Ammonia Plasma-Catalytic Synthesis Using Low Melting Point Alloys

Shah, Javishk; Harrison, Joshua M.; Carreon, Maria L.

doi:10.3390/catal8100437

Cited by 33 publications

(48 citation statements)

References 44 publications

(47 reference statements)

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“…The reported yields in Table are obtained from individual ammonia yield (%) vs. time (min) plots (Figure S5–S11). In these plots, it can be seen that a steady state is achieved in less than 12 minutes, which is consistent with earlier experiments …”

Section: Resultssupporting

confidence: 92%

“…Table S4 summarizes the binding energies for atomic N, atomic H, NH, NH 2 and NH 3 species on different metals. Some of these metals have also been experimentally tested in an earlier work . The standard deviation for the reported yields was less than 5 % for all cases.…”

Section: Resultsmentioning

confidence: 98%

“…We decided to focus on Ga‐rich alloys as Ga seems to have a highly desirable “hydrogen sink” behavior, but its hydrogen yield is not as high due to its tendency to form nitride. We synthesized some easily accessible alloys with Al, Cu, Zn, Pd, Ag, Sn, and Au, complementing the Ga−In alloys studied in earlier work . The compositions and results are summarized in Table .…”

Section: Resultsmentioning

confidence: 99%

“…The experiments were conducted as per the setup described in our previous work . Briefly, the experiments were performed in an in‐house built RF plasma reactor as schematized in Figure .…”

Section: Methodsmentioning

confidence: 99%

“…Furthermore, more than 14 unique bi‐metallic alloys were used for ammonia synthesis in this manuscript, which opens a broad category of new catalysts that can be applied to other plasma‐catalytic processes to improve the efficiency significantly without altering any process parameters. These bimetallic catalysts can be loaded as bulk materials as well as impregnated or embedded in a porous framework which makes them extremely versatile.…”

Section: Introductionmentioning

confidence: 99%

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Enhancement of the Yield of Ammonia by Hydrogen‐Sink Effect during Plasma Catalysis

et al. 2019

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Plasma‐catalytic ammonia synthesis has been known since the early 1900s, but only until now efforts to optimize catalysts for this purpose are emerging. Here, we investigate various transition metals, low‐melting‐point metals, and gallium‐rich alloy catalysts for their activity towards ammonia production under a plasma environment. The best three pure metal catalysts were Ni, Sn and Au, which are not traditional catalysts for the current industrial ammonia synthesis. The ammonia yields for these catalysts were 34 %, 29 %, and 19 %, respectively. Synergistic effects were detected when employing alloys, as some alloys presented ∼25–50 % higher yields than their constituent metals. The employed metals were classified into two categories. Category I metals (Cu, Ag, Au and Fe), which are nitrophobic (excluding Fe, the Haber‐Bosch catalyst) and poor hydrogen sinks. For these metals, the measured concentration of Hα in the gas phase tended to correlate inversely with ammonia yield and directly with the H binding strength on the catalyst surface. Category II metals (Ga, In, Sn and Ni), which are good hydrogen sinks, tend to have a lower concentration of Hα in the gas phase than that of category I metals, which is consistent with their expected sink behavior. For these metals, the concentration of Hα correlates with ammonia yield. Plasma characterization experiments and DFT calculations suggest that the higher performance of Ni and Sn is related to the benefit of dissolving hydrogen to slow down H recombination, which is a feature that could be potentially optimized in future studies by rationally altering the catalyst composition.

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Section: Resultssupporting

confidence: 92%

Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Enhancement of the Yield of Ammonia by Hydrogen‐Sink Effect during Plasma Catalysis

et al. 2019

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Emerging Materials and Methods toward Ammonia‐Based Energy Storage and Conversion

et al. 2021

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Efficient storage and conversion of renewable energies is of critical importance to the sustainable growth of human society. With its distinguishing features of high hydrogen content, high energy density, facile storage/transportation, and zero-carbon emission, ammonia has been recently considered as a promising energy carrier for long-term and large-scale energy storage. Under this scenario, the synthesis, storage, and utilization of ammonia are key components for the implementation of ammonia-mediated energy system. Being different from fossil fuels, renewable energies normally have intermittent and variable nature, and thus pose demands on the improvement of existing technologies and simultaneously the development of alternative methods and materials for ammonia synthesis and storage. The energy release from ammonia in an efficient manner, on the other hand, is vital to achieve a sustainable energy supply and complete the nitrogen circle. Herein, recent advances in the thermal-, electro-, plasma-, and photocatalytic ammonia synthesis, ammonia storage or separation, ammonia thermal/ electrochemical decomposition and conversion are summarized with the emphasis on the latest developments of new methods and materials (catalysts, electrodes, and sorbents) for these processes. The challenges and potential solutions are discussed.

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A Bifunctional Catalyst for Green Ammonia Synthesis from Ubiquitous Air and Water

et al. 2023

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Ammonia (NH3) is essential for modern agriculture and industry, and due to its high hydrogen density and no carbon emission, NH3 is also expected to be the next‐generation of “clean” energy carrier. Herein, directly from air and water, the plasma‐electrocatalytic reaction system for NH3 production, which combines two steps of plasma‐air‐to‐NOx− and electrochemical NOx− reduction reaction (eNOxRR) with a bifunctional catalyst, have been successfully established. Especially, the bifunctional catalyst of CuCo2O4/Ni can simultaneously promote the plasma‐air‐to‐NOx− and eNOxRR processes. The easy adsorption and activation of O2 by CuCo2O4/Ni greatly improve the NOx− production rate at the first step. Further, CuCo2O4/Ni can also resolve the over bonding of the key intermediate of *NO, and thus reduce the energy barrier of the second step of eNOxRR. And finally, the “green” NH3 production achievs the excellent FENH3 (96.8%) and high‐record NH3 yield rate of 145.8 mg h−1 cm−2 with large partial current denstity (1384.7 mA cm−2). Moreover, an enlarged self‐made H‐type electrolyzer improves the NH3 yield to be 3.6 g h−1, and the obtained NH3 is then rapidly converted to a solid of magnesium ammonium phosphate hexahydrate, which favors the easy storage and transportation of NH3.This article is protected by copyright. All rights reserved

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Ammonia Plasma-Catalytic Synthesis Using Low Melting Point Alloys

Cited by 33 publications

References 44 publications

Enhancement of the Yield of Ammonia by Hydrogen‐Sink Effect during Plasma Catalysis

Enhancement of the Yield of Ammonia by Hydrogen‐Sink Effect during Plasma Catalysis

Emerging Materials and Methods toward Ammonia‐Based Energy Storage and Conversion

A Bifunctional Catalyst for Green Ammonia Synthesis from Ubiquitous Air and Water

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