MgH with NbO as additive, for hydrogen storage: Chemical, structural and kinetic behavior with heating

Friedrichs, O.; Aguey-Zinsou, F.; Fernández, José-Ramón; Sánchez-López, J.C.; Justo, A.; Klassen, Thomas; Bormann, R.; Fernández, A.

doi:10.1016/j.actamat.2005.08.024

Cited by 244 publications

(123 citation statements)

References 8 publications

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“…The niobium (Nb3d) spectra were drawn in Fig 5 after calibration. A decrease of the Nb3d signal with ball-milling can be seen, reasserting the results from elsewhere [16], [17]. The decrease could be explained as the milled MgH 2 particles covered the surface of Nb 2 O 5 , preventing the detector from getting enough signal from inside.…”

Section: Resultssupporting

confidence: 52%

Correlation between kinetics and chemical bonding state of catalyst surface in catalyzed magnesium hydride

Isobe

Morita

et al. 2011

International Journal of Hydrogen Energy

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We reported on the hydrogen desorption properties, microstructure, kinetics, and decreased, compared with that of the sample ball-milled for 0.02 h. TEM observations revealed that the distribution of Nb 2 O 5 in MgH 2 was gradually improved during ball-milling. On the other hand, we confirmed by XPS that in the sample ball-milled for 0.2 h, Nb 2 O 5-x phase(s) existed at least on the surface. It can be suggested that these deoxidized Nb 2 O 5-x phases eventually decrease E a as substantial catalyst rather than Nb 2 O 5 itself.

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Section: Resultssupporting

confidence: 52%

Correlation between kinetics and chemical bonding state of catalyst surface in catalyzed magnesium hydride

Isobe

Morita

et al. 2011

International Journal of Hydrogen Energy

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“…When we performed the fast Fourier transformation (FFT) and the inverse fast Fourier transformation (IFFT) on the selected area near the edge of Nb 2 O 5 particle, we obtained the lattice image with the d-spacing of 2.13Å, which matches the value of MgNb 2 O 3.67 (100). The existence of this ternary phase has also been reported elsewhere [15,21]. Nevertheless, the results so far still can not draw a clear conclusion on the catalytic effect of this ternary phase.…”

Section: Catalyzedmentioning

confidence: 62%

Catalytic Effect of Nb2O5 in MgH2-Nb2O5 Ball-Milled Composites

Isobe

Wang

et al. 2012

Catalysts

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We report a study on the desorption properties, crystallography and chemical state of MgH 2 and 1 mol% Nb 2 O 5 ball-milled composites. Desorption temperatures of the composites decreased with increase of ball-milling time. Size of MgH 2 crystallites decreased during ball-milling. Reduction of Nb 2 O 5 after ball-milling was confirmed by tracing the chemical state of Nb and was further supported by TEM observation. The reduced phases may act as more effective catalysts improving the desorption properties.

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“…One effect is a shift to smaller particle and crystallite sizes during milling. During sorption at higher temperatures the additives prevent rigorous grain growth (Friedrichs et al, 2006). However, structural changes during sorption processes as well as the function and distribution of different additives have hardly been investigated up to now.…”

Section: Introductionmentioning

confidence: 99%

Small-angle scattering investigations of magnesium hydride used as a hydrogen storage material

Pranzas¹,

Dornheim²,

Bösenberg³

et al. 2007

J Appl Cryst

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In this work, high‐energy ball‐milled magnesium hydride samples used for hydrogen storage are investigated using small‐ and ultra‐small‐angle neutron scattering (SANS) as well as small‐angle X‐ray scattering (SAXS). Size distributions of inhomogeneities with dimensions from 10 Å up to more than 10 µm, corresponding to crystallite and particle sizes obtained by X‐ray diffraction and electron microscopy, are determined as a function of milling time, milling tool material and added metal oxide catalysts in order to study the influence of the microstructure on the sorption kinetics. Significant changes of the volume fraction distributions are found for samples containing the catalyst chromium oxide, particularly when the catalyst particles are nanometre‐sized. Cr2O3 is an effective agent for breaking up particles during the milling process. The comparison of SANS and SAXS curves give some of the first information about the distribution of hydrogen‐containing structures. Using anomalous small‐angle X‐ray scattering, an energy‐dependent scattering is found for an MgHx sample with 1 mol% Fe2O3. From the separated scattering curve a size distribution of hard spheres is obtained with a size range which is expected for crystallite and particle sizes of the Fe2O3 catalyst. Chemical shifts in the absorption spectra give information about the stability of the metal oxide catalysts during the milling process.

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MgH with NbO as additive, for hydrogen storage: Chemical, structural and kinetic behavior with heating

Cited by 244 publications

References 8 publications

Correlation between kinetics and chemical bonding state of catalyst surface in catalyzed magnesium hydride

Correlation between kinetics and chemical bonding state of catalyst surface in catalyzed magnesium hydride

Catalytic Effect of Nb2O5 in MgH2-Nb2O5 Ball-Milled Composites

Small-angle scattering investigations of magnesium hydride used as a hydrogen storage material

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