Ammonia Electrolysis Research Articles

On-board hydrogen storage and production: An application of ammonia electrolysis

Abstract On-board hydrogen storage and production via ammonia electrolysis was evaluated to determine whether the process was feasible using galvanostatic studies between an ammonia electrolytic cell (AEC) and a breathable proton exchange membrane fuel cell (PEMFC). Hydrogen-dense liquid ammonia stored at ambient temperature and pressure is an excellent source for hydrogen storage. This hydrogen is released from ammonia through electrolysis, which theoretically consumes 95% less energy than water electrolysis; 1.55 Wh g −1 H 2 is required for ammonia electrolysis and 33 Wh g −1 H 2 for water electrolysis. An ammonia electrolytic cell (AEC), comprised of carbon fiber paper (CFP) electrodes supported by Ti foil and deposited with Pt–Ir, was designed and constructed for electrolyzing an alkaline ammonia solution. Hydrogen from the cathode compartment of the AEC was fed to a polymer exchange membrane fuel cell (PEMFC). In terms of electric energy, input to the AEC was less than the output from the PEMFC yielding net electrical energies as high as 9.7 ± 1.1 Wh g −1 H 2 while maintaining H 2 production equivalent to consumption.

Kinetic study of electrolytic ammonia removal using Ti/IrO 2 as anode under different experimental conditions

This study reports electrolytic degradation and kinetic modeling of electrolytic degradation of ammonia using Ti/IrO 2. The experimental and modeling results are compared with those previously obtained using Ti/RuO 2 anode. Synthetic solution containing predetermined ammonia concentration and the raw municipal wastewater collected after the aerobic or the anaerobic treatment were used in different sets of experiments. The experimental conditions varied for electrolytic degradation of ammonia present in the synthetic feed were initial chloride concentration, initial pH and applied current density. The results show that the ammonia removal followed pseudo zero-order kinetics. The current density ( j) and the initial Cl − concentration ([Cl −]) affected the constant of the pseudo zero-order kinetics, expressed as k Ti/Ir O 2 = 0.0020 [ C l − ] j +0.4848 and k Ti/Ru O 2 = 0.0026 [ C l − ] j − 0 .7417 . The ammonia removal rate averaged at 8.5 using Ti/IrO 2 and was comparable to the rate (11.7 mg N L −1 h −1) obtained using Ti/RuO 2 anode, at 15.4 mA cm −2 current density, 300 mg L −1 Cl − and pH of 7. Higher current density and as well as the chloride concentration resulted in greater ammonia degradation. On the other hand, pH did not seem to have any effect on electrolytic degradation of ammonia. More than 95% ammonia degradation in municipal wastewater effluents collected after aerobic or anaerobic treatment was achieved. The ammonia nitrogen in the electrolytically treated wastewater effluents collected at the end of aerobic and anaerobic environments were 0.9, 0.5 mg N L −1 using Ti/IrO 2 and 0.5, 0.2 mg N L −1 by using Ti/RuO 2 anodes, respectively.

Catalytic electrolysis of ammonia on platinum in alkaline solution for hydrogen generation

Catalytic electrolysis of ammonia provides a promising technique for generation of hydrogen and, simultaneously, maintenance of environmental sustainability. In this work, the electro-oxidation of ammonia on platinum (Pt) electrode was systematically studied in alkaline solution by cyclic voltammetry. The effects of operating conditions and the electrochemical test parameters, such as ammonia concentration, KOH concentration, electrode rotating speed, temperature, upper switch potential, potential sweep rate and cyclic number, on the ammonia oxidation and hydrogen evolution were investigated. The ammonia oxidation on Pt electrode is controlled by mass-transfer process of ammonia towards the electrode surface. However, the adsorption and desorption of N x H y intermediates play important roles in ammonia oxidation and hydrogen evolution. Determination of the ammonia electro-oxidation kinetics depends on a comprehensive consideration of mass-transfer and adsorption/desorption processes. There is an optimal ammonia concentration and KOH concentration to maximize the ammonia oxidation and hydrogen evolution simultaneously. The ammonia electro-oxidation current decreases with the increasing electrode rotating speed, and increases with the elevated temperature. The cell efficiency for ammonia electrolysis on Pt electrode can be up to 45%. Increasing ammonia and KOH concentrations could increase the electrolytic cell efficiency slightly.

Optimization of the Cathode for the Production of Hydrogen through Ammonia Electrolysis -II

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Economic and Practical Feasibility Studies of Ammonia Electrolysis as In-Situ Hydrogen Producers for Stationary Fuel Cells

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On-Board Hydrogen Storage and Production: An Application of Ammonia Electrolysis

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Effect of catalyst on electrolysis of ammonia effluents

The electrolysis of ammonia (NH 3) was studied as a remediation process for the removal of ammonia from wastewater, with the advantage of producing hydrogen while returning clean water to the environment. An electro-catalyst able to support the electro-oxidation of ammonia at low concentrations was designed. Two substrates were tested, Raney nickel and carbon fiber. Carbon fiber was found to be a better substrate for the electrolysis of ammonia at low concentrations. The performance of noble metals such as Rh, Pt and Ir, electroplated on the carbon fiber substrate was also evaluated. Rh–Pt–Ir and Pt–Ir on carbon fiber substrate were found to be the most promising electrodes for the electrolysis of ammonia at low concentrations. The maximum ammonia conversion was 91.49 ± 0.01% for a typical concentration of ammonia found in sewage water and the Faradaic efficiency was 91.81 ± 0.13% on the selected anode.

Electrochemical impedance of nitrogen fixation mediated by fullerene–cyclodextrin complex

A water-soluble complex fullerene and γ-cyclodextrin [C 60(γCD) 2] mediates an electrocatalytic conversion of dinitrogen to ammonia. The EIS data obtained under the atmosphere of argon or nitrogen were analyzed. A decrease of the charge-transfer resistance in the presence of nitrogen was found and used for selection of the most efficient potential for the electrochemical nitrogen fixation. Optimization was verified by the preparative electrolysis and detection of ammonia.

Optimization of the Cathode for the Production of Hydrogen through Ammonia Electrolysis

not Available.

Investigation on electroplating Pt-Ir over Toray Carbon Paper as Electrodes for Ammonia Electrolysis

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06/01589 On the use of ammonia electrolysis for hydrogen production: Vitse, F. et al. Journal of Power Sources, 2005, 142, (1–2), 18–26

06/01589 On the use of ammonia electrolysis for hydrogen production: Vitse, F. et al. Journal of Power Sources, 2005, 142, (1–2), 18–26

Electrochemical conversion characteristics of ammonia to nitrogen

In order to evaluate the electrolytic decomposition characteristics of ammonia to nitrogen, this work has studied several experimental variables of electrolytic ammonia decomposition. The effects of the pH and the chloride ion in the solution, kinds of anodes such as IrO 2, RuO 2, and Pt on the electrolytic decomposition of ammonia were compared, and the existence of a membrane equipped in the cell, the changes of the current density, the initial ammonia concentration, and so on were investigated for the decomposition. The performances of the electrode were totally in the order of RuO 2≈IrO 2>Pt in both the acid and alkali conditions. The ammonia decomposition was the highest at a current density of 80 mA/cm 2, over which it decreased, because the adsorption of the ammonia at the electrode surface was hindered by the hydroxyl ions in the solution. The ammonia decomposition yield increased with the concentration of the chloride ion in the solution. However, the increment rate became much lesser over 10 g/l of the chloride ion. The RuO 2 electrode among the tested anodes generated the most OH radicals which could oxidize the ammonium ion at pH 7.

Electrolytic ammonia synthesis from water and nitrogen gas in molten salt under atmospheric pressure

The authors proposed a novel ammonia synthesis method from water vapor and nitrogen gas under atmospheric pressure at lower temperature than the Haber-Bosch process. In this process, water vapor reacts with nitride ions (N 3−) to form ammonia and oxide ions in molten salts. By conducting electrolysis, nitride ions are supplied into the melt at the cathode and oxide ions are removed from the melt at the anode. In the present study, ammonia synthesis according to above principle was confirmed to be possible experimentally.

Investigation of Anodic Reaction of Electrolytic Ammonia Synthesis in Molten Salts Under Atmospheric Pressure

The kinetics of a novel ammonia synthesis reaction in molten salts were investigated. To evaluate current efficiencies and ammonia synthesis rates, potentiostatic electrolyses were conducted under various electrolysis conditions in molten LiCl-KCl-CsCl containing 0.5 mol % . The ammonia synthesis rate depended on the hydrogen partial pressure of the feed gas, not on the electrolysis potential. The relationship between ammonia synthesis rate and temperature was described by the Arrhenius equation, and the activation energy of the ammonia synthesis reaction was . From the obtained results, the mechanism of the ammonia synthesis reaction was discussed.

Electrolytic Ammonia Synthesis from Hydrogen Chloride and Nitrogen Gases with Simultaneous Recovery of Chlorine under Atmospheric Pressure

Electrolytic Ammonia Synthesis from Hydrogen Chloride and Nitrogen Gases with Simultaneous Recovery of Chlorine under Atmospheric Pressure

Electrolytic Ammonia Synthesis in Molten Salts under Atmospheric Pressure Using Methane as a Hydrogen Source

Electrolytic Ammonia Synthesis in Molten Salts under Atmospheric Pressure Using Methane as a Hydrogen Source

On the use of ammonia electrolysis for hydrogen production

An ammonia alkaline electrolytic cell for the production of hydrogen is presented. Challenges involved in using ammonia electro-oxidation for sustainable, low-cost, high-purity hydrogen production are identified and solutions are proposed. Electrodeposition was selected as a technique of preparing low-loading ammonia electrocatalysts. The efficiency of the electrolytic cell was improved by using bimetallic electrodeposited catalysts (at both electrodes) containing Pt and a low concentration of secondary metals (Ru, Ir). Pt–Ir deposits showed the highest activity toward ammonia oxidation. An experimental procedure is shown which minimizes the reversible deactivation of the electrode. Significant current densities were obtained (above 100 mA cm −2) during electrolysis testing at relatively low metal loading, low cell voltages, and high cell efficiencies. These results point to ammonia electrolysis as a promising candidate for an alternative process for low-cost, low-temperature, high-purity hydrogen production.

A role for ammonia in the hydrogen economy

Ammonia (NH 3) is a non-polluting fuel which produces only water and nitrogen as products of combustion. Therefore, it could be an alternative to hydrogen for vehicle motive power in the hydrogen economy. For this role ‘electrolytic ammonia’ would be prepared by catalytic combination of electrolytic hydrogen and atmospheric nitrogen. The background and developmental status of hydrogen and ammonia as motor-vehicle fuels are reviewed. Engine tests have demonstrated that ammonia can replace gasoline or diesel fuel for motor vehicles, giving near-theoretical values of engine power and efficiency. Ammonia is superior to hydrogen as a vehicle fuel for several reasons: it can be stored and transported as a liquid at ambient temperatures in low-pressure containers; per unit volume ammonia has 1.3 times the heating value of liquid hydrogen; ammonia is distributed internationally in quantities of over 100 million tons per year, and procedures and facilities are established world-wide for its safe handling and distribution. These factors would greatly facilitate the commercial adoption of ammonia as a practical replacement for carbonaceous fuels. The projected cost of supplying ‘electrolytic ammonia’ to motor vehicle filling stations is estimated to be roughly half the cost of supplying electrolytic liquid hydrogen for the same purpose, i.e. $10.5–12.5 GJ −1 for ammonia vs $25–30 GJ −1 for LH 2 (1988$). A summary is presented of the physical and thermo-chemical characteristics and estimated costs of ammonia in comparison with hydrogen, as liquid, compressed gas or stored as metal hydride. Properties of gasoline, methanol, ethanol and liquified methane are also listed.