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Wyszukujesz frazę "ammonia" wg kryterium: Temat


Wyświetlanie 1-9 z 9
Tytuł:
Characterization of FeCo based catalyst for ammonia decomposition. The effect of potassium oxide
Autorzy:
Lendzion-Bieluń, Zofia
Pelka, Rafał
Czekajło, Łukasz
Powiązania:
https://bibliotekanauki.pl/articles/778513.pdf
Data publikacji:
2014
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
ammonia decomposition
hydrogen
FeCo catalyst
Opis:
FeCo fused catalyst was obtained by fusing iron and cobalt oxides with an addition of calcium, aluminium, and potassium oxides (CaO, Al2O3, K2O). An additional amount of potassium oxide was inserted by wet impregnation. Chemical composition of the prepared catalysts was determined with an aid of the XRF method. On the basis of XRD analysis it was found that cobalt was built into the structure of magnetite and solid solution of CoFe2O4 was formed. An increase in potassium content develops surface area of the reduced form of the catalyst, number of adsorption sites for hydrogen, and the ammonia decomposition rate. The nitriding process of the catalyst slows down the ammonia decomposition.
Źródło:
Polish Journal of Chemical Technology; 2014, 16, 4; 111-116
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Studies of the Ammonia Decomposition over a Mixture Of α - Fe(N) And γ - Fe4n
Autorzy:
Kiełbasa, K.
Arabczyk, W.
Powiązania:
https://bibliotekanauki.pl/articles/779244.pdf
Data publikacji:
2013
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
catalytic ammonia decomposition
kinetics
iron catalyst
Opis:
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, at 475oC. The nitriding potentials were changed gradually in the range from 19.10-3 to 73.10-3 Pa-0.5 in the reactor for an intermediate area where two phases exist simultanously: Fe(N) and γ’-Fe4. In the area wherein P > 73.10-3 Pa-0.5, approximately stoichiometric composition of γ’ - Fe4N 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’ - Fe4N 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’ - Fe4N.
Źródło:
Polish Journal of Chemical Technology; 2013, 15, 1; 97-101
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The activity of fused-iron catalyst doped with lithium oxide for ammonia synthesis
Autorzy:
Jedrzejewski, R.
Lendzion-Bieluń, Z.
Arabczyk, W.
Powiązania:
https://bibliotekanauki.pl/articles/779518.pdf
Data publikacji:
2016
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
iron catalyst
ammonia synthesis
lithium oxide
Opis:
The iron catalyst precursor promoted with Al2O3, CaO, and Li2O was obtained applying the fusing method. Lithium oxide forms two phases in this iron catalyst: a chemical compound with iron oxide (Li2Fe3O4) and a solid solution with magnetite. The catalyst promoted with lithium oxide was not fully reduced at 773 K, while the catalyst containing potassium was easily reducible at the same conditions. After reduction at 873 K the activity of the catalyst promoted with lithium oxide was 41% higher per surface than the activity of the catalyst promoted with potassium oxide. The concentration of free active sites on the surface of the catalyst containing lithium oxide after full reduction was greater than the concentration of free active sites on the surface of the catalyst promoted with potassium oxide.
Źródło:
Polish Journal of Chemical Technology; 2016, 18, 2; 78-83
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of the Content of Promoters in Magnetite and Wustite Phases in the Fused Iron Catalyst
Autorzy:
Lendzion-Bieluń, Z.
Jędrzejewski, R.
Powiązania:
https://bibliotekanauki.pl/articles/779352.pdf
Data publikacji:
2013
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
iron catalyst
promoters
ammonia synthesis
selective etching
Opis:
Taking advantage of differences in etching rates of crystallographic phases, forming an oxidized form of the fused iron catalyst, a content of promoters in main phases, magnetite and wustite, was determined. A calcium oxide content in magnetite and wustite was 0.54 wt% and 3.59 wt%, respectively. Aluminum oxide was found in the magnetite phase, and its content was 4.5 wt%. The third promoter, potassium oxide, was almost completely located outside these phases. XRD and ICP-OES instrumental methods were used in the investigations.
Źródło:
Polish Journal of Chemical Technology; 2013, 15, 1; 27-29
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Properties and activity of the cobalt catalysts for NH3 &enspsynthesis obtained by co-precipitation – the effect of lanthanum addition
Autorzy:
Zybert, M.
Karasińska, M.
Truszkiewicz, E.
Mierzwa, B.
Raróg-Pilecka, W.
Powiązania:
https://bibliotekanauki.pl/articles/778653.pdf
Data publikacji:
2015
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
ammonia synthesis
cobalt catalyst
promoter
lanthanum
coprecipitation
Opis:
In modern research on catalysts for NH3&enspsynthesis a lot of attention is paid to cobalt. In this work the new catalytic systems based on cobalt are presented. Unsupported cobalt catalysts singly promoted (La or Ba) and doubly promoted (La and Ba) were prepared and tested in NH3&enspsynthesis reaction under commercial synthesis conditions. Characterization studies revealed that lanthanum plays a role of a structural promoter, which improves the surface of catalyst precursors and prevents from sintering during calcination. However, lanthanum has a negative effect on the reduction of cobalt oxide, but the addition of barium promoter (Co/La/Ba catalyst) diminishes the negative impact of La. The co-promotion of cobalt with lanthanum and barium results in the increasing of the active phase surface and improvement of its activity in NH3&enspsynthesis.
Źródło:
Polish Journal of Chemical Technology; 2015, 17, 1; 138-143
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cobalt-lanthanum catalyst precursors for ammonia synthesis: determination of calcination temperature and storage conditions
Autorzy:
Zybert, M.
Tarka, A.
Mierzwa, B.
Raróg-Pilecka, W.
Powiązania:
https://bibliotekanauki.pl/articles/778044.pdf
Data publikacji:
2017
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
ammonia synthesis
catalyst precursor
cobalt
lanthanum
thermal analysis
Opis:
A thermal decomposition of a cobalt-lanthanum catalyst precursor containing a mixture of cobalt and lanthanum compounds obtained by co-precipitation were studied using thermal analysis coupled with mass spectrometry (TG-MS). Studies revealed that the calcination in air at 500°C is sufficient to transform the obtained cobalt precipitate into Co3 O4 , but it leads to only partial decomposition of lanthanum precipitate. In order to obtain Co/La catalyst precursor containing La2 O3  the calcination in air at the temperature about 800°C is required. However, it is unfavorable from the point of view of textural properties of the catalyst precursor. A strong effect of storage conditions on the phase composition of the studied cobalt-lanthanum catalyst precursor, caused by the formation of lanthanum hydroxide and lanthanum carbonates from La2 O3  when contacting with air, was observed.
Źródło:
Polish Journal of Chemical Technology; 2017, 19, 2; 61-66
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of Fe2+/Fe3+ mole ratio based on the change of precursor lattice parameters of wustite based iron catalysts for the ammonia synthesis
Autorzy:
Jurkowski, Artur
Lendzion-Bieluń, Zofia
Powiązania:
https://bibliotekanauki.pl/articles/778447.pdf
Data publikacji:
2019
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
wustite ammonia catalyst
XRD technique
manganometry
wustite lattice parameter
Opis:
In the presented article, oxide forms of iron catalysts with the wustite structure and with a R = Fe2+/Fe3+ molar ratio in the range from 3.78 to 8.16 were investigated. The chemical composition of the tested catalyst precursors was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The X-ray diffraction (XRD) technique was used to determine the phase composition and location of reflections characteristic of the Fe1−xO phase. The molar ratio of iron ions R = Fe2+/Fe3+ was determined by manganometric titration. The distribution of promoters in the structure of iron catalyst precursors with different R = Fe2+/Fe3+  ratio was determined by a selective etching method. The dependence of the lattice parameter ao value in the crystal structure Fe1−xO on the molar ratio R = Fe2+/Fe3+ was determined. On the basis of the determined dependence, R can easily be calculated in catalyst precursors of the wustite structure.
Źródło:
Polish Journal of Chemical Technology; 2019, 21, 3; 48-52
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The analysis of distribution of the reaction mixture in ammonia oxidation reactor
Autorzy:
Moszkowski, Bartosz
Wajman, Tomasz
Sobczak, Krzysztof
Inger, Marek
Wilk, Marcin
Powiązania:
https://bibliotekanauki.pl/articles/779139.pdf
Data publikacji:
2019
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
Nitric acid
ammonia oxidation reactor
flow distribution
CFD simulation
Opis:
This article describes the influence of various design modifications of the ammonia oxidation reactor operating in nitric acid plant TKIV in Kędzierzyn-Koźle on flow distribution of an air-ammonia mixture. The CFD (Computational Fluid Dynamics) simulations of turbulent flow were carried out with SST k-ω turbulence model to close the system of RANS (Reynolds Averaged Navier-Stokes) equations. The simulation results show that the properly selected perforated plate screen and the conical diffuser ensure uniform flow of gas on the ammonia oxidation catalysts and on the catalysts for nitrous oxide decomposition. It was proved experimentally achieving uniform temperature of nitrous gases in different locations under the catalytic gauzes and high efficiency of ammonia oxidation and nitrous oxide decomposition.
Źródło:
Polish Journal of Chemical Technology; 2019, 21, 1; 9-12
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of cathode materials on the electrochemical reduction of nitric acid
Autorzy:
Vasudevan, D.
Powiązania:
https://bibliotekanauki.pl/articles/778362.pdf
Data publikacji:
2010
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
elektroredukcja
kwas azotowy
hydroksylamina
amoniak
katoda
electroreduction
nitric acid
hydroxylamine
ammonia
conventional and modified cathodes
mechanism
Opis:
Electrochemical or chemical reduction of nitric acid is a well studied area in literature due to the importance of the products formed. The present work focuses on the effect of conventional cathode materials including PbO2, amalgamated Cu, graphite, Pb, Pt and a modified electrode material Ti/TiO2 on the reduction of nitric acid. Ammonia and hydroxylamine are the main products which are estimated by conventional titration methods. Other conditions being similar, the product distribution varies quite drastically as a function of the electrode material and Ti/TiO2 is found to favor a higher ratio of hydroxylamine to ammonia formation compared to other electrodes. The conditions have also been optimized based on the maximum yield of the product.
Źródło:
Polish Journal of Chemical Technology; 2010, 12, 1; 35-37
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-9 z 9

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