Search

Summary: Since the triple bond in a nitrogen molecule is considered to be one of the strongest bond to break, the ammonia synthesis under atmospheric pressure and mild temperature becomes a remarkably challenging problem. In the present research study, a novel method is introduced for electrochemical ammonia synthesis through integrating the reactor with the electromagnetic zero‐voltage switching (ZVS) device. The reactor is tested under an induced electromagnetic (EM) field in galvanostatic mode by varying the operating parameters that include temperature, flow rate, and current density. The experimental setup is designed and operated toward performing the electrochemical synthesis. The maximum Faradaic efficiency achieved with EM field is 4.5%, and the ammonia formation rate is found to be 1.21 × 10−10 mol cm−2s−1 at an applied constant current of 6.4 mA cm−2 and EM field of 49 mT. Furthermore, the experiments are extended to include the ammonia synthesis with and without EM field influence on the reaction; in which case, the reduction potential becomes 1.25 V with the presence of EM field, while it is 1.7 V without EM field when the applied current of 6.4 mA cm−2 is incorporated. This study demonstrates that the electrochemical ammonia synthesis, via nitrogen reduction, can be achieved spontaneously, which is beyond the classical approach for electrochemical ammonia synthesis. [ABSTRACT FROM AUTHOR]

• Ammonia production goes green. • Small-scale modular ammonia plants are flexible and efficient. • The ammonia market is resilient in COVID-19 crises. This paper focuses on the challenges, opportunities and future potentials with ammonia as a carbon-free fuel, and covers recent technological solutions to overcome the barriers with the production, storage and usage of green ammonia. One way to decarbonize the energy industry is by converting electrical energy into chemical energy via water electrolysis to produce hydrogen. Hydrogen can then be stored, used in a fuel cell to generate electricity, or burnt cleanly with air to generate heat, steam, producing only water as a by-product. However, hydrogen has an extremely low density, even when compressed, which means that its energy density on a volumetric basis remains distinctly substandard to most liquid fuels, hydrogen also has a much wider range of concentrations over which it remains potentially explosive. Ammonia alternatively is ~ 18% hydrogen by weight, which means that in terms of hydrogen density, it is ~ 50% higher than compressed or liquefied hydrogen. One major advantage is that there is an existing infrastructure for the production, transport and distribution of ammonia worldwide. Although ammonia in theory can be combusted to produce only nitrogen and water as emissions, in practice, several challenges arise, nitrous oxides (NOx) are often generated, especially if the combustion happens at higher temperatures and/or under pressure, in vehicle engines, gas turbines and as rocket fuel. To overcome such challenges, further research into ammonia combustion phenomena is required. This review sheds light on recent technological advancements with ammonia from the production point to the utilization end point. Moreover, the study concludes with a techno-economic evaluation and global market trends of ammonia in the COVID-19 crises. [ABSTRACT FROM AUTHOR]

The galvanizing industry uses the concentrated hydrochloric acid in its metal surface treatment processes known as pickling. Every year tons of waste acid solutions polluted with metals ions are discharged to the environment after neutralization process. In this study, a novel photoelectrochemical reactor is designed and developed for the production of hydrogen and chlorine gas from spent hydrochloric acid generated in the galvanizing industry. The novel reactor design allows all the hydrogen gas to flow from the reactor without any dead zone in the cathode compartment, while chlorine gas is carried out with aqueous 5 M HCl at the surface of the illuminated photoanode without any dissolution. Further, the unique design of the cathode corrosion-resistant high surface area (3 × the anode) results in good proton and H+ transfer rate while the TiO 2 coated photoanode further enhances the charge transfer process and chlorine gas production. The characterization of the coated stainless steel is tested by the energy-dispersive X-ray (EDX) analysis and scanning electron microscope (SEM) images. The photoelectrochemical potentiostatic experiments with and without sunlight are performed on the reactor. The hydrogen and chlorine gas production rates are observed as 3 mL/min and 0.5 mL/min, respectively. Also, a comprehensive thermodynamic analysis of the photoelectrochemical reactor is conducted, and energy, exergy, and quantum efficiencies are found as 45.55%, 73.75%, and 6%, respectively. The exergoeconomic assessment study shows that the lowest exergy cost rate is achieved with sunlight illumination for a hydrogen exergy cost of 1.7 $/kg and chlorine exergy cost rate of 0.3 $/kg at an applied potential of 2 V. Unlabelled Image • A unique design of the photoelectrochemical reactor is proposed for efficient hydrogen and chlorine gas production. • An exergoeconomic assessment of the photoelectrochemical reactor yields low cost in acidic medium. • Electrochemical characterization of the coated photoanode in the chlorine gas evolution reaction is presented. [ABSTRACT FROM AUTHOR]

A novel solar PV and wind energy based system is proposed in this study for capturing carbon dioxide as well as producing hydrogen, urea and power. Both Aspen Plus and EES software packages are employed for analyses and simulations. The present system is designed in a way that PEM electrolyzer is powered by the wind turbines for hydrogen production, which is further converted into ammonia and then synthesizes urea by capturing CO 2 and additional power is supplied to the community. The solar PV is employed to power the cryogenic air separation unit and the additional power is used for the industrial purpose. In the proposed system, ammonia does not only capture CO 2 but also synthesizes urea for fertilizer industry. The amount of electrical power produced by the system is 2.14 MW. The designed system produces 518.4 kmol/d of hydrogen and synthesizes 86.4 kmol/d of urea. Furthermore, several parametric studies are employed to investigate the system performance. • A novel solar-wind hybrid energy system is developed for hydrogen and urea production. • Produced hydrogen is converted into ammonia and synthesizes urea by capturing CO 2. • The amount of electrical power produced by the system is 2.14 MW. • Designed system produces 518.4 kmol/d of H 2 and synthesizes 86.4 kmol/d of urea. [ABSTRACT FROM AUTHOR]