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Tytuł:
Preparation, Characterization and Catalytic Properties of SBA-15-SO₃H Supported Tungstophosphoric Acid for Esterification Reaction
Autorzy:
Erdem, B.
Erdem, S.
Çıtak, A.
Yavru, C.
Öksüzoğlu, R.
Powiązania:
https://bibliotekanauki.pl/articles/1031202.pdf
Data publikacji:
2017-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.43.Gt
82.65.+r
Opis:
SBA-15-SO₃H supported tungstophosphoric acid (TPA, H₃PW₁₂O₄₀) mesoporous materials were synthesized by impregnation of TPA into the hydrothermally synthesized SBA-15-SO₃H and the catalytic performances were compared for the esterification reaction. The physical and chemical properties of the catalysts were characterized by XRD, SEM/EDX, FT-IR and N₂ adsorption/desorption techniques. The characterization results show that TPA/SBA-15-SO₃H retained the typical mesoporous structure of SBA-15-SO₃H. The experimental results indicated that TPA/SBA-15-SO₃H is a more efficient catalyst than SBA-15-SO₃H for the esterification reaction. The higher activity of TPA/SBA-15-SO₃H compared with that of SBA-15-SO₃H was consistent with the material having the low pKa value, confirming that the esterification rate was mostly dependent on the acid strength of the additional functional groups of solid acid catalyst. Accordingly, the reason for the catalytic activity difference was simply explicated by the effect of TPA, having low pKa value, affecting the pore structure and the total acidity.
Źródło:
Acta Physica Polonica A; 2017, 132, 3; 1041-1044
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Silicon Etching in $XeF_2$ Environment
Autorzy:
Knizikevičius, R.
Powiązania:
https://bibliotekanauki.pl/articles/1400495.pdf
Data publikacji:
2013-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.65.Cf
82.35.Gh
82.65.+r
Opis:
Enhancement of silicon etching rate in $XeF_2$ environment is considered by a proposed model, which includes processes of adsorption, activation, chemical reactions, relaxation, desorption, and sputtering. The enhancement of silicon etching rate is explained by considering hydrocarbon molecules from background gas contamination in the vacuum chamber, and assuming that hydrocarbon radicals enhance the etching rate. The composition of the adsorbed layer during silicon etching in $XeF_2$ environment is calculated. It is found that hydrocarbon radicals intensify reaction of $XeF_2$ molecules with Si atoms on the surface and that this changes the kinetics of the etching rate. Using the obtained theoretical results the difference in kinetics of the etching rates of first and subsequent run is explained.
Źródło:
Acta Physica Polonica A; 2013, 124, 1; 137-140
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Temperature Dependent Catalytic Activity of Ag/PET Ion-Track Membranes Composites
Autorzy:
Borgekov, D.
Mashentseva, A.
Kislitsin, S.
Kozlovskiy, A.
Russakova, A.
Zdorovets, M.
Powiązania:
https://bibliotekanauki.pl/articles/1402216.pdf
Data publikacji:
2015-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
62.23.Pq
82.65.+r
82.20.Pm
Opis:
Electroless deposition has been used to coat finely porous polyethylene terephthalate (PET) track-etched membranes with silver, forming silver nanotubes within the pores with inner and outer diameters of 60 and 100 nm. The sample's X-ray diffraction pattern shows a face-centered cubic crystalline phase of silver with the lattice constant 4.0838 nm. The average size of silver nanoclusters, as obtained from the scanning electron microscopy analysis is about 30 nm which is consistent with the X-ray diffraction results. The temperature dependent catalytic activity of prepared composites is demonstrated for two model reactions such as reduction of 4-nitrophenol (4-NP) and decomposition of hydrogen peroxide. Apparent constant rates and activation energy as well as reusability of catalysts were determined. The developed composite catalyst could be used consecutively for several runs without any damages for 4-NP reduction. For hydrogen peroxide reaction decomposition the reaction rate of the second cycle is reduced 2.4 times. Moreover, the second reuse reduced conversion of H₂O₂ to 54.7% suggests removal of active Ag centers during the first cycle of testing.
Źródło:
Acta Physica Polonica A; 2015, 128, 5; 871-874
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis, Structure, and Catalytic Activity of Au/Poly(ethylene terephthalate) Composites
Autorzy:
Mashentseva, A.
Borgekov, D.
Zdorovets, M.
Russakova, A.
Powiązania:
https://bibliotekanauki.pl/articles/1365723.pdf
Data publikacji:
2014-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
62.23.Pq
82.65.+r
82.20.Pm
Opis:
A standard technique of electroless gold deposition was modified by changing the composition of Ag-based activation solution. This allows preparation of two types of poly(ethyleneterephthalate) (PET) track etched membranes coated entirely with gold after 1, 5, and 24 h of reaction at 4°C. After dissolving the polymer template, gold nanotubes with outer diameter of 70-80 nm were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. Reduction of p-nitrophenol to p-aminophenol by sodium borohydride was used to investigate the catalytic activity of as-prepared Au/PET membrane. All experiments were carried out for five consecutive cycles and rate constant of the pseudo-first-order reaction was calculated. It was found that Au/Ag/PET composites prepared after activation for 3 min in Ag-based solution (with potassium sodium tartrate as reducing agent) more effective catalyst (k=0.087 $min^{-1}$) was obtained when the Au/PET samples activated with ammonia silver nitrate solution (k=0.041 $min^{-1}$).
Źródło:
Acta Physica Polonica A; 2014, 125, 6; 1263-1266
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Resonant Charge Exchange in Atom Scattering on Atoms Adsorbed on Metal Surfaces
Autorzy:
Wiertel, M.
Taranko, E.
Taranko, R.
Powiązania:
https://bibliotekanauki.pl/articles/2030724.pdf
Data publikacji:
2002-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
79.20.-m
82.65.+r
34.70.+e
Opis:
The ionization probability of an atom scattered from an atom adsorbed on a metal surface has been studied theoretically within the time-dependent Anderson-Newns model. The effect of the metal electron density of states, the band filling as well as the relative position of the scattered atom and adsorbed atom energy levels have been considered and the comparison with the results obtained for clean surfaces has been made.
Źródło:
Acta Physica Polonica A; 2002, 101, 6; 837-855
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structure Characterization and Catalytic Properties of Cr$\text{}_{2}$O$\text{}_{3}$ Doped with MgO Supported on MgF$\text{}_{2}$
Autorzy:
Goslar, J.
Wojciechowska, M.
Zieliński, M.
Tomska-Foralewska, I.
Przystajko, W.
Powiązania:
https://bibliotekanauki.pl/articles/2043607.pdf
Data publikacji:
2005-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
68.43.Fg
82.65.+r
Opis:
A characterization of double oxide systems containing Cr$\text{}_{2}$O$\text{}_{3}$ doped with MgO and supported on MgF$\text{}_{2}$ was carried out. The catalysts were prepared by impregnation and co-impregnation methods and characterized by the Brunauer-Emmett-Teller method, EPR, and temperature programmed reduction. The results proved the interactions between supported oxides and the presence of spinel-like phase after treatment at 400ºC. Magnesium oxide clearly influences the catalytic activity as well as selectivity of chromium catalysts supported on MgF$\text{}_{2}$. The MgO-Cr$\text{}_{2}$O$\text{}_{3}$/MgF$\text{}_{2}$ systems were active and selective in the reaction of CO oxidation at the room temperature and in the dehydrogenation of cyclohexene.
Źródło:
Acta Physica Polonica A; 2005, 108, 2; 323-330
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural Characterization of $Al_2O_3$ and $CeO_2$ Supported Ni, Co Loaded Ceramic Monolithic Catalysts
Autorzy:
Guldal, N.
Baykara, S.
Powiązania:
https://bibliotekanauki.pl/articles/1216529.pdf
Data publikacji:
2014-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.15.-z
81.70.-q
82.65.+r
Opis:
This paper discusses structural characterizations of monolithic catalysts prepared by incorporating Ni and Co supported over a porous alumina and ceria layer by using respective nitrates and $H_2PtCl_6$ as precursors. Monolithic catalysts were synthesized by dip-coating of 400 cpsi cordierite ceramic monolithic pieces cut in 20 × 13 $mm^2$ (L× D) into appropriate solutions of metals, followed by calcination in air at 800C for 4 h. Phases of catalysts were characterized with X-ray diffraction. Morphological analysis and elemental composition were determined by scanning electron microscope and energy dispersive spectroscopy. The specific surface area analysis have been studied using the Brunauer-Emmett-Teller method. Metal contents were determined by inductively coupled plasma optical emission spectrometry.
Źródło:
Acta Physica Polonica A; 2014, 125, 2; 281-284
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of an Adsorbed Atom on Resonant Charge Exchange in Atom Scattering on Metal Surfaces
Autorzy:
Taranko, R.
Taranko, E.
Wiertel, M.
Powiązania:
https://bibliotekanauki.pl/articles/2035749.pdf
Data publikacji:
2003-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
79.20.-m
82.65.+r
34.70.+e
Opis:
A simple model describing resonant charge transfer between the free-electron metal surface and an atom colliding with it at some distance from another adsorbed atom is presented. The negative ionization probability of a scattered atom is studied within the time-dependent Anderson-Newns model and the time-evolution operator approach. With appropriate models for the considered system, the ionization probability is shown to oscillate with the distance between the adsorbed atom and the collision point of the scattered atom with the metal surface. These oscillations are results of the indirect interaction between the adsorbed and the scattered atoms due to the coupling of both atoms with the metal energy band.
Źródło:
Acta Physica Polonica A; 2003, 103, 5; 483-497
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Chemically Modified Activated Carbons as Catalysts of Oxidative Dehydrogenation of n-Butane
Autorzy:
Malaika, A.
Wower, K.
Kozłowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/1535911.pdf
Data publikacji:
2010-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Rm
81.65.Mq
81.40.Gh
82.65.+r
Opis:
Commercial availability and low price of light alkanes make them very attractive in many branches of industry. Potentially interesting is their use in the process of oxidative dehydrogenation leading to production of olefins. This study was undertaken to characterise the oxidative dehydrogenation of n-butane to 1,3-butadiene (important substrate in production of synthetic rubber and polyamides) taking place over the modified carbon catalysts obtained from peach stones precursor. The catalytic tests were performed in the temperature range 250-450°C at oxygen/n-butane ratio of 1:1. For the majority of the activated carbon samples studied at the lowest temperature the only product was $CO_2$. At 300°C the products of dehydrogenation of n-butane and side products appeared. With increasing temperature the amount of compounds generated increased and in the group of C4 hydrocarbons the dominant were 1-butene and 1,3-butadiene. The most effective catalyst was the sample oxidised with air, the least effective was the sample modified with ammonium peroxydisulphate.
Źródło:
Acta Physica Polonica A; 2010, 118, 3; 459-464
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Influence of the Au Nanoparticles Dimension on the Photocatalytic Performances of $TiO_2-Au$ Porous Composites
Autorzy:
Melinte, G.
Baia, M.
Georgescu, D.
Baia, L.
Iancu, V.
Diamandescu, L.
Popescu, T.
Cotet, L.
Barbu-Tudoran, L.
Danciu, V.
Simon, S.
Powiązania:
https://bibliotekanauki.pl/articles/1491327.pdf
Data publikacji:
2012-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Rm
81.07.Wx
82.80.Ej
68.37.Lp
82.65.+r
82.50.Hp
Opis:
The influence of Au nanoparticles dimension on the photocatalytic performances of the $TiO_2$ aerogels-Au composites was evaluated. Structural and morphological peculiarities of the $TiO_2$ aerogel, unloaded and loaded with 5 and 22 nm Au nanoparticles, were studied by transmission electron microscopy technique, X-ray diffraction and $N_2$-sorption measurements. UV-Vis diffuse reflectance measurements were performed to determine the band gap energies. The photocatalytic activity was evaluated by monitoring the salicylic acid photodegradation. It was found that the Au nanoparticles promote the anatase phase crystallization and produce the decrease of the specific surface area and band gap energy values. The porous composite with the smallest Au nanoparticles dimension exhibits the best photocatalytic performances.
Źródło:
Acta Physica Polonica A; 2012, 121, 1; 208-210
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-10 z 15

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