Catalytic Ammonia Decomposition Over Fe/Fe4N

Pelka, Rafał; Moszyńska, I.; Arabczyk, W.

doi:10.1007/s10562-008-9758-0

Cited by 66 publications

(43 citation statements)

References 14 publications

(16 reference statements)

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“…The simultaneous occurrence of ammonia decomposition and nitridation of the iron active species was addressed by Arabczyk and Pelka [34,35] by comparing the decomposition activity of Fe and Fe 4 N. The activation energy of the latter was approximately double compared to the former highlighting that surface nitrides formation is undesirable during ammonia decomposition with a consequent reduction of the reaction rates. Detection of FeN x as the predominant active phase on the surface was identified by a combination of high resolution TEM, elemental mapping and electron energy loss spectroscopy (EELS).…”

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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“…From the literature it is known that especially the reaction order of hydrogen can be negative depending on the type of catalyst. [22,23] Therefore, a dilution of the product gases should increase the overall reaction rate of the catalyst. The opposite could be expected for dilution of the reagent: if the ammonia concentration enters with a positive reaction order in the kinetics, a dilution with noble gases would lead to a reduction of the reaction rate.…”

mentioning

confidence: 99%

High‐Temperature Stable, Iron‐Based Core–Shell Catalysts for Ammonia Decomposition

Feyen

Weidenthaler

Güttel

et al. 2010

Chemistry A European J

113

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High-temperature, stable core-shell catalysts for ammonia decomposition have been synthesized. The highly active catalysts, which were found to be also excellent model systems for fundamental studies, are based on α-Fe(2)O(3) nanoparticles coated by porous silica shells. In a bottom-up approach, hematite nanoparticles were firstly obtained from the hydrothermal reaction of ferric chlorides, L-lysine, and water with adjustable average sizes of 35, 47, and 75 nm. Secondly, particles of each size could be coated by a porous silica shell by means of the base-catalyzed hydrolysis of tetraethylorthosilicate (TEOS) with cetyltetramethylammonium bromide (CTABr) as porogen. After calcination, TEM, high-resolution scanning electron microscopy (HR-SEM), energy-dispersive X-ray (EDX), XRD, and nitrogen sorption studies confirmed the successful encapsulation of hematite nanoparticles inside porous silica shells with a thickness of 20 nm, thereby leading to composites with surface areas of approximately 380 m(2) g(-1) and iron contents between 10.5 and 12.2 wt %. The obtained catalysts were tested in ammonia decomposition. The influence of temperature, iron oxide core size, possible diffusion limitations, and dilution effects of the reagent gas stream with noble gases were studied. The catalysts are highly stable at 750 °C with a space velocity of 120,000 cm(3) g(cat)(-1) h(-1) and maintained conversions of around 80 % for the testing period time of 33 h. On the basis of the excellent stability under reaction conditions up to 800 °C, the system was investigated by in situ XRD, in which body-centered iron was determined, in addition to FeN(x), as the crystalline phase under reaction conditions above 650 °C.

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“…The infl uence of water vapour in the gas phase 45 and sulfur adsorbed on solid surface 46, 47 on the rate of ammonia decomposition process was analyzed. The catalytic ammonia decomposition reaction proceeds with different rates depending on the solid phase present in the nitridnig process 48 . Ammonia decomposition kinetic studies are available in the literature and most of those descriptions are focused on low ammonia concentrations and/ or low temperature.…”

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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Catalytic Ammonia Decomposition Over Fe/Fe4N

Cited by 66 publications

References 14 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

High‐Temperature Stable, Iron‐Based Core–Shell Catalysts for Ammonia Decomposition

Removal of phenol from wastewater using activated waste tea leaves

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