Improved hydrogen sorption of sodium alanate by optimized processing

Eigen, N.; Gosch, F.; Dornheim, Martin; Klassen, Thomas; Bormann, R.

doi:10.1016/j.jallcom.2007.10.079

Cited by 33 publications

(30 citation statements)

References 17 publications

(25 reference statements)

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“…While hydrogen liberation is thermodynamically favorable at moderate temperatures, hydrogen uptake had not been possible until in 1997 Bogdanovic et al demonstrated that mixing of NaAlH 4 with a Ti-based catalyst leads to a material, which can be reversibly charged with hydrogen (Bogdanovic, 1997). By using a tube vibration mill of Siebtechnik GmbH Eigen et al (Eigen et al, 2007;Eigen et al, 2008) showed that upscaling of material synthesis is possible: After only 30 min milling under optimised process conditions in such a tube vibration mill in kg scale, fast absorption and desorption kinetics with charging/discharging times of less than 10 min can be obtained. NaAlH 4  1/3 Na 3 AlH 6 + 2/3 Al + H 2 (g)  NaH + Al +3/2 H 2 (g)…”

Section: Hydrogen Storage In Light Weight Hydridesmentioning

confidence: 99%

Thermodynamics of Metal Hydrides: Tailoring Reaction Enthalpies of Hydrogen Storage Materials

Dornheim¹

2011

Thermodynamics - Interaction Studies - Solids, Liquids and Gases

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Section: Hydrogen Storage In Light Weight Hydridesmentioning

confidence: 99%

Thermodynamics of Metal Hydrides: Tailoring Reaction Enthalpies of Hydrogen Storage Materials

Dornheim¹

2011

Thermodynamics - Interaction Studies - Solids, Liquids and Gases

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“…NaAlH 4 can be readily reformed within 2 to 10 min at around 100 C, but at rather high pressures of 80 bar or more [20][21][22].…”

Section: Thermodynamic Limitations Of Lightweight Hydrides J189mentioning

confidence: 99%

Tailoring Reaction Enthalpies of Hydrides

Dornheim¹

2010

Handbook of Hydrogen Storage

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In view of the future use of hydrogen as a renewable fuel for mobile and stationary applications the development of cost and energy efficient, safe and reliable hydrogen storage technologies enabling high volumetric and gravimetric storage densities remains one of the most challenging tasks.One major advantage of metal hydrides is the ability to store hydrogen in a very energy efficient way enabling hydrogen storage at rather low pressures without further need for liquefaction or compression. However, depending on the hydrogen reaction enthalpy of the specific storage material during hydrogen uptake, a huge amount of heat (equivalent to 15% or more of the energy stored in hydrogen) can be generated and has to be removed in a rather short time. On the other hand, during desorption the same amount of heat has to be applied to facilitate the endothermic hydrogen desorption process. If, in the case of stationary applications, during hydrogen uptake the generated amount of heat is stored and used for desorption again, or if, in the case of mobile applications, it is used as process heat for applications near to a filling station, the highest energy efficiencies of the whole hydrogen storage tank-utilization system can be accomplished, see Figure 7.1.In most mobile applications fast recharging of a hydrogen storage tank ought to be possible within only a few minutes. If a 4 kg hydrogen storage tank based on conventional room temperature hydrides with reaction enthalpies of around DH ¼ 30 kJ (mol H 2 ) À1 is considered, like in the case of FeTiH 2 (À28 kJ (mol H 2 ) À1 for TiFeH and À35 kJ (mol H 2 ) À1 for TiFeH 2Àx , Buchner [1]) or LaNi 5 (DH ¼ À31 kJ (mol H 2 ) À1 ) about 60 MJ heat is thereby produced. This value increases still further if more stable medium-or even high-temperature metal hydrides/complex hydrides are chosen. Therefore, it is desirable to develop materials with high storage capacities as well as moderate reaction heats. MgH 2 is an example of a high-temperature metal hydride with a high gravimetric storage capacity and a large value of reaction enthalpy. It has a formation enthalpy of DH ¼ À75 kJ (mol H 2 ) À1 and thus during Handbook of Hydrogen Storage. Edited by Michael Hirscher

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“…Srinivasan et al showed that the NaH/Al precursor synthesized by dry milling takes up initially roughly 1 wt.% of hydrogen, while by using milling in pentane suspension 3.5 wt.% could be absorbed [34]. However, it was also shown that the milling time has substantial influence: Both kinetics and storage capacity show an optimum over the milling time [36]. Despite the high sensitivity of material properties to the process, Fig.1 shows for sodium alanate that a simplified processing route can lead to comparable product qualities: Hydrogenation of purified NaAlH 4 milled together with TiCl 3 takes about 1 h in the second absorption [37].…”

Section: Dymova Et Al Milled Alhmentioning

confidence: 99%

“…After the first hydrogenation (activation) a more porous morphology results. This further enhances kinetics, so that hydrogen is rapidly absorbed within a few minutes at 100 bar and 125 °C in the case of sodium alanate [36]. The efficient refinement mechanism of the microstructure in such light metal / light metal hydride systems does not necessitate the use of high intensity mills for the process.…”

Section: Dymova Et Al Milled Alhmentioning

confidence: 99%

Industrial production of light metal hydrides for hydrogen storage

Eigen¹,

Keller²,

Dornheim³

et al. 2007

Scripta Materialia

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Light metal hydrides show a high potential for reversible hydrogen storage applications. In view of the potential future storage of large amounts of hydrogen, an economic tonnage scale production will be required. This view point set introduces production methods and discusses the potential for simplifying processing routes and reducing costs in view of an industrial mass production. For this purpose, sodium alanate, for which a cost-competitive production on large scale is considered to be feasible already to date, is used as an example for future promising hydrides like complex hydrides or reactive hydride composites.

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Improved hydrogen sorption of sodium alanate by optimized processing

Cited by 33 publications

References 17 publications

Thermodynamics of Metal Hydrides: Tailoring Reaction Enthalpies of Hydrogen Storage Materials

Thermodynamics of Metal Hydrides: Tailoring Reaction Enthalpies of Hydrogen Storage Materials

Tailoring Reaction Enthalpies of Hydrides

Industrial production of light metal hydrides for hydrogen storage

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