Structural and Compositional Changes during Hydrogenation/Dehydrogenation of the Li−Mg−N−H System

Hu, Jianjiang; Liu, Yongfeng; Wu, Guotao; Xiong, Zhitao; Chen, Ping

doi:10.1021/jp075757s

Cited by 96 publications

(117 citation statements)

References 19 publications

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“…The structural similarity of LiNH 2 to Li 2 Mg(NH) 2 suggests that the identified LiNH 2 should act as an important reaction intermediate. Similar speculation was also proposed by Hu et al 26 The proposed LiNH 2 mediation (that is, LiNH 2 formation is an elementary reaction step) suggests that incorporating foreign LiNH 2 may enhance the inherent reaction. To verify the favorable effect of LiNH 2 , we prepared and examined the Li-Mg-N-H samples containing respective LiNH 2 and Li 3 N additive with regard to dehydrogenation performance.…”

Section: Discussionsupporting

confidence: 82%

Effect of Li₃N additive on the hydrogen storage properties of Li-Mg-N-H system

Fang

Dai

et al. 2009

J. Mater. Res.

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The effect of Li 3 N additive on the Li-Mg-N-H system was examined with respect to the reversible dehydrogenation performance. Screening study with varying Li 3 N additions (5, 10, 20, and 30 mol%) demonstrates that all are effective for improving the hydrogen desorption capacity. Optimally, incorporation of 10 mol% Li 3 N improves the practical capacity from 3.9 wt% to approximately 4.7 wt% hydrogen at 200 C, which drives the dehydrogenation reaction toward completion. Moreover, the capacity enhancement persists well over 10 de-/rehydrogenation cycles. Systematic x-ray diffraction examinations indicate that Li 3 N additive transforms into LiNH 2 and LiH phases and remains during hydrogen cycling. Combined structure/property investigations suggest that the LiNH 2 "seeding" should be responsible for the capacity enhancement, which reduces the kinetic barrier associated with the nucleation of intermediate LiNH 2 . In addition, the concurrent incorporation of LiH is effective for mitigating the ammonia release.

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Section: Discussionsupporting

confidence: 82%

Effect of Li₃N additive on the hydrogen storage properties of Li-Mg-N-H system

Fang

Dai

et al. 2009

J. Mater. Res.

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“…The absorbances at 3196 and 3162 cm À1 in the heat-treated sample were a result of the NÀH stretches of Li 2 Mg 2 (NH) 3 . [41] The other peaks were also identified ( Figure 5 c). In addition, we also found that the reaction of KLi 3 (NH 2 ) 4 and MgNH can be performed at lower temperatures but at slower reaction rates, for example, heating at 156 8C for 1 h.…”

Section: And Mgnhmentioning

confidence: 86%

Solid–Solid Heterogeneous Catalysis: The Role of Potassium in Promoting the Dehydrogenation of the Mg(NH₂)₂/2 LiH Composite

et al. 2013

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Considerable efforts have been devoted to the catalytic modification of hydrogen storage materials. The K‐modified Mg(NH2)2/2 LiH composite is a typical model for such studies. In this work, we analyze the origin of the kinetic barrier in the first step of the dehydrogenation and investigate how K catalyzes this heterogeneous solid‐state reaction. Our results indicate that the interface reaction of Mg(NH2)2 and LiH is the main source of the kinetic barrier at the early stage of the dehydrogenation for the intensively ball‐milled Mg(NH2)2/2 LiH sample. K can effectively activate Mg(NH2)2 as well as promote LiH to participate in the dehydrogenation. Three K species of KH, K2Mg(NH2)4, and Li3K(NH2)4 likely transform circularly in the dehydrogenation (KH↔K2Mg(NH2)4↔KLi3(NH2)4), which creates a more energy‐favorable pathway and thus leads to the overall kinetic enhancement. This catalytic role of K in the amide/hydride system is different from the conventional catalysis of transition metals in the alanate system.

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“…Although the dehydrogenation temperatures of the RHCs are lower than those of the individual hydrides, a further decrease in dehydrogenation temperature down to around 100°C has not yet been experimentally observed, even though there are a couple of RHCs with predicted or extrapolated values of the equilibrium dehydrogenation temperatures below 100°C [193,234]. One possible way to realize this challenging goal is to combine high-capacity (complex) metal hydrides with a third element/compound that may promote the formation of even more stable dehydrogenation products with a reaction enthalpy preferably below 35 kJ/molH 2 .…”

Section: Reactive Hydride Compositesmentioning

confidence: 98%

Complex and liquid hydrides for energy storage

et al. 2016

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The research on complex hydrides for hydrogen storage was initiated by the discovery of Ti as a hydrogen sorption catalyst in NaAlH 4 by Boris Bogdanovic in 1996. A large number of new complex hydride materials in various forms and combinations have been synthesized and characterized, and the knowledge regarding the properties of complex hydrides and the synthesis methods has grown enormously since then. A significant portion of the research groups active in the field of complex hydrides is collaborators in the International Energy Agreement Task 32. This paper reports about the important issues in the field of complex hydride research, i.e. the synthesis of borohydrides, the thermodynamics of complex hydrides, the effects of size and confinement, the hydrogen sorption mechanism and the complex hydride composites as well as the properties of liquid complex hydrides. This paper is the result of the collaboration of several groups and is an excellent summary of the recent achievements.

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Structural and Compositional Changes during Hydrogenation/Dehydrogenation of the Li−Mg−N−H System

Cited by 96 publications

References 19 publications

Effect of Li₃N additive on the hydrogen storage properties of Li-Mg-N-H system

Effect of Li₃N additive on the hydrogen storage properties of Li-Mg-N-H system

Solid–Solid Heterogeneous Catalysis: The Role of Potassium in Promoting the Dehydrogenation of the Mg(NH₂)₂/2 LiH Composite

Complex and liquid hydrides for energy storage

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Structural and Compositional Changes during Hydrogenation/Dehydrogenation of the Li−Mg−N−H System

Cited by 96 publications

References 19 publications

Effect of Li3N additive on the hydrogen storage properties of Li-Mg-N-H system

Effect of Li3N additive on the hydrogen storage properties of Li-Mg-N-H system

Solid–Solid Heterogeneous Catalysis: The Role of Potassium in Promoting the Dehydrogenation of the Mg(NH2)2/2 LiH Composite

Complex and liquid hydrides for energy storage

Contact Info

Product

Resources

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Effect of Li₃N additive on the hydrogen storage properties of Li-Mg-N-H system

Effect of Li₃N additive on the hydrogen storage properties of Li-Mg-N-H system

Solid–Solid Heterogeneous Catalysis: The Role of Potassium in Promoting the Dehydrogenation of the Mg(NH₂)₂/2 LiH Composite