Studies of the Kinetics of Ammonia Decomposition on Promoted Nanocrystalline Iron Using Gas Phases of Different Nitriding Degree

Kiełbasa, Karolina; Pelka, Rafał; Arabczyk, W.

doi:10.1021/jp9099286

Cited by 44 publications

(33 citation statements)

References 11 publications

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“…The purity of the inlet ammonia stream and the presence of other gases and/or impurities can also have a beneficial or detrimental effect on the catalyst, some of them capable of altering the iron surface [41]. For example, the presence of CO 2 and H 2 O was found to maintain the metallic active state of iron, leading to an enhanced activity [13].…”

Section: Iron-based Catalystsmentioning

confidence: 99%

H2 Production via Ammonia Decomposition Using Non-Noble Metal Catalysts: A Review

2016

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The wide-spread implementation of the so-called hydrogen economy is currently partially limited by an economically feasible way of storing hydrogen. In this context, ammonia has been commonly presented as a viable option for chemical storage due its high hydrogen content (17.6 wt%). However, its use as an energy carrier requires the development of catalytic systems capable of releasing hydrogen at adequate rates and conditions. At the moment, the most active catalytic systems for the decomposition of ammonia are based on ruthenium, however its cost and scarcity inhibit the wide scale use of these catalysts. This issue has triggered research on the development of alternative catalysts based on more sustainable systems using more readily available, non-noble metals mainly iron, cobalt and nickel as well as a series of transition metal carbides and nitrides and bimetallic systems, which are reviewed herein. There have been some promising cobaltand nickel-based catalysts reported for the decomposition of ammonia but metal dispersion needs to be increased in order to become more attractive candidates. Conversely, there seems to be less scope for improvement of iron-based catalysts and metal carbides and nitrides. The area with the most potential for improvement is with bimetallic catalysts, particularly those consisting of cobalt and molybdenum.

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Section: Iron-based Catalystsmentioning

confidence: 99%

H2 Production via Ammonia Decomposition Using Non-Noble Metal Catalysts: A Review

2016

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“…Iron nanocrystallites size distribution was determined by measuring the nitriding reaction rate of the catalyst as described by Pelka et al [7]. The rate of chemical reactions occurring between gas phase and iron was measured in a tubular reactor making it possible both to measure by thermogravimetry the reaction product content in the solid sample, and to analyze the composition of the gas phase [11]. The gas flow rate at the inlet to the reactor was controlled by means of electronic flowmeters.…”

Section: Methodsmentioning

confidence: 99%

Magnetic characterization of nanocrystalline iron samples with different size distributions

Typek

Żołnierkiewicz

Pelka

et al. 2014

Materials Science-Poland

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Nanocrystalline iron was obtained by fusing magnetite and promoters. The oxidized form was reduced with hydrogen and passivated (sample P0). The average nanocrystallite size in sample P0 was d(P0) =16 nm and the width of size distribution was σ (P0) = 18 nm. Samples of nanocrystalline iron with narrower diameter ranges and larger and smaller average crystallite sizes were also synthesized. They were: sample P1 (d(P1) = 28 nm, σ (P1) = 5 nm), sample P2 (d(P2) = 22 nm, σ (P1) = 5 nm), sample P3 (d(P3) = 12 nm, σ (P1) = 9 nm). These four samples were studied at room temperature by dc magnetization measurements and ferromagnetic resonance at microwave frequency. Correlations between samples sizes distributions (average size and width of the sizes) and magnetic parameters (effective magnetization, anisotropy field, anisotropy constant, FMR linewidth) were investigated. It was found that the anisotropy field and effective magnetization determined from FMR spectra scale linearly with nanoparticle sizes, while the effective magnetic anisotropy constant determined from the hysteresis loops decreases with nanoparticle size increase.

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“…In our previous work 53 , it was found that nitriding degree of iron catalyst (ratio of moles of nitrogen to moles of iron in sample) is a function of the nitriding potential (the gas phase composition infl uences on the nitriding degree of solid samples) and temperature as well…”

Section: -8mentioning

confidence: 99%

Removal of phenol from wastewater using activated waste tea leaves

Kazmi¹,

Saleemi²,

Feroze³

et al. 2013

Polish Journal of Chemical Technology

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An industrial pre-reduced iron catalyst for ammonia synthesis was nitrided in a differential reactor equipped with the systems that made it possible to conduct both the thermogravimetric measurements and hydrogen concentration analyser in the reacting gas mixture. The nitriding process, particularly the catalytic ammonia decomposition reaction, was investigated under an atmosphere of ammonia-hydrogen mixtures, under the atmospheric pressure, , approximately stoichiometric composition of γ' -Fe 4 N phase exists and saturating of that phase by nitrogen started. The rate of the catalytic ammonia decomposition was calculated on the basis of grain volume distribution as a function of conversion degree for that catalyst. It was found that over γ' -Fe 4 N phase in the stationary states the rate of catalytic ammonia decomposition depends linearly on the logarithm of the nitriding potential. The rate was decreasing along with increase in the nitriding potential. For the intermediate area, the rate of ammonia decomposition is a sum of the rates of reactions which occur on the surfaces of both Fe(N) and γ' -Fe 4 N.

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Studies of the Kinetics of Ammonia Decomposition on Promoted Nanocrystalline Iron Using Gas Phases of Different Nitriding Degree

Cited by 44 publications

References 11 publications

H2 Production via Ammonia Decomposition Using Non-Noble Metal Catalysts: A Review

H2 Production via Ammonia Decomposition Using Non-Noble Metal Catalysts: A Review

Magnetic characterization of nanocrystalline iron samples with different size distributions

Removal of phenol from wastewater using activated waste tea leaves

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