Reduced Enthalpy of Metal Hydride Formation for Mg–Ti Nanocomposites Produced by Spark Discharge Generation

Anastasopol, A.; Pfeiffer, Tobias; Middelkoop, Joost; Lafont, Ugo; Canales-Perez, Roger J.; Schmidt‐Ott, A.; Mulder, Fokko M.; Eijt, S.W.H.

doi:10.1021/ja3123416

Cited by 83 publications

(83 citation statements)

References 60 publications

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“…The modified thermodynamics may result from the finely dispersed character of MnCl 2 in the IRH-33 super activated carbon in combination with the large volumetric expansion of MnCl 2 upon ammoniate formation [27]. Such effects have been observed in the field of metal hydrides [38,39]. The ammonia adsorption isotherm at 20°C, 50°C and 77°C look similar and have only shifted to higher NH 3 partial pressure as the adsorption process is exothermic.…”

Section: Nh 3 Adsorption Isotherms On Mncl 2 Impregnated Irh-33mentioning

confidence: 94%

Ammonia sorbent development for on-board H2 purification

Hassel¹,

Karra²,

Santana³

et al. 2015

Separation and Purification Technology

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a b s t r a c tThe application of chemical hydrides (e.g. ammonia borane) and amide-based hydrogen storage materials would benefit from an effective means to remove ammonia, which is an impurity that is detrimental to the performance of a PEM fuel cell. One option is to adsorb ammonia on a sorbent with high capacity that would also be regenerable. Such a sorbent was developed by impregnating super activated carbon with metal chlorides (MgCl 2 , ZnCl 2 , MnCl 2 ). The sorbent was characterized through static and dynamic adsorption experiments. It was shown to have a good cyclic stability. The filter weight, volume and pressure drop appears reasonable for an onboard vehicle application when it would be replaced/regenerated every 1800 miles, similar to an oil change.

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Section: Nh 3 Adsorption Isotherms On Mncl 2 Impregnated Irh-33mentioning

confidence: 94%

Ammonia sorbent development for on-board H2 purification

Hassel¹,

Karra²,

Santana³

et al. 2015

Separation and Purification Technology

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“…25,28,29 This technique have focused on fabricating NPs using spark ablation (at low frequencies) for a number of new applications (Table S1). 3,6,7,19,25,29,[33][34][35][36][37][38]31,[39][40][41][42][43][44] Note that carrier gases and electrodes determine the particle composition. 25 Although manufacturing electrodes may not be particularly green, the use of recycled metals allows the green manufacturing of NPs.…”

Section: High-yield and Continuous Synthesis Of Ultrapure Inorganic Nmentioning

confidence: 99%

“…29 Spark discharges using resistance-inductance-capacitance (RLC) circuits (referred to as RLCS from this point onwards; cf. Figure S1) 7,31 have an upper operating frequency threshold of a few hundred Hz. A continuous arc discharge develops above that threshold, which yields larger particles associated with a higher mass production rate.…”

Section: High-yield and Continuous Synthesis Of Ultrapure Inorganic Nmentioning

confidence: 99%

Green manufacturing of metallic nanoparticles: a facile and universal approach to scaling up

et al. 2016

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“…Anastasopol et al have prepared Mg−Ti nanometer-sized composites by spark discharge generation, and indeed, a destabilization of MgH 2 has been found. 13 Thin-film multilayer stacks prepared by magnetron sputtering is a more practical approach to systematically study nanometer-sized Mg. 14 16 They showed that the equilibrium hydrogen pressure for hydrogenation of Mg at a given temperature depends type of cap layer. Ni and Pd, which are miscible with Mg, effectively increase the equilibrium pressure.…”

Section: ■ Introductionmentioning

confidence: 99%

Destabilization of Mg Hydride by Self-Organized Nanoclusters in the Immiscible Mg–Ti System

et al. 2015

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Mg is an attractive hydrogen storage material not only because of its high gravimetric and volumetric hydrogen capacities but also because of it low material costs. However, the hydride of MgH 2 is too stable to release hydrogen under moderate conditions. We demonstrate that the formation of nanometer-sized clusters of Mg reduces the stability of MgH 2 by the interface energy effect in the immiscible Mg−Ti system. Ti-rich Mg x Ti 1−x (x < 0.5) thin films deposited by magnetron sputtering have a hexagonal close packed (HCP) structure, which forms a face-centered cubic (FCC) hydride phase upon hydrogenation. Positron Doppler broadening depth profiling demonstrates that after hydrogenation, nanometer-sized MgH 2 clusters are formed which are coherently embedded in an FCC TiH 2 matrix. The P (pressure)−T (optical transmission) isotherms measured by hydrogenography show that these MgH 2 clusters are destabilized. This indicates that the formation of nanometer-sized Mg allows for the development of a lightweight and cheap hydrogen storage material with a lower desorption temperature. ■ INTRODUCTIONMg is one of the typical lightweight metals with a density of 1.74 g cm −3 , which is much less than that of many transition and rare earth metals. 1 Mg has a hexagonal close-packed (HCP) structure, and that forms the hydride phase MgH 2 by hydrogenation. MgH 2 has a rutile-type body-centered tetragonal (BCT) structure (α-MgH 2 ) at moderate temperatures and pressures. 2,3 The gravimetric hydrogen capacity is 7.6 mass %, which is higher than most metal hydrides. The volumetric hydrogen capacity of 109 g-H 2 l −1 corresponds to 2.9 times the gaseous hydrogen concentration under a pressure of 70 MPa and 1.6 times the one of liquid hydrogen at 20 K. 4 Mg is one of the most attractive hydrogen storage materials not only because of the high capacity but also the low material costs. However, MgH 2 is too stable to desorb hydrogen at moderate temperatures and pressures and thus unsuited for practical applications. The enthalpy for hydride formation is −75 kJ mol −1 -H 2 , 2,3 which corresponds to a dehydrogenation temperature of around 550 K under a hydrogen pressure of 0.1 MPa. Furthermore, the slow reaction kinetics for hydrogenation and dehydrogenation is a disadvantage for using it as hydrogen storage material. The diffusion of hydrogen in both Mg and MgH 2 has been studied, 2,5,6 and the activation energy for hydrogen diffusion in MgH 2 of 140 kJ mol −1 is particularly high. 6 This value is around 2−5 times those in hydrides of LaNi 5 7 and V. 8 A possible way to destabilize MgH 2 and enhance the reaction kinetics is to reduce the size of Mg. It has been calculated that MgH 2 is destabilized by decreasing the size on a nanometer scale. 9−11 The destabilization is remarkable for a MgH 2 cluster with a diameter below 1.3 nm, corresponding to 19 Mg atoms or less. 11 On the basis of these calculations, the dehydrogenation temperature for a MgH 2 cluster of 0.9 nm would be more than 100 K lower than for bulk MgH 2 under a given hydr...

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Reduced Enthalpy of Metal Hydride Formation for Mg–Ti Nanocomposites Produced by Spark Discharge Generation

Cited by 83 publications

References 60 publications

Ammonia sorbent development for on-board H2 purification

Ammonia sorbent development for on-board H2 purification

Green manufacturing of metallic nanoparticles: a facile and universal approach to scaling up

Destabilization of Mg Hydride by Self-Organized Nanoclusters in the Immiscible Mg–Ti System

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