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.

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.

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.

A simulation study on the hydrogen storage properties of fullerene family molecules Cx(x = 56,60,70) and their hydrides

2016 ◽  
Vol 30 (22) ◽  
pp. 1650303
Author(s):  
Wei Dai ◽  
Ming Xiao ◽  
Mu-Qing Chen ◽  
Jia-Jing Xu ◽  
Yong-Jian Tang
Keyword(s):  
Hydrogen Storage ◽  
Energy Barrier ◽  
Hydrogen Adsorption ◽  
High Energy ◽  
Hydrogen Energy ◽  
Carbon Cage ◽  
First Principle Calculation ◽  
Hydrogen Storage Properties ◽  
Hydrogen Molecules ◽  
Storage Properties

Hydrogen storage is a key factor for the application of hydrogen energy. From first principle calculation, we have acquired the energy barrier for hydrogen molecules to pass through the hexagonal rings and pentagonal rings of the fullerene. Then the absorption energy and energy barrier are used to analyze the hydrogen adsorption capacity of the fullerene family and their hydrides. We have also studied the hydrogen storage properties of the fullerene family and their hydrides by grand canonical Monte Carlo method. It is found that the weight density of hydrogen storage at ambient temperature and pressure can reach 7.71 wt.%. The results show that it is difficult for hydrogen to get into the carbon cage of the fullerene because of the high energy barrier, while it is beneficial to destroy the fullerene structure for the processes of absorption and desorption. Meanwhile, fullerene hydrogenation is an effective method to improve the hydrogen storage properties. Our study facilitates the design and synthesis of hydrogen storage materials, and provides theoretical support to improve the hydrogen storage capability for materials.

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.

Development of Magnesium-Based Material with Hydrogen-Storage Capacity of 7 wt%

2021 ◽  
Vol 21 (8) ◽  
pp. 4353-4361
Author(s):  
Myoung Youp Song ◽  
Seong Ho Lee ◽  
Young Jun Kwak ◽  
Eunho Choi
Keyword(s):  
Hydrogen Storage ◽  
Ball Milling ◽  
Storage Capacity ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Hydrogen Storage Capacity ◽  
Hydrogen Storage Properties ◽  
Energy Ball ◽  
Milling In Hydrogen ◽  
Storage Properties

TiCl3 was chosen as an additive to increase hydriding and dehydriding rates of Mg. In our previous works, we found that the optimum percentage of additives that improved the hydriding and dehydriding features of Mg was approximately ten. Specimens consisting of 90 wt% Mg and 10 wt% TiCl3 (named Mg–10TiCl3) were prepared by high-energy ball milling in hydrogen. The specimens’ hydriding and dehydriding properties were then studied. Mg–10TiCl3 had an effective hydrogenstorage capacity (the quantity of hydrogen absorbed in 60 min) of approximately 7.2 wt% at 593 K under 12 bar H2 at the second cycle. After high-energy ball milling in hydrogen, Mg–10TiCl3 contained Mg, β-MgH2, and small amounts of γ-MgH2 and TiH1.924. TiH1.924 remained undercomposed even after dehydriding at 623 K in a vacuum for 2 h. The hydriding and dehydriding properties of Mg–10TiCl3 were compared with those of other specimens such as Mg–10Fe2O3, Mg–10NbF5, and Mg–5Fe2O3–5Ni, for which the hydrogen-storage properties were previously reported.

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.

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