Atmospheric‐pressure nonthermal plasma synthesis of ammonia over ruthenium catalysts

Kim, Hyun‐Ha; Teramoto, Yoshiyuki; Ogata, Atsushi; Takagi, Hideyuki; Nanba, Tetsuya

doi:10.1002/ppap.201600157

Cited by 127 publications

(242 citation statements)

References 38 publications

(35 reference statements)

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“…They suggested that the enhancement by the ferroelectric material is attributed to two main reasons: (1) effect on the discharge behavior, which resulted in a higher electron density, and (2) the catalytic effect of the ferroelectric material surface. Due to the good performance in conventional ammonia synthesis process, Ru based catalysts have been selected as the reference n plasma-assisted process [101,115,121,150]. However, the ionization energy of Ru is 7.36 eV, and it might be difficult to be ionized by atmospheric DBD plasma.…”

Section: Catalysts Selectionmentioning

confidence: 99%

Recent Progress of Plasma-Assisted Nitrogen Fixation Research: A Review

et al. 2018

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Nitrogen is an essential element to plants, animals, human beings and all the other living things on earth. Nitrogen fixation, which converts inert atmospheric nitrogen into ammonia or other valuable substances, is a very important part of the nitrogen cycle. The Haber-Bosch process plays the dominant role in the chemical nitrogen fixation as it produces a large amount of ammonia to meet the demand from the agriculture and chemical industries. However, due to the high energy consumption and related environmental concerns, increasing attention is being given to alternative (greener) nitrogen fixation processes. Among different approaches, plasma-assisted nitrogen fixation is one of the most promising methods since it has many advantages over others. These include operating at mild operation conditions, a green environmental profile and suitability for decentralized production. This review covers the research progress in the field of plasma-assisted nitrogen fixation achieved in the past five years. Both the production of NOx and the synthesis of ammonia are included, and discussion on plasma reactors, operation parameters and plasma-catalysts are given. In addition, outlooks and suggestions for future research are also given.

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Section: Catalysts Selectionmentioning

confidence: 99%

Recent Progress of Plasma-Assisted Nitrogen Fixation Research: A Review

et al. 2018

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“…There has been some work carried out on ammonia synthesis using plasma catalysis. [16][17][18] Over the years, energy yields have been as high as 35 g-NH 3 /kWh while using a pulsed AC atmospheric pressure dielectric barrier discharge (DBD) reactor, [19] showing the potential of small-scale production of ammonia using plasma-catalysis. Recently, Peng et al [20] employed a pulsed DBD reactor with MgCl 2 acting as catalyst and absorbent, leading to enhanced conversions.…”

Section: Introductionmentioning

confidence: 99%

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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“…In recent years, there have been several reports of ammonia synthesis using dielectric barrier discharge, microwave, glowing arc discharge, and radiofrequency (RF) plasma [9]. Among the most notable reports are Patil [13], all of them performed in a dielectric barrier discharge (DBD). These reports indicated the highest energy yield of ammonia in the range of 5-35 g-NH 3 /kWh.…”

Section: Introductionmentioning

confidence: 99%

Ammonia Plasma-Catalytic Synthesis Using Low Melting Point Alloys

2018

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The Haber-Bosch process has been the commercial benchmark process for ammonia synthesis for more than a century. Plasma-catalytic synthesis for ammonia production is theorized to have a great potential for being a greener alternative to the Haber-Bosch process. However, the underlying reactions for ammonia synthesis still require some detailed study especially for radiofrequency plasmas. Herein, the use of inductively coupled radiofrequency plasma for the synthesis of ammonia when employing Ga, In and their alloys as catalysts is presented. The plasma is characterized using emission spectroscopy and the surface of catalysts using Scanning Electron Microscope. A maximum energy yield of 0.31 g-NH3/kWh and energy cost of 196 MJ/mol is achieved with Ga-In (0.6:0.4 and 0.2:0.8) alloy at 50 W plasma power. Granular nodes are observed on the surface of catalysts indicating the formation of the intermediate GaN.

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Atmospheric‐pressure nonthermal plasma synthesis of ammonia over ruthenium catalysts

Cited by 127 publications

References 38 publications

Recent Progress of Plasma-Assisted Nitrogen Fixation Research: A Review

Recent Progress of Plasma-Assisted Nitrogen Fixation Research: A Review

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

Ammonia Plasma-Catalytic Synthesis Using Low Melting Point Alloys

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