Comparisons between MgH2- and LiH-containing systems for hydrogen storage applications

Markmaitree, Tippawan; Osborn, William; Shaw, Leon L.

doi:10.1016/j.ijhydene.2007.10.052

Cited by 39 publications

(26 citation statements)

References 52 publications

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“…The unmodified mixture lost a total of 10.94 wt% during decomposition, which is significantly higher than the theoretical hydrogen capacity of 8.14 wt%. This increase is attributed to release of ammonia from the decomposition of unreacted LiNH 2 and the slow reaction kinetics between MgH 2 and NH 3 [17,18].…”

Section: Decomposition Of the Modified And Unmodified Systemsmentioning

confidence: 99%

“…Through the use of Draeger tubes on the 2:1 LiNH 2 :MgH 2 system, Luo et al showed that ammonia concentration was strongly dependent on the desorption temperature with concentrations of 180ppm measured at 180°C and 720ppm at 240°C [17]. In a separate analysis, the effect of milling duration on ammonia release from the 2:1 mixture during heating was investigated, resulting in over 30 ppm/mg for unmilled samples and under 10 ppm/mg fo samples milled for 180 minutes using high-energy milling [18]. In a separate study on the effect of the variation of LiH composition in the Mg(NH 2 ) 2 -LiH mixture, Hu et al observed that if the molar ratio of LiH was below 2, ammonia evolution occurred during dehydrogenation reactions and if the molar ratio was above 2 a reduction in hydrogen storage efficiency was observed [19].…”

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confidence: 99%

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The effects of halide modifiers on the sorption kinetics of the Li-Mg-N-H System

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Lascola

et al. 2012

International Journal of Hydrogen Energy

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The effects of different transition metal halides (TiCl 3 , VCl 3 , ScCl 3 and NiCl 2 ) on the sorption properties of the 1:1 molar ratio of LiNH 2 to MgH 2 are investigated. The modified mixtures were found to contain LiNH 2 , MgH 2 and LiCl. TGA results showed that the hydrogen desorption temperature was reduced with the modifier addition in this order: TiCl 3 > ScCl 3 > VCl 3 > NiCl 2 . Ammonia release was not significantly reduced resulting in a weight loss greater than the theoretical hydrogen storage capacity of the material. The isothermal sorption kinetics of the modified systems showed little improvement after the first dehydrogenation cycle over the unmodified system but showed drastic improvement in rehydrogenation cycles. X-ray diffraction and Raman spectroscopy identified the cycled material to be composed of LiH, MgH 2 , Mg(NH 2 ) 2 and Mg 3 N 2 .

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Section: Decomposition Of the Modified And Unmodified Systemsmentioning

confidence: 99%

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confidence: 99%

The effects of halide modifiers on the sorption kinetics of the Li-Mg-N-H System

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Lascola

et al. 2012

International Journal of Hydrogen Energy

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“…Similarly, the ammonia release from the Spex milled sample peaked at 285 °C. The source of ammonia can be attributed to the decomposition of unreacted LiNH 2 , the slow reaction kinetics between MgH 2 and NH 3 from decomposing LiNH 2 [12,33,34] and/or the decomposition of Mg(NH 2 ) 2 , which runs parallel to the H 2 desorption of the hydride-amide system [35]. Janot et al showed that a mixture of 2:1 LiNH 2 :MgH 2 lost significantly more weight than a 2:1 LiH:Mg(NH 2 ) 2 at 200 °C into primary vacuum due to ammonia release [12].…”

Section: Decomposition Behavior Of Unmodified As-milled Materialsmentioning

confidence: 99%

Affects of Mechanical Milling and Metal Oxide Additives on Sorption Kinetics of 1:1 LiNH2/MgH2 Mixture

2011

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Abstract:The destabilized complex hydride system composed of LiNH 2 :MgH 2 (1:1 molar ratio) is one of the leading candidates of hydrogen storage with a reversible hydrogen storage capacity of 8.1 wt%. A low sorption enthalpy of ~32 kJ/mole H 2 was first predicted by Alapati et al. utilizing first principle density function theory (DFT) calculations and has been subsequently confirmed empirically by Lu et al. through differential thermal analysis (DTA). This enthalpy suggests that favorable sorption kinetics should be obtainable at temperatures in the range of 160 °C to 200 °C. Preliminary experiments reported in the literature indicate that sorption kinetics are substantially lower than expected in this temperature range despite favorable thermodynamics. Systematic isothermal and isobaric sorption experiments were performed using a Sievert's apparatus to form a baseline data set by which to compare kinetic results over the pressure and temperature range anticipated for use of this material as a hydrogen storage media. Various material preparation methods and compositional modifications were performed in attempts to increase the kinetics while lowering the sorption temperatures. This paper outlines the results of these systematic tests and describes a number of beneficial additions which influence kinetics as well as NH 3 formation.

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“…The results indicate that the NH 3 concentration is around 180 ppm at 180 • C and 720 ppm at 240 • C, restricting the cycling and then the applicability. Markmaitree et al [57] compared the reaction kinetics and the NH 3 emission of the 2LiNH 2 + MgH 2 and LiNH 2 + LiH systems. The 2LiNH 2 + MgH 2 mixture seems to possess a higher activation energy and NH 3 emission than the LiNH 2 + LiH mixture.…”

Section: Li-mg-n-h Systemmentioning

confidence: 99%

“…The magnesium amide forms and then decomposes to MgNH at a reasonable rate from 250 • C with the release of NH 3 [57]. Further ammonia is produced in the last step, then reacts with residual MgH 2 and the reaction cycle continues.…”

Section: Li-mg-n-h Systemmentioning

confidence: 99%

Recent Progress and New Perspectives on Metal Amide and Imide Systems for Solid-State Hydrogen Storage

et al. 2018

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Hydrogen storage in the solid state represents one of the most attractive and challenging ways to supply hydrogen to a proton exchange membrane (PEM) fuel cell. Although in the last 15 years a large variety of material systems have been identified as possible candidates for storing hydrogen, further efforts have to be made in the development of systems which meet the strict targets of the Fuel Cells and Hydrogen Joint Undertaking (FCH JU) and U.S. Department of Energy (DOE). Recent projections indicate that a system possessing: (i) an ideal enthalpy in the range of 20-50 kJ/mol H 2 , to use the heat produced by PEM fuel cell for providing the energy necessary for desorption; (ii) a gravimetric hydrogen density of 5 wt. % H 2 and (iii) fast sorption kinetics below 110 • C is strongly recommended. Among the known hydrogen storage materials, amide and imide-based mixtures represent the most promising class of compounds for on-board applications; however, some barriers still have to be overcome before considering this class of material mature for real applications. In this review, the most relevant progresses made in the recent years as well as the kinetic and thermodynamic properties, experimentally measured for the most promising systems, are reported and properly discussed.

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Comparisons between MgH2- and LiH-containing systems for hydrogen storage applications

Cited by 39 publications

References 52 publications

The effects of halide modifiers on the sorption kinetics of the Li-Mg-N-H System

The effects of halide modifiers on the sorption kinetics of the Li-Mg-N-H System

Affects of Mechanical Milling and Metal Oxide Additives on Sorption Kinetics of 1:1 LiNH2/MgH2 Mixture

Recent Progress and New Perspectives on Metal Amide and Imide Systems for Solid-State Hydrogen Storage

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