scholarly journals Effect of Al, Fe Addition on Thermodynamic Stability and Hydrogen Desorption KInetics from MgH2 Phase OF Mechanical Alloy

2015 ◽  
Vol 16 (3) ◽  
pp. 576-585 ◽  
Author(s):  
О.G. Еrshova ◽  
A.Yu. Koval ◽  
Yu.М. Solonin ◽  
V.D. Dobrovolsky
Keyword(s):  
Mechanical Alloy ◽  
Mechanochemical Synthesis ◽  
Thermodynamic Stability ◽  
Thermal Desorption Spectroscopy ◽  
Hydrogen Desorption ◽  
Hydrogen Atmosphere ◽  
Desorption Kinetics ◽  
Reactive Milling ◽  
Kinetics Of ◽  
Complex Doping

With the aim of lowering the temperature, improve the kinetics of the decomposition of stoichiometric hydride MgH2 was investigated the possibility of its complex doping Al, Fe using mechanochemical synthesis (RMS). The MA1 sample was derived by reactive milling  Mg + 10 wt% Al + 10 wt. % Fe powder mixture in the hydrogen atmosphere at pressure of 1.2 MPa in a reactor for 10 h. The formation (in conditions of mechanochemical synthesis) of hydride of solid solution of Al and Fe in magnesium Mg(Al,Fe)H2 was experimentally checked. Found that adding to magnesium Al & Fe leads to lower of thermodynamic stability and, consequently, to lower the temperature of the beginning of desorption of hydrogen to 250 0C at 0,1MPa H2 (compared to MgH2 without Al and Fe). After the first cycles of hydrogenation-dehydrogenation from gas phase MA, established by isobaric thermal desorption spectroscopy, the effect of lowering the temperature of the beginning desorbtion 315 0C (for non-alloy phase MgH2) to 250 0C was observed. Adding to magnesium aluminum with Fe significantly improves the kinetics of desorption of hydrogen from the hydride phase MgH2 mechanical alloy produced by RMS.

Influence of aluminum location on hydrogen sorption kinetics of magnesium-based materials

2014 ◽  
Vol 07 (03) ◽  
pp. 1450034 ◽  
Author(s):  
Shixue Zhou ◽  
Tonghuan Zhang ◽  
Naifei Wang ◽  
Tao Li ◽  
Haili Niu ◽  
...  
Keyword(s):  
Hydrogen Absorption ◽  
Particle Surface ◽  
Hydrogen Desorption ◽  
Sorption Kinetics ◽  
Al Alloy ◽  
Desorption Kinetics ◽  
Reactive Milling ◽  
Crystallite Sizes ◽  
Apparent Activation Energies ◽  
Kinetics Of

Hydrogen storage materials from Mg – Al alloy and Mg + Al mixture were prepared by reactive milling under H 2 atmosphere with carbonized anthracite as milling aid. The crystal structure of the materials and influence of Al location on hydrogen absorption/desorption kinetics were investigated. Results show that Mg partly got hydrided into β- MgH 2 and γ- MgH 2 during reactive milling. The average crystallite sizes of β- MgH 2 in the as-milled Mg – Al alloy and Mg + Al mixture were calculated by Scherrer equation to be 10 nm and 17 nm, respectively. In the process of hydrogen desorption, the catalytic ability of Al in Mg crystal lattice was not as effective as that on particle surface. The apparent activation energies for hydrogen desorption of the two materials were estimated by Kissinger equation to be 112.2 kJ/mol and 63.7 kJ/mol, respectively. Mg 17 Al 12 reacted with H 2 to convert into MgH 2 and elemental Al during static hydrogenation at 300°C. For the hydrogenated Mg + Al mixture, the obvious increase of crystallite size resulted in a low rate of hydrogen absorption and a high temperature for hydrogen desorption.

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.

The Kinetics of Hydrogen Desorption From Zirconium Hydride

2013 ◽  
Author(s):  
Mingwang Ma ◽  
Ruiyun Wan ◽  
Yuan Wang ◽  
Yanlin Cheng ◽  
Li Liang ◽  
...  
Keyword(s):  
Thermal Desorption ◽  
Thermal Desorption Spectroscopy ◽  
Hydrogen Desorption ◽  
Pressure Effects ◽  
Zirconium Hydride ◽  
Desorption Kinetics ◽  
Desorption Process ◽  
Exponential Factor ◽  
Predict Weight Loss ◽  
Kinetics Of

Thermal desorption spectroscopy (TDS) was used to study the thermal desorption kinetics of zirconium hydride films, which were deposited on molybdenum substrates and thermally charged with gas phase hydrogen. The observed desorption peaks were attributed to phase transforming steps. The activation energy and pre-exponential factor for desorption kinetics was estimated as 116 kJ/mol and 8762 s−1 according to Kissinger relation, respectively. A simulation of TDS spectra was made, which showed that the desorption process followed a first order kinetics. The kinetic parameters were then utilized to predict weight loss behavior at a temperature profile. Pressure effects that can potentially reduce the desorption rate were discussed.

The Role of Cr in H Desorption Kinetics in Rapidly Solidified Al

2014 ◽  
Vol 783-786 ◽  
pp. 264-269 ◽  
Author(s):  
Iya I. Tashlykova-Bushkevich ◽  
Keitaro Horikawa ◽  
Goroh Itoh
Keyword(s):  
High Temperature ◽  
Thermal Desorption ◽  
High Purity ◽  
Thermal Desorption Spectroscopy ◽  
Secondary Phase ◽  
Hydrogen Desorption ◽  
Oxide Surface ◽  
Desorption Kinetics ◽  
Hydrogen Trapping ◽  
Rapidly Solidified

Hydrogen desorption kinetics for rapidly solidified high purity Al and Al-Cr alloy foils containing 1.0, 1.5 and 3.0 at % Cr were investigated by means of thermal desorption analysis (TDA) at a heating rate of 3.3°C/min. For the first time, it was found that oxide inclusions of Al2O3 are dominant high-temperature hydrogen traps compared with pores and secondary phase precipitates resulted in rapid solidification of Al and its alloys. The correspondent high-temperature evolution rate peak was identified to be positioned at 600°C for high purity Al and shifted to 630°C for Al-Cr alloys. Amount of hydrogen trapped by dislocations increases in the alloys depending on Cr content. Microstructural hydrogen trapping behaviour in low-and intermediate temperature regions observed here was in coincidence with previous data obtained for RS materials using thermal desorption spectroscopy (TDS). The present results on hydrogen thermal desorption evolution indicate that the effect of oxide surface layers becomes remarkable in TDA measurements and show advantages in combinations of both desorption analysis methods to investigate hydrogen desorption kinetics in materials.

scholarly journals Improvement of Hydrogen Desorption Characteristics of MgH2 With Core-shell Ni@C Composites

Molecules ◽  
2018 ◽  
Vol 23 (12) ◽  
pp. 3113 ◽  
Author(s):  
Cuihua An ◽  
Qibo Deng
Keyword(s):  
Low Cost ◽  
Hydrogen Desorption ◽  
Core Shell ◽  
Desorption Kinetics ◽  
Hydrogen Storage Materials ◽  
High Hydrogen ◽  
Dehydrogenation Kinetics ◽  
Materials Research ◽  
High Theoretical Capacity ◽  
Kinetics Of

Magnesium hydride (MgH2) has become popular to study in hydrogen storage materials research due to its high theoretical capacity and low cost. However, the high hydrogen desorption temperature and enthalpy as well as the depressed kinetics, have severely blocked its actual utilizations. Hence, our work introduced Ni@C materials with a core-shell structure to synthesize MgH2-x wt.% Ni@C composites for improving the hydrogen desorption characteristics. The influences of the Ni@C addition on the hydrogen desorption performances and micro-structure of MgH2 have been well investigated. The addition of Ni@C can effectively improve the dehydrogenation kinetics. It is interesting found that: i) the hydrogen desorption kinetics of MgH2 were enhanced with the increased Ni@C additive amount; and ii) the dehydrogenation amount decreased with a rather larger Ni@C additive amount. The additive amount of 4 wt.% Ni@C has been chosen in this study for a balance of kinetics and amount. The MgH2-4 wt.% Ni@C composites release 5.9 wt.% of hydrogen in 5 min and 6.6 wt.% of hydrogen in 20 min. It reflects that the enhanced hydrogen desorption is much faster than the pure MgH2 materials (0.3 wt.% hydrogen in 20 min). More significantly, the activation energy (EA) of the MgH2-4 wt.% Ni@C composites is 112 kJ mol−1, implying excellent dehydrogenation kinetics.

Investigation of surface and near-surface effects on hydrogen desorption kinetics of MgH2

2014 ◽  
Vol 39 (2) ◽  
pp. 862-867 ◽  
Author(s):  
Sandra Kurko ◽  
Igor Milanović ◽  
Jasmina Grbović Novaković ◽  
Nenad Ivanović ◽  
Nikola Novaković
Keyword(s):  
Surface Effects ◽  
Hydrogen Desorption ◽  
Desorption Kinetics ◽  
Near Surface ◽  
Kinetics Of

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.

Hydriding and Dehydriding Characteristics of As-Spun Nanocrystalline and Amorphous Mg20Ni10-xMnx (x = 0-4) Alloys

2011 ◽  
Vol 347-353 ◽  
pp. 3420-3424
Author(s):  
Yang Huan Zhang ◽  
Xiao Gang Liu ◽  
Le Le Chen ◽  
Hui Ping Ren ◽  
Guo Fang Zhang ◽  
...  
Keyword(s):  
Amorphous Phase ◽  
Hydrogen Absorption ◽  
Melt Spinning ◽  
Hydrogen Desorption ◽  
Absorption Capacity ◽  
Desorption Kinetics ◽  
Nanocrystalline And Amorphous ◽  
Cast Alloys ◽  
Mn Content ◽  
Kinetics Of

The nanocrystalline and amorphous Mg2Ni-type Mg20Ni10-xMnx (x = 0, 1, 2, 3, 4) alloys were synthesized by melt-spinning technique. The structures of the as-cast and spun alloys were characterized by XRD, SEM and HRTEM. The hydrogen absorption and desorption kinetics of the alloys were measured. The results show that the substitution of Mn for Ni, instead of changing the major phase Mg2Ni, leads to the formation of Mg and MnNi phases. No amorphous phase is detected in the as-spun Mn-free alloy, but the as-spun alloys substituted by Mn display the presence of an amorphous phase, suggesting that the substitution of Mn for Ni enhances the glass forming ability of the Mg2Ni-type alloy. The hydrogen absorption capacity of the as-cast alloys first increases and then decreases with the variation of the amount of Mn substitution. The hydrogen desorption capacity of the alloys markedly increases with growing Mn content.

Crystallitic Structure and Thermodynamics of Magnesium-Based Hydrogen Storage Materials from Reactive Milling under Hydrogen Atmosphere

2013 ◽  
Vol 724-725 ◽  
pp. 1021-1024
Author(s):  
Shi Xue Zhou ◽  
Qian Qian Zhang ◽  
Nai Fei Wang ◽  
Zong Ying Han ◽  
Wei Xian Ran ◽  
...  
Keyword(s):  
Hydrogen Storage ◽  
Xrd Analysis ◽  
Hydrogen Desorption ◽  
Hydrogen Atmosphere ◽  
Hydrogen Storage Materials ◽  
Storage Materials ◽  
Reactive Milling ◽  
Anthracite Coal ◽  
Enthalpy And Entropy Changes ◽  
Hoff Equation

Magnesium-based hydrogen storage materials were prepared by reactive milling of magnesium under hydrogen atmosphere with crystallitic carbon, prepared from anthracite coal, as milling aid. The XRD analysis shows that in the presence of 30 wt.% of crystallitic carbon, the Mg easily hydrided into β-MgH2of crystal grain size 29.7 nm and a small amount of γ-MgH2after 3 h of milling under 1 MPa H2. The enthalpy and entropy changes of the hydrogen desorption reaction are 42.7 kJ/mol and 80.7 J/mol K, respectively, calculated by the vant Hoff equation from thep-C-Tdata in 300-380°C.

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