Method for producing ammonia nitrogen

Abstract

The present invention relates to a method for producing ammonia nitrogen by supplying dinitrogen (N2) to an electrochemical cell, the electrochemical cell comprising at least one working electrode and at least one counter electrode immersed in a composition maintained under stirring, the composition containing at least one compound (I) comprising at least one element of group 13 of the periodic table. The present invention also relates to an electrochemical cell for reducing dinitrogen to ammonia nitrogen.

Description

Technical Field

[0001] The present invention relates to a method for producing ammonia nitrogen by supplying dinitrogen (N2) to an electrochemical cell, the method comprising at least one working electrode immersed in a composition comprising at least one compound (I) containing at least one element of Group 13 of the periodic table, and at least one counter electrode, and also relates to an electrochemical cell for reducing dinitrogen to ammonia nitrogen.

Background Art

[0002] Nitrogen (N) plays an important role in the composition of living organisms. In particular, it is a main component of amino acids, proteins including enzymes, and nucleic acids that make up DNA and RNA. It is also an essential nutrient for the growth of crops. However, although nitrogen is very abundant on the earth's surface (there is more nitrogen in the biosphere, hydrosphere, and atmosphere than the combined amount of carbon, hydrogen, and phosphorus), it basically exists as a very stable gaseous form known as dinitrogen (N2). Therefore, even though it is so abundant, humans can only benefit very little from it. Only microorganisms such as rhizobia involved in symbiotic nitrogen fixation by leguminous plants can utilize this form of nitrogen, convert it into ammonia nitrogen, and then into organic nitrogen, from which other organisms can utilize it and convert it into other forms of reactive nitrogen.

[0003] Ammonia, which is reactive nitrogen, is an important molecule mainly used in the agricultural field and also has the ability to store energy (especially hydrogen). Liquid ammonia can also be used as a fuel to replace fossil-derived liquefied petroleum gas (LPG).

[0004] Until the 19th century, ammonia was produced by distilling liquid manure or extracting it from domestic sewage. Since the latter half of the 19th century, it has been obtained as a by-product of the manufactured gas (town gas) industry. Large-scale industrial production of ammonia by the Haber-Bosch process began in the early 20th century (1909 - 1913). In this method, ammonia can be synthesized on an industrial scale from dinitrogen and dihydrogen (H2) in the presence of a solid iron-based catalyst. The ammonia production by this method is about 200 million tons per year, exceeding symbiotic fixation on a global scale since the end of the 20th century and is still in use. However, in this Haber-Bosch process, high pressures and high temperatures such as 100 - 300 bar and 300 - 550 °C are used, consuming extremely large amounts of energy, requiring centralized and safe production, and having the drawbacks of high operating costs and transportation costs. Furthermore, such a method generates a very large amount of carbon dioxide (about 1.5% of the world's CO2 production), causes environmental problems, and still has a low yield (20%).

[0005] In view of the increasing demand for ammonia and the environmental problems associated with the industrial production of ammonia, other methods, particularly methods using more efficient catalysts to reduce the required temperature and pressure, have been proposed. In particular, U.S. Patent No. 6,037,459 describes a method comprising a first step of contacting dinitrogen with a compound having the formula M(NR1R2)3 (wherein M is a transition metal (e.g., molybdenum), and R1 and R2 are selected from tertiary alkyl groups, phenyl groups, and substituted phenyl groups) to form a metal complex having a nitride ligand, and a second step of reducing the complex in the presence of a hydrogen source to produce ammonia. This method is carried out under normal temperature and pressure conditions. U.S. Patent No. 6,037,459 only describes the yield of N≡N triple bond cleavage, and the production of ammonia (the second step) is not shown.

[0006] Alternative methods based on biocatalysts, photocatalysts, or electrocatalysts have also been described. In particular, Li et al. [Adv. Mater., 2017, 29, 1700001, 1 - 6] have described graphite oxide and reduced cerium dioxide CeO x-Proposed is the use of an electrode material containing amorphous gold nanoparticles supported on RGO. The method of Li et al. uses an electrochemical cell that is continuously supplied by a stream of dinitrogen, said cell comprising a saturated Ag / AgCl / KCl reference electrode, a platinum counter electrode, a working electrode consisting of said electrode material deposited on carbon paper, a pretreated Nafion211® membrane, and an electrolyte consisting of dilute hydrochloric acid. Said electrode material is used as a cathode electrode catalyst. Thereby, it functions as a reducing agent for N2, and as a result, N2 reacts with H + protons on the surface of said material to produce NH3. Applying a potential to said material is a means of reducing the activation barrier of the N2 reduction reaction (NRR). However, the yield is still low and the raw materials (noble metals such as gold and ruthenium) are rare and extremely expensive. Furthermore, the reduction of dinitrogen competes with the reduction of protons (H + ) to dihydrogen H2.

Summary of the Invention

Problems to be Solved by the Invention

[0007] Accordingly, an object of the present invention is to solve the drawbacks of the prior art, and in particular, to provide a simple, economical, and easy-to-implement method for producing ammonia nitrogen that preferably uses recyclable and abundant raw materials, reduces carbon emissions, and is carried out under relatively mild reaction conditions.

Means for Solving the Problems

[0008] A first object of the present invention is A method for producing ammonia nitrogen, wherein said ammonia nitrogen is selected from ammonium (NH4 + ), ammonia (NH3), and mixtures thereof, and comprising at least the following steps: i) A step of supplying dinitrogen (N2) to an electrochemical cell, said electrochemical cell comprising at least one working electrode and at least one counter electrode immersed in a composition maintained under stirring, said composition comprising at least one electrolyte solution and the following formula (I): R 1 R 2comprising at least one compound satisfying MY(I), wherein - M is an element of Group 13 of the periodic table, - R 1 and R 2 are the same or different and are selected from an alkyl group, an aryl group, an arylalkyl group, an -OR group, and an -SR group, R is an alkyl group, an aryl group, or an arylalkyl group, and - Y is a group selected from a halogen -X, -OR 3 group, -SR 3 group, a triflate group, a mesylate group, and a triflimidate group, and R 3 is an alkyl group, an aryl group, or an arylalkyl group step, ii) a step of applying a potential difference between the working electrode and the counter electrode, or a step of applying a potential or a current to the working electrode, and iii) a step of acid - hydrolyzing the composition characterized by comprising.

[0009] The method of the present invention is simple, easy to implement, economical, and enables the obtaining of ammonia - like nitrogen under relatively mild reaction conditions. In particular, by using the compound of formula (I) defined above in a reducing medium (i.e., by the supply of electrons from the working electrode), the activation of the triple bond of dinitrogen and the formation of an intermediate species that leads to ammonia - like nitrogen by hydrolysis are made possible. Finally, importantly, this method is industrially feasible, uses renewable and abundant raw materials, and can reduce the environmental impact.

[0010] Step i) The compound of formula (I) R 1 R 2 MY According to the present invention, boron is particularly preferred as the element M.

[0011] R 1 group and R 2 group The compound of formula (I) R 1 R 2The compound of MY is not a radical compound.

[0012] In the compound of formula (I), R 1 forms a single covalent bond with element M, and R 2 forms a single covalent bond with element M.

[0013] R 1 and R 2 are the same or different and are selected from an alkyl group, an aryl group, an arylalkyl group, an -OR group, and an -SR group, and R is an alkyl group, an aryl group, or an arylalkyl group.

[0014] R 1 group and / or R 2 The alkyl group as a group can be linear or branched, cyclic or acyclic. The alkyl group can contain 1 to 14 carbon atoms, preferably 2 to 10 carbon atoms. The alkyl group is preferably selected from ethyl, propyl, isopropyl, cyclohexyl, bicyclo[2.2.1]-2-heptyl, and isopinocampheyl. Among such groups, any one of cyclohexyl, bicyclo[2.2.1]-2-heptyl, or isopinocampheyl is particularly preferred.

[0015] R 1 group and / or R 2 The alkyl group as a group contains one or more heteroatoms such as an oxygen atom or a sulfur atom under the condition that one carbon atom of the alkyl group is directly bonded to element M of formula (I) and any heteroatom(s) present in the alkyl group are not directly covalently bonded to another heteroatom.

[0016] R 1 group and / or R 2The aryl group as the base may be substituted or unsubstituted. The aryl group may contain 6 to 30 carbon atoms, preferably 6 to 18 carbon atoms. The aryl group is preferably selected from a phenyl group, a -C6F5 group, a 2,4,6-(Me)3-C6H2 group, and a 2,4,6-(iPr)3-C6H2 group. Among such groups, either the 2,4,6-(Me)3-C6H2 group or the 2,4,6-(iPr)3-C6H2 group is particularly preferred.

[0017] R 1 group and / or R 2 When the aryl group as the base is particularly substituted (i.e., in the substituents of the aryl group), it may contain one or more heteroatoms such as an oxygen atom or a nitrogen atom, and it is understood that the carbon atoms of the aryl group are directly bonded to the element M of formula (I).

[0018] R 1 group and / or R 2 The arylalkyl group as the base is a group containing at least one alkyl group and at least one aryl group directly bonded by a carbon-carbon covalent bond (of the aryl group) or via an oxygen atom or a nitrogen atom, and the aryl group and the alkyl group are R 1 group and R 2 as defined above for the group. The alkylaryl group may be directly bonded to the element M of formula (I) via the carbon atom of the aryl group or via the carbon atom of the alkyl group.

[0019] The R alkyl group of the -OR group or -SR group may be linear or branched, cyclic or acyclic. The R alkyl group may contain 1 to 10 carbon atoms, preferably 1 to 4 carbon atoms.

[0020] The R aryl group of the -OR group or -SR group may be substituted or unsubstituted. The R aryl group may contain 6 to 30 carbon atoms, preferably 6 to 18 carbon atoms. The R aryl group is preferably selected from a phenyl group, a naphthyl group, an anthracenyl group, or a pyrenyl group.

[0021] The R arylalkyl group of the -OR group or -SR group is a group containing at least one alkyl group and at least one aryl group directly bonded by a carbon-carbon bond (of the aryl group) or via an oxygen atom or a sulfur atom, and the aryl group and the alkyl group are as defined above for the R group.

[0022] R 1 group and R 2 group may, in particular via a carbon-carbon bond, be covalently bonded to form a divalent group, and the said R 1 group and R 2 group are as defined above. In this embodiment, the divalent group does not form a planar ring with the element M.

[0023] For example, the divalent group may be an alkyl group (i.e., R 1 and R 2 are alkyl groups), preferably a 9-bicyclo[3.3.1]nonane group.

[0024] According to one embodiment of the present invention, R 1 and R 2 may be the same or different and are selected from an alkyl group, an aryl group, and an arylalkyl group.

[0025] According to a preferred embodiment of the present invention, at least one of the R 1 group and the R 2 group is an alkyl group, and more preferably, both the R 1 group and the R 2 group are alkyl groups.

[0026] According to a particularly preferred embodiment of the present invention, R 1 and R 2 are the same.

[0027] The R 1 group and the R 2 group of the compound (I) are non-stabilizing groups. That is, these functions are the radicals R 1 R 2Rather than stabilizing M°, it is to enhance the reactivity with respect to dinitrogen N2 as a result.

[0028] Y group Y is a group selected from halogen -X, -OR 3 group, -SR 3 group, triflate group (-OSO2CF3), mesylate group (-OSO2CH3), and triflimidate group (NTf2 or N(SO2CF3)2), and R 3 is an alkyl group, an aryl group, or an arylalkyl group.

[0029] X is preferably a chlorine atom or a bromine atom, and particularly preferably a chlorine atom.

[0030] R 3 The alkyl group can be linear or branched, cyclic or acyclic. R 3 The alkyl group can contain 1 to 10 carbon atoms, preferably 1 to 4 carbon atoms.

[0031] R 3 The aryl group can be substituted or unsubstituted. R 3 The aryl group can contain 6 to 30 carbon atoms, preferably 6 to 18 carbon atoms. R 3 The aryl group is preferably selected from phenyl, 2,4,6-(Me)3-C6H2, 2,4,6-(iPr)3-C6H2, and naphthyl.

[0032] R 3 The arylalkyl group is a group containing at least one alkyl group and at least one aryl group directly bonded by a carbon - carbon covalent bond of (the aryl group) or via an oxygen atom or a sulfur atom, and the aryl group and the alkyl group are as defined above for the R 3 group.

[0033] Y is preferably halogen X.

[0034] The Y group of the compound (I) is a nucleophilic group. That is, its function is to promote the formation of the radical R 1 R 2 M°.

[0035] According to a particularly preferred embodiment of the present invention, the compound of formula (I) is selected from dialkylchloroborane, dialkylbromoborane, dialkylchloroaluminum compounds, and dialkylbromoaluminum compounds, such as diisopinocampheylborane halide, dicyclohexylborane or bis(bicyclo[2.2.1]-2-heptyl)borane, or haloboranes based on 9-borabicyclo[3.3.1]nonane.

[0036] The compound of formula (I) has the advantage of being readily available commercially or being easily synthesizable.

[0037] The compound of formula (I) has the characteristics of a Lewis acid, that is, a chemical substance in which one of the constituent atoms has an electron gap.

[0038] Working electrode The working electrode preferably comprises (or preferably consists of) at least one inert conductive material.

[0039] The inert conductive material can be selected from carbon, platinum, stainless steel, and metal oxides.

[0040] The carbon can be vitreous carbon, pyrolytic carbon, or diamond doped with, for example, boron or sulfur.

[0041] The conductive material is preferably in the form of a porous material such as a foam (e.g., carbon foam), felt, net, or fabric.

[0042] When the conductive material is a metal oxide, it can be transparent.

[0043] Indium tin oxide is a metal oxide that can be used as the conductive material.

[0044] In the present invention, the term "inert conductive material" means that the conductive material does not chemically react with various elements present in the electrochemical cell.

[0045] Preferably, the inert conductive material of the working electrode has a specific surface area measured by the BET method of at least 0.1 m 2 / g, particularly preferably at least 100 m 2 / g. Thereby, the contact surface between the working electrode and the composition, particularly between the working electrode and the compound of formula (I), is optimized.

[0046] During step i), the working electrode is completely or partially immersed in the composition. This promotes the contact between the working electrode and the compound of formula (I), and thus a large exchange surface area is obtained.

[0047] Counter electrode The counter electrode preferably comprises (or preferably consists of) at least one inert conductive material.

[0048] The inert conductive material can be selected from carbon, platinum, stainless steel, and metal oxides.

[0049] The carbon can be graphite, pyrolytic carbon, or diamond doped with, for example, boron or sulfur.

[0050] The conductive material can be in the form of a porous material such as a foam (e.g., carbon foam), felt, net, or fabric.

[0051] When the conductive material is a metal oxide, it can be transparent.

[0052] Indium tin oxide is an example of a metal oxide that can be used as the conductive material.

[0053] Preferably, the inert conductive material of the counter electrode has a specific surface area measured by the BET method of at least 0.1 m 2 / g, particularly preferably at least 100 m2 It is / g. This makes it possible to optimize the exchange surface between the counter electrode and the electrolyte solution (multiple compartments) or the composition (one single compartment).

[0054] The counter electrode is preferably completely or partially immersed in the electrolyte solution.

[0055] The electrolyte solution can be that of the composition. In this embodiment, in step i), the counter electrode is completely or partially immersed in the composition. This promotes the contact between the counter electrode and the composition and a large exchange surface is obtained.

[0056] The electrolyte solution of the composition The electrolyte solution conducts an electric current through the electrochemical cell.

[0057] The electrolyte solution can contain (or consist of) a combination of an organic solvent and a salt, or an ionic liquid.

[0058] Ionic liquids are well known to those skilled in the art and can be regarded as molten salts at room temperature (e.g., 18 - 25 °C). Ionic liquids have an organic cation component and function as solvents in the present invention in the same way as conventional organic solvents.

[0059] In the present invention, the organic solvent shall mean a conventional organic solvent, i.e., one that does not contain a salt or is not in the form of a salt.

[0060] The organic solvent is preferably selected from aprotic organic solvents, in particular, ethers, carbonates, nitriles, amides, and phosphoramides, such as THF (tetrahydrofuran), methyl THF, N,N'-dimethylformamide, acetonitrile, benzonitrile, hexamethylphosphoramide, or propylene carbonate.

[0061] The salt is preferably soluble in the organic solvent at a concentration of at least about 0.1 mol / L, for example, in the range of about 0.1 - 0.5 mol / L.

[0062] The salt is preferably an inert salt.

[0063] In the present invention, the term "inert salt" means that the salt does not chemically react with various elements present in the electrochemical cell and is not reduced at the working electrode, particularly within the operating potential range of the electrochemical cell.

[0064] The salt can be selected from alkali metal salts and quaternary ammonium salts, preferably from quaternary ammonium salts.

[0065] Examples of alkali metal salts include lithium salts such as LiTFSI, LiPF6, or LiClO4.

[0066] Examples of quaternary ammonium salts include tetraalkylammonium salts such as tetra-n-butylammonium bis(trifluoromethanesulfonyl)imide (TBATFSI), tetra-n-ethylammonium perchlorate, tetra-n-butylammonium hexafluorophosphate, or tetra-n-propylammonium tetrafluoroborate.

[0067] The ionic liquid can be selected from ammonium salts, imidazolium salts, phosphonium salts, pyrrolidinium salts, and piperidinium salts, preferably from alkylammonium salts, alkylimidazolium salts, alkylphosphonium salts, alkylpyrrolidinium salts, and alkylpiperidinium salts.

[0068] The ionic liquid preferably contains an anion part of the bis(trifluoromethanesulfonyl)imide type.

[0069] Examples of ionic liquids include triethylbutylammonium bis(trifluoromethanesulfonyl)imide, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, trimethylbutylammonium bis(trifluoromethanesulfonyl)imide, 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide, N-propyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide, or 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.

[0070] The ionic liquid is preferably immiscible with water. This facilitates subsequent purification.

[0071] Reference electrode The electrochemical cell may be provided with a reference electrode. This can be used to control the potential of the working electrode and limit the resistance drop (ohmic drop).

[0072] The reference electrode can be selected from a saturated silver nitrate electrode Ag / AgNO3, a saturated calomel electrode (SCE), or a silver chloride electrode Ag / AgCl.

[0073] The reference electrode is preferably completely or partially immersed in the electrolyte solution.

[0074] The electrolyte solution may be that of the composition. In this embodiment, in step i), the counter electrode is completely or partially immersed in the composition.

[0075] In step i), a composition containing the compound of formula (I) and the electrolyte solution is contacted with dinitrogen (N2).

[0076] During step i), dinitrogen is preferably supplied to the electrochemical cell in a continuous flow. Preferably, dinitrogen is supplied to the electrochemical cell by bubbling dinitrogen into the composition of the electrochemical cell.

[0077] Step i) is preferably carried out in a dry or anhydrous medium. That is, step i) is preferably carried out in a glove box or in a suitable apparatus so that the composition is not in contact with air and / or moisture.

[0078] Upon contact with moisture and / or air, H2 and / or R 1 R 2 MOMR 1 R 2 and other by-products are formed.

[0079] The dinitrogen supplied to the electrochemical cell is preferably dry dinitrogen.

[0080] To protect the reaction medium from moisture and / or air, the electrochemical cell is preferably sealed.

[0081] Step i) can continue for about 0.5 to 20 hours, preferably about 2 to 12 hours.

[0082] Step i) is preferably carried out at a temperature in the range of -80 to about 60 °C, particularly preferably 0 to about 30 °C.

[0083] In step i), the composition is kept under stirring, for example, by using a mechanical or magnetic stirrer, or by using a flow or circulation electrochemical cell, or by bubbling only dinitrogen into the composition in the electrochemical cell. Stirring promotes the contact between the composition, dinitrogen and the electrodes, thereby promoting the reaction in step ii).

[0084] Step i) can be carried out at a pressure in the range of about 1 to 200 bar, preferably 1 to 100 bar. Industrially, a pressure of 1 bar is advantageous.

[0085] Step i) is preferably carried out at atmospheric pressure.

[0086] The compound of formula (I) has a molar concentration in the composition of about 10 -5 ~10 -1 mol / L, preferably about 10-3 ~10 -2 can be in the range of mol / L.

[0087] Step ii) Step ii) includes applying a potential or current to the working electrode, or applying a potential difference between the working electrode and the counter electrode.

[0088] The applied potential, potential difference, or current must be sufficient to reduce the compound (I) to the radical R 1 R 2 to M°. The range of the potential value or current value can vary depending on the type of working electrode used, temperature, R 1 and / or R 2 and the properties of the electrolyte solution, etc.

[0089] The potential difference applied between the working electrode and the counter electrode can be in the range of about 2 - 50 V, preferably about 3 - 20 V.

[0090] This method of applying a potential difference between the working electrode and the counter electrode is particularly suitable when the electrochemical cell does not have a reference electrode.

[0091] The potential applied to the working electrode can preferably be in the range of about -4 to -1 V, preferably about -3 to -2 V, with respect to the saturated silver nitrate Ag / AgNO3 reference electrode.

[0092] This method of applying a potential to the working electrode is particularly suitable when the electrochemical cell has a reference electrode.

[0093] The current applied to the working electrode can be in the range of about 0.01 - 10 A, preferably about 0.5 - 1 A.

[0094] The working electrode and the counter electrode are electrically connected to a voltage source or a current source.

[0095] In step ii), the working electrode functions as an electron donor. When electrons come into contact with compound (I), they are directly released into the solution. In that case, the working electrode is used for the reduction of compound (I), and then compound (I) reacts with dinitrogen to form one or more chemical species based on nitrogen and element M, in particular the following formula (II): N(MR 1 R 2 ) 3-x H x (x is an integer from 0 to 3). Therefore, the working electrode is not involved in the chemical process of dinitrogen reduction itself.

[0096] The formation of one or more chemical species based on nitrogen and element M defined above can be explained, in particular, by the implementation of a radical chain reaction involving one or more radicals based on element M that react with nitrogen in dinitrogen because they are unstable.

[0097] Compound (I), due to its formula (I), and thus the definitions of Y, M, R 1 , and R 2 , has the ability to activate the triple bond of dinitrogen in the reducing medium and minimize or avoid the dimerization of the radical R 1 R 2 M°.

[0098] Therefore, step ii) performs the electrochemical reduction of compound (I), which is completely different from the prior art electrochemical methods that perform surface treatment where the working electrode serves both as an electron donor and a catalyst.

[0099] Step ii) can be carried out under constant potential or constant current conditions.

[0100] According to a particularly preferred embodiment of the present invention, steps i) and ii) are carried out simultaneously. That is, dinitrogen is supplied to the electrochemical cell simultaneously while applying a potential, potential difference, or current.

[0101] The electrochemical cell used in step i) may comprise a single compartment containing the composition, electrodes, and dinitrogen as defined in the present invention, and in particular may comprise two compartments C1 and C2, especially for separating the counter electrode from the working electrode. Thereby, the diffusion phenomenon between the two electrodes is avoided. Alternatively, it may comprise three compartments C1, C2, and C3, and while ensuring electrical contact between compartments C1 and C2, the counter electrode may also be insulated from the working electrode.

[0102] An electrochemical cell comprising two compartments C1 and C2 preferably - Compartment C1 containing the composition as defined in the present invention, the working electrode (entirely or partially) immersed in said composition, and the reference electrode (entirely or partially) immersed in said composition if a reference electrode is present, - Compartment C2 containing the counter electrode (entirely or partially) immersed in the electrolyte solution, and - A membrane separating the two compartments C1 and C2 is provided.

[0103] The membrane can be a sintered glass, an ion exchange membrane such as a cationic membrane (e.g., Nafion®), or a polymer material such as a fluorinated organic polymer material.

[0104] The electrolyte solution in compartment C2 can contain (or consist of) a combination of an organic solvent and a salt, or an ionic liquid.

[0105] The organic solvent is preferably selected from aprotic organic solvents, and in particular from ethers, carbonates, nitriles, amides, and phosphoramides such as THF (tetrahydrofuran), methyl THF, N,N´-dimethylformamide, acetonitrile, benzonitrile, hexamethylphosphoramide, or propylene carbonate.

[0106] The electrolyte solution in compartment C2 may further contain oxidizable species, especially for preventing the oxidation of the organic solvent in compartment C1.

[0107] The oxidizable species can preferably be selected from ferrocene, tetrathiafulvalene, or tetrathiafulvalene derivatives.

[0108] The salt is preferably soluble in an organic solvent at a concentration of at least about 0.1 mol / L, for example, in the range of about 0.1 to 0.5 mol / L.

[0109] The salt is preferably an inert salt.

[0110] The salt can be selected from alkali metal salts and quaternary ammonium salts, preferably from quaternary ammonium salts.

[0111] Examples of alkali metal salts include lithium salts such as LiTFSI, LiPF6, or LiClO4.

[0112] Examples of quaternary ammonium salts include tetraalkylammonium salts such as TBATFSI, tetra-n-ethylammonium perchlorate, tetra-n-butylammonium hexafluorophosphate, or tetra-n-propylammonium tetrafluoroborate.

[0113] The ionic liquid can be selected from ammonium salts, imidazolium salts, phosphonium salts, pyrrolidinium salts, and piperidinium salts, preferably from alkylammonium salts, alkylimidazolium salts, alkylphosphonium salts, alkylpyrrolidinium salts, and alkylpiperidinium salts.

[0114] The ionic liquid preferably contains an anion part of the bis(trifluoromethanesulfonyl)imidate type.

[0115] Examples of the ionic liquid include triethylbutylammonium bis(trifluoromethanesulfonyl)imide, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, trimethylbutylammonium bis(trifluoromethanesulfonyl)imide, 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide, N-propyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide, or 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.

[0116] The ionic liquid is preferably immiscible with water. This facilitates subsequent purification.

[0117] Compartment C2 does not contain compound (I).

[0118] The electrolyte solution (each salt) in compartment C2 can be the same as the electrolyte solution (each salt) in compartment C1.

[0119] Step iii) At the end of step ii), a chemical species based on nitrogen and element M is present in the composition, and then in step iii) this is hydrolyzed in an acidic medium to form ammoniacal nitrogen.

[0120] In the present invention, ammoniacal nitrogen refers to two of the most reduced forms of nitrogen, namely ammonium (NH4 + ) and ammonia (NH3). Thus, ammoniacal nitrogen is selected from ammonium (NH4 + ), ammonia (NH3), and mixtures thereof. Generally, depending on the conditions of step iii), especially the amount of acid, ammonium (excess acid) or ammonia (N(MR 1 R 2 ) 3-x H x stoichiometric amount relative to) is obtained.

[0121] The hydrolysis in step (iii) in an acidic medium can be carried out by bringing the crude reaction product obtained in the preceding step (ii) into contact with an acid solution or a (gaseous) gaseous acid.

[0122] The acid solution may contain an aqueous solvent (such as water) and at least one acid such as hydrochloric acid, hydrobromic acid, sulfuric acid, or nitric acid, or an aprotic organic solvent and at least one acid such as hydrochloric acid, hydrobromic acid, sulfuric acid, or nitric acid.

[0123] The aprotic organic solvent may be selected from ethers such as diethyl ether or dioxane, and alkanes such as hexane or heptane.

[0124] The acidic gas may be hydrochloric acid gas.

[0125] In step (iii), when an acid is used in excess, particularly with respect to the compound of formula (I), ammonium is advantageously generated.

[0126] The aqueous solvent is preferably water.

[0127] The pH of the acid solution can be in the range of 0 to 6.

[0128] Step (iii) can continue for about 1 to 30 minutes, preferably about 2 to 10 minutes. Step (iii) is very rapid and is almost an instantaneous step.

[0129] Step (iii) is preferably carried out at a temperature in the range of -20 to about 40 °C, particularly preferably 0 to about 20 °C.

[0130] Step (iii) is preferably carried out with stirring.

[0131] Step (iii) is preferably carried out at atmospheric pressure.

[0132] In step (iii), ammonia NH3 and / or ammonium NH4 + is generated.

[0133] In step iii), the reaction crude product obtained in the preceding step ii) is brought into contact with an acid solution by adding the acid solution to the composition.

[0134] Other steps of the method The procedure may further include step ii-1) of stopping the current or potential applied to the working electrode, or the potential difference applied between the working electrode and the counter electrode, after step ii) and before step iii).

[0135] After step ii) or ii-1) and before step iii), the method may further include a purification step ii-2). In step ii-2), at least a part of any by-products (e.g., salts) formed during step ii) is removed. That is, in step ii-2), the chemical species based on nitrogen and element M formed in step ii) are separated from the salt.

[0136] Step ii-2) can be carried out by extracting the reaction mixture formed in step ii) or ii-1) using a non-polar organic solvent in particular. The chemical species based on nitrogen and element M formed in step ii) or ii-1) are soluble in the non-polar organic solvent and can be separated from the salt by filtration.

[0137] The non-polar organic solvent can be selected from alkanes such as hexane, pentane, or heptane.

[0138] A preferred non-polar organic solvent is pentane.

[0139] The method may further include step i-0) of preparing the compound of formula (I) before step i).

[0140] The compound of formula (I) can be prepared according to the procedures of double hydroboration or hydroalumination described in the following papers: H.C. Brown, N. Ravindran, J. Am. Chem. Soc. 1976, 98, 1798 - 1806, and H.C. Brown, N. Ravindran, J. Am. Chem. Soc. 1976, 98, 1785 - 1798, or by the reaction of 2 equivalents of an alkene and 1 equivalent of a monohalogenoborane (e.g., having the formula YBH2, where Y is as defined in the present invention) in THF or diethyl ether at room temperature.

[0141] Generally, 1 equivalent of the compound MH2Y reacts with 2 equivalents of the alkene R’CH=CH2 to form the compound (R’CH2CH2)2MY.

[0142] In the method of the present invention, preferably, no gaseous species other than dinitrogen (N2) is used as the starting reagent.

[0143] This method may also include step iv) of recycling the compound (I).

[0144] In this embodiment, step iii) preceding step iv) is preferably carried out by contacting the crude reaction product obtained in the preceding step ii), ii - 1), or ii - 2) with an acid solution containing an aprotic organic solvent and at least one acid, or with a gaseous acid in an inert atmosphere, where the acid solution and the gaseous acid are as defined above to preferably form ammonia NH3, and then step iv) can be carried out by distillation of ammonia NH3. The remaining liquid composition contains the compound (I) in an electrolyte solution and can be reused in another reaction.

[0145] A second object of the present invention is an electrochemical cell for reducing dinitrogen to ammonia nitrogen, characterized by comprising: * At least one electrolyte solution and a composition containing at least one compound satisfying the following formula (I): R 1 R 2 MY (I), where - M is an element of Group 13 of the periodic table, preferably selected from boron, aluminum, and mixtures thereof, - R 1 and R 2 are the same or different and are selected from an alkyl group, an aryl group, an arylalkyl group, -OR group, and -SR group, R is an alkyl group, an aryl group, or an arylalkyl group, and - Y is a group selected from halogen -X, -OR 3 group, -SR 3 group, triflate group, mesylate group, and triflimidate group, R 3 is an alkyl group, an aryl group, or an arylalkyl group composition, * A working electrode (entirely or partially) immersed in the composition, and * A counter electrode (entirely or partially) immersed in the composition or in an electrolyte solution.

[0146] The electrochemical cell may also include a reference electrode (entirely or partially) immersed in the composition or in an electrolyte solution. The electrochemical cell, electrolyte solution, composition, compound satisfying formula (I), working electrode, counter electrode, and reference electrode are as defined in the first object of the present invention.

[0147] The accompanying drawings illustrate the present invention.

Brief Description of the Drawings

[0148]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0149] Further features and advantages of the present invention will become apparent from the description of non - limiting examples of the method and electrochemical cell according to the present invention.

Example

[0150] Figure 1 shows an electrochemical cell 1 for reducing dinitrogen to ammonia nitrogen, comprising a composition 2 containing at least one electrolyte solution and at least one compound satisfying formula (I), a working electrode 3 immersed in the composition, and a counter electrode 4 immersed in the composition. The electrochemical cell 1 may further comprise a reference electrode 5 and a system 6 (e.g., a tube) for introducing dinitrogen into the electrochemical cell via an inlet 7. The system 6 is arranged such that dinitrogen 8 can be taken up by the composition 2 in the vicinity of the working electrode 3 or released from the composition 2.

[0151] The electrochemical cell 1 may further comprise an inlet and an outlet (not shown in Figure 1) for causing the composition to flow through the electrochemical cell 1, for example using a pump system.

[0152] The electrochemical cell 1 may further comprise an outlet (not shown in Figure 1) for discharging dinitrogen and thereby causing it to flow through the electrochemical cell 1.

[0153] Figure 2 shows an electrochemical cell 10 for reducing dinitrogen to ammonia nitrogen, comprising: - a first compartment C111 including a composition 21 containing at least one electrolyte solution and at least one compound satisfying formula (I), a working electrode 30 immersed in the composition, and optionally a reference electrode 50, and - a second compartment C212 including a counter electrode 40 immersed in an electrolyte solution 22.

[0154] The two compartments are separated by a membrane 90.

[0155] Compartment C1 also includes a system 60 (e.g., a tube) for introducing dinitrogen into the electrochemical cell via an inlet 70. The system 60 is arranged such that dinitrogen 80 can be taken up by the composition 21 in the vicinity of the working electrode 30 or released from the composition 21.

[0156] Example 1 A method for producing ammonia nitrogen from dinitrogen using an electrochemical cell comprising a composition containing dicyclohexylchloroborane as a compound of formula (I) An electrochemical cell having three compartments C1, C2, and C3 is used in the method of the present invention and comprises: - Compartment C1 comprising: · 3 mL of anhydrous THF, 6×10 -4 moles of tetra-n-butylammonium bis(trifluoromethanesulfonyl)imide (TBATFSI) [TBATFSI concentration 0.2 mol / L], and 9×10 -5 moles of dicyclohexylchloroborane [compound (I) concentration 0.03 mol / L], a composition maintained under stirring, · A working electrode consisting of a glassy carbon rod embedded in a glassy carbon foam (10 mm×5 mm×7 mm), the working electrode being immersed in the composition, and · A reference electrode consisting of a silver wire immersed in an acetonitrile solution containing 10 -2 mol / L silver nitrate and 0.2 mol / L TBATFSI, - Compartment C2 including a counter electrode consisting of a glassy carbon (or graphite) rod embedded in a carbon felt piece (10 mm×10 mm×100 mm), the counter electrode being immersed in an electrolyte solution containing DMF and TBATFSI [TBATFSI concentration 0.2 mol / L], - Compartment C3 including an electrolyte solution containing anhydrous tetrahydrofuran (THF) and TBATFSI [TBATFSI concentration 0.2 mol / L], - A membrane separating compartments C1 and C3, consisting of a sintered glass disk, and - A membrane separating compartments C3 and C2, consisting of a sintered glass disk.

[0157] Compartment C3 ensures electrical contact between compartments C1 and C2 while restricting the diffusion of components between the working electrode and the counter electrode.

[0158] The body of the reference electrode contacts the composition in compartment C1 via a glass extension containing an electrolyte solution comprising anhydrous THF and TBATFSI [TBATFSI concentration 0.2 mol / L]. Thereby, the reference electrode is immersed in the composition.

[0159] Supply dinitrogen (N2) to the above-described electrochemical cell and place the electrochemical cell in a glove box under a nitrogen atmosphere (step i). Next, apply a potential of -2.7 V to the working electrode for 4 hours (step ii). The progress of the reaction is monitored by coulometry. After electrolysis stops, the amount of ammonium produced is estimated from a 0.5 mL sample of the electrolytic solution. This sample is treated by adding an excess of HCl (ether solution) (step iii), and subsequently all volatile species are evaporated under reduced pressure. The amount of ammonium produced is estimated by analysis of the residue by 1H NMR spectroscopy recorded in DMSO-d6 in the presence of trimethoxybenzene used as an internal reference.

[0160] Example 2 Control method (not included in the present invention) The control method reproduces the above experiment in the absence of the compound of formula (I) or in the absence of the application of a potential. No formation of ammonium was observed.

Claims

1. A method for producing ammoniacal nitrogen, wherein the ammoniacal nitrogen is ammonium (NH ４ ＋ ), ammonia (NH ３ ), and a mixture thereof, comprising at least the following steps: i) Dinitrogen (N) into an electrochemical cell ２ A step of supplying ) wherein the electrochemical cell comprises at least one working electrode and at least one counter electrode immersed in a composition maintained under stirring, and the composition comprises at least one electrolyte solution and the following formula (I): R １ R ２ A compound comprising at least one compound satisfying MY(I), in which, - M is an element in Group 13 of the periodic table. - R １ and R ２ R is the same or different, selected from alkyl groups, aryl groups, arylalkyl groups, -OR groups, and -SR groups, where R is an alkyl group, aryl group, or arylalkyl group, and -Y is a group selected from halogen-X, -OR ３ group, -SR ３ group, a triflate group, a mesylate group, and a triflimidate group, and R ３ is an alkyl group, an aryl group, or an arylalkyl group process, ii) A step of applying a potential difference between the working electrode and the counter electrode, or a step of applying a potential or current to the working electrode, iii) Step of acid hydrolysis of the composition A method characterized by including the following.

2. The method according to claim 1, characterized in that the element M is selected from boron, aluminum, and mixtures thereof.

3. The two aforementioned bases R １ and R ２ The method according to claim 1, characterized in that is an alkyl group.

4. The method according to claim 1, characterized in that Y is halogen X.

5. The method according to claim 1, characterized in that the working electrode comprises at least one inert conductive material selected from carbon, platinum, stainless steel, and metal oxides.

6. The method according to claim 1, characterized in that the counter electrode comprises at least one inert conductive material selected from carbon, platinum, stainless steel, and metal oxides.

7. The method according to claim 1, characterized in that the electrolyte solution includes a combination of an organic solvent and a salt, or an ionic liquid.

8. The method according to claim 1, characterized in that the electrochemical cell further comprises a reference electrode.

9. The compound of formula (I) is present in 10 units in the composition. －５ ~10 －１ The method according to claim 1, characterized in that it has a molar concentration in the range of mol / L.

10. The method according to claim 1, characterized in that step ii) is carried out under constant potential or constant current conditions.

11. The method according to claim 1, characterized in that steps i) and ii) are performed simultaneously.

12. The method according to claim 1, characterized in that step iii) hydrolysis in an acid medium is carried out by contacting the reaction crude product obtained in the preceding step ii) with an acid solution or gaseous acid.

13. The method according to claim 12, characterized in that the pH of the acid solution is in the range of 0 to 6.

14. The electrochemical cell, - Section C encompassing the composition, the working electrode immersed in the composition, and, if a reference electrode is present, the reference electrode immersed in the composition. １ , - Compartment C containing the counter electrode immersed in the electrolyte solution ２ ,and - The two sections C mentioned above １ and C ２ membrane that separates The method according to claim 1, characterized by comprising:

15. An electrochemical cell for reducing dinitrogen to ammoniacal nitrogen: * At least one electrolyte solution and the following formula (I): R １ R ２ A composition comprising at least one compound satisfying MY(I), wherein, - M is an element in Group 13 of the periodic table. - R １ and R ２ R is the same or different, selected from alkyl groups, aryl groups, arylalkyl groups, -OR groups, and -SR groups, where R is an alkyl group, aryl group, or arylalkyl group, and - Y is halogen-X, -OR ３ Base, -SR ３ The group is selected from a trifluidate group, a trifluidate group, and a trifluidate group, R ３ is an alkyl group, an aryl group, or an arylalkyl group. composition, * Working electrodes immersed in the aforementioned composition, and * Counter electrode immersed in the aforementioned composition or electrolyte solution An electrochemical cell characterized by comprising the following features.

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