The Effects of Oxidized and Oxide-Free Boron on the Mg-B-H Nanohydrides Transformation in the Nearly Nanosized Powders

2007 ◽  
Vol 128 ◽  
pp. 47-52 ◽  
Author(s):  
R.A. Varin ◽  
Ch. Chiu ◽  
Zbigniew S. Wronski ◽  
Andrzej Calka
Keyword(s):  
Hydrogen Desorption ◽  
Hydrogen Release ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Nanosized Powders ◽  
X Ray ◽  
Milled Sample ◽  
Heat Event ◽  
Reactive Mechanical Alloying ◽  
Type Apparatus

In this work oxidized and oxide-free amorphous boron (a-B) powder and elemental Mg were used in an attempt to directly synthesize the Mg(BH4)2 complex hydride by controlled reactive mechanical alloying (CRMA) under hydrogen in a magneto-mill up to 200h. The particle size was refined to the 100-200nm range. Nanocrystalline MgH2 (~6nm crystallite size) was formed within the particles when an oxidized a-B is used. In contrast, a mixture of MgB2 and an amorphous hydride MgHx was formed when an oxide-free a-B was used. Differential scanning calorimetry (DSC) test up to 500°C produced a single endothermic heat event at 357.7°C due to hydrogen desorption. In addition, desorption conducted in a Sieverts-type apparatus revealed ~1.4wt.% of hydrogen release. The X-ray diffraction pattern after DSC test of the 200h milled sample made with oxide-free boron showed the presence of MgB2.

An in-situ X-ray Diffraction Study of the Desorption of TiCl3-doped Sodium Alanate

2004 ◽  
Vol 837 ◽  
Author(s):  
Scott A. Speakman ◽  
Joachim H. Schneibel ◽  
Dewey S. Easton
Keyword(s):  
Rate Constants ◽  
Hydrogen Desorption ◽  
Hydrogen Release ◽  
Desorption Rate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sodium Alanate ◽  
Temperature Programmed ◽  
Type Apparatus

ABSTRACTSodium alanate was milled with and without TiCl3. The hydrogen release and uptake was measured during temperature-programmed absorption and desorption, as well as by isothermal charging and discharging, using a Sieverts' type apparatus. These data were supplemented by in-situ X-ray diffraction studies of hydrogen desorption. Rate constants derived from XRD were slower than those derived from volumetric H2 measurements. Al formation observed in XRD exceeded that expected from the observed decomposition of NaAlH4 and Na3AlH6.

scholarly journals Hydrogen desorption kinetics of MgH2 synthesized from modified waste magnesium

2014 ◽  
Vol 32 (3) ◽  
pp. 385-390
Author(s):  
Aysel Kantürk Figen ◽  
Bilge Coşkuner ◽  
Sabriye Pişkin
Keyword(s):  
Hydrogen Desorption ◽  
Nitrogen Atmosphere ◽  
Desorption Kinetics ◽  
X Ray Diffraction ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Xrf Scanning ◽  
Isothermal Kinetic ◽  
Kinetics Of

AbstractIn the present study, hydrogen desorption properties of magnesium hydride (MgH2) synthesized from modified waste magnesium chips (WMC) were investigated. MgH2 was synthesized by hydrogenation of modified waste magnesium at 320 °C for 90 min under a pressure of 6 × 106 Pa. The modified waste magnesium was prepared by mixing waste magnesium with tetrahydrofuran (THF) and NaCl additions, applying mechanical milling. Next, it was investigated by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) techniques in order to characterize its structural properties. Hydrogen desorption properties were determined by differential scanning calorimetry (DSC) under nitrogen atmosphere at different heating rates (5, 10, and 15 °C/min). Doyle and Kissenger non-isothermal kinetic models were applied to calculate energy (Ea) values, which were found equal to 254.68 kJ/mol and 255.88 kJ/mol, respectively.

scholarly journals Development of a Novel Method for the Fabrication of Nanostructured Zr(x)Ni(y) Catalyst to Enhance the Desorption Properties of MgH2

Catalysts ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 849
Author(s):  
Gracia Shokano ◽  
Zahir Dehouche ◽  
Basile Galey ◽  
Georgeta Postole
Keyword(s):  
Hydrogen Desorption ◽  
Milling Process ◽  
Hydrogen Release ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Electron Microscope Analysis ◽  
Novel Method ◽  
Temperature Programmed ◽  
The Impact

The present work involves the development of a novel method for the fabrication of zirconium nickel (Zr(x)Ni(y)) alloy used as a nanocatalyst to improve the hydrogen storage properties of the Mg/MgH2 system. The catalyst was fabricated through the high-pressure reactor and activated under hydrogen prior to being mechanically milled with the MgH2 for 5 h under argon. The microstructure characterisation of the samples was determined via SEM-EDX (scanning electron microscope analysis–energy dispersive X-ray spectroscopy), XRD (X-ray diffraction) and FE-HRTEM (field emission high resolution transmission electron microscopy), and the desorption characteristic of the nanocomposite (10 wt.% Zr(x)Ni(y)–MgH2) was determined via TPD (temperature-programmed desorption). The nanostructured MgH2 powder milled with 10 wt.% of the activated Zr(x)Ni(y) based nanocatalyst resulted in a faster hydrogen release—5.9 H2-wt.% at onset temperature 210 °C/peak temperature 232 °C. The observed significant improvement in the hydrogen desorption properties was likely to be the result of the impact of the highly dispersed catalyst on the surface of the Mg/MgH2 system, the reduction in particle size during the ball milling process and/or the formation of Mg0.996Zr0.004 phase during the milling process.

Hydriding Behaviour of Mg-C Nanocomposites

2003 ◽  
Vol 801 ◽  
Author(s):  
A. Bassetti ◽  
E. Bonetti ◽  
A. L. Fiorini ◽  
J. Grbovic ◽  
A. Montone ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Differential Scanning Calorimetry ◽  
Weight Ratio ◽  
Hydrogen Desorption ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Carbon Nanocomposites ◽  
X Ray ◽  
Scanning Electron

ABSTRACTMagnesium carbon nanocomposites for hydrogen storage have been synthesized by ball milling with different amount of benzene, acting as a lubricant. Their microstructure has been studied by X-ray diffraction and scanning electron microscopy, while the hydrogen desorption temperature has been tested by differential scanning calorimetry. Experimental results show that the microstructure after milling, the hydrogenation capabilities of the material and the reactivity with the air are related to the amount of additives. In particular the carbon to benzene ratio seems to play a major role. In fact, with an optimum value of carbon to benzene weight ratio of 1/6, the amount of carbon being 15 wt% of the milled mixture, a decomposition heat equal to 57% of pure MgH2 was measured, even after air manipulation of the sample.

Effect of Heat Treatments on TiH2: Surface Composition and Hydrogen Release

2016 ◽  
Vol 879 ◽  
pp. 2032-2037 ◽  
Author(s):  
Gabriele Lapi ◽  
Carlo Alvani ◽  
Francesca Varsano ◽  
Saulius Kaciulis ◽  
Roberto Montanari ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Titanium Hydride ◽  
Surface Composition ◽  
Hydrogen Desorption ◽  
Temperature Programmed Desorption ◽  
Heat Treatments ◽  
Hydrogen Release ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Programmed

The present work investigates the effect of heat treatments in air on the surface and structure of titanium hydride (TiH2) and hydrogen desorption. TiH2 has been heated in air at 440 and 540 °C for increasing time up to 180 min. to obtain the samples representative of 12 different oxidation conditions. The samples have been then examined by Temperature Programmed Desorption (TPD), X-Ray Diffraction (XRD) and Photoelectron Spectroscopy (XPS). Experimental results are presented and discussed.

scholarly journals Dehydrogenation/rehydrogenation mechanism in aluminum destabilized lithium borohydride

2009 ◽  
Vol 24 (8) ◽  
pp. 2720-2727 ◽  
Author(s):  
Xuebin Yu ◽  
Guanglin Xia ◽  
Zaiping Guo ◽  
Huakun Liu
Keyword(s):  
Photoelectron Spectroscopy ◽  
Hydrogen Desorption ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Lithium Borohydride ◽  
Hydrogen Storage Properties ◽  
X Ray ◽  
Before And After ◽  
Storage Properties ◽  
Desorption Cycle

LiBH4/Al mixtures with various mol ratios were prepared by ball milling. The hydrogen storage properties of the mixtures were evaluated by differential scanning calorimetry/thermogravimetry analyses coupled with mass spectrometry measurements. The phase compositions and chemical state of elements for the LiBH4/Al mixtures before and after hydrogen desorption and absorption reactions were assessed via powder x-ray diffraction, infrared spectroscopy, and x-ray photoelectron spectroscopy. Dehydrogenation results revealed that LiBH4 could react with Al to form AlB2 and AlLi compounds with a two-step decomposition, resulting in improved dehydrogenation. The rehydrogenation experiments were investigated at 600 °C with various H2 pressure. It was found that intermediate hydride was formed firstly at a low H2 pressure of 30 atm, while LiBH4 could be reformed completely after increasing the pressure to 100 atm. Absorption/desorption cycle results showed that the dehydrogenation temperature increased and the hydrogen capacity degraded with the increase of cycle numbers.

scholarly journals Effects of Ball Milling and TiF3 Addition on the Dehydrogenation Temperature of Ca(BH4)2 Polymorphs

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4828
Author(s):  
Isabel Llamas Jansa ◽  
Oliver Friedrichs ◽  
Maximilian Fichtner ◽  
Elisa Gil Bardají ◽  
Andreas Züttel ◽  
...  
Keyword(s):  
Ball Milling ◽  
Hydrogen Desorption ◽  
Reaction Pathways ◽  
Desorption Peak ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Before And After ◽  
Kinetics Of ◽  
Desorption Reaction

The changes introduced by both ball milling and the addition of small amounts of TiF3 in the kinetics of the hydrogen desorption of three different Ca(BH4)2 polymorphs (α, β and γ) have been systematically investigated. The samples with different polymorphic contents, before and after the addition of TiF3, were characterized by powder X-ray diffraction and vibrational spectroscopy. The hydrogen desorption reaction pathways were monitored by differential scanning calorimetry. The hydrogen desorption of Ca(BH4)2 depends strongly on the amount of coexistent α, β and γ polymorphs as well as additional ball milling and added TiF3 to the sample. The addition of TiF3 increased the hydrogen desorption rate without significant dissociation of the fluoride. The combination of an α-Ca(BH4)2 rich sample with 10 mol% of TiF3 and 8 h of milling led to up to 27 °C decrease of the hydrogen desorption peak temperature.

scholarly journals Hydrogenation Ability of Mg-Li Alloys

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2080 ◽  
Author(s):  
Magda Pęska ◽  
Tomasz Czujko ◽  
Marek Polański
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Hydrogen Desorption ◽  
Az31 Alloy ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
High Hydrogen ◽  
X Ray ◽  
Structure Phase ◽  
Scanning Electron

The Mg-Li binary system is characterized by the presence of α-Mg(Li) and β-Li(Mg) phases, where magnesium exists in ordered and disordered forms that may affect the hydrogenation properties of magnesium. Therefore, the hydrogenation properties of an AZ31 alloy modified by the addition of 4.0 wt.%, 7.5 wt.% and 15.0 wt.% lithium were studied. The morphology (scanning electron microscopy (SEM)), structure, phase composition (X-ray diffraction (XRD)) and hydrogenation properties (differential scanning calorimetry (DSC)) of AZ31 with various lithium contents were investigated. It was found that the susceptibility of magnesium in the form of α-Mg(Li) to hydrogenation was higher than that for the magnesium occupying a disordered position in β-Li(Mg) solid solutions. Magnesium hydride was obtained as a result of hydrogenation of the AZ31 alloy that was modified with 4.0 wt.%, 7.5 wt.% and 15.0 wt.% additions of lithium, and was characterized by high hydrogen desorption activation energies of 250, 187 and 224 kJ/mol, respectively.

Hydrogen Desorption/Absorption Kinetics of MgH2 Catalyzed with TiO2

2014 ◽  
Vol 986-987 ◽  
pp. 88-91
Author(s):  
Yan Wang ◽  
Shi Wei Wu ◽  
Hao Yu ◽  
Na Na Gong ◽  
Zhong Qiu Cao ◽  
...  
Keyword(s):  
Milling Time ◽  
Hydrogen Desorption ◽  
High Energy ◽  
Absorption Kinetics ◽  
Orthorhombic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Milled Sample ◽  
Energy Ball ◽  
Kinetics Of

We report on the preparation and hydrogen desorption/absorption kinetics of nanocrystalline magnesium hydride (MgH2) added commercial TiO2by high-energy ball milling. The phase and composition of the as-milled powders are characterized by X-ray diffraction (XRD). The results show that the milled sample contained MgH2phase, small amount of Mg and various phases of TiO2such as tetragonal and orthorhombic structure. The effect of the milling time (10, 20 and 30 h) on the hydrogen desorption property of MgH2has been investigated and found that the milling time of 20 h has excellent dehydrogenation properties, which can release 3.3 wt% H2within 60 min at 300oC, which indicates that the kinetics of hydrogen desorption of MgH2-TiO2composite has been greatly enhanced compared to the pure MgH2. Moreover, hydrogen absorption kinetics of the sample milled 20 h has been studied and the hydrogen content is 0.7, 0.8 and 1.2 wt% H2at 250, 280 and 300oC within 60 min, respectively.

Catalytic Effect of Ti on H-Desorption/Absorption Properties in MgH2 Prepared by Ball Milling

2014 ◽  
Vol 687-691 ◽  
pp. 4335-4338
Author(s):  
Yan Wang
Keyword(s):  
Ball Milling ◽  
Milling Time ◽  
Hydrogen Desorption ◽  
High Energy ◽  
X Ray Diffraction ◽  
Absorption Properties ◽  
X Ray ◽  
Milled Sample ◽  
Energy Ball ◽  
Kinetics Of

We report on the preparation and hydrogen desorption/absorption kinetics of nanocrystalline magnesium hydride (MgH2) added commercial Ti by high-energy ball milling. The phase and composition of the as-milled powders are characterized by X-ray diffraction (XRD). The results show that the milled sample contained MgH2phase, Ti phase and small amount of MgO phase. When the milling time is 30 h, the hydrogen desorption property of MgH2has been investigated and found that the sample releases 0.43, 0.86 and 0.90 wt% H2in 200 minutes at 280, 290 and 300oC , respectively. Moreover, the sample absorbs 0.48, 0.0.58 and 0.61 wt% H2in 15 minutes at 280, 290 and 300oC , respectively. It can be seen that the kinetics of hydrogen desorption/absorption of MgH2-Ti composite has been greatly enhanced compared to the pure MgH2.

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