1> to <13>. <15> An ammonia production system comprising: a housing for housing a mixture comprising azotobacter, a compound semiconductor, and water, and a gas containing nitrogen; a light irradiation unit for irradiating the mixture with light; and a pressure control unit for controlling the pressure of the gas in the housing. <16> A method for producing ammonia, comprising irradiating the mixture with light in the presence of nitrogen, wherein the mixture comprises azotobacter, a compound semiconductor, and water. <17> The method for producing ammonia according to <16>, wherein the mixture is housed in the housing together with the gas containing nitrogen, and further comprising controlling the pressure of the gas in the housing.

[0006] This disclosure provides a mixture, a system for producing ammonia, and a method for producing ammonia.

[0007] In this disclosure, numerical ranges expressed using "~" mean a range that includes the numbers before and after "~" as the lower and upper limits. In numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Also, in numerical ranges described in this disclosure, the upper or lower limit of that numerical range may be replaced with the values ​​shown in the examples. In this disclosure, each component in a mixture may contain multiple types of the corresponding substance. If there are multiple types of the corresponding substance for each component in a mixture, unless otherwise specified, the amount of each component in the composition means the total amount of those multiple types of substances.

[0008] <Mixture> One embodiment of the present disclosure is a mixture comprising azotobacter, a compound semiconductor, and water.

[0009] As shown in the examples described later, the mixture of this disclosure exhibits superior ammonia production efficiency compared to mixtures containing cyanobacteria as nitrogen-fixing bacteria.

[0010] (Azotobacter) The mixture of this disclosure contains azotobacter. Azotobacter is a type of nitrogen-fixing bacterium and is known to be present in soil and water. In this disclosure, microorganisms that have the ability to convert atmospheric nitrogen molecules into ammonia (called nitrogen-fixing ability) are referred to as nitrogen-fixing bacteria. To date, hundreds of species of microorganisms with nitrogen-fixing ability have been discovered. These are all microorganisms belonging to either the bacteria domain (eubacteria) or the archaea domain (archaea). Nitrogen-fixing bacteria can grow using nitrogen molecules as their sole nitrogen source. The enzyme involved in the nitrogen-fixing ability of nitrogen-fixing bacteria is nitrogenase, and under ideal reaction conditions in a test tube, nitrogenase undergoes the following reaction: N ２ +8H ＋ +8e － +16ATP → 2NH ３ +H ２+16ADP+16Pi Nitrogenase is a complex enzyme consisting of dinitrogenase, which reduces nitrogen molecules, and dinitrogenase reductase, which donates electrons to dinitrogenase. There are three types of dinitrogenase: Mo type, V type, and Fe type, but all nitrogen-fixing bacteria possess the Mo type dinitrogenase, which has an iron-molybdenum cofactor at its active site.

[0011] The mixtures of this disclosure may contain one or more types of azotobacter. If the azotobacter has been treated, such as by cell disruption, the treated product will also be referred to as "azotobacter" in this disclosure.

[0012] Azotobacter produces ATP, which is necessary for nitrogen fixation, through oxygen respiration. More specifically, oxygen is consumed in the oxygen respiration system bound to the surface of the azotobacter cell, generating ATP. Nitrogenase is present inside the azotobacter cell, and nitrogen fixation is carried out using the ATP produced on the cell surface.

[0013] The type of Azotobacter contained in the mixture of this disclosure is not particularly limited as long as it is a microorganism classified in the genus Azotobacter of the family Pseudomonadaceae. Examples of microorganisms classified in the genus Azotobacter of the family Pseudomonadaceae include Azotobacter vinelandii, Azotobacter paspali, and Azotobacter chroococcum. Among these, Azotobacter vinelandii is preferred from the viewpoint of the stability of ammonia production efficiency.

[0014] As for Azotobacter, you may use specimens obtained from a biological resource bank such as ATCC (American Type Culture Collection). Examples of Azotobacter available from biological resource banks include Azotobacter vinelandii ATCC 478, Azotobacter vinelandii ATCC 7496, Azotobacter vinelandii ATCC 13705, and Azotobacter vinelandii ATCC BAA-1303.

[0015] Azotobacter may be modified as desired. For example, azotobacter may be modified to increase the nitrogenase content it contains. In this disclosure, azotobacter modified to increase the nitrogenase content it contains is also referred to as "modified azotobacter".

[0016] Modified azotobacter exhibits enhanced potential nitrogen fixation capacity compared to unmodified azotobacter. Using modified azotobacter in a mixture increases the opportunities for nitrogenase to receive electrons generated by the decomposition of water molecules by the compound semiconductor, compared to simply increasing the amount of azotobacter in the mixture. As a result, the effective nitrogen fixation capacity of azotobacter (i.e., nitrogenase activity) tends to improve.

[0017] There are no particular limitations on the method for increasing the nitrogenase content in azotobacter. For example, modified azotobacter can be obtained by culturing azotobacter under conditions that promote nitrogenase increase. For example, nitrogenase increases under nitrogen starvation conditions. Therefore, modified azotobacter may be obtained by culturing azotobacter in a nitrogen-free medium such as Burks medium (BM medium) or BM+Mo medium (BM medium with molybdenum salt added). Alternatively, modified azotobacter may be obtained by techniques such as genetic engineering.

[0018] Whether the content of nitrogenase contained in Azotobacter is increased by modification can be determined, for example, based on the metal content in the Azotobacter. Specifically, when the content of Mo and Fe, particularly Mo, contained in the modified Azotobacter is increased compared with that of Azotobacter before modification, it can be determined that the amount of Fe-Mo type nitrogenase contained in Azotobacter is increased. Therefore, it can be determined that a modified Azotobacter with an increased nitrogenase content is obtained. In an embodiment of the present disclosure, an Azotobacter having a Mo content of 0.30 µmol / g cell mass or more may be determined as a modified Azotobacter; an Azotobacter having a Mo content of 1.00 µmol / g cell mass or more may be determined as a modified Azotobacter; an Azotobacter having a Mo content of 1.50 µmol / g cell mass or more may be determined as a modified Azotobacter; an Azotobacter having a Mo content of 2.00 µmol / g cell mass or more may be determined as a modified Azotobacter; and an Azotobacter having a Mo content of 2.30 µmol / g cell mass or more may be determined as a modified Azotobacter.

[0019] The content of Mo and Fe in Azotobacter may be measured by inductively coupled plasma atomic emission spectrometry (ICP-AES).

[0020] (Compound Semiconductor) The mixture of the present disclosure includes a compound semiconductor. In the present disclosure, a compound semiconductor refers to a semiconductor composed of a plurality of elements. The compound semiconductor included in the mixture of the present disclosure is not particularly limited as long as it is a substance having a property of absorbing light to decompose water into hydrogen and oxygen.

[0021] Examples of the compound semiconductor include metal oxides or composite oxides, metal halides, metal sulfides, metal selenides, metal tellurides, and metal nitrides. Examples of the metal oxide or composite oxide include TiO ２ , ZnO, In ２ O ３ , SnO ２ , ZrO ２ , Ta ２O ５ , Nb ２ O ５ Fe ２ O ３ Ga ２ O ３ WO ３ SrTiO ３ Examples include: Metal halides such as AgI, AgBr, CuI, and CuBr; Metal sulfides such as ZnS and TiS ２ ,ZnO,In ２ S ３ SnS, SnS ２ ZrS ２ Ag ２ S, PbS, CdS, TaS ２ CuS, Cu ２ S, WS ２ MoS ２ CuInS ２ Examples include CdSe and TiSe. ２ , ZrSe ２ , Bi ２ See ３ In ２ See ３ , SnSe, SnSe ２ Ag ２ Se, TaSe ２ , CuSe, Cu ２ Se, WSe ２ MoSe ２ CuInSe ２ Examples include CdTe and TiTe. ２ , ZrTe ２ , Bi ２ Te ３ In ２ Te ３ , SnTe, SnTe ２ Ag ２ Te, TaTe ２ ,CuTe,Cu ２ Te, WTe ２ MoTe ２ Examples include GaN as an example of a metal nitride. From the viewpoint of catalytic activity and availability, TiO ２ ZnO and SnO２ At least one compound semiconductor selected from the group consisting of TiO is preferred, ２ ZnO and SnO ２ More preferably, at least one compound semiconductor selected from the group consisting of TiO ２ Compound semiconductors containing TiO are even more preferred. ２ Compound semiconductors that are such as the above are particularly preferred. The compound semiconductor contained in the mixture may be one type or two or more types.

[0022] In this disclosure, commercially available compound semiconductors may be used, or compound semiconductors obtained through synthesis may be used. Titanium oxide (TiO) may be used as the compound semiconductor. ２ )When using particles, commercially available titanium dioxide (TiO ２ Examples of particles include 718467 (Sigma-Aldrich), P25 (manufactured by Nippon Aerosil Co., Ltd.), ST-01 (manufactured by Ishihara Sangyo Co., Ltd.), SP-210 (manufactured by Showa Denko Corporation), DSL-18NRT (manufactured by Dysol Corporation), Ti-NanoxideT / SP (manufactured by Solaronix Corporation), and PST-18NR (manufactured by JGC Catalysts & Chemicals Co., Ltd.). The titanium dioxide (TiO2) obtained by synthesis... ２ As particles, crystalline titanium oxide particles obtained from titanium alkoxide or the like by hydrolysis and autoclave using the sol-gel method may be used, and titanium oxide particles obtained from titanium alkoxide by the sol-gel method are preferred. An example of the sol-gel method is the method described in J. Am. Ceram. Soc., 80, 3157 (1997).

[0023] Compound semiconductors are preferably in particulate form. Hereinafter, particulate compound semiconductors will also be referred to as compound semiconductor particles. The average particle diameter of compound semiconductor particles is preferably as small as possible. For example, the average particle diameter of compound semiconductor particles is preferably 300 nm or less, and more preferably 200 nm or less. The average particle diameter of compound semiconductor particles is preferably 5 nm to 200 nm, and more preferably 10 nm to 150 nm.

[0024] The compound semiconductor contained in the mixture may be a combination of compound semiconductor particles with different average particle sizes.

[0025] The specific surface area of ​​compound semiconductors is 50 m². ２ It is preferable that the value is 1 / g or more. The specific surface area of ​​the compound semiconductor is a value measured by the BET method using nitrogen gas.

[0026] (Specific Compounds) The mixtures of this disclosure may contain compounds (hereinafter also referred to as "specific compounds") having a cyclic group containing a heteroatom and a functional group selected from the group consisting of a carboxyl group, a phosphate group, and a sulfone group. As shown in the examples described later, when the mixture contains specific compounds, the amount of hydrogen produced in addition to ammonia tends to increase. From this result, it is thought that specific compounds function to enhance the activity of hydrogenase, an enzyme contained in nitrogen-fixing bacteria. Furthermore, it is thought that specific compounds also function as sacrificial agents for compound semiconductors (substances that donate electrons to compound semiconductors).

[0027] The specific compound has a carboxyl group (-COOH) and a phosphate group (-PO). ４ H ２ ) and sulfone group (-SO ３ The compound has a functional group selected from the group consisting of H) (hereinafter also referred to as a specific functional group). From the viewpoint of improving the efficiency of ammonia production, it is preferable that the specific compound has at least one sulfone group.

[0028] The specific functional group may be directly or indirectly bonded to the complex atom contained in the cyclic group containing the complex atom (hereinafter also simply referred to as the cyclic group). For example, the specific functional group may be bonded to the complex atom contained in the cyclic group via an aliphatic hydrocarbon group having 1 to 3 carbon atoms.

[0029] From the viewpoint of improving the efficiency of ammonia production, the number of specific functional groups contained in the specific compound is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1.

[0030] Examples of cyclic groups included in specific compounds include cyclic groups containing at least one complex atom selected from nitrogen, oxygen, silicon, phosphorus, and sulfur atoms. From the viewpoint of improving the efficiency of ammonia production, it is preferable that the cyclic group contains at least one complex atom selected from nitrogen and oxygen atoms, more preferably contains at least one nitrogen atom, and even more preferably contains only nitrogen atoms.

[0031] From the viewpoint of improving the efficiency of ammonia production, the number of complex atoms contained in the cyclic group is preferably 1 to 5, more preferably 1 to 3, and even more preferably 1 or 2.

[0032] From the viewpoint of improving the efficiency of ammonia production, the number of carbon atoms in the cyclic group is preferably 4 to 20, more preferably 4 to 10, and even more preferably 4 to 6.

[0033] From the viewpoint of improving the efficiency of ammonia production, the number of cyclic groups contained in the specific compound is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1.

[0034] The cyclic group contained in a particular compound may be a monocyclic or polycyclic cyclic group. Examples of monocyclic cyclic groups include pyrrolidine, 3-pyrroline, 2-pyrroline, 2H-pyrrole, 1H-pyrrole, pyrazolidine, imidazolidine, 2-pyrazoline, 2-imidazoline, pyrazole, imidazole, 1,2,4-triazole, 1,2,3-triazole, tetrazole, tetrahydrofuran, furan, 1,3-dioxolane, tetrahydrothiophene, thiophene, oxazole, isoxazole, isothiazole, thiazole, 1,2-oxathiolane, 1,3 -Oxathiolane, 1,2,5-oxadiazole, 1,2,3-oxadiazole, 1,2,4-thiadiazole, 1,2,5-thiadiazole, sulforane, 2,4-thiazolidinedione, succinimide, 2-oxazolidone, hydantoin, piperidine, pyridine, piperazine, pyridazine, pyrimidine, pyrazine, 1,2,4-triazine, 1,3,5-triazine, tetrahydropyran, 2H-pyran, 4H-pyran, pyririum, 1,4-dioxane, 1, 4-Dioxin, Thiane, 2H-Thiopyran, 4H-Thiopyran, 1,3-Dithiane, 1,4-Dithiane, 1,3,5-Tritiane, Morpholine, 4H-1,2-Oxazine, 2H-1,2-Oxazine, 6H-1,2-Oxazine, 4H-1,3-Oxazine, 2H-1,3-Oxazine, 6H-1,3-Oxazine, 4H-1,4-Oxazine, 2H-1,4-Oxazine, Thiomorpholine, 4H-1,4-Thiazine, 2H-1,2-Thiazine, 6H-1,2-Thiazine Examples include cyclic groups contained in heterocyclic compounds selected from the group consisting of 2H-1,4-thiazine, cytosine, thymine, uracil, thiomorpholine dioxide, 2,3-dihydroazepine, 2,5-dihydroazepine, 4,5-dihydroazepine, azepine, 2H-azepine, 3H-azepine, 4H-azepine, 1,2-diazepine, 1,3-diazepine, 1,4-diazepine, oxepane, thiepine, 1,4-thiazepine, azocan, azosine, thiocan, and azesine.

[0035] Polycyclic cyclic groups include pyrrolizidine, 1,4,5,6-tetrahydrocyclopenta[b]pyrrole, 1,3a,4,6a-tetrahydropyrrolo[3,2-b]pyrrole, 1,4-dihydropyrrolo[3,2-b]pyrrole, 1,6-dihydropyrrolo[2,3-b]pyrrole, 6H-floo[2,3-b]pyrrole, 4H-floo[3,2-b]pyrrole, 4H-thieno[3,2-b]pyrrole, 6H-thieno[2,3-b]pyrrole, indoline, 3H-indole, 1H-indole, 2H-isoindole, indoridine, 1H-indazole, Benzimidazole, 7-azaindole, 4-azaindole, 5-azaindole, 6-azaindole, 7-azaindole, pyrazolo[1,5-a]pyrimidine, purine, benzofuran, isobenzofuran, benzo[c]thiophene, benzo[b]thiophene, benzo[d]isoxazole, benzo[c]isoxazole, benzo[d]isothiazole, benzo[c]isothiazole, benzo[d]oxazole, benzo[d]thiazole, benzo[c][1,2,5]thiadiazole, 1,2-benzoisothiazole-3(2H)-one , adenine, guanine, decahydroisoquinoline, decahydroquinoline, 1,2,3,4-tetrahydroquinoline, 1,2-dihydroquinoline, 1,2-dihydroisoquinoline, quinoline, isoquinoline, 4H-quinoridine, quinoxaline, phthalazine, quinazoline, cinnoline, 1,8-naphthyridine, pyrido[3,2-d]pyrimidine, pyrido[4,3-d]pyrimidine, pyrido[3,4-b]pyrazine, pyrido[2,3-b]pyrazine, pteridine, 2H-chromene, 1H-isochromene, 3H-isochromene, 2H-chromene-2-one, 2H-benzo[e][1,2]oxazine, 2H-benzo[e][1,3]oxazine, 2H-benzo[b][1,4]oxazine, quinoline-2(1H)-one, isoquinoline-1(2H)-one, fluorene, carbazole, dibenzofuran, acridine, phenazine, phenoxazine, phenothiazine, phenoxatiin, quinuclidine, 1-azaadamantane, 2-azaadamantane, spiro[cyclobutan-1,3'-indole], 1-oxaspiro[4.5]decane, 1,6-dioxaspiro[3.4]octane, 3',4',5',Examples of cyclic groups included in heterocyclic compounds selected from the group consisting of 6'-tetrahydro-3H-spiro[isobenzofuran-1,2'-pyran], 1-oxaspiro[4.4]nonane-2-one, 2-oxa-7-azaspiro[3.5]nonane, 1,4-dioxa-7-azaspiro[4.4]nonane, 1,3-diazaspiro[4.4]nonana-2-en-4-one, 2,9-diazaspiro[5.5]undecane-1-one, 8-azaspiro[4.5]decane-7,9-dione, 1,3,8-triazaspiro[4.5]decane-4-one, and 1,4-dithia-7-azaspiro[4.4]nonane.

[0036] The specific compound preferably has a monocyclic cyclic group, more preferably has a monocyclic cyclic group containing one or more nitrogen atoms, and even more preferably has a monocyclic cyclic group containing two or more nitrogen atoms. If the specific compound has a monocyclic cyclic group, the cyclic group may be a five-membered ring, a six-membered ring, or a seven-membered ring, and is preferably a six-membered ring.

[0037] The cyclic group contained in a specific compound may or may not contain a double bond. From the viewpoint of improving the efficiency of ammonia production, it is preferable that the cyclic group does not contain a double bond.

[0038] The specific compound may further have a hydroxyl group (-OH) or a thiol group (-SH). When the specific compound has a hydroxyl group or a thiol group, the hydroxyl group or thiol group may be directly or indirectly bonded to a complex atom contained in the cyclic group. For example, the hydroxyl group or thiol group may be bonded to a complex atom contained in the cyclic group via an aliphatic hydrocarbon group having 1 to 3 carbon atoms. From the viewpoint of improving the efficiency of ammonia production, it is preferable that the specific compound further has a hydroxyl group.

[0039] The specific compound may be in a state where a specific functional group forms a salt with a cation. Examples of cations include sodium ions, potassium ions, and ammonium ions.

[0040] The specific compound may be a compound represented by the following general formula (1).

[0041]

[0042] In general formula (1), R is a monovalent group that does not contain a hydrogen atom or a specific functional group, X is a specific functional group, Y is a cyclic group containing a complex atom, Z is an oxygen atom or a sulfur atom, and n and m are integers from 1 to 3, independently of each other.

[0043] Examples of monovalent groups that do not contain the specific functional group represented by R in general formula (1) include substituted or unsubstituted aliphatic hydrocarbon groups, oxygen-containing groups, sulfur-containing groups, and nitrogen-containing groups having 1 to 3 carbon atoms. Examples of substituted or unsubstituted aliphatic hydrocarbon groups having 1 to 3 carbon atoms include linear alkyl groups having 1 to 3 carbon atoms such as methyl groups, ethyl groups, and n-propyl groups; monoalkyl-substituted alkyl groups having 3 carbon atoms such as isopropyl groups; and cyclic alkyl groups having 3 carbon atoms such as 1,1,2-trimethylpropyl groups and 1,2,2-trimethylpropyl groups. Examples of oxygen-containing groups include alkoxy groups, aryloxy groups, ester groups, ether groups, acyl groups, carbonate groups, hydroxyl groups, and peroxy groups. Examples of sulfur-containing groups include those obtained by replacing the oxygen atom of the above oxygen-containing group with a sulfur atom. Examples of nitrogen-containing groups include amino groups, monoalkylamino groups, dialkylamino groups, imino groups, amide groups, imide groups, hydrazino groups, hydrazono groups, nitro groups, nitroso groups, cyano groups, isocyano groups, cyanate ester groups, amidino groups, diazo groups, and ammonium salts of amino groups.

[0044] From the viewpoint of improving the efficiency of ammonia production, it is preferable that R in general formula (1) be a hydrogen atom or a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 3 carbon atoms, independently of each other. In this case, it is more preferable that at least one of R is a hydrogen atom, and even more preferable that all of R are hydrogen atoms.

[0045] Specific examples and preferred embodiments of the specific functional group represented by X in general formula (1) are the same as the specific examples and preferred embodiments of the specific functional group contained in the specific compound described above.

[0046] Specific examples and preferred embodiments of the cyclic group containing a complex atom represented by Y in general formula (1) are the same as the specific examples and preferred embodiments of the cyclic group containing a complex atom contained in the specified compound described above.

[0047] In general formula (1), Z is either an oxygen atom or a sulfur atom. That is, the compound represented by general formula (1) has a hydroxyl group (-OH) or a thiol group (-SH). From the viewpoint of improving the efficiency of ammonia production, it is preferable that Z is an oxygen atom. That is, it is preferable that the compound represented by general formula (1) has a hydroxyl group.

[0048] In general formula (1), n ​​and m are preferably 2 or 3, and more preferably 2.

[0049] A cyclic group containing a complex atom represented by Y may have a piperazine ring. Examples of cyclic groups having a piperazine ring include the cyclic group represented by the following general formula (2).

[0050]

[0051] The specific examples and preferred embodiments of R in general formula (2) are the same as the specific examples and preferred embodiments of R in general formula (1).

[0052] In some embodiments of this disclosure, at least a portion of the specific compound contained in the mixture may be HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid, a compound represented by the structure shown below), or the entire amount of the specific compound may be HEPES.

[0053]

[0054] (Electron Mediator) The mixture of the present disclosure may further contain an electron mediator. When the mixture contains an electron mediator, electrons generated by the action of the compound semiconductor are effectively supplied to azotobacter by the electron mediator. As a result, the nitrogen fixation reaction of azotobacter is promoted.

[0055] Examples of electron mediators include viologen compounds such as methyl viologen dichloride, ethyl viologen dichloride, and benzyl viologen dichloride, as well as 2-amino-2-hydroxymethyl-1,3-propanediol, triethanolamine (TEOA), bis(2-hydroxyethyl)iminotris(hydroxymethyl)methane (Bis-Tris), and triethylamine (TEA). The mixture may contain only one or more electron mediators.

[0056] From the viewpoint of electron transfer from compound semiconductors to azotobacter, the electron mediator may be a viologen compound or methyl viologen dichloride.

[0057] (Alcohol Compounds) The mixtures of this disclosure may further contain alcohol compounds. The inventors believe that the alcohol compounds function, for example, as sacrificial agents for compound semiconductors (substances that donate electrons to compound semiconductors). Examples of alcohol compounds include monohydric alcohols, dihydric alcohols, trihydric alcohols, and tetrahydric or higher alcohols, with dihydric or trihydric alcohols being preferred, and trihydric alcohols being more preferred. The number of carbon atoms in the alcohol compound is preferably 1 to 10, more preferably 2 to 5, and even more preferably 3. Specific examples of alcohol compounds include methanol, ethanol, ethylene glycol, propylene glycol, glycerol, and triethanolamine. Among these, glycerol is preferred as the alcohol compound. The mixture may contain only one or two or more alcohol compounds, but it is preferable to contain at least a trihydric alcohol, more preferably glycerol, and even more preferably only glycerol.

[0058] (Nitrates) The mixtures of this disclosure may further contain nitrates. As shown in the examples described later, the ammonia production efficiency tends to improve when the mixture contains nitrates. Specific examples of nitrates include lithium nitrate, sodium nitrate, potassium nitrate, beryllium nitrate, magnesium nitrate, calcium nitrate, strontium nitrate, barium nitrate, aluminum nitrate, zinc(II) nitrate, copper(II) nitrate, iron(III) nitrate, silver(I) nitrate, and ammonium nitrate. Among these, sodium nitrate or potassium nitrate is preferred as the nitrate, and sodium nitrate is more preferred. The mixture may contain only one type of nitrate or two or more types, but it is preferable to contain at least one from the group consisting of sodium nitrate and potassium nitrate, more preferably sodium nitrate, and even more preferably sodium nitrate as the total amount of nitrate.

[0059] (Nitrogen Metabolism Inhibitors) The mixture of this disclosure may further contain nitrogen metabolism inhibitors. Nitrogen metabolism inhibitors act antagonistically with glutamate to inhibit the activity of glutamine synthase (an enzyme that produces glutamine from glutamate and ammonia), thereby suppressing ammonia consumption by Azotobacter. As a result, the efficiency of ammonia production tends to increase. Specific examples of nitrogen metabolism inhibitors include methionine sulfoxiamine (MSX), bialaphos, glufosinate, and the like. The mixture may contain only one or two or more nitrogen metabolism inhibitors.

[0060] (Other Components) The mixture of this disclosure may contain other components not included in the components described above. Examples of other components include pH adjusters, buffers, and phosphates. Examples of phosphates include nicotinamide adenine dinucleotide phosphate (NADPH). The other components included in the mixture may be one type or two or more types.

[0061] (Physical properties of the mixture) The content of each component in the mixture is not particularly limited and can be selected according to the desired amount of ammonia produced. The content of azotobacter in the mixture may be, for example, 5 g / L or more, 10 g / L or more, or 30 g / L or more. The content of azotobacter in the mixture may be, for example, 500 g / L or less, 200 g / L or less, or 100 g / L or less. The content of compound semiconductors in the mixture may be, for example, 50 mg / L or more, 100 mg / L or more, or 1000 mg / L or more. The content of compound semiconductors in the mixture may be, for example, 50,000 mg / L or less, 10,000 mg / L or less, or 5,000 mg / L or less. The content of specific compounds in the mixture may be, for example, 10 mmol / L or more, 50 mmol / L or more, or 100 mmol / L or more. The content of a specific compound in the mixture may be, for example, 1000 mmol / L or less, 500 mmol / L or less, or 200 mmol / L or less. The content of an alcohol compound in the mixture may be, for example, 50 mmol / L or more, 100 mmol / L or more, or 500 mmol / L or more. The content of an alcohol compound in the mixture may be, for example, 5000 mmol / L or less, 2000 mmol / L or less, 1000 mmol / L or less, or 800 mmol / L or less. The content of an electron mediator in the mixture may be, for example, 1 mmol / L or more, 5 mmol / L or more, or 8 mmol / L or more. The content of an electron mediator in the mixture may be, for example, 500 mmol / L or less, 100 mmol / L or less, or 50 mmol / L or less. The content of a nitrate in the mixture may be, for example, 0.1 mg / L or more, 1 mg / L or more, or 3 mg / L or more. The nitrate content in the mixture may be, for example, 100 mg / L or less, 50 mg or less, or 20 mg / L or less.

[0062] The ratio of the mass of the compound semiconductor to the mass of azotobacter in the mixture (compound semiconductor / azotobacter) can be selected from, for example, 0.01 to 0.25, preferably from 0.02 to 0.15, and more preferably from 0.03 to 0.08. The ratio of the mass of the specific compound to the mass of azotobacter in the mixture (specific compound / azotobacter) can be selected from, for example, 0.1 to 10.0, preferably from 0.2 to 5.0, and more preferably from 0.3 to 1.0.

[0063] From the viewpoint of maintaining the activity of Azotobacter in the mixture, the pH of the mixture is preferably 5.5 to 8.5, more preferably 6.5 to 8.0, and even more preferably 7.0 to 8.0.

[0064] <Ammonia Production System> One embodiment of the present disclosure is an ammonia production system comprising: a storage unit for containing a mixture comprising azotobacter, a compound semiconductor, and water, and a gas containing nitrogen; a light irradiation unit for irradiating the mixture with light; and a pressure control unit for controlling the pressure of the gas in the storage unit.

[0065] The ammonia production system of this disclosure is used for the production of ammonia using biological nitrogen fixation. Specifically, it is used for the production of ammonia using the nitrogen fixation ability of Azotobacter. The outline of the process by which ammonia is produced by the ammonia production system of this disclosure is as follows: When light is irradiated onto a mixture containing Azotobacter, a compound semiconductor, and water, the compound semiconductor absorbs the light and decomposes the water molecules into hydrogen and oxygen. The electrons (e) generated during the decomposition of water molecules － ) is the nitrogen fixation reaction (N) of nitrogenase contained in azotobacter. ２ +8H ＋ +8e － → 2NH ３ +H ２ It is used in ) and ammonia is produced.

[0066] (Container) The containment unit contains a mixture (hereinafter simply referred to as the mixture) containing azotobacter, a compound semiconductor, and water, and a gas containing nitrogen. The material of the containment unit is not particularly limited as long as it can contain the mixture and the gas containing nitrogen. For example, the material of the containment unit may be glass, metal, resin, etc. The shape and size of the containment unit are not particularly limited and can be selected according to the scale of the ammonia production system, etc. From the viewpoint of ensuring opportunities for contact between azotobacter contained in the mixture and nitrogen molecules, it is preferable that the containment unit be in a state that can be sealed off from the outside air.

[0067] Details and preferred embodiments of the mixture contained in the containment section and the components contained in the mixture are the same as those described above for details and preferred embodiments of the mixture and components contained in the present disclosure.

[0068] The "nitrogen-containing gas" contained in the containment section may consist solely of nitrogen, or of nitrogen and other gases. From the viewpoint of ammonia production efficiency, the proportion of nitrogen in the nitrogen-containing gas is preferably 50% by volume or more, more preferably 70% by volume or more, even more preferably 90% by volume or more, and may even be 100% by volume. If the nitrogen-containing gas contains other gases, the type of other gas is not particularly limited. The other gas is preferably an inert gas such as helium, neon, argon, krypton, or xenon.

[0069] The method for containing the mixture and the nitrogen-containing gas in the containment chamber is not particularly limited. For example, the mixture may be contained in the containment chamber, then the inside of the containment chamber may be degassed to create a vacuum, and then the nitrogen-containing gas may be supplied to the containment chamber. Alternatively, the mixture may be supplied to a containment chamber filled with nitrogen-containing gas. The temperature of the mixture contained in the containment chamber can be selected from, for example, a range of 20°C to 40°C.

[0070] (Light Irradiation Unit) The light irradiation unit irradiates the mixture contained in the container with light. The irradiation conditions (irradiation amount, etc.) of the light irradiated onto the mixture by the light irradiation unit are not particularly limited and can be set according to the amount of the mixture, the content of each component contained in the mixture, etc. The wavelength of the light irradiated onto the mixture by the light irradiation unit is not particularly limited. From the viewpoint of ammonia production efficiency, it is preferable that the light irradiated onto the mixture includes ultraviolet light. As the light source of the light irradiation unit, a light source corresponding to the desired wavelength can be used without particular limitation. The light source may be placed outside the container or inside the container.

[0071] (Pressure Control Unit) The pressure control unit controls the pressure of the nitrogen-containing gas in the containment unit. As shown in the embodiments described later, controlling the pressure of the nitrogen-containing gas in the containment unit tends to improve the efficiency of ammonia production by azotobacter. The reason for this is not clear, but for example, it is thought that increasing the pressure of the nitrogen-containing gas in the containment unit promotes the diffusion of nitrogen molecules into the mixture, and thus increases the opportunities for contact between azotobacter and nitrogen molecules in the mixture.

[0072] The method for controlling the gas pressure within the containment by the pressure control unit is not particularly limited. For example, the gas pressure within the containment may be controlled by adjusting the amount of nitrogen-containing gas supplied to the containment. Alternatively, the gas pressure within the containment may be controlled by adjusting the volume of the containment.

[0073] The gas pressure in the containment section controlled by the pressure control unit is not particularly limited and can be set according to the amount of mixture contained in the containment section, the content of each component in the mixture, etc. From the viewpoint of increasing the efficiency of ammonia production, the gas pressure in the containment section may be controlled to be 50 Torr or higher, 100 Torr or higher, or 200 Torr or higher. The upper limit of the gas pressure in the containment section is not particularly limited, but for example, it may be controlled to be 760 Torr (1 atmosphere) or lower.

[0074] <Method for producing ammonia> One embodiment of the present disclosure is a method for producing ammonia, comprising irradiating a mixture with light in the presence of nitrogen, wherein the mixture comprises azotobacter, a compound semiconductor, and water.

[0075] The ammonia production method described herein utilizes biological nitrogen fixation. Specifically, ammonia is produced by utilizing the nitrogen fixation ability of Azotobacter.

[0076] Details and preferred embodiments of the mixtures and components contained in the mixtures used in the methods of this disclosure are the same as the details and preferred embodiments of the mixtures and components contained in the mixtures described above.

[0077] In the method disclosed herein, the method of irradiating the mixture with light in the presence of nitrogen is not particularly limited. For example, the mixture may be irradiated with light while in contact with a gas containing nitrogen. The mixture and the gas containing nitrogen may be in contact at the liquid surface of the mixture or in contact within the liquid (for example, by bubbling the gas containing nitrogen into the mixture). The irradiation conditions (irradiation amount, etc.) of the light irradiated onto the mixture are not particularly limited and can be set according to the amount of the mixture, the content of each component contained in the mixture, etc. The wavelength of the light irradiated onto the mixture is not particularly limited. From the viewpoint of ammonia production efficiency, it is preferable that the light irradiated onto the mixture contains visible light or ultraviolet light. The temperature of the mixture irradiated with light can be selected from, for example, a range of 20°C to 40°C.

[0078] The method of this disclosure involves a mixture being contained in a containment chamber with a nitrogen-containing gas, and may further include controlling the pressure of the nitrogen-containing gas within the containment chamber. Details and preferred embodiments of the containment chamber are the same as those in the ammonia production system described above.

[0079] The method for controlling the gas pressure within the containment is not particularly limited. For example, the gas pressure within the containment may be controlled by adjusting the amount of nitrogen-containing gas supplied to the containment. Alternatively, the gas pressure within the containment may be controlled by adjusting the volume of the containment.

[0080] The controlled gas pressure within the containment is not particularly limited and can be set according to the amount of mixture contained in the containment, the content of each component in the mixture, etc. From the viewpoint of increasing the efficiency of ammonia production, the gas pressure within the containment may be controlled to 50 Torr or higher, 100 Torr or higher, or 200 Torr or higher. The upper limit of the gas pressure within the containment is not particularly limited, but for example, it may be controlled to 760 Torr (1 atmosphere) or lower.

[0081] The embodiments of this disclosure will be described in more detail below based on examples, but this disclosure is not limited in any way by the examples. In the following tests, Azotobacter vinelandii ATCC BAA-1303 (obtained from the American Type Culture Collection) was used as Azotobacter. Anabaena variantis ATCC 29413 (obtained from the American Type Culture Collection) was used as cyanobacteria.

[0082] (Preparation Example 1: Preparation of Azotobacter) Azotobacter was cultured using the method described in the following literature: Carruthers, BM, Garcia, AK, Rivier, A., & Kacar, B. (2021). Automated laboratory growth assessment and maintenance of Azotobacter vinelandii. Current Protocols, 1, e57. doi: 10.1002 / cpz1.57

[0083] Azotobacter was cultured with shaking at 26°C and 140 rpm. BM+Mo medium was used as the culture medium. The BM+Mo medium was prepared by adding 20 μ mmol of sodium molybdate dihydrate to 100 mL of Burks medium. Five days after the start of culture, the medium was centrifuged (10,000 G, 5 minutes) to collect the cells in pellet form. The cells collected from the medium were resuspended in water (50 mL) containing 100 mmol / L of a specific compound (HEPES) to obtain a suspension.

[0084] The Fe and Mo content of Azotobacter in the suspension was measured by ICP emission spectrometry (measurement equipment: ICP-OES, PerkinElmer, Optima 5300DV). The results showed that the Fe content was 1.99 μmol / g cell mass and the Mo content was 2.56 μmol / g cell mass. For comparison, the Fe and Mo content of Azotobacter cultured in BM medium (Burks medium without sodium molybdate dihydrate) was measured by ICP emission spectrometry. The results showed that the Fe content was 1.61 μmol / g cell mass and the Mo content was 0.10 μmol / g cell mass. The Mo content of azotobacter cultured in BM+Mo medium was significantly higher than that of azotobacter cultured in BM medium, suggesting an increase in Fe-Mo type nitrogenase in azotobacter cultured in BM+Mo medium. Based on these results, the azotobacter obtained in Production Example 1 was determined to be a modified azotobacter.

[0085] <Example 1> To the suspension of azotobacter obtained in Preparation Example 1, a compound semiconductor with a particle size of 140 nm and a specific surface area of ​​53 m² was added. ２ TiO / g ２ A mixture (100 mL, pH 7.5) was prepared by adding particles, HEPES as a specific compound, glycerol as an alcohol compound, methyl viologen dichloride as an electron mediator, and water.

[0086] The content of each component in the mixture is as follows. The ratio of the mass of the compound semiconductor to the mass of azotobacter (compound semiconductor / azotobacter) is 0.05. • Azotobacter: 50 g / L • Compound semiconductor: 2500 mg / L • Specific compound: 100 mmol / L • Alcohol compound: 684 mmol / L • Electron mediator: 10 mmol / L

[0087] (Ammonia Production Test) The following ammonia production test was performed on the mixture (100 mL) obtained above. The mixture (100 mL) was placed in a quartz reaction vessel (volume: 200 mL), and nitrogen gas was supplied after degassing. The nitrogen gas was supplied so that the pressure inside the reaction vessel was 60 Torr. After supplying nitrogen gas to the reaction vessel, the temperature was set to 30°C and the pressure to 100 mW / cm². ２ Under these conditions, the mixture was irradiated with light (light source: solar simulator, Yamashita Densou, YSS-80A). Hydrogen (H) generated while the mixture was irradiated with light was analyzed. ２ ) production amount and nitrogen (N ２ The consumption of ) was measured using an online connected TCD type gas chromatograph. The amount of ammonia produced was measured using an ion chromatograph (Dionex, USA) to obtain ammonium cations (NH₄). ４ ＋ The amount of ) produced was measured. The results 25 hours after the start of light irradiation are shown in Table 1.

[0088] <Example 2> An ammonia production test was carried out in the same manner as in Example 1, except that nitrogen gas was supplied to the reaction vessel so that the pressure inside the reaction vessel was 200 Torr. The results 25 hours after the start of light irradiation are shown in Table 1.

[0089] <Example 3> An ammonia production test was carried out in the same manner as in Example 1, except that nitrogen gas was supplied to the reaction vessel so that the pressure inside the reaction vessel was 380 Torr. The results 25 hours after the start of light irradiation are shown in Table 1.

[0090] <Example 4> An ammonia production test was carried out in the same manner as in Example 1, except that nitrogen gas was supplied to the reaction vessel so that the pressure inside the reaction vessel was 380 Torr. The results 72 hours after the start of light irradiation are shown in Table 1.

[0091] <Example 5> 3 mg / L sodium nitrate (NaNO) ３ A mixture was obtained in the same manner as in Example 1, except that the following was added. Using this mixture (100 mL), an ammonia production test was carried out in the same manner as in Example 1, except that nitrogen gas was supplied to the reaction vessel so that the pressure inside the reaction vessel was 380 Torr. The results 72 hours after the start of light irradiation are shown in Table 1.

[0092] <Example 6> A mixture was obtained in the same manner as in Example 1, except that glycerol was not used. An ammonia production test was carried out in the same manner as in Example 3, except that this mixture (100 mL) was used. The results 25 hours after the start of light irradiation are shown in Table 1.

[0093] <Example 7> A mixture was obtained in the same manner as in Example 1, except that glycerol was not used. An ammonia production test was carried out in the same manner as in Example 4, except that this mixture (100 mL) was used. The results 72 hours after the start of light irradiation are shown in Table 1.

[0094] <Example 8> In Preparation Example 1, cells recovered from the culture medium were resuspended in water (50 mL) containing 100 mmol / L of an alcohol compound (glycerol) to obtain a suspension. In this suspension, a compound semiconductor with a particle size of 140 nm and a specific surface area of ​​53 m² was added. ２ TiO / g ２ A mixture (100 mL, pH 7.5) was prepared by adding particles, glycerol as an alcohol compound, methyl viologen dichloride as an electron mediator, and water. The ammonia production test was carried out in the same manner as in Example 3, except that this mixture (100 mL) was used. The results 25 hours after the start of light irradiation are shown in Table 1.

[0095] The content of each component in the mixture is as follows. The ratio of the mass of the compound semiconductor to the mass of azotobacter (compound semiconductor / azotobacter) is 0.05. • Azotobacter: 50 g / L • Compound semiconductor: 2500 mg / L • Alcohol compound: 100 mmol / L • Electron mediator: 10 mmol / L

[0096] <Example 9> An ammonia generation test was carried out in the same manner as in Example 4, except that the mixture (100 mL) obtained in Example 8 was used. The results 72 hours after the start of light irradiation are shown in Table 1.

[0097] <Example 10> 10 mg / L sodium nitrate (NaNO) ３ A mixture was obtained in the same manner as in Example 1, except that the following was added. Using this mixture (100 mL), an ammonia production test was carried out in the same manner as in Example 1, except that nitrogen gas was supplied to the reaction vessel so that the pressure inside the reaction vessel was 380 Torr. The results 72 hours after the start of light irradiation are shown in Table 1.

[0098] (Preparation Example 2: Preparation of Cyanobacteria) Cyanobacteria were cultured by shaking under conditions of 5,000 Lux of light irradiation, 26°C, and 140 rpm. AA+Mo medium was used as the culture medium. For the AA+Mo medium, 20 μ mmol of sodium molybdate dihydrate was added to 100 mL of Allen & Arnon medium. Two weeks after the start of culture, the medium was centrifuged (10,000 G, 5 minutes) to collect pellet-like cells. The collected cells were resuspended in water (50 mL) containing 100 mmol / L of a specific compound (HEPES) to obtain a suspension.

[0099] The Fe and Mo content of cyanobacteria in the suspension was measured by ICP emission spectrometry (measurement equipment: ICP-OES, PerkinElmer, Optima 5300DV). The results showed that the Fe content was 1.25 mmol / g cell mass and the Mo content was 0.03 μmol / g cell mass. The Mo content of the cyanobacteria was significantly higher than that of the cyanobacteria before culture, suggesting an increase in Fe-Mo type nitrogenase.

[0100] <Comparative Example 1> To the cyanobacteria suspension obtained in Preparation Example 2, a compound semiconductor with a particle size of 140 nm and a specific surface area of ​​53 m² was added. ２ TiO / g ２ A mixture (100 mL, pH 7.5) was prepared by adding particles, HEPES as a specific compound, glycerol as an alcohol compound, methyl viologen dichloride as an electron mediator, and water. An ammonia production test similar to that in Example 1 was performed on this mixture (100 mL). The results 25 hours after the start of light irradiation are shown in Table 1.

[0101] The content of each component in the mixture is as follows. The ratio of the mass of compound semiconductor to the mass of cyanobacteria (compound semiconductor / cyanobacteria) is 0.05. • Cyanobacteria: 50 g / L • Compound semiconductor: 2500 mg / L • Specific compound: 100 mmol / L • Alcohol compound: 684 mmol / L • Electron mediator: 10 mmol / L

[0102] <Comparative Example 2> The ammonia production test was carried out in the same manner as in Comparative Example 1, except that nitrogen gas was supplied to the reaction vessel so that the pressure inside the reaction vessel was 200 Torr. The results 25 hours after the start of light irradiation are shown in Table 1.

[0103] <Comparative Example 3> The ammonia production test was carried out in the same manner as in Comparative Example 1, except that nitrogen gas was supplied to the reaction vessel so that the pressure inside the reaction vessel was 380 Torr. The results 25 hours after the start of light irradiation are shown in Table 1.

[0104]

[0105] As shown in the results in Table 1, the example using a mixture containing Azotobacter as a nitrogen-fixing bacterium produced a larger amount of ammonia and demonstrated superior ammonia production efficiency compared to the comparative example using a mixture containing cyanobacteria as a nitrogen-fixing bacterium. Furthermore, as shown in the results of Examples 1 to 3, changing the pressure of the nitrogen gas supplied to the reaction vessel containing the Azotobacter mixture tends to change the amount of ammonia produced. In contrast, as shown in the results of Comparative Examples 1 to 3, changing the pressure of the nitrogen gas supplied to the reaction vessel containing the cyanobacteria mixture does not significantly change the amount of ammonia produced. These results suggest that controlling the pressure of the nitrogen-containing gas is effective in increasing the ammonia production efficiency in a method of producing ammonia using a mixture containing Azotobacter.

[0106] The disclosure of Japanese Patent Application No. 2025-056976 is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted to be incorporated by reference.

Claims

1. A mixture containing azotobacter, a compound semiconductor, and water.

2. The mixture according to claim 1, further comprising a compound having a cyclic group containing a heteroatom and a functional group selected from the group consisting of a carboxyl group, a phosphate group and a sulfone group.

3. The mixture according to claim 1 or claim 2, further comprising an alcohol compound.

4. The mixture according to claim 1 or claim 2, further comprising a nitrate.

5. The mixture according to claim 2, wherein the compound comprises a compound represented by the following general formula (1). [In the general formula (1), each R is independently a hydrogen atom or a monovalent group that does not contain a functional group selected from the group consisting of a carboxyl group, a phosphate group and a sulfone group, X is a functional group selected from the group consisting of a carboxyl group, a phosphate group and a sulfone group, Y is a cyclic group containing a hetero atom, Z is an oxygen atom or a sulfur atom, and n and m are each independently an integer of 1 to 3.]] 6. The mixture according to claim 5, wherein in general formula (1), Y is a cyclic group represented by the following general formula (2). [In general formula (2), R is a monovalent group that does not contain a hydrogen atom or a functional group selected from the group consisting of a carboxyl group, a phosphate group, and a sulfone group, independently of each other.] 7. The mixture according to claim 1 or claim 2, wherein the compound semiconductor comprises titanium oxide.

8. The mixture according to claim 1 or claim 2, wherein the mixture further comprises an electron mediator.

9. The mixture according to claim 1 or claim 2, wherein the Mo content of the azotobacter is 0.30 μmol / g cell mass or more.

10. The mixture according to claim 2, wherein the content of the compound in the mixture is 10 mmol / L or more.

11. The mixture according to claim 3, wherein the alcohol compound comprises a trivalent alcohol.

12. The mixture according to claim 1 or claim 2, wherein the ratio of the mass of the compound semiconductor to the mass of the azotobacter in the mixture (compound semiconductor / azotobacter) is 0.01 to 0.

25.

13. The mixture according to claim 2, wherein the ratio of the mass of the compound to the mass of the azotobacter in the mixture (compound / azotobacter) is 0.1 to 10.

0.

14. The mixture according to claim 1 or claim 2, for use in the production of ammonia.

15. An ammonia production system comprising: a containment section for containing a mixture comprising azotobacter, a compound semiconductor, and water, and a gas containing nitrogen; a light irradiation section for irradiating the mixture with light; and a pressure control section for controlling the pressure of the gas in the containment section.

16. A method for producing ammonia, comprising irradiating a mixture with light in the presence of nitrogen, wherein the mixture comprises azotobacter, a compound semiconductor, and water.

17. The method for producing ammonia according to claim 16, wherein the mixture is contained in a containment chamber together with a gas containing nitrogen, and the pressure of the gas in the containment chamber is further controlled.

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