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Wyświetlanie 1-5 z 5
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:
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:
Initial Assessment of Graphite Precipitates in Vermicular Cast Iron in the As-Cast State and after Thermal Treatments
Autorzy:
Soiński, M. S.
Jakubus, Aneta
Borowiecki, B.
Mierzwa, P.
Powiązania:
https://bibliotekanauki.pl/articles/2126913.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
vermicular cast iron
graphite precipitates
thermal treatments
austempering
żeliwo wermikularne
morfologia grafitu
obróbka termiczna
hartowanie
Opis:
The purpose of the work was to determine the morphology of graphite that occurs in vermicular cast iron, both in the as-cast state and after heat treatment including austenitization (held at a temperature of 890°C or 960°C for 90 or 150 min) and isothermal quenching (i.e. austempering, at a temperature of 290°C or 390°C for 90 or 150 min). In this case, the aim here was to investigate whether the heat treatment performed, in addition to the undisputed influence of the cast iron matrix on the formation of austenite and ferrite, also affects the morphology of the vermicular graphite precipitates and to what extent. The investigations were carried out for the specimens cut from test coupons cast in the shape of an inverted U letter (type IIb according to the applicable standard); they were taken from the 25mm thick walls of their test parts. The morphology of graphite precipitates in cast iron was investigated using a Metaplan 2 metallographic microscope and a Quantimet 570 Color image analyzer. The shape factor F was calculated as the quotient of the area of given graphite precipitation and the square of its perimeter. The degree of vermicularization of graphite was determined as the ratio of the sum of the graphite surface and precipitates with F <0.05 to the total area occupied by all the precipitations of the graphite surface. The examinations performed revealed that all the heat-treated samples made of vermicular graphite exhibited the lower degree of vermicularization of the graphite compared to the corresponding samples in the as-cast state (the structure contains a greater fraction of the nodular or nearly nodular precipitates). Heat treatment also caused a reduction in the average size of graphite precipitates, which was about 225μm2 for the as-cast state, and dropped to approximately 170-200 μm2 after the austenitization and austempering processes.
Źródło:
Archives of Foundry Engineering; 2021, 21, 4; 131--136
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Content of PAHs, activities of γ-radionuclides and ecotoxicological assessment in biochars
Autorzy:
Gondek, K.
Mierzwa-Hersztek, M.
Smreczak, B.
Baran, A.
Kopeć, M.
Mróz, T.
Janowski, P.
Bajda, T.
Tomczyk, A.
Powiązania:
https://bibliotekanauki.pl/articles/778621.pdf
Data publikacji:
2016
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
biochar
sewage sludge
PAHs
γ-radionuclides
Vibrio fischeri
Opis:
The aim of this research was to determine the effect of thermal conversion temperature and plant material addition to sewage sludge on the PAHs content and the activity of selected γ-radionuclides in biochars, and to conduct an ecotoxicological assessment. The pyrolysis of the mixtures of sewage sludge and plant materials at 300°C and such temperature caused an increase in the contents of 2- and 3-ring hydrocarbons. During the pyrolysis of organic materials at 600°C, the amount of the following compounds was reduced in biochars: benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, indeno[1,2,3c,d]pyrene, dibenzo[a,h]anthracene, and benzo[g,h,i]perylene. Among γ-radioisotopes of the elements, natural radiogenic isotopes were dominant. 137Cs was the only artificial radioactive isotope. The pyrolysis of the mixtures of municipal sewage sludge and plant materials revealed that isotope  40K had the highest radioactive activity. In the case of other analysed nuclides, activities of  212Pb,  214Pb,  214Bi, and  137Cs were determined after the sample pyrolysis. The extracts from the mixtures of sewage sludge and plant materials were non-toxic to Vibrio fischeri.
Źródło:
Polish Journal of Chemical Technology; 2016, 18, 4; 27-35
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mineral composition of fruits and leaves of San Andreas® everbearing strawberry in soilless cultivation
Autorzy:
Gondek, K.
Mierzwa-Hersztek, M.
Kopec, M.
Zaleski, T.
Bogdal, S.
Bieniasz, M.
Blaszczyk, J.
Kaczmarczyk, E.
Kowalczyk, B.
Knaga, J.
Nawrocki, J.
Pniak, M.
Jarosz, R.
Powiązania:
https://bibliotekanauki.pl/articles/1192501.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet Warmińsko-Mazurski w Olsztynie / Polskie Towarzystwo Magnezologiczne im. Prof. Juliana Aleksandrowicza
Tematy:
mineral composition
everbearing strawberry
soilless cultivation
Opis:
Technological progress in the cultivation of horticultural and fruit plants makes the use of soil becoming less and less important. Growing plants in soilless substrates is becoming more and more common. The aim of the study was to determine the variability of the mineral composition of fruits and leaves of everbearing strawberry of the San Andreas® variety in soilless cultivation. Research was carried out at the experimental plantation of Polski Instytut Truskawki Sp. z o.o. (geographical coordinates: 50°02′11″N and 19°81′19″E). The cultivation of everbearing strawberry of the San Andreas® variety was carried out in a gutter system under covers in coconut substrate. The stability of the chemical composition of strawberry leaves and fruits depends on fertilisation, weather factors, and the quality of water used for fertigation. Despite maintaining the content of nutrient in the rhizosphere at the level recommended for organic substrates, low potassium and calcium content and high magnesium content in strawberry leaves were determined. Among the macroelements analysed in strawberry leaves, the lowest variation coefficient values were found for nitrogen, magnesium and calcium, and in fruits – for nitrogen, phosphorus, and magnesium. The highest variation coefficients were obtained for phosphorus and sodium in strawberry leaves, and for sulphur and sodium in strawberry fruits. Variation coefficient values of copper, zinc, and manganese content in leaves were similar. The content of iron in leaves and zinc in fruits was characterised by the lowest variation coefficients during the growing period.
Źródło:
Journal of Elementology; 2020, 25, 4; 1333-1347
1644-2296
Pojawia się w:
Journal of Elementology
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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