Mechanically alloyed metal hydride systems

Huot, Jacques; Liang, Guoxian; Schulz, Robert

doi:10.1007/s003390100772

Cited by 263 publications

(177 citation statements)

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“…The milling process is characterized by highenergy collision/grinding between grinding balls or between ball and container walls, which repeatedly induces fracturing and cold welding of sample particles. Fundamentals, application, and recent development of the milling technique can be found in general reviews 29,30 and books. 31,32 The mixtures of NaH + Al + Ti (1:1:0.04) and NaAlH 4 + Ti (1:0.04) were mechanically milled by using a Fritsch 7 Planetary mill at 400 rpm in a bowl, together with grinding balls made of stainless steel, respectively.…”

Section: Methodsmentioning

confidence: 99%

Exploration of the Nature of Active Ti Species in Metallic Ti-Doped NaAlH₄

2005

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Clarification of the nature of active Ti species has been a key challenge in developing Ti-doped NaAlH 4 as a potential hydrogen storage medium. Previously, it has been greatly hindered by the invisibility of Ticontaining species in conventional analysis techniques. In the present study, for the first time, the catalytically active Ti-containing species have been definitely identified by X-ray diffraction in the hydrides doped with metallic Ti. It was found that mechanical milling of a NaH/Al mixture or NaAlH 4 with metallic Ti powder resulted in the formation of nanocrystalline Ti hydrides. The variation of the preparation conditions during the doping process leads to a slight composition variation of the Ti hydrides. The catalytic enhancement arising upon doping the hydride with commercial TiH 2 was quite similar to that achieved in the hydrides doped with metallic Ti. Moreover, the cycling stability that was previously established in metallic Ti-doped hydrides was also observed in the hydrides doped with TiH 2 . These results clearly demonstrate that the in situ formed Ti hydrides act as active species to catalyze the reversible dehydrogenation of NaAlH 4 . The mechanism by which Ti hydrides catalyze the reversible de-/hydrogenation reactions of NaAlH 4 was discussed.

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Section: Methodsmentioning

confidence: 99%

Exploration of the Nature of Active Ti Species in Metallic Ti-Doped NaAlH₄

2005

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“…• Enhancing the rate of hydrogen absorption and desorption • Reducing reaction enthalpy so that desorption can take place at a lower temperature • Improving cyclic hydrogenation/dehydrogenation (reversibility and durability for over 1,000 cycles) • Enabling large scale production Many methods such as catalyst addition (Ni, V, Nb, Fe, Ti, metal oxides, graphite, carbon nanotubes (CNTs)) [66][67][68][69][70], ball milling to decrease the crystallite and particle size [71][72][73][74], and mechanochemical methods [71,72,[75][76][77] have been developed to improve the kinetics of hydrogen absorption and reduce the reaction enthalpy. Table 5 shows the effect of milling time on particle size, crystallite size, and desorption temperatures [71,72].…”

Section: Magnesium Hydride and Its Nanostructuresmentioning

confidence: 99%

Advances in the application of nanotechnology in enabling a ‘hydrogen economy’

2008

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Hydrogen is gaining a great deal of attention as an energy carrier as well as an alternative fuel. However, in order to fully implement the so called 'hydrogen economy' significant technical challenges need to be overcome in the fields of production and storage of hydrogen and its point of use especially in fuel cells for the automotive industry. The purpose of this review is to present and discuss recent advances in the use of nanomaterials for solar hydrogen production and on-board solid state storage of hydrogen. The role of nanotechnology in enhancing the efficiency of fuel cells and reducing their cost is also discussed.

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“…Для магния наряду с тет-рагональным гидридом β-MgH 2 известен также мета-стабильный орторомбический гидрид γ-MgH 2 , форми-рующийся из β-MgH 2 при давлениях в несколько ги-гапаскаль или МА в планетарных мельницах [12,13]. При температурах, близких к комнатной в Mg раство-ряется всего около 1 at.% водорода, а растворимость углерода пренебрежимо мала.…”

Section: Introductionunclassified

Дефекты упаковки и механизмы деформационно-индуцированных превращений ГПУ-металлов (Ti, Mg) при механоактивации в жидких углеводородах

Lubnin¹,

Дорофеев²,

Ніконова³

et al. 2017

Физика Твердого Тела

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Методами рентгеновской дифракции, растровой электронной микроскопии и химического анализа исследована эволюция структуры и субструктуры металлов Ti и Mg с гексагональной плотноупакованной (ГПУ) решеткой при их механоактивации в планетарной мельнице в среде жидких углеводородов (толуол, н-гептан), а также с добавками углеродных материалов (графита, фуллерита, нанотрубок). Изучены термическое поведение и водородаккумулирующие свойства получаемых механокомпозитов. При механоактивации Ti и Mg наблюдаются деструкция жидких углеводородов, образование метастабильного нанокристаллического карбогидрида титана Ti(C,H)x и гидрида магния beta-MgH2 соответственно. Механизмы образования Ti(C,H)x и MgH2 при механоактивации являются деформационными и связаны с накоплением дефектов упаковки, образованием гранецентрированной кубической (ГЦК) укладки атомов. Метастабильный Ti(C,H)x распадается при температуре 550oC, происходит частичное обратное превращение ГЦКГПУ. Накопление дефектов кристаллического строения (границ нанозерен, дефектов упаковки), деструкция углеводородов и образование механокомпозитов приводят к ускорению последующего гидрирования магния в реакторе Сивертса. Работа выполнена при финансовой поддержке РФФИ (грант N 16-32-00487) и УрО РАН (N 15-20-2-22). DOI: 10.21883/FTT.2017.11.45063.015

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Mechanically alloyed metal hydride systems

Cited by 263 publications

References 1 publication

Exploration of the Nature of Active Ti Species in Metallic Ti-Doped NaAlH₄

Exploration of the Nature of Active Ti Species in Metallic Ti-Doped NaAlH₄

Advances in the application of nanotechnology in enabling a ‘hydrogen economy’

Дефекты упаковки и механизмы деформационно-индуцированных превращений ГПУ-металлов (Ti, Mg) при механоактивации в жидких углеводородах

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Mechanically alloyed metal hydride systems

Cited by 263 publications

References 1 publication

Exploration of the Nature of Active Ti Species in Metallic Ti-Doped NaAlH4

Exploration of the Nature of Active Ti Species in Metallic Ti-Doped NaAlH4

Advances in the application of nanotechnology in enabling a ‘hydrogen economy’

Дефекты упаковки и механизмы деформационно-индуцированных превращений ГПУ-металлов (Ti, Mg) при механоактивации в жидких углеводородах

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Exploration of the Nature of Active Ti Species in Metallic Ti-Doped NaAlH₄

Exploration of the Nature of Active Ti Species in Metallic Ti-Doped NaAlH₄