Methods and systems for synthesis using an underwater electrical arc

Abstract

Methods and systems for synthesis using an underwater electric arc. Such methods and systems form an electrical arc between an anode and a cathode positioned under water or within an aqueous mist and introduce an added material into the vicinity of the electrical arc. The formation of the electrical arc in the vicinity of the added material facilitates synthesis of chemical products from the added material. Such synthesized chemical products include ammonia, hydrogen, cyanide, and hydrogen cyanide.

Description

METHODS AND SYSTEMS FOR SYNTHESIS USING AN UNDERWATER ELECTRICAL ARCCROSS-REFERENCE TO RELATED PATENT APPLICATIONS

[0001] The application claims priority to U.S. Patent Appl. Serial No. 63 / 555,283, filed February 19, 2024, entitled “Methods And Systems For Synthesis Using An Underwater Electrical Arc,” to James M. Tour, et al., which application is commonly owned by the owner of the present invention and is incorporated herein in its entirety.TECHNICAL FIELD

[0002] The present invention relates to methods and systems for synthesis using an underwater electric arc. In particular, the invention relates to the selective synthesis of ammonia or other inorganic soluble nitrogen species, such as for example cyanide and nitrite, by flowing gas, including, but not limited to, nitrogen, air, or a combination thereof, through an electric arc underwater. The invention also relates to the synthesis of hydrogen gas in an underwater electric arc. The invention also relates to the synthesis of liquids or polymers from the reaction of carbon dioxide in an underwater electric arc.GOVERNMENT INTEREST

[0003] This invention was made with government support under Grant No. FA9550-22-1- 0526, awarded by the Air Force Office of Scientific Research, and Grant Nos. W912HZ-21-2- 0050 and W912HZ-24-2-0027, ERDC Army Corps of Engineers. The United States government has certain rights in the invention.SUMMARY OF THE INVENTION

[0004] The present invention relates to methods and systems for synthesis using an underwater electric arc. In some embodiments of the present invention, selectivity for a given nitrogen species can be tuned by replacing the electrode material in the water in combination with changing the input gas between nitrogen and air. In such an embodiment, the majority ofinorganic nitrogen products remain dissolved in aqueous phase inside the reactor for facile separation.

[0005] An electric arc, interchangeably referred to as an arc discharge herein, is a channel of ionized plasma which forms between two electrodes under sufficiently strong electric fields. Substances which normally serve as resistive media, including dispersed gas or water, can form an electric arc if the electric field exceeds the dielectric strength of the substance (about 65 kV / mm in the case of deionized water). [Jones 1995}. The resistance of an electric arc effectively drops to zero, and the temperature of the plasma can exceed 5000 °C.

[0006] In general embodiments, the present invention is directed to a method for producing chemical products. The method can include forming an electrical arc between an anode and a cathode positioned under water or within an aqueous mist. The method includes introducing an added material into the vicinity of the electrical arc. The formation of the electrical arc in the vicinity of the added material facilitates the production of the chemical products from the added material.

[0007] Implementations of the invention can include one or more of the following features:

[0008] The added material can include an added gas.

[0009] The added material can include two or more added gases.

[0010] The chemical product can include ammonia (NH3).

[0011] The chemical product can include protonated ammonia.

[0012] The chemical product can include hydrogen (H2).

[0013] The chemical product can include an oxygen atom-bearing nitrogen species.

[0014] The chemical product can include cyanide or hydrogen cyanide.

[0015] The added gas can include nitrogen (N2).

[0016] The added gas can include air.

[0017] The added gas can include carbon dioxide (CO2).

[0018] The chemical products can be selected from the group consisting of carboxylic acids, alcohols, polymers, and combinations thereof.

[0019] The added gas can further include nitrogen (N2).

[0020] The added gas can be selected from the group consisting of organic gases and inorganic gases.

[0021] The two or more added gases can include a mixture of at least two gases selected from the group consisting of nitrogen (N2), air, carbon dioxide (CO2), organic gases, and inorganic gases.

[0022] The added material can include an added liquid.

[0023] The added material can include an added solid material, which added solid material does not short circuit the electrical arc.

[0024] The electric arc can be made in an open system at atmospheric pressure.

[0025] The electric arc can be made in a sealed system at high pressures up to 500 atm.

[0026] At least one of the anode or the cathode can be made of brass.

[0027] At least one of the anode or the cathode can be made of zinc.

[0028] The anode can be made of zinc and the cathode is made of brass.

[0029] The anode can be made of brass and the cathode is made of zinc.

[0030] The method can include the introduction of the added material through a hollow core, where the hollow core can be in at least one of the anode and the cathode.

[0031] Each of the anode and the cathode can be made of carbon.

[0032] Each of the anode and the cathode can be made of graphite.

[0033] At least one of the anode or the cathode can be selected from the group consisting of brass, zinc, carbon, graphite, copper, tungsten, tungsten carbide, aluminum, and steel.

[0034] At least one of the anode or the cathode can be a metal alloy.

[0035] At least one of the anode or the cathode can be a metal.

[0036] At least one of the anode or the cathode can be a metal carbide.

[0037] The chemical products can be selected from the group consisting of carbon monoxide, methanol, alcohols, formic acid, carboxylic acids, dicarboxylic acids, oxalic acid, polyalcohols, polymers, cyclic organic compounds, lactones, lactams, esters, amides, and combinations thereof.

[0038] The aqueous source can contain an additive.

[0039] The additive can be a metal salt or metal oxide.

[0040] The additive can be an acid or a base.

[0041] The additive can be the acid. The acid can be a Lewis acid or a Bronsted acid.

[0042] The additive can be the base. The base can be a Lewis base or a Bronsted base.

[0043] The additive can catalyze the formation of the chemical products.

[0044] The additive can include sodium chloride.

[0045] The additive can include seawater salts.

[0046] The aqueous source can include seawater.

[0047] The aqueous source can include salt water.

[0048] The aqueous source can include brine.

[0049] The anode can be made of zinc.

[0050] The cathode can be made of brass.

[0051] The cathode can be made of tungsten.

[0052] The cathode can be made of metal carbide or carbon.

[0053] The cathode can be made of graphite or carbon fiber.

[0054] The anode can be made of zinc and the cathode can be made of brass.

[0055] The anode can be made of brass and the cathode can be made of tungsten.

[0056] The anode can include zinc.

[0057] The anode can be made of metal carbide or carbon.

[0058] The anode can be made of graphite or carbon fiber.

[0059] The forming and use of the electrical arc can utilize a direct current (DC).

[0060] The forming and use of the electrical arc can utilize an alternating current (AC).

[0061] The reaction can be conducted under a pressure of between 1 atm and 500 atm.

[0062] The added material can include an added gas introduced at the pressure between 1 atm and 500 atm.

[0063] The added gas introduced at the pressure between 1 atm and 500 atm can be N2 or air.

[0064] In general embodiments, the present invention is directed to a system for producing chemical products, which systems is operable to perform one or more of the above-described methods.

[0065] Implementations of the invention can include one or more of the following features:

[0066] The system can have an Ml configuration.

[0067] The Ml configuration can be selected from the group consisting of MIT configurations, MIS configurations, and MIF configurations.BRIEF DESCRIPTION OF THE DRAWINGS

[0068] FIG. 1 shows a scheme of an embodiment of a method of the present invention. Four steps of underwater arc discharge are shown to produce ammonia. The nitrogen gas source can either be pure N2 or air. An arc discharge can be generated from any electric power source but generally can be realized with a commercially available arc welder. Other nitrogen species may be produced depending on the electrodes that generate the arc.

[0069] FIGS. 2A-2G show six arc formation geometries. FIG. 2A shows feeding the nitrogen source gas stream in between two electrodes. FIG. 2B shows spraying a fine aerosol of water and nitrogen gas mixture into the electric arc. FIG. 2C shows suspending a hollow electrode near a large concave electrode and letting the nitrogen source gas disperse radially into the arc. FIG. 2D shows feeding the nitrogen source gas stream between two very close pieces of carbonfelt. FIG. 2E shows “MIT” striking that feeds the nitrogen source gas from one hollow electrode and strikes the other electrode at a 90° angle. FIG. 2F shows “MIS” striking that holds a hollow electrode at an acute angle relative to the solid electrode, ensuring that the nitrogen source gas can flow up into the arc. FIG. 2G shows “M1F” that is a configuration having one electrode flat on the bottom of a large beaker while the other electrode strikes it at an angle (shown) or perpendicular (not shown) to the bottom electrode. The designation “Ml” is given to a hollow electrode pointing to the side of a solid electrode, with the two dominant configurations referred to as “MIT” (perpendicular, or “Tee”), “MIS” (45° angle in a Schlenk flask), and “M1F” (one electrode striking a Flat surface). The advantage of the configurations in FIGS. 2C and 2G are when any metal that falls off the electrodes, it falls to the bottom and can be re-used since it has not left the reaction site.

[0070] FIGS. 3A-3B show reactor design and equipment that can be utilized in embodiments of the present invention with FIG. 3A showing Ml S configuration and FIG. 3B showing MIT configuration. Glassware can be from the Ace Glass catalog. The gas outlet can be open to the air or attached via tubing (such as PTFE 0.25” tubing) to a liquid trap.

[0071] FIG. 4 shows design and equipment that can be utilized in embodiments of the present invention for trapping with FIG. 4 showing ammonia trapping in dilute hydrochloric acid. FIG.4 shows a 500 nm fritted bubbler connected to ’A” PTFE tubing suspended in 0.1 M HC1 in a Schlenk flask. The sample port is open to the air to let pressure equalize.

[0072] FIGS. 5A-5C are time-sequential still images of an underwater electric arc utilized in an embodiment of the present invention. As shown in FIGS. 5A-5C, electrodes are sealed by O-rings and threaded fittings into a glass reactor full of water. By applying a voltage from an arc welder and manipulating the electrodes, an arc discharge appears. The high plasma temperature is apparent from the bright white-blue glow during discharge shown in FIG. 5B and the blackbody glow of the cooling electrodes after the arc breaks shown in FIG. 5C.

[0073] FIGS. 6A-6D show UV-vis spectrometry calibration curves for, respectively, (A) ammonium concentration, (B) nitrite concentration, (C) nitrate concentration, and (D) cyanide concentration.

[0074] FIG. 7 shows a log-log scatter plot of ammonia production rate vs. energy cost of production for arc discharge procedures with at least one metal electrode.

[0075] FIGS. 8A-8F show bar plots breaking down ammonia production by various parameters. FIG. 8A shows ammonia production rate vs. anode material, with bar hues distinguishing cathode material. FIG. 8B shows ammonia energy cost vs. anode material, with bar hues distinguishing cathode material. FIG. 8C shows ammonia production rate vs. input power into the system, with bar hues distinguishing anode material. FIG. 8D shows ammonia energy cost vs. input power into the system, with bar hues distinguishing anode material. FIG. 8E shows ammonia production rate vs. nitrogen source for MIS with zinc anode and hollow brass cathode, with bar hues distinguishing reactor liquid. FIG. 8F shows ammonia energy cost vs. nitrogen source for the most effective setup for Ml S with zinc anode and hollow brass cathode, with bar hues distinguishing reactor liquid. The black lines in FIGS. 8A-8F are standard deviations.

[0076] FIG. 9A shows a scatter plot of ammonia production rate vs. energy consumption per kg of ammonia for various nitrogen fixation processes in the literature, specifically the following processes (i) Haber-Bosch; (ii) plasma electrolytic [Hawtof 2019 ,' (iii) plasma jet [Kubota 2010],' (iv) electrochemistry [Fu 2023,' Fu 2024,' Du 2022,' Ye 2020],' (v) laser [Wang 2023],' and (vi) mechanochemistry [Han 2021], The solid stars show nitrogen configurations of embodiments of the present invention, achieving approximately 10 times the production rate of the fastest method and similar energy efficiency. The hollow stars show embodiments of the present invention with air as the feedstock instead.

[0077] FIG. 9B shows a scatter plot comparing the same methods as compared in FIG. 9A,but showing the amount of time and cost in dollars required to generate 1 kg of ammonia. (The dollar cost assumes an average business electricity price of 8.76 cents per kWh.).

[0078] FIGS. 10A-10C show visible light spectroscopy of an ammonium synthesis. FIG. 10A shows the background subtraction algorithm on the emitted arc spectrum fitted to a blackbody curve. FIG. 10B shows the temperatures reached by the underwater electric. FIG. 10C shows that the heating and cooling rates versus time.

[0079] FIG. 11 shows a comparison of the present invention to competitors in the prior art, emphasizing selectivity (purity of the dissolved ammonia product) and production rate.

[0080] FIGS. 12A-12B show the effect of oxygen proportion on ammonia yield in embodiments of the present invention. FIG. 12A shows the yield rate of ammonia and energy cost per kg of ammonia over varying partial pressure of oxygen in the nitrogen stream. FIG. 12B shows the presence of oxygen does not significantly change the purity of ammonia produced vs. other nitrogen species with zinc and brass electrodes.

[0081] FIG. 13 shows energy cost of ammonia synthesis using de-ionized water and air with varying water volume and air flow rate.

[0082] FIG. 14 shows an X-ray pattern comparison of NH4Q between NH4Q extracted from an embodiment of the present invention and a 95% pure sample.

[0083] FIG. 15 shows the synthesis of NH4Q (with NH3 equivalent) from air and H2O over time in a bench scale embodiment of the present invention).

[0084] FIG. 16A shows the synthesis of the present invention using nitrous oxide.

[0085] FIG. 16B shows the synthesis of the present invention using dissolved nitrate and nitrite.

[0086] FIG. 17 shows NO2- and NCh' series selectivity for the nitrate and nitrite synthesis.

[0087] FIG. 18 shows UV-Vis detection in a liquid chromatography system showing the presence of foil can increase production of hydrogen cyanide.

[0088] FIG. 19A shows energy efficiency and production rate of HCN for current generated by the arc welder or other power source.

[0089] FIG. 19B shows energy efficiency and production rate of HCN for different materials for the arc electrodes.

[0090] FIGS. 20A-20C show selectivity for methods of the present invention for hydrogen cyanide production based upon, respectively, HCN selectivity from (FIG. 20A) different N2 sources, (FIG. 20B) different electrode combinations, and (FIG. 20C) different liquid sources.

[0091] FIGS. 21A-21B shows influence of light deflection using a metal foil on nitrate concentration and on nitrite concentration, respectively.

[0092] FIGS. 22A-22B show thermal conductivity detection (TCD analysis) of hydrogen generated from, respectively, fresh water and municipal wastewater, in embodiments of the present invention.

[0093] FIGS. 23A-23C show hydrogen production can be achieved and controlled by variations of the present invention. FIG. 23A shows that current generated by the arc welder or other power source can be used to control production rate and energy efficiency. FIG. 23B shows hydrogen production can be achieved with different materials for the arc electrodes. FIG. 23C shows can be achieved with a variety of liquid sources.

[0094] FIGS. 24A-24C show selectivity of hydrogen production for variations of the present invention. FIG. 24A shows selectivity based upon current generated by the arc welder or other power source. FIG. 24B shows selectivity with different materials for the arc electrodes. FIG. 23C shows selectivity with a variety of liquid sources.

[0095] FIGS. 25A-25B show life cycle assessment (LCA) utilizing an embodiment of the present invention for generating H2 to show the global warming potential measured in CO2 generation, the energy input for the process, and the overall cost, respectively. Each histogram represents the results of 10,000 Monte Carlo simulations of the relevant LCA, where theamount of each resource input in each step of the procedure was randomly sampled from a triangular distribution between -30% and +30% of the most likely value. Histograms that overlapped were allowed to stack on top of one another. The y-axis labeled “probability” shows the probability of each process consuming or producing the amount of resources on the x-axis (e.g., global warming potential, water energy).

[0096] FIG. 25C shows a techno-economic analysis (TEA) utilizing an embodiment of the present invention for generating H2. The x-axis shows the cost in US dollars per kilogram of H2 generated, and the y-axis shows the probability of that cost according to 10,000 Monte Carlo simulations as in the previous claim.

[0097] FIG. 25D is a radar plot summarizing the LCA shown in FIGS. 25A-25B and the TEA shown in FIG. 25C..DETAILED DESCRIPTION

[0098] The present invention relates to methods and systems for synthesis using an underwater electric arc. In some embodiments of the present invention, selectivity for a given nitrogen species can be tuned by replacing the electrode material in the water in combination with changing the input gas between nitrogen and air. In such an embodiment, the majority of inorganic nitrogen products remain dissolved in aqueous phase inside the reactor for facile separation.

[0099] In the process of the present invention, nitrogen gas can be bubbled through liquid water and into an arc discharge, as shown in FIG. 1. The gas naturally flows upward (against gravity), meaning that as the reaction occurs, the produced gas flows up and away from the arc. The hot gas then can collide with cold water, which will cool it rapidly. As the produced gas has been heated by plasma, its temperature likely exceeds 1000 °C, while the surrounding liquid water cannot exceed 100 °C while at ambient pressure. Accordingly, the present invention caninvolve the immediate quenching of high-temperature gas in liquid water after arc discharge, distinct from other synthesis processes based on arc discharge or plasma.

[0100] The underwater electric arc method can be versatile. Other nitrogen species, such as nitrite or cyanide, can also be selectively produced by changing the electrode materials, if necessary, adjusting the tested parameters. Ammonia, in certain embodiments, can be the chief nitrogen product because ammonia has extensive value for fertilizer production and serves as a sustainable carbon-free energy carrier of hydrogen. Nevertheless, other products could be generated in this process. In the absence of a nitrogen source, the underwater electric arc method produces hydrogen gas instead.

[0101] The present invention can include a nitrogen source. Both air and nitrogen (N2, often called “dinitrogen,” “molecular nitrogen” or just “nitrogen”) contain enough nitrogen to allow for ammonia production, but pure nitrogen (98% or higher) produces more ammonia than air, with other conditions remaining the same.

[0102] The present invention can include a power source. Any direct current source can generate an electric arc, so any DC power source could be used. For example, the present invention can use constant-current sources, such as two different stick arc welders with different power ratings.

[0103] The present invention can include arc formation geometry. The electrodes can be of various shapes and sizes and held at different angles while still being able to form an electric arc. In addition, the gaseous nitrogen source can be fed in different ways. The arc geometries are shown in FIGS. 2A-2G. Overall, one set of efficient and productive configurations for ammonia synthesis are shown in FIGS. 2E-2G. The designation “Ml” is given to a hollow electrode pointing to the side of a solid electrode, hence the two dominant configurations are called MIT (perpendicular, or “Tee”) and MIS (45° angle in a Schlenk flask). A third possible “Ml” configuration for the underwater electric arc is called “M1F” (for “flat”) and is aconfiguration having one electrode flat on the bottom of a large beaker while the other electrode strikes it at an angle, as shown in FIG. 2G, or the electrode could strike perpendicular to the bottom electrode (not shown).

[0104] For gas flow rate, the flow rate of the nitrogen source gas affects the composition of reactants at the electric arc, meaning that there is an optimal stoichiometry. In some embodiments, there is an optimum of 4 L / min for nitrogen gas, such that the flow rate is constant for data shown below.

[0105] For voltage, since the dielectric strength of water is high, higher voltage supplied to the system allows for easier arc striking, as well as more stable and durable arcs.

[0106] For current, depending on the power source, altering the desired current will affect the power supplied to the reaction system.

[0107] The present invention can include an electrode material. As discussed below, the electrodes can degrade during the reaction. Graphite, copper, aluminum, steel, brass, tungsten carbide, and zinc can all be used as anode and cathode materials. Among these, zinc and alloys of zinc such as brass have strong abilities to facilitate ammonia synthesis.

[0108] The present invention can employ a nitrogen source. In some embodiments, the methods were performed with either nitrogen gas or air (which is mostly nitrogen and oxygen). Such embodiments showed that nitrogen gas facilitates ammonia synthesis better than air.

[0109] For the reactor liquid, water can serve a dual purpose as a quenching agent and hydrogen source, but it has been discovered that the water need not be pure. For example, by mixing 4.62 g of CORALIFE Biocube Marine Fish Tank Aquarium Salt in 120 mL of deionized water, a solution approximating seawater can be made. Reactors utilizing such mixture are referred to herein as a type of “saltwater” or “seawater” reactor.

[0110] The present invention can employ a striking technique. In some embodiments, the methods on the present invention were conducted by manually controlling the electrodes. Thespecific way that electrodes are drawn together and apart significantly affects the quality of the electric arc and can further affect the ammonia yield rate. Optimization and automation will eventually control the feed rates of the anode and / or electrodes. Spinning of the electrodes will slow their degradation rates and mitigate their lopsided degradation.

[0111] Optimizing over these parameters, the present invention can achieve an ammonia production rate of about 0.185 mg / s, with an energy cost of 2-3 MWh / kg NH3. Accordingly, the ammonia production rate can far surpass that of prior lab-scale nitrogen fixation approaches in literature with comparable energy cost. And this production rate superiority will translate to larger scales and manufacturing scales.

[0112] Diagrams of MIS reactor configuration 300 and MIT reactor configuration 310 are shown in FIGS. 3A-3B, respectively. The Schlenk flask (140 mL) 301 with threaded sample port and the threaded glass tees can be joined together with threaded fittings and O-rings. In the exemplary MIS configuration shown in FIG. 3A, the hollow ’A” (outer diameter) electrode 303 is secured with an O-ring into the sample port, while the solid electrode 302 is only secured with an O-ring if it is also A” in outer diameter. In the exemplary MIT configuration in FIG. 3B, both electrodes 302-303 are A” in outer diameter and are secured into the glass tee 311 with O-rings. Water is utilized (filled to water line 308)

[0113] In both the exemplary MIS and MIT, shown in FIGS. 3A-3B, respectively, the nitrogen source is bubbled in gas inlet 305 through the hollow electrode 303, and gaseous products are allowed to escape through a gas outlet 306. Sealing the system near the electric arc prevents water vapor and ammonia loss. If desired, the gas outlet 306 can be fed into an ammonia trap 400, as shown in FIG. 4. Likewise, upon scaling, the unreacted nitrogen can be recycled through the arc reactor cell. Water is utilized (filled to water line 308) and an ice bath307 can be utilized, as shown in FIG. 3A.

[0114] The arc welder shown in FIGS. 3A-3B can be stick arc welders 304 that are commercially available, such as for example DEKOPRO 110 / 220 V MMA Welder, 160 A ARC Welder Machine (5.8 kW max) (welder 1), or Amico Professional Welding Machine, 200 Amp Stick Arc DC Welder (10 kW max) (welder 2).

[0115] In some embodiments, power measurement has shown that welder 1 (the “smaller welder”) outputs approximately 1 kW of power on average, while welder 2 (the “larger welder”) outputs approximately 2 kW of power on average. Both welders can spike their power outputs 1 kW above their average to start an arc, but they will quickly fall back to the average during a sustained arc. Because stick welders are current-controlled devices, their voltage will drop once an arc is established; however, before arc formation, each device raises the voltage to the limit prescribed by their power rating. This voltage, known as the striking voltage, will affect the easy degree of electric arc formation, described in more detail below.

[0116] In certain embodiments, if desired, a Schlenk flask, FIG. 4, 401 with 30-80 mL of 0.1 M HC1 (filled to fill line 408) can be connected at gas inlet 405 to the gas outlet 306 of the reactor (such as shown in FIGS. 3A-3B and 4) by ’A” PTFE tubing and immersed in an ice bath (0-5 °C) 407. A Swagelok filter / bubbler 402 with varying pore size can feed the produced gas into the HC1 solution. Smaller pore sizes increase the pressure gradient within the reactor by limiting the rate of flow out via gas outlet 406 while increasing the miscibility of gas bubbles with HC1. For the evaluated embodiments driven by a small amount of total energy (5 - 10 Wh), an HC1 trap is not necessary; ammonia is highly soluble in water at low temperatures (2), and very little of ammonium chloride has been detected in the HC1 trap in practice. Nevertheless, if a larger pressure gradient is desired, an HC1 trap is a simple addition to the apparatus. In embodiments, the ammonia can be isolated by distillation from the water.

[0117] Once the electrodes are in place, gas is flowing, and the arc welder is on, the electrodes can be manipulated using standard stick welding equipment (which comes included withcommercial arc welders). Striking an arc requires the electrodes to briefly touch together and then slowly be drawn apart from one another. FIG. 5 shows static images of the sequential stages of electric arc formation underwater. In the first stage, the electrodes touch one another, allowing current to flow freely at the point of contact, FIG. 5A. In the second stage, the electrodes are pulled apart. An about 1 -millimeter displacement apart causes a strong localized electric field to exceed the dielectric strength of water, creating an electric arc. Once the arc begins, the electrodes can typically be drawn about 5 - 10 mm apart for a short duration. Such an electric arc glows brightly, even through water, FIG. 5B.

[0118] As the arc sustains itself, the water nearby is rapidly vaporized, which causes noticeable bubbles within the reactor. These bubbles inevitably break the arc if given enough time, with arc lifetimes ranging from 0.1 to 10 seconds. In the third stage of arc discharge, the arc is broken by the bubbling, leaving the electrodes to quench in the surrounding liquid water. In the third image, FIG. 5C, the blackbody glow of graphite electrodes is clearly visible.

[0119] The underwater arc discharge can produce steam, but it also can break the H-OH bond, ionize hydrogen to H+, and facilitate the formation of O2 gas, H, and -OH radicals. [Dasgupta 1986\. Flammable gas can be produced during this process, as experimentally confirmed by placing a commercial flammable gas detector above the water during arc testing.

[0120] Because ammonia is a representative soluble nitrogen species explored herein, the effect of parameters on ammonia production is set forth in FIGS. 8A-8F, as described in more detail below. However, other species, including nitrogen species, can be selectively synthesized if desired.

[0121] Certain implementations of the present invention can use a selective nitrite synthesis technique. In such embodiments, the MIT set-up can be prefilled with 50 mL 1 M isopropyl alcohol (IP A) in water, used with a hollow graphite cathode to feed in air, with a flow rate of5.1 L / min, and use a solid brass anode. In such an embodiment, the small DEKO arc weldercan be set to setting 50 and connected to a 120 VAC outlet. From this, the process can include, starting the arc discharge underwater with a total energy consumption of 5 Wh. In this embodiment, nitrite is the dominant inorganic soluble nitrogen species.

[0122] Certain implementations of the present invention can use a selective cyanide synthesis technique. In such embodiments, the MIT set-up can be prefilled with 100 mL DI, use of a hollow graphite cathode to feed in nitrogen, with a flow rate of 4 L / min, and use of a solid graphite anode. In such an embodiment, the small arc welder (DEKO) can be set with 50 A (a.u.) output current and 120 V input voltage supply, then the arc discharge can be started underwater with a total energy consumption of 5 Wh. In this embodiment, cyanide is the dominant inorganic soluble nitrogen species. When non-carbon electrodes are used for the anode and cathode, no cyanide is generated.

[0123] Ammonia concentration can be approximated by commercial test kits, then further precisely quantified by the Nessler method using a UV-vis spectrometer based on procedures established in literature. [Bhattacharya 2019], The calibration curve of ammonium is plotted in FIG. 6A. FIG. 6A shows an excellent linear relationship for the sample involving 0.2-10 ppm ammonium. If the sample has a possible ammonium concentration over 10 ppm, the sample can be diluted by 10 times and then the UV-vis analysis can be conducted. Ammonium (NH4+) has a slightly higher molecular weight than ammonia. The results in FIGS. 7 and BASF show normalizing for this difference so that the yields of ammonia are shown (this slightly decreases the mass yield).

[0124] Nitrite can be initially quantified by commercial testing kits, then further quantified by a UV-vis spectrometer based on the Hach method 10207, such as for example USEPA Diazotization Method). The calibration curve is plotted in FIG. 6B. FIG. 6B shows an excellent linear relationship for the sample involving 50 ppb to 2 ppm ammonium.

[0125] Nitrate (calculated as nitrogen) can be initially quantified by the commercial testing kits, such as for example Red Sea, then further quantified by a UV-vis spectrometer based on Hach method 10206, such as for example the USEPA Dimethylphenol Method. The calibration curve is plotted in FIG. 6C. FIG. 6C shows an excellent linear relationship for the sample involving 0.2-10 ppm nitrate nitrogen (ca. 0.9-45 ppm nitrate).

[0126] Free cyanide can be analyzed by the Hach method 10265, such as for example by the USEPA Pyridine Barbituric Acid Method, using a UV-vis spectrometer. The calibration curve is plotted in FIG. 6D FIG. 6D shows an excellent linear relationship for the sample involving 10-500 ppb cyanide.

[0127] The present invention is supported by performed methods conducted by varying the parameters of the invention, as discussed above. Since the discovery that graphite can be oxidized to form cyanide, the energy efficiency and production rate have been improving. FIG. 7 shows a log-log plot of production rate versus the energy cost for the tests conducted since the shift away from graphite electrodes and toward metal electrodes. FIG. 7 suggests that this technology has large potential for optimization because both production rate and efficiency are increasing together. Accordingly, the synthesis parameters have yet to force a trade-off between these two desirable quantities.Additional Characteristics of Ammonia Synthesis

[0128] As discussed herein, embodiments of the present invention facilitated ammonia synthesis. The variation in production rate and energy cost can be explained by splitting the data by the synthesis parameters discussed above. FIGS. 8A-8B show the effect of anode and cathode material on ammonia production; zinc and brass outperform other metals in both production rate and energy efficiency. A zinc anode with a brass (alloy of copper and zinc) cathode has the highest ammonia production rate of all combinations.

[0129] FIGS. 8C-8D show the effect of the power source and anode material on ammonia production. In this embodiment, the data presented was gathered using two power sources. For example, in this embodiment, there was one arc welder with an average power output around 1 kW and a larger arc welder with an average power output around 2 kW. In such an embodiment, the 2 kW arc welder was used only with zinc anodes, but the improvement is clear from the 1 kW welder. In this embodiment, the smaller welder achieved a maximum production rate of about 40 pg / s, while the larger welder surpassed 251 pg / s. The 2 kW welder has shown efficient tests, with energy costs approximately 2.3 MWh / kg. In contrast, the most efficient test conducted with the 1 kW welder is just over 3 MWh / kg, which is 25% more energy-expensive.

[0130] FIGS. 8E-8F examine the MIS configuration with zinc anodes and brass cathodes specifically because they constitute the dominant combination of geometry and electrode material. FIGS. 8E-8F stratify by nitrogen source and reactor liquid (either deionized water or artificial seawater). FIGS. 8E-8F reveal: (i) pure nitrogen gas facilitates ammonia synthesis faster and more efficiently than air; (ii) the use of deionized water is not necessary: seawater is as effective with pure nitrogen as deionized water; and (iii) most surprisingly and unexpectedly, seawater with air yields more ammonia with higher efficiency than deionized water in air.

[0131] Furthermore, a direct comparison between the larger welder (90 V striking voltage) and the smaller welder (60 V striking voltage) with the same geometry, electrode types, and nitrogen source revealed that, under pure nitrogen (and with all other parameters constant), the higher striking voltage leads to more than 3 times the production rate as the lower striking voltage and at half the energy cost. This suggests that increasing the striking voltage will non- linearly increase the production rate, a major consideration for future industrialization of the process.

[0132] Several promising results from this underwater arc synthesis process are shown in FIGS. 9A-9B. Even with significant space for optimization, the underwater arc method achieves an order of magnitude higher production rate of ammonia than other laboratory processes while demonstrating a competitive energy efficiency. This will likely further show similar process comparisons upon scale-up and commercialization.

[0133] As shown in FIGS. 10A-10C, the underwater electric arc reaches temperatures of between 5000 K and 9000 K as shown by the blackbody peak of the arc under visible light spectroscopy. FIG. 10B Analysis was conducted by running a background subtraction algorithm on the emitted arc spectrum (main spectrum 1001) and then fitting a blackbody curve (Plank fit 1002). FIG. 10A. Heating and cooling rates depended on the window size when calculating the moving average rate of change, but a peak rate of around 200,000 - 400,000 K / s was observed. See FIG. 10C (with plots 1021-1022 for window sizes of 5.0 ms and 12.5 ms, respectively).

[0134] FIG. 11 shows a comparison of the present invention to competitors in the prior art, emphasizing selectivity (purity of the dissolved ammonia product) and production rate (NH3 yield rate from direct NH3 synthesis from N2 and H2O). Cluster 1101 reflects embodiments of the present invention. Each point in FIG. 11 is labeled X-Y, where X is the nitrogen source (e.g., air, N2O, N2 gas) and Y is the aqueous environment (e.g., water, ethanol, sulfuric acid). The points not in cluster 1101 are from other state-of-the-art experiments in literature, and the word in parentheses (e.g., laser) represents the means of nitrogen fixation.

[0135] Additional embodiments of the present invention revealed the effect of oxygen proportion on ammonia yield. FIGS. 12A-12B. FIG. 12A shows the yield rate of ammonia (plot 1201) and energy cost per kg of ammonia (plot 1202) over varying partial pressure of oxygen in the nitrogen stream. Generally, while it is possible to generate ammonia in oxygen- enriched air, less oxygen always facilitates faster and more efficient ammonia production.However, as shown in FIG. 12B, with zinc and brass electrodes, the presence of oxygen does not significantly change the purity of ammonia produced vs. other nitrogen species.

[0136] FIG. 13 shows the energy cost of ammonia synthesis using de-ionized water and air with varying water volume and air flow rate. In some embodiments, it was found for the M1F configuration that preferred conditions were around 2 L / min for gas flow rate and 420 mL for water volume.

[0137] By treating the dissolved ammonia with hydrochloric acid (HC1) and water evaporation, ammonium chloride can be extracted in solid form. FIG. 14 shows that the X-ray diffraction pattern for the extracted NH4CI is nearly identical to 99.5% pure NH4Q from Millipore-Sigma. Through repeated trials, more than 1 gram of NH4Q (0.35 grams of NH3 equivalent) was synthesized from air and H2O at the bench-scale. FIG. 15.

[0138] Ammonia can also be synthesized using nitrous oxide in embodiment of the invention. FIG. 16A shows the synthesis of the present invention using nitrous oxide. Plots 1601-1602 show, respectively, NH3 yield rate and NH3 energy efficiency for N2O. Data 1603-1604 show, respectively, NH3 yield rate and NH3 energy efficiency for N2 / O2, P(O2)=33.kPa. These reveal that this synthesis was much more efficient than equal amounts of separate nitrogen and oxygen gas.

[0139] Ammonia can also be synthesized with the present methods using dissolved nitrate and nitrite. FIGS. 16B. Plots 1611-1612 show, respectively, NH3 yield rate and NH3 energy efficiency for NO2-N. Plots 1613-1614 show, respectively, NH3 yield rate and NH3 energy efficiency for NO3-N. These syntheses reflected diminishing returns on yield rate and energy efficiency when concentrations were higher than 120 ppm. FIG. 17 shows NCh' and NCh' series selectivity for the nitrate and nitrite synthesis, which reflects diminishing returns on ammonia selectivity are also found for nitrate and nitrite synthesis when concentrations are above 120 ppm.Characteristics of Hydrogen Cyanide Synthesis

[0140] As discussed herein, embodiments of the present invention facilitated hydrogen cyanide synthesis. The underwater electric arc of the present invention (for HNC synthesis, as well as other synthesis methods) may be conducted with or without a foil covering to reflect energy back into the reaction vessel. According to UV-Vis detection in liquid chromatography, the presence of foil increased production of hydrogen cyanide. FIG. 18. In FIG. 18, plots 1801- 1803 are for Al foil, Cu foil, and No foil, respectively. The amount of time taken for each synthesis is listed in parentheses in the legend of FIG. 18. Plot 1802 shows that the addition of copper foil allows for nearly an identical HCN yield as no foil in one-third of the time.

[0141] FIG. 19A shows energy efficiency and production rate of HCN for current generated by the arc welder or another power source. See FIG. 19A (plots 1901-1902 for energy efficiency and production rate, respectively). It is thus shown that the input current for the electric arc is optimized for cyanide production rate and energy cost at 50 A.

[0142] Hydrogen cyanide production can be achieved with different materials for the arc electrodes. FIG. 19B shows energy efficiency and production rate for different materials for the arc electrodes. In FIG. 19B, “G” represents graphite, “B” represents brass, “Zn” is zinc, “W” is tungsten, “CF” is carbon fiber, and “Cu” is copper. Each material is written with “+” for the anode material and for the cathode material. See FIG. 19B (plots 1911-1912 for energy efficiency and production rate, respectively). As shown in FIG. 19B, the electrode combinations of (i) graphite-carbon fiber and (ii) copper-graphite, were each shown to be preferential combinations for the embodiment evaluated.

[0143] FIGS. 20A-20C show selectivity for methods of the present invention for hydrogen cyanide production. FIG. 20A shows that the underwater electric arc method for hydrogen cyanide production is highly selective if a pure nitrogen stream is used but is also about 75% selective when using air and nitrous oxide. FIG. 20B shows that the underwater electric arcmethod for hydrogen cyanide production is highly selective under multiple electrode combinations, including tungsten-graphite, graphite-graphite, graphite-carbon fiber, and copper-graphite. FIG. 20C shows that hydrogen cyanide can be produced in a wide array of liquids using the underwater electric arc method, and it is still highly selective in ethanol, deionized water (DI), HPLC-grade water, tap water, and saltwater (SW).

[0144] FIGS. 21A-21B show the influence of light deflection on nitrate concentration and nitrite concentration respectively during HCN synthesis. In each plot, the absorption spectrum is shown and the corresponding ion concentration is written in the legend. In FIG. 21A, plots 2101-2103 (No foil, Al foil, and Cu foil, respectively) show that both aluminum and copper foil suppress the formation of nitrate during HCN synthesis. Likewise, in FIG. 21B, plots 2111-2113 (No foil, Al foil, and Cu foil, respectively) show that aluminum and copper foil suppress the formation of nitrite during HCN synthesis. Wrapping the reaction vessel in foil and allowing light from the arc to reflect back into the reactor will significantly reduce the concentration of nitrate and nitrite ions produced, increasing the selectivity of the process for hydrogen cyanide.Characteristics of Hydrogen Synthesis

[0145] As discussed herein, embodiments of the present invention facilitated hydrogen synthesis, i.e., embodiments of the present invention include use of an underwater electric arc without a nitrogen source to generate hydrogen gas.

[0146] FIGS. 22A-22B show gas chromatography with thermal conductivity detection (GC- TCD) of hydrogen generated by embodiments of the present invention. FIG. 22A shows GC- TCD analysis of the gaseous products generated by an underwater electric arc from fresh water. The strong hydrogen peak in FIG. 22A clearly demonstrates hydrogen generation. The GC- TCD analysis in FIG. 22B shows hydrogen gas was produced with an underwater electric arc in municipal wastewater.

[0147] FIGS. 23A-23C show hydrogen production can be achieved and controlled by variations of the present invention. FIG. 23A shows that current generated by the arc welder or other power source can be used to control production rate and energy efficiency (z.e., such as for obtaining a higher production rate while achieving a lower energy efficiency). See FIG. 23A (with plots 2301-2302 for production rate and energy efficiency, respectively). Note that the units mg / kJ show the mass yield per energy used, meaning that a high value implies higher energy efficiency and lower energy consumption.

[0148] FIG. 23B shows that hydrogen production can be achieved with different materials for the arc electrodes. See FIG. 23B (with plots 2311-2312 for production rate and energy efficiency, respectively). FIG. 23B reveals that for the configuration of this embodiment, graphite electrodes had the highest production rate and efficiency.

[0149] FIG. 23C shows the H2 production rate that can be achieved with a variety of liquid sources, including deionized water (DI), wastewater (WW), high-performance liquid chromatography-grade water (HPLC), saltwater (SW), tap water (TW), ethanol (EtOH), and isopropyl alcohol (IP A). See FIG. 23C (with plots 2321-2322 for production rate and energy efficiency, respectively).

[0150] FIGS. 24A-24C show selectivity for hydrogen production for variations of the underwater arch methods. As shown in FIG. 24 A, the underwater arch method is highly selective based upon current generated by the arc welder or other power source, except for currents at or above 150 A. As shown in FIG. 24B, the underwater arc method is highly selective for hydrogen gas generation using various electrode materials except for a combination of tungsten and steel. As shown in FIG. 24C, the underwater arc method is highly selective (~ 90%) for hydrogen gas generation in various liquid sources.

[0151] FIGS. 25A-25D show life cycle assessment (LCA) and techno-economic analysis (TEA) utilizing the underwater electric arc method for generating H2, which shows that theunderwater electric arc is competitive with electrolysis (PEM) and steam methane reforming (SMR) in terms of global warming potential and unit cost. In FIG. 25A, plots 2501-2504 are LCA plots for kg CO2 eq for (a) underwater electric arc method for salt H2O, (b) underwater electric arc method for waste H2O, (c) PEM electrolysis, and (c) SMR, respectively. In FIG. 25B, plots 2511-2514 are LCA plots for energy use for (a) underwater electric arc method for salt H2O, (b) underwater electric arc method for waste H2O, (c) PEM electrolysis, and (d) SMR, respectively. In FIG. 25C, plots 2521-2524 are TEA plots of the unit cost per kg of hydrogen for (a) underwater electric arc method for salt H2O, (b) underwater electric arc method for waste H2O, (c) PEM electrolysis, and (d) SMR, respectively. In FIG. 25D, areas 2531-2533 are radar plot areas comparing relative cost, production rate, energy consumption, consumables, and GWP for (a) underwater electric arc method, (b) PEM electrolysis, and (d) SMR, respectively. These LCA and TEA plots show that the underwater electric arc is competitive with electrolysis and steam methane reforming (SMR) in terms of global warming potential and unit costAdditional Aspects of the Present Syntheses

[0152] Overall, the present invention has been demonstrated to be a promising method for generating ammonia at competitive energy efficiency and production rates. High input power, zinc electrodes, and careful geometric considerations have been the determining factors for increasing ammonia production at lab scale. Such promising methods that have been found include embodiments that have the following combinations of parameters:• Zn anode, Brass 260 cathode, 4 L / min N2,100 A, deionized water: 251 pg / s, 2846 kWh / kg NH3;• Zn anode, Brass 260 cathode, 6 L / min N2, 100 A, deionized water: 225 pg / s, 2469 kWh / kg NH3;• Zn anode, Brass 260 cathode, 6 L / min N2, 100 A, seawater: 226 pg / s, 3687 kWh / kgNH3;• Zn anode, Brass 260 cathode, 7.7 L / min air, 100 A, deionized water: 73.2 pg / s, 11383 kWh / kg NH3;• Zn anode, Brass 260 cathode, 7.7 L / min air, 100 A, seawater: 168 pg / s, 5411 kWh / kg NH3; and• Brass 260 anode, tungsten cathode, 4 L / min N2, 50 A, deionized water: 169.6 pg / s, 3008 kWh / kg NH3.

[0153] The present invention, in some embodiments, can be applied as an industrial technique for ammonia production to rival the Haber-Bosch process. The Haber-Bosch process uses steam methane reformation, which produces 11 kg CO2 in order to generate 1 kg pure hydrogen (H2) gas. Technologies to generate hydrogen from methane without releasing CO2 have not reached maturity, and therefore every kilogram of ammonia produced industrially produces approximately 1.5 kg of CO2 in addition to the 11 kg of CO2 produced in making the H2 by steam methane reforming. The method described in this disclosure is approximately 3 times more energy efficient than the lab-scale Haber-Bosch process, and does not require any H2 made from carbon sources which could produce CO2. In this process, the hydrogen atoms originate in water. If the electricity is supplied by renewable energies such as wind or solar, or if supplied by nuclear energy, near zero CO2 would be generated in the overall process. Hence, if the energy efficiency further increases and the reaction system is powered by renewable electricity, this method can be a carbon-free method for producing ammonia from air and water.

[0154] The present invention, in other embodiments, can be applied as a small-scale decentralized nitrogen fixation system. At the core of the underwater arc discharge system for ammonia synthesis, a power source, a pair of electrodes, water, and compressed air or nitrogen are required. No expensive solvents, high pressure cells, or catalysts are required. As a result,the method is likely to be more feasible than other methods at small scales in remote locations, or in developing economies. The data in this disclosure shows that gram-scale synthesis is already possible with a commercially available arc welder unit which costs $125 and weighs 5 kg. This technology may allow for nitrogen fixation to be decentralized, promoting fertilizer availability, and food security in the regions worldwide without the capital to establish large ammonia production plants.

[0155] The present invention can be performed at high pressure, such as up to 500 atm. At higher pressures, there is generally more rapid diffusion of the gas to the electrode surface, thereby increasing the production for the overall desired product. There would be greater production with nearly the same energy input, thereby enhancing efficiency.

[0156] The present invention, in other embodiments, can be applied as a zero-carbon fuel production. Ammonia fuel can be a zero-carbon alternative to hydrogen fuel. High-pressure tanks and cryogenic temperature conditions are not required to transport ammonia, thereby mitigating the cost and safety concern for storage and transportation compared to hydrogen fuel. Because the underwater arc discharge method produces ammonia from water, electricity, and air without generating CO2, it may serve to produce or replenish ammonia fuel to power a more carbon-free society. The lightweight nature of the power source and the lack of need for huge reactors makes ammonia fuel production possible at a small or large scale.

[0157] In certain embodiments, the present invention has the capability to fix nitrogen directly using water as a more sustainable, earth-abundant and accessible hydrogen source than pure hydrogen. Moreover, in some embodiments, the present invention allows for sustaining an arc discharge in a liquid medium. In the same or differing embodiments, the present invention provides for the use of a current-controlled source rather than a voltage-controlled source.

[0158] In some embodiments, the present invention provides for the use of liquid water as both a reactant and quenching medium. Moreover, in some embodiments, the discovery of zinc as a viable and cost-effective reactant for ammonia synthesis under arc discharge conditions.

[0159] In certain embodiments, the present invention has the versatility of the method of producing different nitrogen species by simply replacing the electrode materials. In some embodiments, the present invention has ability to synthesize ammonia without high pressure, specifically designed catalysts, or organic solvents.

[0160] The present invention has enhanced synthesis of ammonia in an inert gaseous medium. Prior methods involved generating an arc discharge in a pressure cell containing either helium, argon, or neon and flowing a carefully mixed stream of nitrogen and hydrogen. First published in 1931 [Brewer 1931], this method cannot be competitive with the Haber-Bosch process, did not involve an arc discharge underwater, and needed an independent hydrogen source.

[0161] Prior art teachings also provide converting nitrogen plasma into ammonia by firing the plasma into liquid water. [Hawtof 2019,' Kubota 2010], Such a technique does not use an arc discharge or zinc metal, does not maintain a plasma underwater, and is not competitive with other methods in the literature in terms of efficiency or production rate.

[0162] Prior art teachings also use electrochemical nitrogen reduction reactions (eNRR). These techniques require lithium / calcium nitride as mediator and specific organic solvents. [Fu 2023,' Fu 202F, Du 2022 Ye 2020], These prior art references do not use arc discharge or plasma, and state-of-the-art ammonia yield rate is only 2.8 pg / s, less than 2% of the method in this disclosure.

[0163] Prior art teachings also use laser reduction of nitrogen. These techniques requires lithium oxide (Li2O) as a mediator and a laser source. [Wang 2023], Though this technique may demonstrate a high energy efficiency (322.7 kWh / kg NH3), the ammonia production rate is 16.7 pg / s, which is less than 10% of the rate demonstrated by the present invention using anunderwater arc discharge process at bench-scale. Further, this technique has no proven implementations of a scale-up. The cost of laser sources increases greatly when scaling up, which makes it less economically competitive than the present invention.

[0164] Prior art teachings also use mechanochemical nitrogen fixation by ball milling. Although this technique demonstrates high energy efficiency (1.25 MWh / kg NH3) and could be scalable, the demonstrated ammonia production rate is 5.12 pg / s, which is less than 5% of the rate demonstrated by the present invention using an underwater arc discharge process at bench-scale. This prior art method has no arc discharge. Instead, a delicate and sophisticated pre-treatment of iron catalyst is required prior to mechanically hydrogenate nitrogen, in order to maximize the exposed active catalyst sites. [Han 2021}.

[0165] While embodiments of the invention have been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit and teachings of the invention. The embodiments described and the examples provided herein are exemplary only, and are not intended to be limiting. Many variations and modifications of the invention disclosed herein are possible and are within the scope of the invention. The scope of protection is not limited by the description set out above, but is only limited by the claims which follow, that scope including all equivalents of the subject matter of the claims.

[0166] The disclosures of all patents, patent applications, and publications cited herein are hereby incorporated herein by reference in their entirety, to the extent that they provide exemplary, procedural, or other details supplementary to those set forth herein.

[0167] Amounts and other numerical data may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example,a numerical range of approximately 1 to approximately 4.5 should be interpreted to include not only the explicitly recited limits of 1 to approximately 4.5, but also to include individual numerals such as 2, 3, 4, and sub-ranges such as 1 to 3, 2 to 4, etc. The same principle applies to ranges reciting only one numerical value, such as “less than approximately 4.5,” which should be interpreted to include all of the above-recited values and ranges. Further, such an interpretation should apply regardless of the breadth of the range or the characteristic being described.

[0168] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which the presently disclosed subject matter belongs. Although any methods, devices, and materials similar or equivalent to those described herein can be used in the practice or testing of the presently disclosed subject matter, representative methods, devices, and materials are now described.

[0169] Following long-standing patent law convention, the terms “a” and “an” mean “one or more” when used in this application, including the claims.

[0170] Unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in this specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the presently disclosed subject matter.

[0171] As used herein, the term “about” and “substantially” when referring to a value or to an amount of mass, weight, time, volume, concentration or percentage is meant to encompass variations of in some embodiments ±20%, in some embodiments ±10%, in some embodiments ±5%, in some embodiments ±1%, in some embodiments ±0.5%, and in some embodiments±0.1% from the specified amount, as such variations are appropriate to perform the disclosedmethod.

[0172] As used herein, the term “substantially perpendicular” and “substantially parallel” is meant to encompass variations of in some embodiments within ±10° of the perpendicular and parallel directions, respectively, in some embodiments within ±5° of the perpendicular and parallel directions, respectively, in some embodiments within ±1° of the perpendicular and parallel directions, respectively, and in some embodiments within ±0.5° of the perpendicular and parallel directions, respectively.

[0173] As used herein, the term “and / or” when used in the context of a listing of entities, refers to the entities being present singly or in combination. Thus, for example, the phrase “A, B, C, and / or D” includes A, B, C, and D individually, but also includes any and all combinations and subcombinations of A, B, C, and D.REFERENCES

[0174] Bhattacharya, S., et cd., “Underwater Electrical Discharges: Temperature, Density and Basic Instability Features with Different Anode Materials,” Plasma Chem. Plasma Process., 2019, 39, 4, 1019-1048 [‘Bhattacharya 2019”).

[0175] Brewer, A K., et al., “The Synthesis of Ammonia in the Low Voltage Arc,” J. Am. Chem. Soc., 1931, 53, 8, 2968-2978 (“Brewer 1931”).

[0176] Dasgupta, P., et al., “Solubility of Ammonia in Liquid Water and Generation of Trace Levels of Standard Gaseous Ammonia,” Atmos. Environ.

[1967] , 1986, 20, 3, 565-570 [‘Dasgupta 1986”).

[0177] Du, H.L., etal., “Electroreduction of Nitrogen with Almost 100% Current-to- Ammonia Efficiency,” Nature, 2022, 609, 722-727 [‘Du 2022”).

[0178] Fu, X., et al., “Continuous-flow Electrosynthesis of Ammonia by Nitrogen Reduction and Hydrogen Oxidation,” Science, 2023, 379, F l-T l [‘Fu 2023”).

[0179] Fu, X., et al., “Calcium-Mediated Nitrogen Reduction for Electrochemical AmmoniaSynthesis,” Nat. Mater., 2024, 23, 101-107 (“Fw 2024").

[0180] Han, GF., et al., “Mechanochemistry for Ammonia Synthesis under Mild Conditions,” Nat. Nanotechnol., 2021, 16, 325-330 (“Han 2021").

[0181] Hawtof, R., et al., “Catalyst-free, Highly Selective Synthesis of Ammonia from Nitrogen and Water by a Plasma Electrolytic System,” Set. Adv., 2019, 5, eaat5778 (“Hawtof 2019").

[0182] Jones, H., et al., “Development of Pulsed Dielectric Breakdown in Liquids,” J. Phys.D: Appl. Phys., 1995, 28, 178 f Jones 1995").

[0183] Kubota, Y., et al. , “Synthesis of Ammonia through Direct Chemical Reactions Between an Atmospheric Nitrogen Plasma Jet and a Liquid,” Plasma Fusion Res., 2010, 5, 042-042 (“Kubota 2010").

[0184] Wang, H., et al., “Laser-Induced Nitrogen Fixation,” Nat. Commun., 2023, 14, 5668 (f Wang 2023").

[0185] Ye, TN., et al., “Vacancy-Enabled N2 Activation for Ammonia Synthesis on an Ni- Loaded Catalyst,” Nature, 2020, 583, 391-395 (“Ye 2020").

[0186] Zhao, Y., et al. , “Ammonia Detection Methods in Photocatalytic and Electrocatalytic Experiments: How to Improve the Reliability of NH3 Production Rates?” Adv. Sci., 2019, 6, 8, 1802109 (“ Zhao 2019").

Claims

WHAT IS CLAIMED IS:

1. A method for producing chemical products, the method comprising:(a) forming an electrical arc between an anode and a cathode positioned under water or within an aqueous mist; and(b) introducing an added material into the vicinity of the electrical arc, wherein the formation of the electrical arc in the vicinity of the added material facilitates the production of the chemical products from the added material.

2. The method of Claim 1, wherein the chemical product comprises ammonia (NH3).

3. The method of Claims 1 , wherein the chemical product comprises protonated ammonia.

4. The method of Claim 1, wherein the chemical product comprises hydrogen (H2).

5. The method of Claim 1, wherein the chemical product comprises an oxygen atombearing nitrogen species.

6. The method of Claim 1, wherein the chemical product comprises cyanide or hydrogen cyanide.

7. The method of any of Claims 1-6, wherein the added material comprises an added gas.

8. The method of Claim 7, wherein the added material comprises two or more added gases.

9. The method of Claim 7, wherein the added gas comprises nitrogen (N2).

10. The method of Claim 7, wherein the added gas comprises air.

11. The method of any of Claims 7-10, wherein the added gas comprises carbon dioxide (CO2).

12. The method of Claim 11, wherein the chemical products are selected from the group consisting of carboxylic acids, alcohols, polymers, and combinations thereof.

13. The method of Claim 7, wherein the added gas is selected from the group consisting of organic gases and inorganic gases.

14. The method of Claim 8, wherein the two or more added gases comprise a mixture of at least two gases selected from the group consisting of nitrogen (N2), air, carbon dioxide (CO2), organic gases, and inorganic gases.

15. The method of any of Claims 1-6, wherein the added material comprises an added liquid.

16. The method of any of Claims 1-6, wherein the added material comprises an added solid material, and wherein the added solid material does not short circuit the electrical arc.

17. The method of any of Claims 1-16, wherein at least one of the anode or the cathode is made of brass.

18. The method of any of Claims 1-16, wherein at least one of the anode or the cathode is made of zinc.

19. The method of any of Claims 1-18, wherein the method comprises the introduction of the added material through a hollow core, wherein the hollow core is in at least one of the anode and the cathode.

20. The method of any of Claims 1-16, wherein each of the anode and the cathode is made of carbon.

21. The method of any of Claim 1-16, wherein at least one of the anode or the cathode is selected from the group consisting of brass, zinc, carbon, graphite, copper, tungsten, tungsten carbide, aluminum, and steel.

22. The method of any of Claims 1-16, wherein at least one of the anode or the cathode is selected from the group consisting of metal alloys, a metals, and metal carbides.

23. The method of any of Claims 1-22, wherein the chemical products are selected from the group consisting of carbon monoxide, methanol, alcohols, formic acid, carboxylic acids, dicarboxylic acids, oxalic acid, a polyalcohols, polymers, cyclic organic compounds, lactones, lactams, esters, amides, and combinations thereof.

24. The method of any of Claims 1-23, wherein the aqueous source contains an additive.

25. The method of Claim 24, wherein the additive is a metal salt or metal oxide.

26. The method of Claim 24, wherein the additive is an acid or a base.

27. The method of Claim 24, wherein the additive catalyzes the formation of the chemical products.

28. The method of Claim 24, wherein the additive comprises sodium chloride.

29. The method of any of Claims 1-28, wherein the reaction is conducted under a pressure of between 1 atm and 500 atm.

30. The method of Claim 29, wherein the added material comprises an added gas introduced at the pressure between 1 atm and 500 atm.

Images