scholarly journals Effects of Milling in Hydrogen on Magnesium Hydride with a Hydride-Forming Titanium Additive

2021 ◽  
pp. X
Author(s):  
Myoung Youp SONG ◽  
Eunho CHOI
Keyword(s):  
Storage Capacity ◽  
Hydrogen Uptake ◽  
Shear Stresses ◽  
Mechanical Grinding ◽  
Hydrogen Storage Capacity ◽  
Release Rates ◽  
Cycle Number ◽  
Milling In Hydrogen ◽  
Effective Hydrogen ◽  
Uptake And Release

A hydride-forming element titanium (Ti) was selected as an additive to improve the hydrogen uptake and release properties of MgH2. The hydrogen uptake and release properties of three Ti-added MgH2 alloys [named MgH2-xTi (x = 6, 12, and 15)] prepared by milling in hydrogen (reactive mechanical grinding) were investigated and those of MgH2-12Ti were studied in more detail because it had the highest initial hydrogen uptake and release rates and the largest quantities of hydrogen absorbed and released for 60 min. At the cycle number, n, of one (n = 1), MgH2-12Ti absorbed 4.01 wt.% H for 2.5 min and 6.39 wt.% H for 60 min at 573 K in 12 bar H2, having an effective hydrogen storage capacity of 6.39 wt.%. MgH2-12Ti released 0.44 wt.% H for 2.5 min and 1.86 wt.% H for 60 min at 593 K in 1.0 bar H2. γ-MgH2, TiH1.924, and MgO were formed during reactive mechanical grinding. We believe that the brute forces and tensile, compressive, or shear stresses, which are applied to the materials during reactive mechanical grinding, introduce imperfections, fabricate cracks, expose fresh and clean surfaces, decrease the particle size, and disperse the additive among the particles. The γ-MgH2, TiH1.924, and MgO formed during reactive mechanical grinding and their pulverization during reactive mechanical grinding are believed to make these effects stronger.

scholarly journals Milling Processes and Hydrogen Storage Properties of Mg-Graphene Composites

2019 ◽  
Vol 25 (3) ◽  
pp. 286-291
Author(s):  
Young Jun KWAK ◽  
Eunho CHOI ◽  
Myoung Youp SONG
Keyword(s):  
Hydrogen Storage ◽  
Hydrogen Uptake ◽  
Weight Percent ◽  
Particle Sizes ◽  
Cycle Number ◽  
Reactive Milling ◽  
Milling In Hydrogen ◽  
Storage Properties ◽  
Effective Hydrogen ◽  
Uptake And Release

Graphene was chosen as an additive to improve the hydrogen uptake and release properties of magnesium (Mg). Five weight percent of graphene was added to Mg or pre-milled Mg by milling in hydrogen (reactive milling). The milling processes and hydrogen uptake and release properties of the graphene-added Mg were investigated. Adding graphene to Mg and then milling the mixture of Mg and graphene in hydrogen for 6 h [named M5G (6 h)] had little effects on the improvement of hydrogen uptake and release properties of Mg. Pre-milling of Mg (for 24 h) and then adding 5 wt.% of graphene by milling in hydrogen (for 30 min) (named M5G) significantly increased the hydrogen uptake and release rates and the quantities of hydrogen absorbed and released for 60 min of Mg. The activation of M5G was completed after cycle number, CN, of two (CN = 2). M5G had a high effective hydrogen-storage capacity of 6.21 wt.% at 623 K in 12 bar H2 at CN = 3. M5G released 0.25 wt.% hydrogen for 2.5 min and 5.28 wt.% hydrogen for 60 min H2 in 1.0 bar H2 at 623 K at CN = 3. Pre-milling of Mg and then adding graphene by milling in hydrogen and hydrogen uptake-release cycling are believed to create defects, produce cracks and clean surfaces, and decrease particle sizes. DOI: http://dx.doi.org/10.5755/j01.ms.25.3.20567

scholarly journals Hydriding and Dehydriding Features of a Titanium-Added Magnesium Hydride Composite

2020 ◽  
Vol 26 (2) ◽  
pp. 199-204
Author(s):  
Eunho CHOI ◽  
Myoung Youp SONG
Keyword(s):  
Hydrogen Storage ◽  
Sorption Behavior ◽  
Particle Sizes ◽  
Mechanical Grinding ◽  
Hydrogen Storage Capacity ◽  
Hydrogen Storage Properties ◽  
Milled Sample ◽  
Milling In Hydrogen ◽  
Storage Properties ◽  
Effective Hydrogen

Magnesium has excellent hydrogen-storage properties except low hydriding and dehydriding rates. In the present work, titanium (Ti) was chosen as an additive to increase the hydriding rate of Mg and the dehydriding rate of MgH2. 15 wt.% Ti was added to MgH2 by milling in hydrogen (reactive mechanical grinding). The hydriding and dehydriding features of the Ti-added MgH2 composite (named 85 MgH2 + 15 Ti) were investigated. At the first cycle (n = 1), 85 MgH2 + 15 Ti absorbed 2.96 wt.% H for 2.5 min and 5.51 wt.% H for 60 min at 593 K in 12 bar H2, having an effective hydrogen-storage capacity of 5.51 wt.%. β-MgH2, γ-MgH2, TiH1.924, MgO, and MgTi2O4 were formed during reactive mechanical grinding. Reactive mechanical grinding of MgH2 with Ti is believed to create imperfections, produce cracks and clean surfaces, and decrease particle sizes. The phases formed during reactive mechanical grinding and their pulverization during reactive mechanical grinding are believed to make these effects stronger. Since the γ-MgH2 phase is believed to be decomposed at n = 1, the existence of the γ-MgH2 phase in the milled sample does not contribute to the improvement of the sorption behavior of Mg.

scholarly journals Improvement in Hydriding and Dehydriding Features of Mg–TaF5–VCl3 Alloy by Adding Ni and x wt% MgH2 (x = 1, 5, and 10) Together with TaF5 and VCl3

Micromachines ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1194
Author(s):  
Young-Jun Kwak ◽  
Myoung-Youp Song
Keyword(s):  
Particle Size ◽  
Hydrogen Storage ◽  
Mechanical Milling ◽  
Storage Capacity ◽  
Reaction Rates ◽  
Cycling Performance ◽  
Hydrogen Storage Capacity ◽  
Effective Hydrogen

In our previous work, TaF5 and VCl3 were added to Mg, leading to the preparation of samples with good hydriding and dehydriding properties. In this work, Ni was added together with TaF5 and VCl3 to increase the reaction rates with hydrogen and the hydrogen-storage capacity of Mg. The addition of Ni together with TaF5 and VCl3 improved the hydriding and dehydriding properties of the TaF5 and VCl3-added Mg. MgH2 was also added with Ni, TaF5, and VCl3 and Mg-x wt% MgH2-1.25 wt% Ni-1.25 wt% TaF5-1.25 wt% VCl3 (x = 0, 1, 5, and 10) were prepared by reactive mechanical milling. The addition of MgH2 decreased the particle size, lowered the temperature at which hydrogen begins to release rapidly, and increased the hydriding and dehydriding rates for the first 5 min. Adding 1 and 5 wt% MgH2 increased the quantity of hydrogen absorbed for 60 min, Ha (60 min), and the quantity of hydrogen released for 60 min, Hd (60 min). The addition of MgH2 improved the hydriding–dehydriding cycling performance. Among the samples, the sample with x = 5 had the highest hydriding and dehydriding rates for the first 5 min and the best cycling performance, with an effective hydrogen-storage capacity of 6.65 wt%.

scholarly journals Improvement in the Hydrogenation and Dehydrogenation Features of Mg by Milling in Hydrogen with Vanadium Chloride

2021 ◽  
Vol 59 (10) ◽  
pp. 721-729
Author(s):  
Myoung Youp Song ◽  
Seong Ho Lee ◽  
Young Jun Kwak
Keyword(s):  
Solid Solution ◽  
Hydrogen Storage ◽  
Storage Capacity ◽  
Hydrogen Atmosphere ◽  
Starting Material ◽  
Hydrogen Storage Capacity ◽  
Reactive Milling ◽  
Nucleation Sites ◽  
Milling In Hydrogen ◽  
Vanadium Chloride

VCl3 (vanadium (III) chloride) was selected as an additive to Mg to increase the hydrogenation and dehydrogenation rates and the hydrogen storage capacity of Mg. Instead of MgH2, Mg was used as a starting material since Mg is cheaper than MgH2. Samples with a composition of 95 wt% Mg + 5 wt% VCl3 (named Mg-5VCl3) were prepared by milling in hydrogen atmosphere (reactive milling). In the first cycle (n=1), Mg-5VCl3 absorbed 5.38 wt% H for 5 min and 5.95 wt% H for 60 min at 573 K in 12 bar hydrogen. The activation of Mg-5VCl3 was completed after three hydrogenation-dehydrogenation cycles. During milling in hydrogen, β-MgH2 and γ-MgH2 were produced. The formed β-MgH2 and γ-MgH2 are considered to have made the effects of reactive milling stronger as β-MgH2 and γ-MgH2 themselves were being pulverized. The introduced defects and the interfaces between the Mg and the phases formed during the reactive milling and during hydrogenation-dehydrogenation cycling are believed to serve as heterogeneous active nucleation sites for MgH2 and Mg-H solid solution. The phases generated during hydrogenation-dehydrognation cycling are also believed to prevent the particles from coalescing during hydrogenation-dehydrognation cycling.

scholarly journals Improvement in the Hydrogenation and Dehydrogenation Features of Mg by Milling in Hydrogen with Vanadium Chloride

2021 ◽  
Vol 59 (10) ◽  
pp. 709-717
Author(s):  
Myoung Youp Song ◽  
Seong Ho Lee ◽  
Young Jun Kwak
Keyword(s):  
Solid Solution ◽  
Hydrogen Storage ◽  
Storage Capacity ◽  
Hydrogen Atmosphere ◽  
Starting Material ◽  
Hydrogen Storage Capacity ◽  
Reactive Milling ◽  
Nucleation Sites ◽  
Milling In Hydrogen ◽  
Vanadium Chloride

VCl3 (vanadium (III) chloride) was selected as an additive to Mg to increase the hydrogenation and dehydrogenation rates and the hydrogen storage capacity of Mg. Instead of MgH2, Mg was used as a starting material since Mg is cheaper than MgH2. Samples with a composition of 95 wt% Mg + 5 wt% VCl3 (named Mg-5VCl3) were prepared by milling in hydrogen atmosphere (reactive milling). In the first cycle (n=1), Mg-5VCl3 absorbed 5.38 wt% H for 5 min and 5.95 wt% H for 60 min at 573 K in 12 bar hydrogen. The activation of Mg-5VCl3 was completed after three hydrogenation-dehydrogenation cycles. During milling in hydrogen, β-MgH2 and γ-MgH2 were produced. The formed β-MgH2 and γ-MgH2 are considered to have made the effects of reactive milling stronger as β-MgH2 and γ-MgH2 themselves were being pulverized. The introduced defects and the interfaces between the Mg and the phases formed during the reactive milling and during hydrogenation-dehydrogenation cycling are believed to serve as heterogeneous active nucleation sites for MgH2 and Mg-H solid solution. The phases generated during hydrogenation-dehydrognation cycling are also believed to prevent the particles from coalescing during hydrogenation-dehydrognation cycling.

Amelioration of Hydrogen Uptake and Release Features of Magnesium Adding a Polymer Polyvinylidene Fluoride via Milling in Hydrogen in a Planetary Ball Mill

2020 ◽  
Vol 20 (11) ◽  
pp. 7105-7113
Author(s):  
Young Jun Kwak ◽  
Myoung Youp Song
Keyword(s):  
Ball Milling ◽  
Ball Mill ◽  
Polyvinylidene Fluoride ◽  
Hydrogen Uptake ◽  
Hydrogen Atmosphere ◽  
Hydrogen Release ◽  
Planetary Ball Mill ◽  
Planetary Ball Milling ◽  
Milling In Hydrogen ◽  
Uptake And Release

In the present study, a polymer polyvinylidene fluoride (PVDF) was chosen as an adding material to ameliorate hydrogen uptake and release features of Mg. Samples with a composition of 95 wt.% Mg+5 wt.% PVDF (called 95Mg + 5PVDF) were made via milling in hydrogen atmosphere in a planetary ball mill (reactive planetary ball milling). The hydrogen release reaction of magnesium hydride formed in the as-prepared 95Mg+5PVDF during reactive planetary ball milling started at 681 K. In the third cycle (CN = 3), the amount of hydrogen absorbed for 60 min, A (60 min), was 3.44 wt.% hydrogen at 573 K in 12 bar hydrogen. The PVDF is believed to have melted during reactive planetary ball milling, and the sliding or lubrication between Mg particles and hardened steel balls was avoided, leading to a good contact between them and a highly effective milling. The milling in hydrogen atmosphere in a planetary ball mill of Mg with PVDF is believed to have generated defects and cracks. The Mg2C3 produced from PVDF during hydrogen uptake-release cycling is believed to have been spread among particles and to have kept particles from coalescing. To the best of our knowledge, this is the first study to use a polymer PVDF as an additive material for the amelioration of hydrogen uptake and release features of Mg.

Influence of hydrogen spillover on Pt-decorated carbon nanocones for enhancing hydrogen storage capacity: A DFT mechanistic study

2018 ◽  
Vol 20 (32) ◽  
pp. 21194-21203 ◽  
Author(s):  
Nuttapon Yodsin ◽  
Chompoonut Rungnim ◽  
Vinich Promarak ◽  
Supawadee Namuangruk ◽  
Nawee Kungwan ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Hydrogen Storage ◽  
Active Site ◽  
Storage Capacity ◽  
Hydrogen Adsorption ◽  
Hydrogen Uptake ◽  
Mechanistic Study ◽  
Hydrogen Storage Capacity ◽  
Carbon Nanocones ◽  
Hydrogen Migration

The hydrogen adsorption on platinum (Pt)-decorated carbon nanocenes (CNCs) are investigated by DFT calculations. The Pt is an active site for hydrogen adsorption while curvature of CNC enhances hydrogen uptake via hydrogen migration/diffusion on the C–C surface.

scholarly journals Mixed-linker approach in designing porous zirconium-based metal–organic frameworks with high hydrogen storage capacity

2016 ◽  
Vol 52 (50) ◽  
pp. 7826-7829 ◽  
Author(s):  
Ayesha Naeem ◽  
Valeska P. Ting ◽  
Ulrich Hintermair ◽  
Mi Tian ◽  
Richard Telford ◽  
...  
Keyword(s):  
Hydrogen Storage ◽  
High Selectivity ◽  
Storage Capacity ◽  
Metal Organic Framework ◽  
Metal Organic Frameworks ◽  
Hydrogen Uptake ◽  
Hydrogen Storage Capacity ◽  
High Hydrogen ◽  
Metal Organic ◽  
Adsorption Of Co

New zirconium based metal–organic framework (UBMOF-31) synthesised using mixed-linker strategy showing permanent porosity, excellent hydrogen uptake, and high selectivity for adsorption of CO2 over N2.

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