Ammonia production process

Abstract

The invention discloses a green electrochemical ammonia production method, which comprises a reduction reaction tank and an oxidation reaction tank which are separated by a proton conduction / permeable membrane, according to the method, an electrolyte containing metal salt capable of participating in electrochemical reaction, an aromatic mediator and an organic solvent is mainly utilized, and high-efficiency conversion from nitrogen to ammonia gas is realized under the conditions of normal temperature and normal pressure; the cathode is subjected to lithium deposition and nitrogen activation reaction, lithium nitride is generated through an aromatic mediator, and ammonia gas is released through protonation; the anode performs a hydroxide reaction to provide a continuous and stable proton source; the method has high selectivity, energy efficiency and modularization potential, can replace a traditional high-energy-consumption Harber method, and is widely applied to green manufacturing procedures of ammonia fuel, fertilizer and hydrogen storage carriers.

Description

Technical Field

[0001] This invention relates to a highly efficient green ammonia production method using electrochemical energy conversion technology, and particularly to a green ammonia production system and method for nitrogen reduction reaction (NRR) under ambient temperature and pressure conditions. Background Technology

[0002] Ammonia (NH3) is one of the most critical basic raw materials in modern chemical industry, with main applications covering fertilizer synthesis, biomass energy utilization, fine chemical preparation, and the production of pharmaceutical intermediates. Furthermore, due to its high volumetric energy density, easy liquefaction at room temperature and pressure, and convenient storage and transportation, ammonia is considered a highly promising hydrogen storage carrier in the hydrogen economy. A well-established global ammonia transportation and storage infrastructure enables ammonia to play a vital role in energy transition and renewable energy utilization. Especially in the development of zero-carbon fuels, ammonia can be directly used for combustion power generation or as marine fuel, becoming an important option for energy diversification.

[0003] However, currently, over 90% of the world's ammonia production still relies on the Haber-Bosch process. This method requires extremely high pressure and temperature, and uses hydrogen sourced from the steam reforming reaction of fossil fuels. These stringent reaction conditions result in enormous energy consumption, posing a significant challenge to global carbon neutrality and energy transition. Because this process is highly dependent on centralized, large-scale chemical plants, it lacks the flexibility of decentralized production, hindering the future promotion of green energy applications.

[0004] Electrochemical nitrogen reduction reaction (e-NRR) is considered an important alternative to the Haber process. This method directly reduces nitrogen molecules to ammonia using external electrical energy. Theoretically, it can be carried out at room temperature and atmospheric pressure and can be coupled with renewable energy power generation such as solar and wind power to achieve ammonia production with low or even zero carbon emissions. However, current e-NRR technology still faces significant bottlenecks. First, the triple bond of the nitrogen molecule is extremely stable and difficult to activate, resulting in a low reduction reaction rate. Second, the hydrogen evolution reaction (HER) often competes with NRR for electrons and protons, leading to low ammonia production efficiency and difficulty in obtaining high-purity and highly selective products. Furthermore, the electrolytes or solvents commonly used in existing technologies suffer from insufficient stability, causing instability in the reaction system during long-term operation and thus affecting yield and purity.

[0005] In recent years, numerous improvement schemes have been proposed internationally for novel catalysts and reaction designs. For example, transition metal complexes, such as molybdenum or ruthenium coordination compounds, are used as catalysts to improve nitrogen activation efficiency through molecular design; rare earth metal-carbon-based binders are also introduced into the cathode structure to improve the electron transport characteristics of the reaction field. However, these designs often still rely on complex solid-state catalytic materials, and their energy efficiency and durability are difficult to meet the requirements of practical applications.

[0006] Therefore, how to achieve efficient electrochemical synthesis of ammonia at room temperature and pressure, while possessing stability, modularity, and low carbon characteristics, has become a pressing technical problem to be solved globally. Summary of the Invention

[0007] To address the existing problems of high energy consumption, poor stability, and insufficient yield and purity in the Haber process, this invention proposes a dual-cell electrolysis design that combines an aromatic mediator with a metal salt and an organic solvent that can participate in the electrochemical reaction to form a soluble electron transfer medium. This design, combined with a hydrogenation reaction to provide a stable proton source, overcomes the shortcomings of traditional electrochemical nitrogen reduction reactions and opens up new opportunities for green ammonia production technology.

[0008] This invention provides a green ammonia production method achieved by an electrochemical reaction device;

[0009] The steps of this highly efficient green ammonia production method based on a proton source from a hydroxide reaction include:

[0010] Step S1: Nitrogen gas is introduced into the cathode reaction cell and brought into contact with the electrolyte; the electrolyte contains a metal salt (M salt) that can participate in the electrochemical reaction, an organic solvent, and an aromatic mediator;

[0011] Step S2: After applying electrical energy / voltage, a reduction deposition reaction occurs on the cathode surface, reducing the metal salt (Msalt) to metal (M) and depositing it. The reaction formula is as follows (1): M + +e - →M…Formula (1); M is the metal in the metal salt;

[0012] Step S3: The deposited metal then reacts with the aromatic intermediary in the electrolyte to form a soluble metal-aromatic complex intermediate, as shown in the following formula (2): M + X → MX… formula (2); where X is the aromatic intermediary;

[0013] Step S4: The soluble metal-aromatic complex intermediate further reacts with the nitrogen gas introduced in step 1 to generate metal nitride (MN), and the reaction formula is as follows (3): MX + N2 → MN + X… formula (3); where X is the aromatic intermediate;

[0014] Step S5: After lithium nitride gains a proton, it produces ammonia gas, as shown in equation (4): MN + H + →NH3(s)+M + …Equation (4); and

[0015] Step S6: Hydrogen gas undergoes an oxidation reaction at the anode to generate protons and electrons, and then passes through the proton conduction / permeability membrane to the cathode reaction cell to carry out the aforementioned reaction, as shown in equation (5): H2→2H + +2e - …Formula (5).

[0016] The electrochemical reaction device includes a cathode disposed in a cathode reaction tank and immersed in an electrolyte, and an anode. The cathode and the anode are connected by a proton conduction / permeability membrane phase and are electrically connected to each other. The cathode reaction tank is provided with a cathode gas inlet and a cathode gas outlet. The anode is provided with an anode gas inlet and an anode gas outlet. Alternatively, the anode may be attached to the proton conduction / permeability membrane.

[0017] Among them, the metal salts that can participate in electrochemical reactions include group 1A or 2A metal salts; among them, group 1A metal salts include lithium perchlorate (LiClO4), lithium boron difluoride (LiBF4), lithium trifluoromethanesulfonyl imide (LiTFSI), lithium hexafluorophosphate (LiPF6), lithium difluorosulfinyl imide (LiFSI), lithium bis(oxalatoborate) (LiBOB), sodium trifluoromethanesulfonate (NaOTf), sodium perchlorate (NaClO4) or sodium hexafluorophosphate (NaPF6); and group 2A metal salts include calcium salts.

[0018] The proton conduction / permeability membrane comprises a fluorosulfonic acid resin membrane, a high-temperature proton conduction membrane, an inorganic composite membrane, or a basic ion exchange membrane. The fluorosulfonic acid resin membrane comprises a perfluorosulfonic acid resin membrane or a partially fluorinated sulfonic acid resin membrane.

[0019] The solvents include tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), acetone, diethylene glycol dimethyl ether (Diglyme), propylene carbonate (Propylene Carbonate), dimethylformamide (DMF), 1,2-dimethoxyethane (DME), 1,4-dioxane (1,4-Dioxane), 2-methyltetrahydrofuran (2-MeTHF), N,N-diethylacetamide (N,N-Diethylacetamide), N-methylformamide (N-Methylformamide), N,N-diethylformamide (N,N-Diethylformamide), ethylene glycol dimethyl ether series (Glymes), γ-butyrolactone, acetonitrile (Acetonitrile), diethyl ether (Diethyl ether), trimethyl phosphate (Trimethyl Phosphate), and ethylene sulfoxide (Ethylene sulfoxide). Sulfite, diethylene glycol dimethyl ether (DEGDME), THF / n-hexane mixed solvents or mixed solvents thereof.

[0020] The aromatic mediators include naphthalene, anthracene, phenanthrene, pyrene, and fullerene. 60 Biphenyl, fluorene, benzoquinone, benzophenone, or combinations thereof.

[0021] Among them, benzoquinone includes 1,4-benzoquinone; and biphenyl includes 4,4′-di-tert-butylbiphenyl (DTBB).

[0022] The cathode is made of copper, nickel, silver, stainless steel or molybdenum foam, mesh, cloth, sheet or plate; the anode is made of platinum, platinum-modified titanium or platinum-gold alloy foam, mesh, cloth, sheet or plate.

[0023] As can be seen from the above description, the present invention has the following beneficial effects and advantages:

[0024] 1. Ammonia production is carried out efficiently at normal temperature and pressure, reducing energy consumption and carbon emissions.

[0025] Traditional Haber processes require extremely high temperatures and pressures, resulting in massive energy demands and often relying on fossil fuels for hydrogen production, further contributing to significant carbon dioxide emissions. This invention utilizes an electrochemical, metal-mediated nitrogen reduction reaction, combined with aromatic intermediates as electron transfer carriers, to effectively activate and reduce nitrogen to ammonia at ambient temperature and pressure, completely eliminating the need for high-pressure vessels and high-temperature reactors in traditional processes. This not only significantly reduces energy consumption but also enhances system safety and ease of operation. More importantly, because this invention can be directly coupled with renewable energy sources such as geothermal, solar, or wind power, its ammonia production process has virtually zero carbon emissions, contributing to a practical and feasible green alternative in response to the global trend towards net-zero carbon emissions and energy transition.

[0026] 2. Enhancing Reaction Selectivity and Stability by Combining Aromatic Intermediates with Electrochemically Reacting Metal Salts: In existing electrochemical ammonia production studies, the hydrogen evolution reaction (HER) often competes with the nitrogen reduction reaction (NRR) for electrons and protons, resulting in low ammonia generation efficiency that fails to meet the requirements of industrial applications. This invention utilizes aromatic intermediaries (such as naphthalene, anthracene, or pyrene) to form stable, soluble intermediates with electrochemically reacting metal ions. Through a stepwise electron transfer and protonation mechanism, it effectively enhances the activation efficiency of nitrogen and avoids sacrificial solvent or metal ion side reactions. Furthermore, this intermediary mechanism stabilizes the electrochemically reacting metal deposition and the metal nitride compounds formed by its reaction with nitrogen, ensuring continuous stability of the reaction process and preventing performance degradation due to solvent decomposition or catalyst deactivation. This design not only enhances reaction selectivity but also significantly improves system durability, enabling long-term continuous operation and meeting the needs of the energy chemical industry.

[0027] 3. Possesses modular design potential and wide application.

[0028] Compared to the Haber process in centralized large-scale chemical plants, the system proposed in this invention employs a dual-cell electrolysis structure and achieves effective separation of the reactions through proton conduction / permeability membranes. This not only ensures that nitrogen reduction and hydrogen oxidation reactions occur in independent environments but also gives the overall device the potential for modularization, allowing for stacking or combination according to demand. Compared to traditional industrial production, this invention is more flexible and portable, reducing construction and transportation costs and enhancing local energy autonomy. This modular and decentralized application model will enable ammonia energy to play a broader role in the future energy market and become an important hub linking renewable energy and the hydrogen economy. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are merely some examples or embodiments of the present invention and are not intended to absolutely limit the technical scope of the present invention. Unless obvious from the context or otherwise stated, the same reference numerals in the drawings represent the same structures or operations. Wherein:

[0030] Figure 1A , 1B This is a schematic diagram of a preferred embodiment of the system of the present invention.

[0031] Figure 2 This is a flowchart of the method steps of the present invention.

[0032] Figure 3 , Figure 4 This invention provides a preferred embodiment and a comparative example of ultraviolet-visible absorption spectroscopy (UV-Vis) detection and quantitative analysis.

[0033] Symbol explanation:

[0034] 100 Electrochemical Reaction Device

[0035] 10 Electrolyte

[0036] 20 Proton conduction / permeability membrane

[0037] 30 Cathode Reactor

[0038] 31 Cathode

[0039] 32 Cathode Gas Inlet

[0040] 33 Cathode Gas Outlet

[0041] 40 Anode Reaction Tank

[0042] 41 Anode

[0043] 42 Anode Gas Inlet

[0044] 43 Anode gas outlet

[0045] Steps S1-S6 Detailed Implementation

[0046] The present invention will be described and illustrated in detail below with reference to several preferred embodiments. The accompanying drawings are merely some exemplary representations or embodiments of the present invention. Those skilled in the art can apply the present invention to other similar situations without making any further efforts.

[0047] The terms “system,” “apparatus,” “unit,” and / or “module” used in this invention are to distinguish different components, elements, parts, sections, or assemblies at different levels. However, if other terms can achieve the same purpose, they may be replaced by other expressions. As illustrated in this invention, unless the context clearly indicates otherwise, words such as “a,” “an,” “an,” and / or “the” do not specifically refer to the singular and may also include the plural. Generally, the terms “comprising” and “including” only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0048] This invention uses flowcharts to illustrate the operations performed by the system according to embodiments of the invention. It should be understood that the preceding or following operations are not necessarily performed precisely in sequence. Instead, the steps can be processed in reverse order or simultaneously. Furthermore, other operations can be added to these processes, or one or more steps can be removed from them.

[0049] Please refer to Figure 1A A preferred schematic diagram of the system used in the high-efficiency green ammonia production method based on the proton source of the hydroxide reaction of the present invention.

[0050] The method of the present invention is achieved by an electrochemical reaction apparatus 100. The electrochemical reaction apparatus 100 contains an electrolyte 10 and is separated into a cathode reaction tank 30 and an anode reaction tank 40 by a proton-conducting / permeable membrane 20. The reactions in the two tanks can proceed separately, avoiding interference from side reactions and ensuring high selectivity and purity of the product ammonia. A cathode 31 is disposed in the cathode reaction tank 30 and immersed in the electrolyte 10, and an anode 41 is disposed in the anode reaction tank 40 and immersed in the electrolyte 10. The cathode 31 and the anode 41 are electrically connected to each other. The cathode reaction tank 30 has a cathode gas inlet 32 ​​on its bottom side and a cathode gas outlet 33 on its top side; the anode reaction tank 40 has an anode gas inlet 42 on its bottom side and an anode gas outlet 43 on its top side.

[0051] The proton conduction / permeability membrane 20 in this invention preferably comprises a fluorosulfonic acid resin membrane, a high-temperature proton exchange membrane (PEM), an inorganic composite membrane (including silicon-containing or aluminum-containing composite membranes), or an alkaline / anion exchange membrane (AEM). The fluorosulfonic acid resin membrane comprises a perfluorosulfonic acid resin membrane (Nafion membrane) or a partially fluorinated sulfonic acid resin membrane.

[0052] like Figure 1BAs shown, the second preferred embodiment of the electrochemical reaction device 100 is basically the same as the first preferred embodiment described above, except that the anode 41 is directly attached to the proton conduction / permeability membrane 20, forming an integrated electrode-membrane combination structure, replacing the traditional anode reaction tank design that requires a liquid electrolysis environment. In this structure, the anode 41 is attached to the surface of the proton conduction / permeability membrane 20 to generate protons and electrons through a dry or wet oxidation reaction. The protons are directly conducted to the cathode reaction tank through the proton conduction membrane. The membrane has both high proton conductivity and gas barrier properties, so that the anode area does not need to be filled with liquid electrolyte to carry out the electrochemical reaction.

[0053] Furthermore, the integrated structure of the anode 41 and membrane offers several advantages in engineering applications. First, the liquid-free anode reaction tank 40 effectively avoids compositional changes caused by oxidation or evaporation during long-term operation of traditional anode electrolytes. Second, the overall system is more compact, reducing the liquid tank and piping configuration, thus lowering the device's size and weight. Third, the liquid-free environment prevents reaction products from seeping back or contaminating the membrane surface, thereby extending the lifespan of the proton conduction / permeability membrane 20. This design allows for direct connection to a hydrogen source without requiring additional electrolyte maintenance and treatment procedures.

[0054] like Figure 2 As shown, the method steps of the present invention include:

[0055] Step S1: Nitrogen gas (N2) is introduced into the cathode reaction tank 30 through the cathode gas inlet 32 ​​and comes into contact with the electrolyte 10. The electrolyte 10 contains metal salts, organic solvents, and aromatic mediators that can participate in the electrochemical reaction.

[0056] Preferred metal salts capable of participating in electrochemical reactions include Group 1A or Group 1A metal salts with high solubility and stability. Group 1A includes, but is not limited to, lithium salts, potassium salts, or sodium salts. For example, lithium salts include lithium perchlorate (LiClO4), lithium boron difluoride (LiBF4), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF6), lithium bis(fluorosulfinyl)imide (LiFSI), or lithium bis(oxalatoborate) (LiBOB). Sodium salts include sodium trifluoromethanesulfonate (NaOTf), sodium perchlorate (NaClO4), or sodium hexafluorophosphate (NaPF6). Group 2A includes calcium salts.

[0057] The solvents include tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), acetone, diethylene glycol dimethyl ether (Diglyme), propylene carbonate (Propylene Carbonate), dimethylformamide (DMF), 1,2-dimethoxyethane (DME), 1,4-dioxane (1,4-Dioxane), 2-methyltetrahydrofuran (2-MeTHF), N,N-diethylacetamide (N,N-Diethylacetamide), N-methylformamide (N,N-Diethylformamide), ethylene glycol dimethyl ether series (Glymes), γ-butyrolactone, acetonitrile (Acetonitrile), diethyl ether (Diethyl ether), trimethyl phosphate (Trimethyl Phosphate), and ethylene sulfoxide (Ethylene sulfoxide). Sulfite, diethylene glycol dimethyl ether (DEGDME), THF / n-hexane mixed solvents or mixed solvents thereof.

[0058] The aromatic mediators include naphthalene, anthracene, phenanthrene, pyrene, and fullerene. 60 Naphthalene, biphenyl, fluorene, benzoquinone, benzophenone, or combinations thereof, wherein naphthalene is particularly preferred due to its stable π-conjugated structure. The organic solvent comprises water, alcohol, or acetone. Benzoquinone includes, for example, 1,4-benzoquinone; biphenyl includes 4,4′-di-tert-butylbiphenyl (DTBB).

[0059] The cathode 31 is preferably made of a porous structure with high surface area and good conductivity, such as foam, mesh, cloth, sheet, or plate made of carbon, copper, nickel, silver, stainless steel, or molybdenum. Copper foam or stainless steel mesh is preferred because it combines high mechanical strength with low cost.

[0060] Step S2: Under the application of external electrical energy / voltage, the metal ions (M) in the metal salt that can participate in the electrochemical reaction in the cathode 31 +First, a reduction deposition reaction occurs on the surface of the cathode 31 to form metal (M), as shown in the following equation (1):

[0061] M + (aq)+e - (aq)→M(s)…Formula (1);

[0062] Step S3: The deposited metal then reacts with the aromatic intermediate (X, such as Naphthalene) in the electrolyte 10 to generate a soluble metal-aromatic complex intermediate (MX), as shown in equation (2):

[0063] M(s)+X(aq)→MX(aq)…Equation (2); X is the aromatic mediator;

[0064] Step S4: This soluble metal-aromatic complex intermediate further reacts with the nitrogen molecules introduced in step 1, promoting the activation of nitrogen and generating metal nitride (MN), as shown in the following equation (3):

[0065] MX(aq) + N2(g) → MN(aq) + X(aq) … Equation (3); X is the aromatic mediator;

[0066] Step S5: After lithium nitride gains a proton, it produces high-purity ammonia gas, which can be discharged and collected from the cathode gas outlet 33, as shown in equation (4):

[0067] MN(aq)+H + (aq)→NH3(g)+M + (aq)…Formula (4);

[0068] In the aforementioned reaction process, the lithium-aromatic complex intermediate formed by the lithium salt and aromatic intermediary remains in the electrolyte after the nitrogen reduction reaction and is not permanently consumed. This intermediate can be reactivated into a reactive state through a subsequent electrochemical reactivation process, and then participate in the lithium deposition and nitrogen activation processes again in the next cycle. This reversible recycling mechanism allows the overall system to maintain stable reaction efficiency without frequent replenishment of lithium salt or aromatic intermediary during long-term operation. In addition, this recyclability significantly reduces raw material consumption and operating costs, and avoids the impact of changes in electrolyte composition on reaction reproducibility. Through this reversible electron transfer mechanism of lithium-aromatic intermediary, this invention not only possesses high selectivity and high energy efficiency, but also exhibits the sustainable characteristics of resource reuse in green chemistry processes, improving the economic efficiency and environmental friendliness of the system in practical industrial applications.

[0069] Step S6: Hydrogen gas is introduced into the anode gas inlet 42. The hydrogen gas undergoes an oxidation reaction at the anode 41 to generate protons and electrons, which then pass through the proton conduction / permeability membrane 20 to the cathode reaction tank 30 to carry out the aforementioned reaction. After being reduced back to hydrogen gas, it is discharged from the anode gas outlet 43. The reaction formula is as follows (5):

[0070] H2(g)→2H + (aq)+2e - (aq)…Formula (5);

[0071] The anode reactor 40 is continuously supplied with hydrogen (H2) and uses the anode 41, which has high catalytic activity and high porosity, to carry out the hydrogen oxidation reaction (HOR). Preferably, the anode 41 is made of a foam, mesh, cloth, sheet, or plate containing platinum, platinum-modified titanium, platinum-modified stainless steel, platinum-gold alloy, or other precious metal materials with high catalytic efficiency, and preferably has a porosity of 30 μm.

[0072] The protons generated at anode 41 are transferred to cathode reactor 30 via proton conduction / permeability membrane 20, participating in the protonation reaction of lithium nitride to complete the high-purity ammonia (NH3) generation cycle. This invention ensures a stable proton source in the electrochemical reaction and avoids the instability problems of sacrificial solvents in traditional electrolytes. The proton conduction / permeability membrane 20 has good proton conductivity and chemical stability, ensuring effective proton transfer and preventing gas cross-permeation. Through the above design, the system of this invention can operate stably at room temperature and atmospheric pressure, and the generated ammonia can be directly output without additional gas separation procedures. Compared to the traditional Haber process, this invention significantly reduces energy consumption, realizing a green ammonia production system.

[0073] <Preferred Embodiment>

[0074] A preferred embodiment of the present invention is that the metal salt capable of participating in the electrochemical reaction comprises a lithium metal salt, and the corresponding reaction equation is as follows:

[0075] In the cathode reaction cell 30:

[0076] Li+(aq)+e - (aq)→Li(s)…Formula (1);

[0077] Li(s) + X(aq) → LiX(aq) … Equation (2); X is the aromatic mediator;

[0078] 6LiX(aq)+N2(g)→2Li3N(aq)+6X(aq)…Equation (3); X is the aromatic mediator;

[0079] Li3N(aq) + H+ (aq)→NH3(g)+3Li+(aq)…Formula (4);

[0080] In the anode reaction tank 40:

[0081] H2(g)→2H + (aq)+2e - (aq)…Formula (5).

[0082] Preferably, this embodiment is carried out under normal temperature and pressure conditions. The operating voltage range is set to 2.5 to 4.5 volts (V), corresponding to a cathode potential range of approximately –2.5V to –3.5V (relative to the reference electrode), and an anode potential in the range of 0 to 1.5V. The current is controlled within the range of 5mA to 20mA, thereby ensuring both stability and energy efficiency in the reaction process.

[0083] <Validity Test>

[0084] To verify the feasibility of the green electrochemical ammonia production system of the present invention and its ability to generate ammonia at room temperature and pressure, ultraviolet-visible absorption spectroscopy (UV-Vis) detection and quantitative analysis of the preferred embodiment were carried out.

[0085] first, Figure 3 Table 1 below shows the absorption spectra and calibration curves of ammonia standard solutions at different concentrations (0–50 ppm). The test results clearly show a good linear relationship between absorbance and ammonia concentration, with a regression coefficient (R²) exceeding 0.997, proving that the method of this invention can accurately measure the ammonia content in the solution. This result establishes a quantitative detection benchmark for ammonia concentration, providing a reliable analytical basis for subsequent verification of ammonia production in the reaction system.

[0086] Table 1.

[0087] equation y = a + b*x Plot M Weight Unweighted Intercept 0.32616±0.0224 Slope 0.03189±7.38202E Residual Sum of Squares 0.00332 Pearson's correlation coefficient 0.99893 <![CDATA[Coefficient of determination (R 2 , COD)]]> 0.99786 Adjusted coefficient of determination (Adj.R-Square) 0.99733

[0088] Figure 4 The images show the spectral signals obtained under the same operating conditions in the embodiments of the present invention, where hydrogen and nitrogen were simultaneously introduced, and an aromatic mediator, Naphthalene, was added, as well as in the comparative example (without the aromatic mediator). It can be seen that a significant absorption peak appears in the solution near 420 nm after the reaction, and its intensity matches the aforementioned standard ammonia solution curve, confirming that the present invention can indeed successfully reduce nitrogen to ammonia at room temperature and pressure. This absorption signal not only matches the standard ammonia spectrum but also indicates that the aromatic mediator effectively participates in electron transfer during the reaction and promotes nitrogen activation and subsequent ammonia formation.

[0089] Please refer to Table 2 below for a comparison between the preferred embodiment and the comparative example (without the addition of the aromatic mediator).

[0090] Table 2.

[0091]

[0092] Therefore, the above-described technical solution of the present invention demonstrates its feasibility and significant effectiveness. Spectroscopic analysis results show that this system can not only stably generate ammonia, but also precisely quantify the amount produced, further highlighting its green process advantages compared to the traditional high-energy-consuming Haber process.

[0093] In some embodiments, numbers describing the quantity of components and attributes are used. It should be understood that such numbers used in the description of embodiments are modified in some examples with the terms "approximately," "approximately," or "generally." Unless otherwise stated, "approximately," "approximately," or "generally" indicates that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may be changed depending on the characteristics required by individual embodiments. In some embodiments, numerical parameters should take into account specified significant digits and employ a general method of digit reservation. Although the numerical ranges and parameters used to confirm their breadth of scope in some embodiments of the invention are approximate values, in specific embodiments, such values ​​are set as precisely as feasible.

[0094] Finally, it should be understood that the embodiments described in this invention are merely illustrative of the principles of the invention. Other modifications may also fall within the scope of this invention. Therefore, alternative configurations of the embodiments of this invention are considered as examples and not limitations, and are regarded as consistent with the teachings of this invention. Accordingly, the embodiments of this invention are not limited to those explicitly described and illustrated herein.

Claims

1. A method for producing ammonia, characterized in that, The ammonia production method is achieved by an electrochemical reaction device; wherein: The electrochemical reaction device includes a cathode disposed in a cathode reaction tank and immersed in an electrolyte, and an anode. The cathode and the anode are connected by a proton conducting / permeable membrane phase and are electrically connected to each other. The cathode reaction tank is provided with a cathode gas inlet and a cathode gas outlet. The anode is provided with an anode gas inlet and an anode gas outlet. The steps of this ammonia production method include: Step S1: Nitrogen gas is introduced into the cathode reaction tank through the cathode gas inlet and comes into contact with the electrolyte; the electrolyte contains metal salts, organic solvents and aromatic mediators that can participate in the electrochemical reaction. Step S2: After applying electrical energy / voltage, a reduction deposition reaction occurs on the cathode surface, causing the metal salt that can participate in the electrochemical reaction to be deposited as metal (M), as shown in the following equation (1): M + +e - →M(s)…Equation (1); Step S3: The deposited metal then reacts with the aromatic intermediate in the electrolyte to form a soluble metal-aromatic complex intermediate, as shown in equation (2): M+X→MX…Equation (2); where X is the aromatic mediator; Step S4: The soluble metal-aromatic complex intermediate further reacts with the nitrogen gas introduced in step 1 to generate metal nitride (MN), and the reaction formula is as follows (3): MX+N2→MN+X…Equation (3); where X is the aromatic mediator; Step S5: After the metal nitride gains a proton, it generates ammonia gas, which is discharged from the cathode gas outlet as shown in equation (4): MN+H + →NH3(s)+M + …Equation (4); and Step S6: Hydrogen gas is introduced into the anode gas inlet and undergoes an oxidation reaction at the anode to generate protons and electrons. After passing through the proton conduction / permeability membrane, the gas proceeds to the cathode reaction cell to carry out the aforementioned reaction. The reaction formula is as follows (5): H2→2H + +2e - …Formula (5).

2. The ammonia production method as described in claim 1, characterized in that, The electrochemical reaction device contains an electrolyte and is separated into a cathode reaction tank and an anode reaction tank by a proton conduction / permeability membrane. The cathode is disposed in the cathode reaction tank and immersed in the electrolyte, and the anode is disposed in the anode reaction tank and immersed in the electrolyte. The cathode and the anode are electrically connected to each other.

3. The ammonia production method as described in claim 1, characterized in that, The anode is attached to the proton conduction / permeability membrane to generate protons and electrons through a dry or wet oxidation reaction. The protons are then directly conducted to the cathode reaction cell via the proton conduction membrane.

4. The ammonia production method according to claim 1, characterized in that, In step S6, the remaining hydrogen gas is either discharged from the anode gas outlet or returned to the anode gas inlet.

5. The ammonia production method as described in claim 1, characterized in that, Metal salts that can participate in electrochemical reactions include group 1A or 2A metal salts.

6. The ammonia production method as described in claim 5, characterized in that, Group 1A metal salts include lithium perchlorate (LiClO4), lithium boron difluoride (LiBF4), lithium trifluoromethanesulfonyl imide (LiTFSI), lithium hexafluorophosphate (LiPF6), lithium difluorosulfinyl imide (LiFSI), lithium bis(oxalatoborate) (LiBOB), sodium trifluoromethanesulfonate (NaOTf), sodium perchlorate (NaClO4), or sodium hexafluorophosphate (NaPF6); and Group 2A metal salts include calcium salts.

7. The ammonia production method according to claim 1, characterized in that, The proton conduction / permeability membrane includes a fluorosulfonic acid resin membrane, a high-temperature proton conduction membrane, an inorganic composite membrane, or an alkaline ion exchange membrane.

8. The ammonia production method as described in claim 7, characterized in that, The fluorosulfonic acid resin membrane includes a perfluorosulfonic acid resin membrane or a partially fluorinated sulfonic acid resin membrane.

9. The ammonia production method according to claim 1, characterized in that, The organic solvents include tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), acetone, diethylene glycol dimethyl ether (Diglyme), propylene carbonate (Propylene Carbonate), dimethylformamide (DMF), 1,2-dimethoxyethane (DME), 1,4-dioxane (1,4-Dioxane), 2-methyltetrahydrofuran (2-MeTHF), N,N-diethylacetamide (N,N-Diethylacetamide), N-methylformamide (N,N-Diethylformamide), ethylene glycol dimethyl ether series (Glymes), γ-butyrolactone, acetonitrile (Acetonitrile), diethyl ether (Diethyl ether), trimethyl phosphate (Trimethyl Phosphate), and ethylene sulfoxide (Ethylene sulfoxide). Sulfite, diethylene glycol dimethyl ether (DEGDME), THF / n-hexane mixed solvents or mixed solvents thereof.

10. The ammonia production method according to claim 1, characterized in that, This aromatic intermediate includes naphthalene, anthracene, phenanthrene, pyrene, and fullerene. 60 Biphenyl, fluorene, benzoquinone, benzophenone, or combinations thereof.

11. The ammonia production method according to claim 10, characterized in that, Benzoquinone includes 1,4-benzoquinone; and biphenyl includes 4,4′-di-tert-butylbiphenyl (DTBB).

12. The ammonia production method according to any one of claims 1-11, characterized in that, The cathode material includes foam, mesh, cloth, sheet, or plate made of carbon, copper, nickel, silver, stainless steel, or molybdenum.

13. The ammonia production method according to any one of claims 1-10, characterized in that, The anode material includes platinum, platinum-modified titanium, platinum-modified stainless steel, or platinum-gold alloy foam, mesh, cloth, sheet, or plate.

Images