Search results

1

The effect of alloying on the H-atom adsorption on the (100) surfaces of Pd-Ag, Pd-Pt, Pd-Au, Pt-Ag, and Pt-Au. A theoretical study

100%

Matczak P., Romanowski S.

Open Chemistry

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2011

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vol. 9

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issue 3

474-480

EN

The effect of alloying on the adsorption of atomic hydrogen was studied using density functional theory (DFT). In the study the (100) surfaces of Pd-Ag, Pd-Pt, Pd-Au, Pt-Ag, and Pt-Au alloys were considered by means of a cluster model. The structural and energetic properties of the H atom adsorbed on the Pd4Me (Me = Ag, Pt, Au) and Pt4Me (Me = Pd, Ag, Au) clusters were calculated and compared with the H-atom adsorption on monometallic clusters. The effect of alloying on the H-atom adsorption is evident for all the investigated bimetallic systems. However, it strongly depends on the second metal atom, Me, is placed in the surface layer or in the subsurface one. In general, the H atom adsorbed in a site containing the second metal exhibits different properties from those characteristic of its adsorption on Pd(100) and Pt(100). Hence, the modified interaction between atomic hydrogen and the alloyed surfaces may increase the selectivity of the catalytic hydrogenation reactions on such surfaces.

2

Production of hydrogen from steam reforming of glycerol using nickel catalysts supported on Al2O3, CeO2and ZrO2

88%

Manfro R. L., Ribeiro N. F. P., Souza M. M. V. M.

Catalysis for Sustainable Energy

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2012

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vol. 1

60-70

EN

Nickel catalysts supported on Al2O3, CeO2 and ZrO2 were prepared by wet impregnation method and evaluated in steam reforming of glycerol. The catalysts were characterized by chemical composition, textural analysis, crystalline structure and reducibility. The structural characterization of the catalysts revealed a good dispersion of Ni particles using the Al2O3 support, needing higher reduction temperature. The reactions were performed at 500°C with 10 vol.% glycerol solution in a continuous flow reactor. All catalysts showed conversions close to 100%. The selectivity to gas products and formation of liquid by-products were found to be dependent on the type of support. The H2 selectivity showed the following trend: ZrO2 > Al2O3 ≈ CeO2. The catalyst supported on CeO2 showed low activity for water-gas shift reaction, with the highest CO selectivity. All catalysts presented a low formation of CH4. In the liquid phase some by-products were identified (hydroxyacetone, acetic acid, lactic acid, acetaldehyde, acrolein and ethanol) and secondary reaction routes were proposed. Coke formation was higher on Ni/Al2O3 catalyst, but no deactivation was observed during 8 h of reaction.

3

Above-threshold ionization of hydrogen and hydrogen-like ions by X-ray pulses

88%

Bachau H., Budriga O., Dondera M., Florescu V.

Open Physics

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2013

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vol. 11

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issue 9

1091-1098

EN

This paper adresses the problem of above-threshold ionization (ATI) of hydrogen interacting with an intense X-ray electromagnetic field. Two approaches have been used. In the first approach, we calculate generalized differential and total cross sections based on second-order perturbation theory for the electron interaction with a monochromatic plane wave, with the A 2 and A · P contributions from the nonrelativistic Hamiltonian (including retardation) treated exactly. In the second approach, we solve the time-dependent Schrödinger equation (TDSE) for a pulsed plane wave using a spectral approach with a basis of oneelectron orbitals, calculated with L 2-integrable B-spline functions for the radial coordinate and spherical harmonics Y lm for the angular part. Retardation effects are included up to O(1/c), they induce extra terms forcing the resolution of the TDSE in a three dimensional space. Relativistic effects [of O (1/c 2)] are fully neglected. The isoelectronic series of hydrogen is explored in the range Z = 1 − 5 in both TDSE and perturbative approaches. Photoelectron angular distributions are obtained for photon energies of 1 keV and 3 keV for hydrogen, and photon energy of 25 keV for the hydrogenic ion B4+. Perturbative and TDSE calculations are compared.

4

Methane decomposition over Fe supported catalysts for hydrogen and nano carbon yield

75%

Fakeeha A. H., Ibrahim A. A., Naeem M. A., Khan W. U., Abasaeed A. E., Alotaibi R. L., Al-Fatesh A. S.

Catalysis for Sustainable Energy

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2014

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vol. 2

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issue 1

EN

Production of hydrogen, being an environmentally friendly energy source, has gained a lot of attention in the recent years. In this article, iron-based catalysts, with different active metal loadings, supported over magnesia and titania are investigated for hydrogen production via catalytic decomposition of methane. The catalytic activity and stability results revealed that magnesia supported catalysts performed better than titania supported catalysts. Hydrogen reduction temperature of 500°C was obtained suitable for catalyst activation. For magnesia supported catalysts, only higher loadings i.e., 30% and 40% Fe-Mg catalysts showed reasonable activity, while all titania supported catalysts presented less activity as well as deactivation. Among all the catalysts, 30% Fe/MgO catalyst displayed better activity. The formation of carbon nanofibers was evidenced from morphological analysis. FESEM and TEM images showed the generation of nonuniform carbon nanofibers with broader diameter. The catalysts were characterized using different techniques such as BET, H2-TPR, O2-TPO, XRD, TGA, FESEM and TEM.

5

Thermodynamic consequences of hydrogen combustion within a containment of pressurized water reactor

75%

Bury T.

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6

Gas Blowing Ultrasonic Aluminium Degassing Assessment with the Reduced Pressure Test (RPT) Method

75%

Galarraga H., de Cortazar M. G., Arregi E., Artola A., Oncala J. L., Merchan M., Galarraga H., de Cortazar M. G., Arregi E., Artola A., Oncala J. L., Merchan M.

Archives of Foundry Engineering

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2020

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vol. 20

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issue 2

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1 Abasaeed A. E.

1 Al-Fatesh A. S.

1 Alotaibi R. L.

1 Arregi E.

1 Artola A.

1 Bachau H.

1 Budriga O.

1 Bury T.

1 Dondera M.

1 Fakeeha A. H.

1 Florescu V.

1 Galarraga H.

1 Ibrahim A. A.

1 Khan W. U.

1 Manfro R. L.

1 Matczak P.

1 Merchan M.

1 Naeem M. A.

1 Oncala J. L.

1 Ribeiro N. F. P.

1 Romanowski S.