Enhanced hydrogen sorption capacities and kinetics of Mg2Ni alloys by ball-milling with carbon and Pd coating

2003 ◽  
Vol 18 (8) ◽  
pp. 1749-1752 ◽  
Author(s):  
R. Janot ◽  
L. Aymard ◽  
A. Rougier ◽  
G. A. Nazri ◽  
J. M. Tarascon
Keyword(s):  
Ball Milling ◽  
Surface Composition ◽  
Chemical Deposition ◽  
Practical Method ◽  
Hydrogen Desorption ◽  
Hydrogen Storage Alloys ◽  
Alloy Particles ◽  
Ni Alloy ◽  
Kinetics Of ◽  
Determinant Factor

Solid-state hydrogen storage alloys are becoming a practical method to transport and utilize hydrogen as fuel for various technologies. In this paper, the kinetics and capacity of hydrogen desorption from Mg-based alloys have markedly been enhanced by tuning the surface composition of alloy particles. Mg2Ni–Ct, x composites (where t refers to the pregrinding time and x to the Brunauer–Emmet–Teller specific surface area) were prepared by ball-milling the alloy in the presence of preground graphite, and Pd-coated Mg2Ni alloy powders were obtained by controlled chemical deposition of Pd on the alloy surface. We have found that the optimization of the pregrinding step of carbon is a determinant factor in enhancing the hydrogen desorption capacity of the Mg2Ni–10 wt.% C10,320 composites to 2.6 wt.% at 150 °C, the maximum performance so far reported on desorption for Mg-based alloys. Such value can even be raised to 2.8 wt.% by applying Pd deposition on the composite.

Preparation of La-Mg-Ni Hydrogen Storage Composite Alloys by Mechanical Alloying

2013 ◽  
Vol 807-809 ◽  
pp. 2707-2712 ◽  
Author(s):  
Shi Jian Yan ◽  
Xin Wei Zou ◽  
Min Gang Zhang
Keyword(s):  
Hydrogen Storage ◽  
Mechanical Alloying ◽  
Ball Milling ◽  
Metal Powder ◽  
Hydrogen Desorption ◽  
Hydrogen Atmosphere ◽  
Hydrogen Storage Alloys ◽  
Milling Parameters ◽  
Multi Phase ◽  
Mg Content

LaNi5-xwt%Mg hydrogen storage alloys with different Mg content were made from pure La, Mg and Ni metal powder by mechanical alloying, selecting appropriate ball-milling parameters in 0.4MPa hydrogen atmosphere. The characterizations for hydrogen storage alloy show that a multi-phase alloy composed of MgH2, LaH3, Mg2NiH4 and Ni was obtained, the alloy have two hydrogen desorption temperature range, and the alloy with 25wt% Mg content can desorb hydrogen up to 4.02wt%.

scholarly journals The Influence of Complex Doping on Kinetics of Decomposition and Thermal Stability of Mg-Based Mechanical Alloys

2019 ◽  
Vol 20 (4) ◽  
pp. 406-415
Author(s):  
O.G. Ershova ◽  
V.D. Dobrovolsky ◽  
Yu.M. Solonin
Keyword(s):  
Thermal Stability ◽  
Thermal Desorption Spectroscopy ◽  
Hydrogen Desorption ◽  
Hydride Phase ◽  
Hydrogen Storage Alloys ◽  
Reactive Grinding ◽  
Kinetics Of ◽  
Reactive Mechanical Alloying ◽  
Thermal Stability Of ◽  
Complex Doping

Mechanical alloys (MАs) were synthesized by the method of reactive mechanical alloying. At a hydrogen pressure of 0.1 MPa, with the use of thermal desorption spectroscopy, the thermal stability, the kinetics of hydrogen desorption from the hydride phase MgH2 of the obtained MAs were studied. It has been established that the complex doping by of Fe, Si, Ti, leads to a significant improvement in the of hydrogen desorption from the hydride phase MgH2 of MA synthesized by the RMA. Hydrogen capacity CH of MА after reactive grinding for 20 h. was found to be equal to 5.7 % wt. Due to this alloying, the decrease in the thermodynamic stability of MgH2 is not established. The tested materials showed a high potential as hydrogen storage alloys especially for stationary application.

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 Mechanical alloys Mg-Me (Me: Ti, Fe, Ni, Al) & Mg-Me1-Me2(Ме1:Al, Me2: Ti, Fe, Ni) with low resistance and improved kinetics of hydrogenation/dehydrogenation for hydrogen storage applications

2018 ◽  
Vol 6 (1) ◽  
pp. 31-55 ◽  
Author(s):  
O. Ershova ◽  
V. Dobrovolsky ◽  
Y. Solonin
Keyword(s):  
Thermal Stability ◽  
Hydrogen Storage ◽  
Sorption Capacity ◽  
Hydrogen Pressure ◽  
Hydrogen Desorption ◽  
Decomposition Kinetics ◽  
Hydrogen Storage Alloys ◽  
Mechanically Alloyed ◽  
Kinetics Of ◽  
Complex Doping

Changes in MgH2 decomposition kinetics were investigated in dependence on complex doping of MgH2 by Al, Ti, Ni, and Fe. Reactive mechanochemical alloying method (RMA) was applied in the temperature descending regime. It was found that addition of Al+Ni+Ti, Al+Ti, Fe+Ti (see below) and Al+Fe elements combinations led to a lower thermal stability and, consequently, to a lowering of the temperature of hydrogen desorption onset. Whereas desorption began at temperature of 320 °C from the pure MgH2, the aditions of Al, Ni, Ti and Fe lowered the start of the desorption down to 250°C (at hydrogen pressure 0.1 MPa in the reactor). Very fast desorption kineticsprecize at 300 0C and PH 2= 0.1 MPa were observed for Mg+Me mixture in comparison with the pure Mg. Sorption capacity of investigated mechanically-alloyed composites varied from 5 to 6.5 wt. % H2. The tested materials showed a high potential as hydrogen storage alloys especially for stationary application.

Preparation of Amorphous Mg-Ni Alloy by Mechanical Alloying and Investigation on its Hydrogen Storage Properties

2007 ◽  
Vol 546-549 ◽  
pp. 429-432
Author(s):  
Jing Feng Wang ◽  
Xin Liu ◽  
Pei Dao Ding ◽  
Fu Sheng Pan ◽  
Yao Bo Hu
Keyword(s):  
Mechanical Alloying ◽  
Electrochemical Properties ◽  
Ball Milling ◽  
Amorphous Phase ◽  
Hydrogen Desorption ◽  
X Ray Diffraction ◽  
Atom Ratio ◽  
Ni Alloy ◽  
Long Time ◽  
The Relationship

Amorphous Mg-Ni alloy was prepared by mechanical alloying (MA). The state of the amorphous phase was analyzed by X-ray diffraction (XRD). The hydrogen desorption capabilities and electrochemical properties were tested. The analysis of the relationship among the ball-milling parameters, microstructures and properties of the alloy showed that the milling velocities have a critical influence on the formation of Mg-Ni amorphous phase. The higher the milling velocity is, the less the forming time of the amorphous phase is. And with the increasing of the ball-milling time, the amount of Mg-Ni amorphous phase increases. Whereas the hydrogen desorption capabilities and electrochemical properties will decrease if the alloy is ball-milled for a long time after the complete amorphization occurs. Mg, Ni atom ratio also has some obvious influence on the formation of the amorphous phase and the properties of the alloy. Increasing the content of Ni appropriately will improve the efficiency of formation of the amorphous phase, the hydrogen desorption capabilities and electrochemical properties of the alloy.

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.

Carbothermic reduction kinetics of nanocrystallite Fe2O3/NiO composites for the production of Fe/Ni alloy

2008 ◽  
Vol 463 (1-2) ◽  
pp. 585-590 ◽  
Author(s):  
K.S. Abdel-Halim ◽  
M.H. Khedr ◽  
M.I. Nasr ◽  
M.Sh. Abdel-wahab
Keyword(s):  
Carbothermic Reduction ◽  
Reduction Kinetics ◽  
Ni Alloy ◽  
Kinetics Of

Oxidation Kinetics of Cu-Ni Alloy Observed by in situ UHV-TEM

2007 ◽  
Vol 1026 ◽  
Author(s):  
Li Sun ◽  
John E. Pearson ◽  
Judith C. Yang
Keyword(s):  
High Vacuum ◽  
Alloy Film ◽  
Ultra High Vacuum ◽  
Cross Sectional ◽  
Primary Mechanism ◽  
Transmission Electron ◽  
Ni Alloy ◽  
Cu Oxidation ◽  
Kinetics Of

AbstractThe nucleation and growth of Cu2O and NiO islands due to oxidation of Cu-24%Ni(001) films were monitored at various temperatures by in situ ultra-high vacuum (UHV) transmission electron microscopy (TEM). In remarkable contrast to our previous observations of Cu and Cu-Au oxidation, irregular-shaped polycrystalline oxide islands were observed to form with respect to the Cu-Ni alloy film, and an unusual second oxide nucleation stage was noted. Similar to Cu oxidation, the cross-sectional area growth rate of the oxide island is linear indicating oxygen surface diffusion is the primary mechanism of oxide growth.

Kinetics of synthesizing process for obtaining iron nanopowder by chemical-metallurgical method under isothermal conditions

2021 ◽  
pp. 72-77
Author(s):  
Tien Hiep Nguyen ◽  
◽  
Van Minh Nguyen ◽  
Keyword(s):  
Hydrogen Reduction ◽  
Average Particle Size ◽  
Chemical Deposition ◽  
Reduction Process ◽  
Nitrogen Adsorption ◽  
Specific Rate ◽  
Average Particle ◽  
Isothermal Conditions ◽  
Electron Microscopes ◽  
Kinetics Of

In this work the kinetics of synthesizing process of metallic iron nanopowder by hydrogen reduction from α-FeOOH hydroxide under isothermal conditions were studied. α-FeOOH nanopowder was prepared in advance by chemical deposition from aqueous solutions of iron nitrate Fe(NO3)3 (10 wt. %) and alkali NaOH (10 wt. %) at room temperature, pH = 11, under the condition of continuous stirring. The hydrogen reduction process of α-FeOOH nanopowder under isothermal conditions was carried out in a tube furnace in the temperature range from 390 to 470 °C. The study of the crystal structure and composition of the powders was performed by X-ray phase analysis. The specific surface area S of the samples was measured using BET method by low-temperature nitrogen adsorption. The average particle size D of powders was determined via the measured S value. The size characteristics and morphology of the particles were investigated by transmission and scanning electron microscopes. The calculation of the kinetic parameters of the hydrogen reduction process of α-FeOOH under isothermal conditions was carried out by the Gray-Weddington model and Arrhenius equation. It is shown that the rate constant of reduction at 470 °C is approximately 2.2 times higher than in the case at 390 °C. The effective activation energy of synthesizing process of iron nanopowder by hydrogen reduction from α-FeOOH was ~38 kJ/mol, which indicates a mixed reaction mode. In this case, the kinetics overall process is limited by both the kinetics of the chemical reaction and the kinetics of diffusion, respectively, an expedient way to accelerate the process by increasing the temperature or eliminate the diffusion layer of the reduction product by intensive mixing. It is show that Fe nanoparticles obtained by hydrogen reduction of its hydroxide at 410 °C, corresponding to the maximum specific rate of the reduction process, are mainly irregular in shape, evenly distributed, the size of which ranges from several dozens to 100 nm with an average value of 75 nm.

Study on the kinetics of process for obtaining cobalt nanopowder by hydrogen reduction under isothermal conditions

2021 ◽  
Vol 1 (1) ◽  
pp. 49-56
Author(s):  
Hieр Nguyen Tien
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Hydrogen Reduction ◽  
Average Particle Size ◽  
Chemical Deposition ◽  
Average Particle ◽  
Isothermal Conditions ◽  
Electron Microscopes ◽  
Kinetics Of

The kinetics of metallic cobalt nanopowder synthesizing by hydrogen reduction from Co(OH)2 nanopowder under isothermal conditions were studied. Co(OH)2 nanopowder was prepared in advance by chemical deposition from aqueous solutions of Co(NO3)2 cobalt nitrate (10 wt.%) and NaOH alkali (10 wt.%) at room temperature, pH = 9 under continuous stirring. The hydrogen reduction of Co(OH)2 nanopowder under isothermal conditions was carried out in a tube furnace in the temperature range from 270 to 310 °C. The crystal structure and composition of powders was studied by X-ray phase analysis. The specific surface area of samples was measured using the BET method by low-temperature nitrogen adsorption. The average particle size of powders was determined by the measured specific surface area. Particles size characteristics and morphology were investigated by transmission and scanning electron microscopes. Kinetic parameters of Co(OH)2 hydrogen reduction under isothermal conditions were calculated using the Gray–Weddington model and Arrhenius equation. It was found that the rate constant of reduction at t = 310 °C is approximately 1.93 times higher than at 270 °C, so the process accelerates by 1.58 times for 40 min of reduction. The activation energy of cobalt nanopowder synthesizing from Co(OH)2 by hydrogen reduction is ~40 kJ/mol, which indicates a mixed reaction mode. It was shown that cobalt nanoparticles obtained by the hydrogen reduction of its hydroxide at 280 °C are aggregates of equiaxed particles up to 100 nm in size where individual particles are connected to several neighboring particles by contact isthmuses.

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