A method for manufacturing ammonia and uses thereof

Abstract

The disclosure provides a method for manufacturing ammonia. The method comprises providing a metal nitride, a refrigerant fluid, a proton donating compound and optionally one or more of the following: nitrogen gas, a solvent, and an additive. The method also comprises combining the metal nitride, the refrigerant fluid, the proton donating compound and optionally the one or more of the 5 following: nitrogen gas, the solvent, and the additive whereby protonation of the metal nitride takes place to provide ammonia, a metal salt and / or metal hydroxide, and heat.

Description

[0001] A METHOD FOR MANUFACTURING AMMONIA AND USES THEREOF

[0002] Technical field

[0003] The present disclosure relates to a method for manufacturing ammonia. The present disclosure also pertains to a heat pump, such an ammonia heat pump, wherein the method for manufacturing ammonia is performed.

[0004] Background

[0005] Ammonia is an inorganic compound with the chemical formulae NH3, which exists as a colourless gas at room temperature and atmospheric pressure and which can be easily compressed into a clear liquid under pressure. The most common and extensive use of ammonia is as a base material for fertilizers in agriculture. However, ammonia also has many other important commercial and industrial applications. For instance, ammonia may be used as a refrigerant, cleaning agent, such as a household cleaning agent or wastewater treatment agent, as a chemical for the manufacture of products in various contexts, such as pharmaceuticals, pulp, pesticides etc.

[0006] Due to the tremendous importance of ammonia, in particular for fertilizer applications in agriculture, ammonia is one of the most produced industrial chemicals. The main process for manufacturing ammonia is still the Haber-Bosch process, which was developed at the beginning of the 20thcentury. In this process, ammonia is synthesized from nitrogen gas (N2) and hydrogen gas (H2) under high temperature and pressure in the presence of an iron catalyst.

[0007] Unfortunately, however, there are both environmental and economic concerns associated with the Haber-Bosch process. In fact, it has been reported that the Haber-Bosch process is responsible for 1 % to 2 % of the global energy consumption and 1 .44 % of all carbon dioxide emissions. Of course, this is not acceptable in view of climate change concerns and prompts the development of sustainable methods allowing to meet the great demand for ammonia.

[0008] The nitrogen reduction reaction (abbreviated NRR) is an electrochemical reduction process of nitrogen for ammonia production that has been proposed as an alternative to the Haber-Bosch process. The NRR is usually carried out at mild temperature and pressure and can be integrated into a circuit where the energy supply comes from non-fossil sources, which makes it attractive from both an environmental and sustainability point of view. While the mild conditions being used in the NRR are a significant benefit the yields are often low due to the competing hydrogen evolution reaction (abbreviated HER) wherein the protons are reduced to hydrogen gas instead of reacting with the nitrogen. A variant of NNR is the lithium-mediated approach. It proceeds in several steps, including electrochemical deposition of lithium (Li(s)), followed by two chemical processes of dinitrogen splitting (6Li(s) + N2 => 2LisN) and protonation to ammonia (LisN + 3H+=> 3Li++ NH3). A drawback that has been reported is formation of byproducts from the solvents being used in the reaction. Moreover, it is known that the heat evolved during reaction of metal nitrides, such as lithium nitride, with the proton source, such as water, may result in splitting of the formed ammonia into nitrogen gas and hydrogen gas, respectively, thereby contributing to lowering the yield of ammonia.

[0009] US 8,916,123 B2 discloses a process to synthesize ammonia on demand from atmospheric nitrogen and water using electrochemical and non-electrochemical reactions. The overall chemical reaction is: 6LiOH + N2 => 2LiaN (s) + 3 H2O + 3 / 2 O2. The non-electrochemical reaction involves reacting lithium nitride with water and / or steam as follows: LisN (s) + 3 H2O => 3 LiOH + NH3 (g). The formed ammonia is then vented and collected. It is described that the electrolytic cell may comprise a solvent.

[0010] US 2018 / 0029895 A1 discloses an electro-thermochemical lithium cycling for the NH3 synthesis from N2 and H2O. It is stated that the demonstrated process is the unique combination of LiOH electrolysis, Li nitridation, and LisN hydrolysis performed in a stepwise cycle to avoid the hydrogen evolution reaction (HER). It is described that electrolyte solvents may be present.

[0011] Energy Environ. Sci. 2023, 16, 1082-1090 relates to the chemistry of proton carriers in high- performance lithium-mediated ammonia electrosynthesis. It is stated that significant degradation of EtOH during Li-NRR, i.e. lithium-mediated nitrogen reduction reaction, renders this proton carrier unsuitable for practical ammonia synthesis. In contrast, iso-propanol is demonstrated not to be converted to side-products.

[0012] Thus, there is a need for a more sustainable and environmentally friendly way of producing ammonia. In particular, there is a need for a more sustainable and environmentally friendly way of producing ammonia in a good yield, more energy efficient and without or substantially without byproducts.

[0013] Summary

[0014] It is an object of the present disclosure to overcome or at least mitigate one or more of the problems associated with the presently used methods for manufacturing of ammonia. In particular, it is an object of the present disclosure to overcome or at least mitigate one or more of the problems associated with a metal mediated, such as lithium-mediated, nitrogen reduction reaction. It is also an object of the present disclosure to provide aspects and / or advantages not provided by hitherto known techniques.

[0015] Thus, there is provided a method for manufacturing ammonia. The method comprises providing a metal nitride, a refrigerant fluid, a proton donating compound and optionally one or more of the following: nitrogen gas, a solvent, and an additive. The method also comprises combining the metal nitride, the refrigerant fluid, the proton donating compound and optionally the one or more of the following: nitrogen gas, the solvent, and the additive, whereby protonation of the metal nitride takes place to provide ammonia, a metal salt and / or metal hydroxide, and heat.

[0016] Brief description of the drawings

[0017] The embodiments, together with further objects and advantages thereof, may best be understood by making reference to the following description taken together with the accompanying drawings, in which:

[0018] Fig. 1 is an illustration of water activity versus ammonia concentration.

[0019] Description

[0020] The present disclosure provides a method for manufacturing ammonia. The method comprising providing a metal nitride, a refrigerant fluid, a proton donating compound and optionally one or more of the following: nitrogen gas, a solvent, and an additive. The method also comprises combining the metal nitride, the refrigerant fluid, the proton donating compound and optionally the one or more of the following: nitrogen gas, the solvent, and the additive, whereby protonation of the metal nitride takes place to provide ammonia, a metal salt and / or metal hydroxide, and heat

[0021] In an embodiment, the method comprises providing a mixture comprising the refrigerant fluid, the proton donating compound and optionally the one or more of the following: nitrogen gas, the solvent, and the additive. In such an embodiment, the method also comprises combining the metal nitride with the mixture whereby protonation of the metal nitride takes place to provide ammonia, a metal salt and / or metal hydroxide, and heat.

[0022] Unexpectedly, it has been found that the method described herein allows for achieving high yield of ammonia. While not being bound by any specific theory, it is believed that this may be due to hydrogen bonds being formed between the proton source and the refrigerant fluid and / or a reversible reaction taking place between the proton source and the refrigerant fluid thereby lowering the reactivity of the proton source so that side reactions are less likely to take place. The high yields can also be explained by the close proximity between the refrigerant to the reaction centre between the solid nitride and the proton source, where the refrigerant more effectively can moderate, for example by evaporating, the temperature locally.

[0023] For example, the refrigerant fluid may be ammonia and the proton source may be water. In this case the reversible reaction includes protonation of the ammonia into ammonium hydroxide as shown below: (equilibrium)

[0024] Further, hydrogen bonds may form between the water and the ammonia and / or the ammonium hydroxide. Using other hydrogen bonding additives, such as acidic or basic ionic exchanger materials, cellulosic materials and / or acidic or basic minerals, can also help in moderating the activity / reactivity of the proton source, such as water, which is further described herein.

[0025] The metal nitride described herein may be one or more of the following: lithium nitride (LisN), beryllium nitride (Be3N2), magnesium nitride (Mg3N2), sodium nitride (NasN), molybdenum nitride (M02N), aluminium nitride (AIN), zinc nitride (ZnsN2), calcium nitride (CasN2), strontium nitride (SrsN2), barium nitride (BasN2). In particular, the metal nitride may comprise, or consist of, LisN and / or Mg3N2. In an embodiment, the metal nitride is LisN. In another embodiment, the metal nitride is Mg3N2. In a further embodiment, the metal nitride is a combination of LisN and Mg3N2.

[0026] Generally, the reactivity of the different metal nitrides will vary. Typically, the lithium nitride (LisN) is most reactive, followed by magnesium nitride Mg3N2. Aluminium nitride (AIN) is generally less reactive, needing acidic and / or basic conditions and preferable elevated temperatures to react with practical speeds.

[0027] However, the invention makes it possible to tune the proton activity in the mixture to achieve optimized condition when reacting with the metal nitride

[0028] The mixture may be a gas, a liquid or a mixture thereof. Gas mixture as used herein means a mixture in gas form. Correspondingly, liquid mixture as used herein means a mixture in liquid form. Generally, the mixture is a fluid. For instance, the mixture may be a gas comprising ammonia including water steam.

[0029] Alternatively, the mixture may be a liquid comprising an aqueous solution of ammonia. The amount of water and ammonia may depend on the temperature and pressure being used. For example, the amount of proton donor, such as water, may vary from about 0.1 wt% to about 84 wt% based on the total weight of the mixture (i.e., it may even be under saturation concentration). In a further example, the mixture comprises or consists of a super saturated, a saturated or undersaturated solution of ammonia in water (saturation concentration varies with pressure and temperature). The fluid mixture can also be in gas phase, or a mixture of gas and liquid phase.

[0030] The method of the invention makes use of the fact that having a refrigerating fluid in close contact or proximity to the reaction site, i.e., the surface of the metal nitrides, enables effective heat transfer and heat dissipation away from the reaction site. This is advantageous for several reasons, including minimization of side reaction in the form of ammonia (NH3) breakdown into nitrogen (N2) and hydrogen (H2) at high local temperatures. This heat dissipation effect also protects other additives from thermal degradation, such as solvents, proton donating compounds, salts, conductivity enhancers used in the method.

[0031] The use of refrigerating solvents to take up the heat is generally preferred over using supercritical (SC) fluids for several reasons. By networking in SC regime, using refrigerants instead, the invention can exploit phase change to maintain temperatures largely constant during phase changes (i.e., at reaction), and absorb heat by the fluid as well as by evaporation. We make use of any latent-heat and / or the enthalpy of evaporation in the system. The heat transfer coefficient (i.e., heat transfer effectivity) can be very high due to the boiling / evaporation. Using refrigerants, we can also reach maximum thermal buffering and make use of energy recovery via condensation of that refrigerating fluid elsewhere in the system. Accordingly, refrigerants enable the method to be run in, and to generate (and to be used within), a two-phase regime. Further, by net working in the SC regime (for example in SC ammonia temperature >132°C and pressure > 113 bar), the invention relaxes the need for use of high-pressure and hight-temperature equipment. Accordingly, lower pressure equipment can be used (for example designed to operate within the pressure range of 1-50 bars).

[0032] It will be appreciated that the amount of hydrogen gas formed as byproduct, will depend on the amount and / or concentration of water present in the liquid. Thus, the amount of hydrogen gas may be adjusted by selecting a liquid with an appropriate amount or concentration of water. Additionally, or alternatively, the amount of hydrogen gas may be adjusted by selecting values affecting parameters having an impact on the reaction rate between the metal nitride and the proton donor, such as the temperature and / or pressure, at which the reaction is performed, speed at which the proton donor is added, activity of the proton donor, speed at which the metal nitride is added etc. In these ways hydrogen gas formation can be minimized.

[0033] There are several different examples of ammonia water solutions and an ammonia solution, which all behave differently, and can be used differently, in the context of the present invention.

[0034] Saturated ammonia water solutions: This means an ammonia water mixture saturated with ammonia, and in equilibrium at the given temperature and pressure. These mixtures have been found to reduce the reactivity of water with metal nitrides and to form less side products (i.e., less hydrogen by ammonia splitting) when using the method of this invention. Reduced reactivity comes presumably from the reduced water activity, but also by providing effective heat transfer as the saturated solution evaporates ammonia as it is heated (heat of vaporisation moderates), and as more ammonia is formed (evaporation of that also require heat). This happens both locally, at the metal nitride surface as it reacts with the water, but also in the bulk as it heats up, and gets more concentrated (i.e., the produced ammonia transforms the saturated ammonia water solution to an over saturated ammonia water solution).

[0035] Oversaturated (supersaturated) ammonia water solution: This is an ammonia water mixture that contain more ammonia than the equilibrium value at that given temperature and pressure. It might still be able to handle it as the equilibrium value takes some time (i.e. ammonia evaporation is slow) to be reached. Alternatively, if in a confined space and at a constant temperature, the pressure will build up until the new equilibrium point is reached. These mixtures have also been found to reduce the reactivity of water with metal nitrides and to form less side products (i.e., less hydrogen by ammonia splitting) when using the method of this invention. Reduced reactivity comes presumably from the reduced water activity, but also by providing effective heat transfer as the saturated solution evaporates ammonia as it is heated (heat of vaporisation moderates), and as more ammonia is formed (evaporation of that also require heat). This happens both locally, at the metal nitride surface as it reacts with the water, but also in the bulk as it heats up, and gets even more oversaturated (heat of vaporisation moderates). Undersaturated ammonia water solution: This means an ammonia water mixture that contain less ammonia than the equilibrium value at that given temperature and pressure. Also, here we have seen moderation of the reaction, as a “half saturated” (taking 32% saturated solution of ammonia in water, and diluting it with water to 16% ammonia water solution - which we named “half saturated” herein) solution notably reacted more calmly with metal nitrides. Adding enough metal nitride eventually leads to a saturated solution (by the production of more ammonia). Further, the temperature will raise due to the exothermic reaction. Both these effects make their contributions to eventually reach the saturation point.

[0036] Ammonia solution: An essentially dry ammonia that boils around -33°C at 1 bar, and is a liquid at around 10 bar and 20°C. The liquid range of ammonia at other temperatures and pressures can easily be found. Metal nitrides can be added into such an ammonia solution without any noticeable reactions. The proton donating compound, for instance water, can be added to this ammonia nitride mixture and its activity will be moderated by the excess of ammonia. Further, the heat formed in the reaction will be dissipated by the surrounding ammonia, partly evaporating (heat of vaporisation) ensuring an effective heat transfer and thereby minimizing side reactions (such as hydrogen formation by overheating of the ammonia at the metal nitride surface).

[0037] Ammonia water in the gaseous form (ammonia water vapour): This can be made by evaporation of an ammonia water solution, or by adding small amount of water / steam to an ammonia gas or adding ammonia to a water vapour. In all of the cases we have tested to react water in gaseous ammonia water mixtures with the nitrides, the ammonia water vapour has been essentially at equilibrium (i.e. created by slowly heating a saturated or over saturated ammonia water solution so it evaporates “wet ammonia”). But we see no reason to that an oversaturated ammonia water vapour (i.e. contain less water than at equilibrium) should not give similar results on reaction speed, and minimal side product formations (i.e. hydrogen formation).

[0038] Generally, the water activity (OCH2O) of water in the mixture of ammonia and water decreases as the ammonia concentration increases, see Fig. 1 . This means that the activity of water, i.e., the effective concentration (or apparent concentration) of water available for chemical reactions, can be tailored by the amount of water in the mixture between water and ammonia. This in turn can be used to adjust or tailor the amount of hydrogen gas formed as byproduct. Also, other proton donating compounds, and / or hydrogen bonding materials, can be used to moderate the activity of the proton donor, for example water. Examples of such compounds are cellulosic compounds, ion exchange materials, preferably acidic ion exchange materials and minerals, preferably acidic minerals, polymers having hydrogen bonding capabilities such as poly-acids, polyamines, polyalcohols, that interacts with water and enables lower activity of the water. Additionally, they can help with guiding or confining the water to the specific area where they are situated (e.g., a cellulose paper / membrane, ion exchange beads and mineral particles or pastes), given that they are not soluble within the mixture.

[0039] The above-provided discussion of water activity also applies to other proton donors than water, i.e., the activity (effective concentration available for chemical reactions, i.e., proton donation) of the proton donor can be tailored by adjusting the concentration of the proton donor in the refrigerant fluid, preferably ammonia.

[0040] The metal nitride may be combined with the mixture in various ways. For example, the metal nitride may be added to the mixture, or vice versa.

[0041] The refrigerant fluid may be selected from the group consisting of ammonia (NH3; R-717), propane (CaHs; R-290), isobutane (HC(CH3)3; R-600a), propylene (CsHe; R-1270), butane (C4H10; R-600), ethane (CH3CH3; R-170), dimethyl ether (CH3OCH3; R-E170), 2,3,3,3-tetrafluoropropene (CH2CF2CH3), carbon dioxide (CO2), difluoromethane (CH2F2), 1 ,1 ,1 ,2-tetrafluoroethane (CF3CH2F), pentafluoroethane (CF3CHF2), trichlorofluoroethane (CCI3CH2F), dichlorofluoromethane (CHCI2F), chlorodifluoromethane (CHF2CI), 2, 2-dichloro-1 , 1 ,1 -trifluoroethane (CF3CHCI2), and any combination(s) thereof.

[0042] In particular, the refrigerant fluid may comprise, or consist of, ammonia.

[0043] The proton donating compound may comprise, or consist of, a Bronsted acid. Additionally, or alternatively, the proton donating compound may be selected from the group consisting of water, alcohol, such as methanol, propanol, isopropanol or ethanol, ammonium ion, trialkyphosphonium cations or salts thereof, ion exchange resins, acidic rock mineral(s), cellulose and any combination(s) thereof. In particular, the proton donating compound may comprise, or consist of, water. The hydrogen source may also be an electrochemical process generating hydrogen, at one of the electrodes of the electrochemical cell. The ion exchange resins, acidic or basic mineral(s), hydrogen bonding capable polymers, cellulose or any combination(s) thereof, are preferably combined with an additional proton donating compound, for example water.

[0044] The present method may include a solvent, which may form part of the mixture. The solvent may be a non-protic solvent in order to avoid that the solvent acts as a proton donating compound reacting with the metal nitride. For example, the solvent may comprise, or consist of, one or more of the following: an ether, such as cyclopentyl methyl ether (CPME), 2-methoxy-2-methyl butane (TAME), methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), dimethyl ether, diethyl ether, tetrahydroduran (THF), dioxane or dimethoxyethane (DME; glyme); a carbonate, such as ethylenecarbonate (EC; cyclic), dimethylcarbonate (DMC), diethylcarbonates (DEC), ethyl methyl carbonate (EMC), propylenecarbonate (PC; cyclic); sulfolane, hexane, toluene, and any combination(s) thereof. Alternatively, the solvent may be a protic solvent that may provide proton(s) to the metal nitride. In still a further example, the method is free from a solvent.

[0045] The mixture of the method may further comprise an additive, such as an additive selected from the group consisting of an ion conductivity improver, such as a salt, a solubility enhancer, a surfactant, a gas, and any combination(s) thereof. For example, the salt may be a lithium salt, a magnesium salt, or an aluminium salt.

[0046] Illustrative, but non-limiting, examples of lithium salts include lithium hydroxide (LiOH), lithium chloride (LiCI), lithium triflouromethanesulfonate (LiOTf), lithium hexafluorophosphate (LiPF6), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium nitrate (LiNO3), lithium vis(fluorosulfonyl)imide (LiFSI), lithium difluoro(oxalato)borate (LiDFOB), lithium fluoroalkylphosphate salts (LiBFAP), lithium bis(oxalato)borate (LiBOB), lithium perchlorate (l_iCI04) or any combination(s) thereof.

[0047] Illustrative, but non-limiting, examples of magnesium salts include magnesium hydroxide (Mg(OH)2), magnesium chloride (MgCI), magnesium bis(trifluoromethanesulfonyl)imide (Mg(TFSI)2), magnesium borohydride (Mg(BH4)2), magnesium-aluminium chloride complex (MgCI2— AICI3), magnesium tetrachloroaluminate (Mg(AICI4)2), magnesium tritiate (Mg(CF3SO3)2), magnesium nitrate (Mg(N03)2), magnesium perchlorate (Mg(CI04)2), magnesium hexamethyldisilazide + AICI3(Mg(HMDS)2-AICI3), magnesium fluorinated alkyl phosphate (Mg[FAP]2), magnesium hexafluorophosphate (Mg(PF6)2), or any combination(s) thereof.

[0048] Illustrative, but non-limiting, examples of aluminium salts include aluminium chloride (AICI3), aluminium hydroxide (AI(0H)3), aluminium tritiate (AI(OTf)3), aluminium hexafluorophosphate (AI(PF6)3), aluminium nitrate (AI(N03)3), aluminium bis(trifluoromethanesulfonyl)imide (AI(TFSI)3), aluminium sulfate (AI2(S04)3), mixture of aluminium chloride + 1 -ethyl-3-methylimidazolium chloride (AICI3— [EMIm]CI), mixture of aluminium chloride + urea(AICI3-NH2C(O)NH2) (deep eutectic solvent), or any combination(s) thereof.

[0049] For example, the additive may be a salt comprising an ammonium ion allowing for generation of liquid ammonia (to provide a so-called Euforectic solution) at lower pressures (i.e., liquid ammonia salt mixture at 1 atmosphere at room temperature) as described in Joule 6, 772-781 , April 20, 2022. The salt comprising an ammonium ion may be ammonium trifluoromethanesulfonate and / or ammonium hexafluorophosphate, ammonium nitrate or any other salt capable of forming an euforetic solution with ammonia.

[0050] Illustrative, but non-limiting, examples of solubility enhancer (including solubilizing agents, cosolvents, or chelating additives) include glymes, for example mono-, di-, tetra-glymes; tetrahydrofuran (THF), dioxolane (DOL), fluorinated solvents, such as FEC, BTFE, polythylene glycoles (PEGs), fluoroethers (HFEs), such as HFE-7100 (ethoxy-nonafl uorobutane) or HFE-7200 (ethoxynonafluorobutane); sulfolanes, such as sulfolane or methylsulfolane, tetraethylene glycol dimethyl ether (TEGDME), an ionic liquid, eutectic mixtures with for example urea or ethylene glycol, and for aqueous systems also acetonitrile and formamide. Or it can be a complexing / chelati ng agent, such as crown ethers, nitrogen ligand compounds, such as bipyridines, or coordinating amides, or any combination(s) thereof.

[0051] Illustrative, but non-limiting, examples of surfactants include cationic surfactants, such as cetyltrimethylammonium bromide (CTAB), anionic surfactants, such as sodium dodecyl sulfate (SDS), non-ionic surfactants, such as polysorbates (Tween® 80 or Tween® 20), nonylphenol ethoxylates, Triton X-100, sorbitan monooleate (Span 80), PEGs (polyethylene glycols) derivatives, polyethylenoxides (PEOs), fluorosurfactants, such as perfluorinated carboxylic acids, zwitterionic surfactants, for example lecithin, amphiphilic molecules, for example phosphonium-based surfactants, ethoxylated alcohols , alkyl glucosides, ionic liquids with surfactant properties, chelators, such as crown ethers or ethereal surfactants, quaternary ammonium salts, such as tetramethylammonium chloride, or any combination(s) thereof.

[0052] Illustrative, but non-limiting, examples of gases include nitrogen (N2) or hydrogen (H2), for example to set total pressure (or leak control), an inert gas, such as helium (He) or Argon (Ar), for example to set total pressure (or leak control), or it can also be more of an interacting gas, such as sulphur dioxide (SO2, R-764), which can react with water to form sulphuric acid, alternatively, or in addition, it can react with ammonia to form ammonium sulfite or ammonium bisulfite, nitroxy gases (NO, N02, N20), some of which can interact with water to form nitrous acids, alternatively, or in addition, NO2 and NO can react with the ammonia forming ammonium nitrate (NH4N03) or ammonium nitrite (NH4NO2), or carbon dioxide (C02, R-744); which can interact with water to form carbonic acid (H2CO3), alternatively, or in addition, it can interact with ammonia to form ammonium carbonate ((NH4)2CO3), or any combination(s) thereof.

[0053] The one or more of the steps of method may be performed at any suitable temperature and / or pressure. For example, the method may be performed at a temperature from -78 °C to 210 °C, such as a temperature from 55 °C to 180 °C, preferably from 60 °C to 160 °C, and / or a pressure from 0.1 bar to 50 bar, such as from 0.1 bar to 30 bar, preferably from 1 bar to 30, or from 0.1 bar to 5 bar, preferably from 1 bar to 5 bar.

[0054] If desired, one or more of the steps of the method may be performed under inert atmosphere, such as under nitrogen, helium or argon gas. In this way, the risk for a fire or explosion is minimized. Further, the one or more of the steps of method can be performed under different partial pressures of nitrogen, but at same total pressure by adjusting helium, argon gas or hydrogen gas partial pressures.

[0055] The method may comprise an additional step of separating the ammonia produced by the method. This can for example be done by directing the fluid ammonia formed through a valve attached to the apparatus, preferably at a position where the ammonia concentration is high. That valve outlet can further be directed to a drying filter, such as a drying filter comprising a metal nitride, such as a metal nitride described herein, or dried by any other known method or simply taken out as wet. The ammonia produced may subsequently be used in a desired application such as for producing a chemical or fertilizer. Thus, the method may comprise a further step of converting the ammonia into a chemical or fertilizer. For example, the produced ammonia is reacted with nitric acid (HNO3) in an exothermic reaction to form ammonium nitrate (NH4NO3), which is a well-known fertilizer. Alternatively, the produced ammonia is react with carbon dioxide (CO2) under high temperature (typically above 150°C) and high pressure (typically above 100 bar) according to: 2NH3 + CO2 NH4CO2NH2 CO(NH2)2 + H2O; thereby forming Urea (CO(NH2)2) via the two consecutive equilibrium reactions. Urea is used as a fertilizer. Accordingly, the present disclosure provides the use of ammonia produced by the method described herein for the manufacture of a chemical and / or a fertilizer. Ammonia itself can also directly be used as a fertilizer, dry or as a water solution.

[0056] The method described herein may further comprise a step of drying the ammonia produced in the method. For example, the ammonia produced in the method may be dried using a drying filter such as a drying filter comprising a metal nitride, such as a metal nitride described herein.

[0057] The method may be performed in conjunction with an electrochemical cell, such as within an electrochemical cell. The mixture may then serve as an electrolyte. Further, the metal nitride may be formed on or within one of the electrodes of the electrochemical cell.

[0058] The method may also, or alternatively, be performed in conjunction with an electrophoretical / capacitive setup as described herein, such as on one electrode with controllable potential to modify the transport of proton donor to the electrode, i.e., controlling its transport properties and / or the reactivity of the metal / metal- n itride .

[0059] Additionally, or alternatively, the method may be performed in conjunction with a heat pump, such as an ammonia heat pump. Examples of heat pumps are provided in ‘An overview of ammonia-based absorption chillers and heat pumps" in Renewable and Sustainable Energy Reviews 31 (2014) 681 — 707). For example, the heat pump may be one or more of the following: absorption cooler, absorption heater, absorption pump including ammonia based absorption chillers (mono- or cascade-cycle systems), subfreezing refrigeration, compression / absorption chillers and heat pumps including ammonia-based working fluids, NH3-H2O based, binary ammonia-salt solutions, such as NH3- NaSCN and NHs-LiNOs or ternary solutions with for example NH3— H2O— LiBr, NH3-H2O-IJNO3 and / or NHs-FW-hydroxide. Also, the absorption cycle could be set up as a gas boiler rather than a heat pump cycle, or as an diffusion absorption refrigeration cycle. In this way, the (ammonia) heat pump will allow for heating or cooling and also for producing ammonia. Accordingly, there is provided a heat exchanger / pump, such as an ammonia heat exchanger / pump comprising an electrochemical cell wherein the method described herein is performed.

[0060] The invention will be further described by reference to the following examples, which are not intended to limit the scope of the invention. EXAMPLES

[0061] Abbreviations cm centimeter(s) g gram(s) vol% percent by volume wt% percent by weight mg milligram(s) mm millimeter(s) mmol millimole(s) mL milliliter(s) min minute(s)

[0062] THF tetrahydrofuran

[0063] RT room temperature, i.e. from 20 °C to 25 °C such as 22 °C wt% weight percent

[0064] Example 1A: Production of semi-dry liquid ammonia

[0065] A rotavap (i.e., a rotary evaporator) was used for distilling ammonia from an aqueous solution of ammonia wherein the concentration of ammonia was 32 vol%. The distillation was performed under nitrogen gas flow, having a flow rate of 1200 mL / min.

[0066] 500 mL of the aqueous solution of ammonia was added to the rotary flask, which was contacted with the water bath. The distillation / desorption was performed at a temperature from 30 °C to 60 °C (i.e., temperature of the water bath) and the cooling water of the condenser was kept at 6 °C. The ammonia at the top of the condenser (i.e., leaving the condenser top at 6 °C) was distilled at a steady rate as observed using a bubble flask for monitoring. The distilled ammonia gas was trapped using two consecutively mounted cold traps (2 round bottom 3-neck flasks), in a cooling bath comprising a mixture of acetone and carbon dioxide (dry ice) providing a temperature of -78 °C. The first cold trap was found to contain condensate while the second cold trap was substantially free from condensate.

[0067] The condensate of the first cold trap contained 50 mL of liquid ammonia including 0.21 g of water, i.e. the liquid ammonia had a water content of 0.42 wt%. This liquid ammonia was denominated semi- dry (liquid) ammonia. In this document, unless otherwise stated, semi-dry ammonia intends ammonia containing water in an amount of from about 0.2 wt% to about 0.5 wt%, such as about 0.4 wt% based of the total weight of the semi-dry ammonia, such as semi-dry liquid ammonia. The water content of the semi-dry liquid ammonia was determined in the same way as described in Example 1 B.

[0068] Example 1 B: Production of dry liquid ammonia

[0069] A rotavapor was used for distilling ammonia from an aqueous solution of ammonia wherein the concentration of ammonia was 32 vol%. The distillation was performed under nitrogen gas having a flow rate of 1200 mL / min.

[0070] 500 mL of the aqueous solution of ammonia was added to the rotary flask, which was contacted with the water bath. The distillation was performed at a temperature from 30 °C to 60 °C (i.e. , temperature of the water bath) and the cooling water of the condenser was kept at 6 °C. The ammonia at the top of the condenser (i.e., the top of the rotavap) was distilled at a steady rate ((i.e., leaving the condenser top at 6 °C) as observed using a bubble flask for monitoring. There were also noticeable amounts of water condensing on the condenser. The distilled ammonia gas was trapped using two consecutively mounted cold traps (2 round bottom 3-neck flasks), in a cooling bath comprising a mixture of acetone and carbon dioxide (dry ice) providing a temperature of -78 °C. The first cold trap was found to contain condensate while the second cold trap was substantially free from condensate as described above.

[0071] The 50 mL condensate of the first cold trap was evaporated at room temperature via a glass tube containing a NaOH pellets drying filter, i.e., a glass filter provided with 5 g of NaOH pellets , into a 3- necked flask immersed in a cooling bath comprising a mixture of acetone and carbon dioxide (dry ice) providing a temperature of -78 °C. In this way, water free liquid ammonia, i.e. dry liquid ammonia, was condensed into the 3-necked flask. The amount of water remaining in the first cold trap and being trapped by the drying filter was determined by weighing the first cold trap and the drying filter before and after use and was found to be 0.21 g. Thus, the water content of the liquid ammonia in the first cold trap, i.e. the semi-dry liquid ammonia described in example 1 A herein, was 0.42 wt%.

[0072] Example 2: Production of L13N from solid lithium, semi-dry ammonia and nitrogen gas

[0073] 50 mL of semi-dry liquid ammonia from an experiment similar to Example 1Awas kept in an ice bath, allowed to reach a temperature of 0 °C, was mixed with nitrogen gas, by flowing nitrogen through the 3-necked flask and the resulting mixture was led into a heated glass tube so that the ammonia / nitrogen gas mixture exiting the gas tube had a temperature from about 58 °C to 60 °C . The glass tube included a first glass frit provided with NaOH pellets (to remove water) and a second glass frit at the exit, provided with 0.30 g (43.2 mmol) of Li(s), i.e. solid lithium. The nitrogen flow rate was measured to be 170 mL / min. The 50 mL of ammonia was evaporated in one hour. The average concentration of the nitrogen gas in ammonia gas was calculated to be 14 vol%. The temperature of the glass frit provided with Li(s) was measured on the outside of the glass tube during the hour the ammonia / nitrogen was passed through it using an IR thermometer and found to be about 50-60 °C . A fluffy snow flake like material was formed on the Li(s) laying on the glass frit, which material had a weight of 0.33 g. Thus, the weight increase was 30 mg. Assuming that this weight increase is due to addition of nitrogen, via Li3N formation, this means that 2.14 mmol of nitrogen had been added to provide 2.14 mmol of LiaN corresponding to 75 mg of LiaN (the molecular weight of LiaN is 35.01). As the maximum amount of LiaN that may form from 0.30 g of Li (s) is 0.50 grams this means that the turnover for the formation of LiaN during the hour this reaction was performed was 15 %.

[0074] Scraping / dusting of this fluffy snow flake like material formed on the Li(s), on an filter paper in dry environment (desiccator cabinet), gave a greyish powder with no smell. When reacting this powder with a few drops of water on the filter paper, a characteristic smell of ammonia was detected.

[0075] It was concluded that LiaN could be formed from Li(s) and nitrogen gas in the presence of dry ammonia gas. It was also concluded that solid lithium in the presence of ammonia presented no problems.

[0076] Example 3: Reaction of L13N with wet ammonia gas

[0077] This experiment was performed in the same way as Example 1 A except that a glass frit provided with 0.45 grams of LiaN was placed between the rotary flask and the condenser (distance between glass frit and the rotary flask 15-20 cm; i.e., the saturated vapour leaving the rotary flask was almost immediately passed through the glass frit with the LiaN). The equipment was flushed with nitrogen gas during the reaction until the temperature of the water bath reached 40 °C. The temperature of the water bath was increased from 30 °C to 55 °C over 1 hour and 55 minutes as follows: at the time 15:00 h it was set to 30 °C and kept there for 20 min; then it was increased to 35 °C; at the time 16:00 h the temperature was set to 40 °C (N2 flow was removed); at the time 16:15 h the temperature was set to 45 °C; at the time 16:35 h the temperature was set to 50 °C; at the time 16:55 h the temperature was set to 55 °C. In total about 73 mL of wet ammonia gas flowed through the glass frit provided with 450 mg of LisN. The wet ammonia gas has a water content of approximately 3-12 vol% (vapour leaving between 35 and 55°C respectively), and hence that water should react with the LisN provided in its flow path.

[0078] It was observed that the glass frit provided with LisN had a temperature of about 27-30 °C while the temperature of the glass tube just before and after the glass frit had a temperature of only about 23- 25 °C, which is evidence of reaction between the LisN and the water into ammonia. The aforementioned temperature was measured using an IR thermometer. Further, the colour of the LisN (dark grey) changed into a lighter shade of grey, which is also evidence of a reaction of LisN and water into ammonia taking place. Scraping and weighing of the light grey LiOH formed on the glass frit provided an amount of LiOH corresponding to a yield of about 95 %. Thus, the reaction appeared to be complete.

[0079] It was concluded that LisN reacted with water in gaseous ammonia. Further, it was concluded that a high yield of ammonia was obtained despite the fact that the gaseous ammonia only contained a small percentage of water. Moreover, no formation of hydrogen gas was observed.

[0080] Example 4: Reaction of MgsN2 with wet ammonia gas

[0081] This experiment was performed in the same way as Example 3 except that a glass frit provided with 460 mg of MgsN2 was placed between the rotary flask and the condenser (distance between glass frit and the rotary flask 15-20 cm; i.e. the saturated vapour leaving the rotary flask was almost immediately passed through the glass frit with the MgalSb). The temperature of the water bath was increased from 30 °C to 50 °C over 1 .5 hours and the water saturated NH3 (3-12% water; 30-50 °C respectively) flowed through the glass frit provided with MgsN2 (dark grey). The colour of the material on the glass frit changed to become white-grey. The equipment was cooled and scraping the material off the glass frit provided 670 mg of Mg(OH)2 corresponding to a yield of 84 %.

[0082] The formation of Mg(OH)2 was taken as evidence for the formation of ammonia since reaction of MgaN2 with the water of the wet ammonia takes place according to the following equation: MgsN2 + 6H2O(g) => 3Mg(OH)2+ 2NH3.

[0083] It was concluded that MgsN2 reacted with water in gaseous ammonia. Further, it was concluded that a high yield of ammonia was obtained despite the fact that the gaseous ammonia only contained a small amount / percentage of water. Moreover, no formation of hydrogen gas was observed.

[0084] Example 5: Reaction of MgsN2 with water in liquid ammonia

[0085] In this experiment, semi-dry liquid ammonia was produced in accordance with Example 1 A. 460 mg of MgaN2 was added to 165 mL of semi-dry liquid ammonia at a temperature of -78 °C after which the reaction flask was allowed to reach room temperature, and the ammonia was d isti I led / e vaporated off over night, and trapped in a measurement cylinder kept upside down in a water beaker. After scraping the flask, 0.57 g of Mg(OH)2 was obtained (0.12 g of the same material was left in the reaction flask). This corresponds to a yield of 71.5% (in total 86,6% yield if including the Mg(OH)2 material left in the flask). There was no amount of gas measured in the measuring cylinder (all ammonia entering there was dissolved in the water, so no other gases were seen leaving).

[0086] It was concluded that MgaN2 reacted with water in liquid ammonia. Further, it was concluded that a high yield of ammonia was obtained despite the fact that the liquid ammonia only contained a very small amount of water. Moreover, no formation of hydrogen gas was observed, as evidenced by the absence of other gases observed in the measuring cylinder set up to detect them.

[0087] Example 6: Reaction of L13N with water in a mixture comprising liquid ammonia and THF

[0088] 200 mg of LiaN was added to 20 mL of dry ammonia at a temperature of- 30 °C to -40 °C, and during continued stirring 50 mL wet THF (i.e., 1 % of water in THF) was added dropwise. Any formed gases were let out via a tube, set up to capture the gas by using an upside down measuring cylinder in a water bath, but no gases were observed (any escaping / evaporating ammonia should dissolve in the water bath). There was a visible change in the appearance of the greyish solvent / solid phase (LiaN in a mixture of ammonia and THF) into a more white-coloured phase. The reaction mixture was allowed to reach room temperature, and again a water bath and upside down oriented measuring cylinder were used to measure gas formation. However, no gas formation was observed. The solid material was collected, dried and was concluded to be LiOH(s).

[0089] It was concluded that LiaN could react with water in ammonia, such as liquid ammonia in the presence of a solvent, such as THF.

[0090] Example 7: Reaction of MgsN2 with water at an electrode surface

[0091] To 30 mL of dry NHs(l) in a rectangular glass-jar (5x2 cm) at -30 °C was added 3 metallic spatulas with approximately 10 mg of MgaN2 in each spatula. The spatulas were separated by 10 mm - and the 2 outer spatulas were connected to + and - respectively of a 9 V battery using wires and clamps. The middle spatula was kept unconnected (floating) to any potential. Dipping the spatulas carefully, giving time for the powders to "wet" and resting them on the bottom of the jar resulted in that all MgaN2 was submerged and remained in the spatulas. The cooling bath was removed and the jar was allowed to slowly heat up - when ice on the outside was no longer formed it was assumed the jar was at around 0 °C and the experiment was started. The voltage (9 V) was switched on, between the two outer spatulas, and no visible reaction could be seen. Thereafter a wetted (with water) thick filter paper (4 cm wide filter paper piece) was submerged and in contact with the cathode and the anode and bubble formation from the middle spatula (not connected) and the spatula connected to the negative cathode was observed. The positive anode side was less prone to react, and no bubbles were observed. After approximately 1 minute bubble formation was noted at the positive anode. Then the bubble formation ceased - first at the negative cathode side then at the middle spatula and finally also at the positive anode side.

[0092] The above reaction and effect were also observed when slowly dripping water into the jar instead of using the wetted filter paper approach described above. Also, it was noted that by dripping water at one end of the yar, resulted in that the closest spatula reacted first (and then the next etc.). Also by faster dripping of the water, results in that the reaction was completed faster (with or without the voltage turned on) on each spatula.

[0093] It was concluded that it was possible to adjust the reaction speed by adjusting the protonating species movement (here water in a cellulosic matrix) in the liquid ammonia - and hence adjusting the speed of reaction. Thus, water addition and / or voltage adjustment allow(ed) for controlling the reaction speed and the location for the first reaction.

[0094] Example 8: Reaction of MgsN2 with water at high ammonia concentrations, supersaturation and at different temperatures

[0095] 50 mL of an aqueous saturated ammonia solution at room temperature (31 wt% of ammonia in water at 25 °C) in a beaker was cooled down to 0 °C using an ice bath. Semi-dry ammonia was then bubbled through the solution until it was saturated (approximately 48 wt% ammonia in water at 0 °C). The solution was split into 2 equal parts (Part A and Part B; see below) of around 30 mL each.

[0096] Part A: 500 mg of MgaN2 was added in small portions of about 10 mg to 30 mL of the above-mentioned solution at 0 °C in a beaker. It was observed that the MgaN2 changed colour from dark grey into white. Further, NHa(g) was found to leave the flask after being kept at 0 °C over night, as it was collected as semi-dry ammonia in a cold trap having a temperature of - 78 °C (CO2 in acetone). It was concluded that ammonia could be formed from nitrides, such as magnesium nitride reacting with water in a mixture of water and ammonia at a temperature of 0 °C.

[0097] A control experiment was performed using only 30 mL water, cooling it to 0 °C, and adding the 500 mg (in small 10 mg portions) of MgaN2 gave no trapped ammonia in the cold trap. Instead the cold water smelled of ammonia, so the ammonia stayed dissolved in the water. However, there was also visibly formation of gas which did not dissolve in water, which was assumed to be H2(g) due to the vigorous reaction with the water.

[0098] Part B: 30 ml of the above-mentioned solution (around 48% NH3 in water) was placed in a closed tube reactor and kept at 0 °C. To this solution was added a small portion of 50 mg of MgaN2 in a vial floating on the surface of the water / ammonia solution. The tube reactor was closed and allowed to reach room temperature (RT) (pressure built up inside, in the now super saturated ammonia / water). Thereafter, the tube was carefully shaken to enable the vial containing the MgaN2 to turn-over, sink and get to react with the super saturated water-ammonia. There was a fizzing sound but no noticeable temperature increase could be measured (IR thermometer used). The tube reactor was again cooled down to -30 °C and carefully dismantled. There was a whitish-grey solid in the tube, which provided evidence for the formation of Mg(OH)2. It was concluded that the MgaN2 reacted with the water in an saturated approximately 48% ammonia / water mixture at 0 degrees, and also in a supersaturated approximately 48% ammonia / water mixture at RT and elevated pressure.

[0099] Example 9: Comparing L13N reactivity in pure water, undersaturated and saturated ammonia water solution

[0100] A 32 wt% solution of ammonia in water, was diluted to 16 wt% by adding water by adding 50 g pure water to 50 g 32 wt% ammonia water mixture. 30 mL was taken from this solution and added into a beaker. 30 mL of the 32 wt% ammonia solution and pure water were added two other similar beakers, respectively. By carefully adding, with a small spatula, in total 0.20 g of LiaN into each of the beakers (10-15 mg portions were ’’sprinkled” into the solutions), the reactivity could be looked at, and compared. Addition to pure water. The 30 mL water solution almost every time reacted with sparks (small fires) and sometimes high sounds when ’’sprinkling” the LiaN into it. After adding the whole 0.20 g amount, the smell of the water was faint from ammonia in the water.

[0101] Addition to 32 wt% ammonia water: The 30 mL 32 wt% solution reacted more calmly at each portion LiaN added, and sometimes a little fizzy sound could be heard (but no sparks or high sounds). Also, while adding there was whiffs of ammonia that could be smelled further away from the beaker.

[0102] Addition to 16 wt% ammonia water. The reaction with the LiaN in 16 wt% ammonia water was less sluggish than the one with pure water, small fizzing sound was heard while sprinkling the lithium nitride into the beaker. However, if too much was dropped / sprinkled from the spatula sparks could be seen. Also, during the addition, whiffs of ammonia were possible to smell from further away from the beaker.

[0103] It was concluded that it was possible to achieve moderation of the reaction also at undersaturated (i.e., 16 wt%) ammonia water solutions. The moderation was not that pronounced as the moderation in the 32 wt% case, but resulted in a much smoother reaction than in pure water. Also, the evaporation of ammonia (i.e., moderation via vaporization, and liquid to vapour formation) in both the 32 wt% and 16 wt% case indicates that heat is dissipated.

[0104] Example 10: L13N reacting in a refrigerant solution with wetted mineral

[0105] A 250 mL 1 -necked bulb equipped with a magnetic stirrer was cooled down to -78°C (dry ice and acetone bath) and a refrigerant solution (Lighter gas 150 g from Biltema) containing a mixture of butane (45 %), isobutane (28%) and propane (26%) was slowly flushed through the bulb, to condensate the refrigerant solution (flushing stopped at around 50 mL condensed by visual inspection). 50 mg of LiaN(s) was added to the bulb and the bulb was then placed in an ice bath at 0°C and stirring started. 3.0 g of the mineral celite was mixed to a paste with 4.4 g of water, and added in 5 small portions to the bulb. The LiaN powder appeared to “stick to the wet celite pieces”, during stirring and reacted there. The LiaN powder also changed colour from dark-grey / black to lighter grey coloured. After 3 hours at 0°C, the bulb was allowed to reach room temperature over night, and in the morning the wet celite was taken out from the bulb. When pressing and smelling the celite paste, a faint smell of ammonia could be detected from it.

[0106] It was concluded that it was possible to achieve reaction between water and LiaN to ammonia in a refrigerant mixture by adding water in the form of a wet celite slurry. Also, it was concluded that the LiaN powder in the refrigerant mixture did not react before it got stuck to, or entered the water / celite phase / paste. The reaction was visibly also “calm” and not very vigorous.

[0107] Example 11 : LisN reacted in a refrigerant with wetted cellulose paper shreds

[0108] The same setup and procedure as in Example 10 were used. The only difference was that, instead of using a wetted celite paste, we here used a wetted cellulose filter paper. The cellulose filter was made by shredding 1 .6 g of a filter paper and adding 2.4 g of water that was sucked up by the filter paper shreds. The resulting wet pieces were added, in 5 portions, to the refrigerant mixture / LiaN slurry at 0°C. The LiaN powder (dark) appeared to “stick to the wet cellulose shreds / slurry” during stirring and reacted quickly. The LiaN powder changed colour from dark-grey / black to lighter grey colour. The bulb was allowed to reach room temperature overnight, and in the morning the wet paper-lump was taken out from the bulb. No visible powder or traces of LiOH could here be seen, and when pressing and smelling the water / paper lump, a faint small of ammonia could be detected from it. t was concluded that it was possible to achieve a reaction between water and LiaN into ammonia, in a refrigerant mixture by adding water in the form a wet cellulose filter paper. Also, it was concluded that the LiaN powder in the refrigerant mixture did not react before it got stuck to, or entered the water / cellulose phase / paste. The reaction was visibly quick, but not vigorous.

[0109] Example 12: L13N reacted into ammonia by continuous feeding to an ammonia water mixture 11.5 g of 32 wt% ammonia solution was added to two small beakers (4x4 cm). The beakers where both placed on a scale in the fume hood - but only one of them was placed on the on the scale’s measuring plate. The other one was placed just outside the measuring plate, in similar airflow as the one on the measuring plate, to provide a reference. 350mg LiaN was added during 4 minutes to the beakers on the scale’s measuring plate by slowly sprinkling small (10-15 mg) portions into it. The reaction of LiaN with the water in the 32 wt% ammonia water solutions proceed smoothly and the beaker was left 5 min on the scale to cool down. After this, the weight of the two beakers (the one reacted in and the reference) where measured. The reference had lost 0.55 g (5.2 %) of its liquid weight by just being in the fume hood airflow. The beaker, in which the reaction took place, had lost 0.80 g (7.0%) without correcting for the addition of 350 mg of lithium nitride. Correcting for this, it lost 1.15 g (10 %) of its weight of liquid. This means that 0.60 g more (roughly double the amount) of wet ammonia left the beaker, in which the reaction took place, compared to the reference beaker. It was concluded that it was possible to achieve smooth reaction in a saturated 32 wt% ammonia water solution, by reacting LiaN at room temperature and ambient pressure (1 bar), and that the ammonia produced (reached oversaturation) by the nitride reaction as well as the heat formed (evaporated ammonia water), led to increased evaporation speed of ammonia from the reaction beaker compared to the reference beaker.

[0110] Example 13: Mg2Ns and L13N reacted with ammonia methanol solution

[0111] A 7 N ammonia methanol solution was used together with a pure water free methanol solution as reference, to look at relative reactivities with and without ammonia methanol.

[0112] LisN in 7 N ammonia methanol

[0113] 0.20 g of LiaN was added to 30 mL of the 7 N ammonia methanol solution in small (10-15 mg) portions during several minutes. The reaction proceeded quickly, with fizzing sound, but no sparks were seen.

[0114] MgaN2 in 7 N ammonia methanol

[0115] .20 g of MgaN2 was added 30 mL of the 7 N ammonia methanol solution in small (10-15 mg) portions during several minutes. The reaction proceeded smoothly and no sparks were seen.

[0116] Methanol only reacting with LisN and Mg Ns as reference

[0117] 0.20g of MgaN2, and 0.20g of the LiaN, respectively, were added to two beakers with 30 mL of the pure methanol solution in small (10-15 mg) portions during several minutes. The reaction proceeded smoothly but now and then sparks were seen (this was when too large shanks dropped from the spatula while sprinkling).

[0118] It was concluded that it was possible to achieve smoother reaction in 7 N ammonia methanol solutions, with both the nitrides used (compared to pure methanol). Also, it appeared that the MgaN2 reacted more smoothly of the two nitrides. Also, it was concluded that the pure methanol solutions reacted themselves more smoothly than the pure water, see experiment done in Example 9 with pure water.

[0119] Example 14. Reaction of AIN(s) in an ammonia water solution

[0120] 0.50 g of AIN(s) (light grey / beige powder) was added to 30 mL of a 32 wt% ammonia water mixture cooled down to 0°C in a 50 mL tube reactor made of stainless steel. The cap was quickly screwed on to the tube reactor at 0°C, the tube was shaken and was allowed to reach room temperature. Again it was shaken, and the tube reactor was placed in an oven at 60°C for 3 hours, and then cooled back to room temperature (and shaken again). It was further cooled in an ice bath down to 0°C and the screw cap was removed. The slurry inside was dried first at room temperature over-night, and then in the oven at 60°C for 3 hours. The powder, now whitish grey, weighted to 0.89 g AI(OH)3 (93% yield).

[0121] It was concluded that it was possible to achieve a reaction in 32 wt% ammonia water solutions, with aluminium nitride (AIN), especially when heating to elevated temperatures, such as 60°C.

Claims

Claims1 . A method for manufacturing ammonia, the method comprising: providing a metal nitride; providing a refrigerant fluid, a proton donating compound and optionally one or more of the following: nitrogen gas, a solvent, and an additive; and combining the metal nitride, the refrigerant fluid, the proton donating compound and optionally the one or more of the following: nitrogen gas, the solvent, and the additive, whereby protonation of the metal nitride takes place to provide ammonia, a metal salt and / or metal hydroxide, and heat.

2. The method according to claim 1 , wherein the metal nitride is selected from the group consisting of LiaN, MgaN2, and any combination(s) thereof.

3. The method according to claim 2, wherein the metal nitride is LiaN.

4. The method according to any one of the preceding claims, wherein providing the refrigerant fluid, the proton donating compound and optionally the one or more of the following: nitrogen gas, the solvent, and the additive comprises providing a mixture comprising the refrigerant fluid, the proton donating compound and optionally the one or more of the following: nitrogen gas, the solvent, and the additive.

5. The method according to claim 4, wherein the mixture is a gas mixture or a liquid mixture.

6. The method according to any one of the preceding claims, wherein the refrigerant fluid is selected from the group consisting of ammonia, propane, isobutane, 2,3,3,3-tetrafluoropropene, carbon dioxide, difluoromethane, 1 ,1 ,1 ,2-tetrafluoroethane, pentafluoroethane, trichlorofluoroethane, dichlorofluoromethane, chlorodifluoromethane, 2,2-dichloro-1 ,1 ,1 -trifluoroethane and any combination thereof.

7. The method according to any one of the preceding claims, wherein the refrigerant fluid comprises, preferably consists of, ammonia.

8. The method according to any one of the preceding claims, wherein the proton donating compound comprises, preferably consists of, a Bronsted acid.

9. The method according to any one of the claims 1 to 7, wherein the proton donating compound is selected from the group consisting of water, alcohol, ammonium ion, a trialkyphosphonium cation or salt thereof, and any combination(s) thereof.

10. The method according to claim 9, wherein the proton donating compound comprises, preferably consists of, water.11 . The method according to any one of the preceding claims, wherein the solvent is a non-protic solvent, preferably selected from the group consisting of an ether, tetrahydrofuran (THF), sulfolane, hexane, dioxane, toluene, and any combination(s) thereof.

12. The method according to any one of the preceding claims, wherein the additive is selected from the group consisting of an ion conductivity improver, a solubility enhancer, a surfactant, a gas, and any combination(s) thereof.

13. The method according to any one of the preceding claims, wherein the metal nitride is selected from the group consisting of LiaN, MgaN, and any combination(s) thereof; and the mixture comprises, preferably consists of, a saturated or undersaturated solution of ammonia in water.

14. The method according to claim 13, wherein combining the metal nitride, the refrigerant fluid, the proton donating compound and optionally the one or more of the following: nitrogen gas, the solvent, and the additive is performed at a temperature from 55 °C to 210 °C and / or a pressure from 5 bar to 30 bar.

15. The method according to any one of the preceding claims, wherein combining the metal nitride, the refrigerant fluid, the proton donating compound and optionally the one or more of the following: nitrogen gas, the solvent, and the additive takes place in an electrochemical cell and / or in conjunction with a heat exchanger.

16. The method according to any one of the preceding claims, further comprising separating the produced ammonia.

17. The method according to claim 16, further comprising converting the ammonia into a chemical or fertilizer.

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