Mechanism of Improved Hydrogen Absorption Kinetics in Cast Mg-Ni Alloys

2009 ◽  
Vol 618-619 ◽  
pp. 391-394 ◽  
Author(s):  
Kazuhiro Nogita ◽  
Sean Ockert ◽  
Andrew Duguid ◽  
Jordan Pierce ◽  
Matthew Greaves
Keyword(s):  
Hydrogen Storage ◽  
Hydrogen Absorption ◽  
Atomic Scale ◽  
Desorption Kinetics ◽  
Eutectic Alloys ◽  
Atmospheric Conditions ◽  
Hydrogen Storage Properties ◽  
Ni Alloys ◽  
Slow Kinetics ◽  
Storage Properties

The potential for Mg and Mg-Ni alloys to be used as hydrogen storage alloys has been known for some time. Although the maximum storage capacity in these alloys is high (7.6wt%H2 for Mg and 3.4wt%H2 for Mg2Ni), they have, until recently, been disregarded for practical applications due to their slow kinetics and high reaction temperatures. This paper discusses the recent discovery that the non-faceted/faceted hypo-eutectic Mg-Mg2Ni system can, similar to Al-Si eutectic alloys, be modified by trace additions and that this results in improved hydrogen storage properties. The hydrogen storage properties depend on the composition, including trace levels of modifying elements, and processing conditions. In alloys of optimal composition it has been shown that the reversible storage of 6.5-7wt% H2 is possible at a rate of reaction that is far better than that previously documented. In addition, the alloy can be satisfactorily processed in air, as opposed to controlled atmospheric conditions. This paper discusses the mechanism of improved hydrogen absorption/desorption kinetics when eutectic Mg-Ni hypo-eutectic alloys are modified. This discussion is based on atomic scale analysis using electron microscopy and examination with synchrotron radiation.

scholarly journals Preparation of Mg2FeH6Nanoparticles for Hydrogen Storage Properties

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
N. A. Niaz ◽  
I. Ahmad ◽  
N. R. Khalid ◽  
E. Ahmed ◽  
S. M. Abbas ◽  
...  
Keyword(s):  
Hydrogen Storage ◽  
Hydrogen Absorption ◽  
Hydrogen Pressure ◽  
Absorption Rate ◽  
Desorption Kinetics ◽  
Prepared Compound ◽  
Hydrogen Storage Properties ◽  
Storage Properties ◽  
Effective Hydrogen ◽  
Type Apparatus

Magnesium (Mg) and iron (Fe) nanoparticles are prepared by thermal decomposition of bipyridyl complexes of metals. These prepared Mg-Fe (2 : 1) nanoparticles are hydrogenated under 4 MPa hydrogen pressure and 673 K for 48 hours to achieve Mg2FeH6. Their structural analysis was assessed by applying manifold techniques. The hydrogen storage properties of prepared compound were measured by Sieverts type apparatus. The desorption kinetics were measured by high pressure thermal desorption spectrometer (HP-TDS). More than 5 wt% hydrogen released was obtained by the Mg2FeH6within 5 min, and during rehydrogenation very effective hydrogen absorption rate was observed by the compound.

Preparation and Hydrogen Storage Properties of Mg-20 wt.% Mg2Ni0.8Cr0.2 Composite with TiO2 Nanoparticles

2007 ◽  
Vol 121-123 ◽  
pp. 1293-1296
Author(s):  
X.L. Wang ◽  
Jiang Ping Tu ◽  
X.B. Zhang ◽  
C.P. Chen
Keyword(s):  
Hydrogen Storage ◽  
Tio2 Nanoparticles ◽  
Ball Milling ◽  
Driving Force ◽  
Hydrogen Absorption ◽  
Desorption Kinetics ◽  
Combined Effects ◽  
Hydrogen Storage Properties ◽  
Storage Properties

Mg and Mg-Ni-based hydrides were mechanically milled with TiO2 nanoparticles to prepare Mg-20 wt.% Mg2Ni0.8Cr0.2-1.5 wt.% TiO2 composite. XRD results showed that the hydrides decomposed partly during ball milling. Under the combined effects of the catalyst of TiO2 nanoparticles, Mg2Ni0.8Cr0.2 alloy and Ni particles precipitated, and the mechanical driving force, the composite showed rapid hydrogen absorption/desorption kinetics. The absorption temperatures of the composite were greatly decreased and the rates of hydriding were increased. The composite can absorb 4.6 wt.% H at 373 K within 3 min and desorb 4.33 wt.% H at 573 K within 20 min.

Phase Structure and Hydrogen Storage Characterization of the As-Cast Mg-10Ni-2Mm Alloy

2010 ◽  
Vol 650 ◽  
pp. 150-156 ◽  
Author(s):  
N. Xing ◽  
P.C. Bai ◽  
Ying Wu ◽  
Z.C. Lu ◽  
W. Han ◽  
...  
Keyword(s):  
Hydrogen Storage ◽  
Hydrogen Absorption ◽  
Absorption Capacity ◽  
Desorption Kinetics ◽  
Isothermal Temperature ◽  
Hydrogen Storage Properties ◽  
Metallic Particles ◽  
Kinetics Of ◽  
Storage Properties

The microstructural revolution of non-hydrogenated and hydrogenated Mg-based Mg-10Ni-2Mm alloy was studied. PCT and H-absorption/desorption kinetics were performed to evaluate the hydrogen storage properties. Storage capacities of 4.75, 5.03 and 5.27wt.%H for the alloy were obtained at 300, 325 and 350°C, respectively. The phases in the hydrogenated samples are mainly MgH2 and Mg2NiH4. Two absorption/desorption plateau existed in the PCT curves at each isothermal temperature. The values of ΔH and ΔS of the Mg2NiH4-formation was respectively -61.5 kJ/mol H2 and -118.6 J/mol H2 K which is lower compared with literature values. The kinetics of the H-absorption/desorption reactions for the alloy was improved by increasing the temperature. The alloy at 350°C showed the best kinetics performance of the H-absorption/desorption among the three temperatures. It is suggested that metallic particles and Mm may be mainly responsible for the improvement of the H-absorption/desorption kinetics, and Ni for the enhancement of hydrogen absorption capacity of the alloys.

A kinetics study on promising hydrogen storage properties of Mg-based thin films at room temperature

2014 ◽  
Vol 43 (15) ◽  
pp. 5908-5912 ◽  
Author(s):  
Jianglan Qu ◽  
Yang Liu ◽  
Gongbiao Xin ◽  
Jie Zheng ◽  
Xingguo Li
Keyword(s):  
Thin Films ◽  
Hydrogen Storage ◽  
Hydrogen Absorption ◽  
Room Temperature ◽  
Desorption Kinetics ◽  
Kinetics Study ◽  
Hydrogen Storage Properties ◽  
Mild Conditions ◽  
Storage Properties

The thickness effects on hydrogen absorption and desorption kinetics under mild conditions were investigated in Mg-based thin films.

The Influence of Morphology on the Hydrogen Storage Properties of Magnesium Based Materials Processed by Cold Rolling

2014 ◽  
Vol 922 ◽  
pp. 400-405 ◽  
Author(s):  
Julien Lang ◽  
Alexandre Asselli ◽  
Nicolas Hebert ◽  
Jacques Huot
Keyword(s):  
Cold Rolling ◽  
Hydrogen Storage ◽  
Hydrogen Absorption ◽  
Low Cost ◽  
Volume Ratio ◽  
Desorption Kinetics ◽  
Small Surface ◽  
High Hydrogen ◽  
Hydrogen Storage Properties ◽  
Storage Properties

In this communication we report the effect of macro and microstructure on the hydrogen storage properties of magnesium based materials. Magnesium hydride is an attractive material for hydrogen storage applications since it has a high hydrogen volumetric density. Furthermore, the high enthalpy of hydride formation makes it attractive for thermal energy storage applications. Besides, magnesium is an abundant and low cost material. However, the Mg/MgH2 system requires high operating temperatures due to its thermodynamic stability and slow hydrogen absorption and desorption kinetics. Magnesium’s first hydrogenation is a very long and costly process. This work aims to ameliorate this process which would effectively reduce the cost of MgH2. Commercial pure magnesium samples were processed by cold rolling. After processing, the samples presented limited hydrogen absorption due to their small surface area to volume ratio. To overcome this problem the samples were then reduced to powder using a bastard file. The samples were characterized by scanning electron microscopy and presented different morphology. Hydrogen storage properties and morphology are discussed and correlated. Results show an important improvement on the hydrogen absorption and desorption kinetics for the comminuted samples.

Hydrogen storage properties of Ti2−xCrVMx (M = Fe, Co, Ni) alloys

2013 ◽  
Vol 38 (30) ◽  
pp. 13335-13342 ◽  
Author(s):  
Asheesh Kumar ◽  
Seemita Banerjee ◽  
C.G.S. Pillai ◽  
S.R. Bharadwaj
Keyword(s):  
Hydrogen Storage ◽  
Hydrogen Storage Properties ◽  
Ni Alloys ◽  
Storage Properties

Synthesis of Mg (NH2)2 and Hydrogen Storage Properties of Mg (NH2)2–LiH System

2011 ◽  
Vol 347-353 ◽  
pp. 3609-3615
Author(s):  
Ke Zhang ◽  
Xiao Yu Zhao ◽  
Shu Li Liu ◽  
Zhong Qiu Cao ◽  
Hui Zhang
Keyword(s):  
Hydrogen Storage ◽  
Heat Treating ◽  
High Energy ◽  
Molar Ratio ◽  
Desorption Kinetics ◽  
Arrhenius Activation Energy ◽  
Hydrogen Storage Properties ◽  
Desorption Reaction ◽  
Storage Properties ◽  
Static Hydrogen

Mg(NH2)2 was synthesized by first high energy milling MgH2 powder in a 99.995% NH3 atmosphere and then heat treating at 300oC, and hydrogen storage properties of prepared Mg(NH2)2+2.2LiH (molar ratio) had been studied in the temperature range of 150-240oC. It was found that mechanical milling of Mg (NH2)2 and LiH with molar ratio 1:2.2 followed by heat treatment under static hydrogen pressure and dehydrogenating at 208.5oC yields the desired reversible hydrogen storage phase: Li2Mg(NH)2. Desorption kinetics reveal a rapid reaction for the system and the maximum hydrogen capacity can reach 4.6 wt. % at 208.5oC. The system starts to dehydrogenate at 150oC and the Arrhenius activation energy Ea of desorption reaction can be determined to be 25.8 kJ/mol H2 based on the data of kinetics. Additionally, the desorption reaction enthalpy (H) and entropy (S) are calculated to be 42.8 kJ/mol H2 and 149.2 J. K-1/ mol H2 respectively from PCI measurements.

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