Solid-state electrochemical synthesis of ammonia: a review

Amar, Ibrahim A.; Lan, Rong; Petit, Christophe Tg; Tao, Shanwen

doi:10.1007/s10008-011-1376-x

Cited by 290 publications

(267 citation statements)

References 111 publications

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“…However renewable ammonia production must be increased in order for ammonia fuel cells to be a truly sustainable source of energy. Electrochemical synthesis of ammonia will play an important role in this area (Amar et al, 2011). The combination of ammonia production from renewable resources and ammonia energy recovery technologies will form key parts of ammonia economy (Lan et al, 2012).…”

Section: Resultsmentioning

confidence: 99%

Ammonia as a Suitable Fuel for Fuel Cells

2014

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Ammonia, an important basic chemical, is produced at a scale of 150 million tons per year. Half of hydrogen produced in chemical industry is used for ammonia production. Ammonia containing 17.5 wt% hydrogen is an ideal carbon-free fuel for fuel cells. Compared to hydrogen, ammonia has many advantages. In this mini-review, the suitability of ammonia as fuel for fuel cells, the development of different types of fuel cells using ammonia as the fuel and the potential applications of ammonia fuel cells are briefly reviewed.

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Section: Resultsmentioning

confidence: 99%

Ammonia as a Suitable Fuel for Fuel Cells

2014

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“…Renewable chemical fuels such as hydrocarbons, methanol, hydrogen and ammonia may be synthesized from CO 2 , H 2 O and N 2 by solar-driven photochemical [1,2], electrocatalytic [3,4] or thermochemical processes [5]. The latter approach uses the entire spectrum of concentrated solar energy as the source of high-temperature process heat, and as such provides a thermodynamically favourable path to solar fuels and materials production with high energy conversion efficiencies.…”

Section: Introductionmentioning

confidence: 99%

Rational design of metal nitride redox materials for solar-driven ammonia synthesis

2015

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Fixed nitrogen is an essential chemical building block for plant and animal protein, which makes ammonia (NH 3 ) a central component of synthetic fertilizer for the global production of food and biofuels. A global project on artificial photosynthesis may foster the development of production technologies for renewable NH 3 fertilizer, hydrogen carrier and combustion fuel. This article presents an alternative path for the production of NH 3 from nitrogen, water and solar energy. The process is based on a thermochemical redox cycle driven by concentrated solar process heat at 700–1200°C that yields NH 3 via the oxidation of a metal nitride with water. The metal nitride is recycled via solar-driven reduction of the oxidized redox material with nitrogen at atmospheric pressure. We employ electronic structure theory for the rational high-throughput design of novel metal nitride redox materials and to show how transition-metal doping controls the formation and consumption of nitrogen vacancies in metal nitrides. We confirm experimentally that iron doping of manganese nitride increases the concentration of nitrogen vacancies compared with no doping. The experiments are rationalized through the average energy of the dopant d-states, a descriptor for the theory-based design of advanced metal nitride redox materials to produce sustainable solar thermochemical ammonia.

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“…8 Although Nafion-based low temperature electrochemical ammonia synthesis has been demonstrated in several reports, [9][10][11][12][13][14][15] no systematic investigation of noble metal catalysts exists. 2 Further, the alkaline environment of hydroxide exchange membranes (HEMs) promises the employment of non-noble metal catalysts and no acid/base reaction between the produced ammonia and the membrane is expected.…”

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Electrochemical Nitrogen Reduction Reaction on Noble Metal Catalysts in Proton and Hydroxide Exchange Membrane Electrolyzers

Nash

Yang

Anibal

et al. 2017

J. Electrochem. Soc.

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Five noble metal catalysts (Pt/C, Ir/C, Pd/C, Ru/C, and Au/C) are evaluated for electrochemical nitrogen reduction reaction (ENRR) to produce ammonia in both proton exchange membrane (PEM) and hydroxide exchange membrane (HEM) electrolyzers (PEMELs and HEMELs). The competing hydrogen evolution reaction (HER) is found to be the dominant reaction on all catalysts tested in both PEMELS and HEMELs, which is consistent with recent computational predictions that metallic catalysts are unlikely to be selective for ENRR. With the increase of applied potentials, the rate of HER increase significantly, which suppresses the ENRR, leading to significant decreases of faradaic efficiencies. Leaching of quaternary ammonium from HEM is found to interfere with ammonia quantification, which necessitates a pretreatment protocol. Due to the relatively slow kinetics of HER in alkaline solution, faradaic efficiencies in HEMELs are generally higher than those in PEMELs. We believe that these results provide a solid baseline for future research on ENRR in both PEMELs and HEMELs. Ammonia synthesis is one of the foundational chemical processes to the human society, which is estimated to supported approximately 27% of the world's population over the past century.1 The development of the Haber-Bosch process revolutionized modern agriculture, 2 however, the centralized, energy and carbon intensive nature of the Haber-Bosch process 3-5 leaves many aspects to be desired. Distributed and modular ammonia synthesis via the electrochemical nitrogen reduction reaction (ENRR) at or close to ambient conditions, powered by renewable electricity, is an attractive alternative because it allows as-needed production of ammonia, and in turn N-fertilizers, from ubiquitously available resources, i.e., N 2 and water. 4 Widespread adoption of ENRR for ammonia production could drastically reduce the carbon footprint of agricultural activities. In addition, ENRR is compatible with the intermittency of renewable energy sources, e.g., solar and wind, as the ammonia and N-fertilizers can be produced and stored when renewable electricity is available.Electrochemical fixation of atmospheric nitrogen was first attempted in 1908 even before the establishment of the Haber-Bosch process, to make nitric acid via electric discharge. 6 Further studies of ENRR have generally been focused on high temperature proton conductors at 500• C, 7 however, the high operating temperature and the stability of ammonia at such conditions make it unsuitable for distributed deployment. Proton exchange membranes (PEMs) can achieve high proton conductivity (∼100 mS·cm −1 at 25 • C for Nafion) at ambient or slightly elevated temperatures, which opens the possibility for electrochemical ammonia synthesis at those mild conditions. 8 Although Nafion-based low temperature electrochemical ammonia synthesis has been demonstrated in several reports, 9-15 no systematic investigation of noble metal catalysts exists.2 Further, the alkaline environment of hydroxide exchange membranes (HEMs) promises the...

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Solid-state electrochemical synthesis of ammonia: a review

Cited by 290 publications

References 111 publications

Ammonia as a Suitable Fuel for Fuel Cells

Ammonia as a Suitable Fuel for Fuel Cells

Rational design of metal nitride redox materials for solar-driven ammonia synthesis

Electrochemical Nitrogen Reduction Reaction on Noble Metal Catalysts in Proton and Hydroxide Exchange Membrane Electrolyzers

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