Catalytic effect of Zr and Hf on hydrogen desorption/absorption of NaAlH4 and LiAlH4

Suttisawat, Yindee; Rangsunvigit, Pramoch; Kitiyanan, Boonyarach; Muangsin, Nongnuj; Kulprathipanja, Santi

doi:10.1016/j.ijhydene.2006.07.020

Cited by 63 publications

(42 citation statements)

References 20 publications

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“…Moreover, the initial desorption temperature of LiAlH 4 remarkably decreased to 58°C by doping 5 mol % NiFe 2 O 4 nanopowders, which is quite lower than that of LiAlH 4 with the addition of other various previously reported catalysts. 4,5,[17][18][19][20]24,26,30,31 Meanwhile, combining these two considerations from the initial dehydrogenation temperature and hydrogen release capability, the optimal content of NiFe 2 O 4 additive of the doped sample with the best dehydrogenation performance is 3 mol %, and the LiAlH 4 +3 mol % NiFe 2 O 4 sample will be utilized for analyzing the catalytic effect and mechanism of NiFe 2 O 4 in the following tests. Although NiFe 2 O 4 nanopowder has exhibited superior catalytic performance by declining the onset dehydrogenation temperature of LiAlH 4 , the reversibility of the completely dehydrogenated 3 mol % doped sample cannot be tested at 140°C under 6.5 MPa hydrogen pressure, as shown in Figure S1 (Supporting Information), resulting from the thermodynamic properties of LiAlH 4 .…”

Section: Resultsmentioning

confidence: 99%

NiFe₂O₄ Nanoparticles Catalytic Effects of Improving LiAlH₄ Dehydrogenation Properties

Zhai

et al. 2013

J. Phys. Chem. C

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The effects of NiFe 2 O 4 nanoparticles addition on the dehydrogenation behavior of LiAlH 4 were investigated. The onset dehydrogenation temperature for LiAlH 4 +3 mol % NiFe 2 O 4 sample is 61°C, which decreased by 94°C compared with the as-received LiAlH 4 and released ∼7.2 wt % hydrogen when heated to 180°C. Isothermal desorption measurements show that the 3 mol % NiFe 2 O 4 -doped sample releases ∼7.0 wt % of hydrogen in 91 min at 120°C, which is 6.3 wt % higher than the as-received LiAlH 4 under the same conditions. Through calculating the apparent activation energy of the LiAlH 4 samples with and without NiFe 2 O 4 for the first two dehydrogenation stages, the E a of the LiAlH 4 +3 mol % NiFe 2 O 4 sample is 54.3 and 70.8 kJ/mol, resulting in 52.5 and 59% decrease, respectively, compared with the as-received LiAlH 4 . Analyzing the X-ray diffraction and Fourier transform infrared spectroscopy results, it is reasonable to believe that the remarkable improvement of dehydrogenation properties of NiFe 2 O 4 -doped LiAlH 4 results from the in situ formed LiFeO 2 and Al−Ni compounds, providing the active sites for nucleation and growth of the dehydrogenation products.

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Section: Resultsmentioning

confidence: 99%

NiFe₂O₄ Nanoparticles Catalytic Effects of Improving LiAlH₄ Dehydrogenation Properties

Zhai

et al. 2013

J. Phys. Chem. C

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“…In the case of the doped mixture, as shown in Figures 4b-e, Al is observed after the milling process. It is possible that the milling process and a dopant might destabilize the structure of LiAlH 4 [9]. After the hydrogen desorption at 300 °C ( Figure 5), Al and LiH are present in both undoped and doped mixtures, without the formation of AlB 2 .…”

Section: Resultsmentioning

confidence: 99%

“…The formation of LiCl might deteriorate the hydrogen desorption ability of the samples, consequently decreasing the hydrogen desorption capacity. The LiAlH 4 and LiBH 4 mixtures doped with TiO 2 , TiCl 3 , VCl 3 , or ZrCl 4 partially decompose during the milling process because the structure of LiAlH 4 is unstable and the additives might destabilize its structure [9]. These metal catalysts in the hydride systems are reduced by the metal hydrides and transformed to TM-neutral [6,18], as shown in Reactions (1) and (2), where TM is the transition metal, M is the metal, and X can be either V or Ti:…”

Section: Resultsmentioning

confidence: 99%

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A Revisit to the Hydrogen Desorption/Absorption Behaviors of LiAlH4/LiBH4: Effects of Catalysts

et al. 2012

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Abstract:The hydrogen desorption/absorption behaviors of LiAlH 4 /LiBH 4 with a focus on the effects of catalysts, namely TiCl 3 , TiO 2 , VCl 3 , and ZrCl 4 , were investigated using a thermal-volumetric apparatus. The hydrogen desorption was performed from room temperature to 300 °C with a heating rate of 2 °C min −1. The LiAlH 4 -LiBH 4 mixture with a molar ratio of 2:1 decomposed between 100 and 220 °C, and the hydrogen desorption capacity reached up to 6.6 wt %. Doping 1 mol % of a catalyst to the mixture resulted in the two-step decomposition and a decrease in the hydrogen desorption temperature. All the doped samples provided lower amountz of desorbed hydrogen than that obtained from the undoped one. No hydrogen absorption was observed under 8.5 MPa of hydrogen pressure and 300 °C for 6 h. Despite the fact each of the catalysts may affect the hydrogen storage behaviors of the mixture differently, none resulted in a change in the sample reversibility.

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“…For NaAlH 4 , Bogdanovi c and Schwickardi [1] could show that the addition of a catalyst enhances the kinetics, lowers the decomposition temperature, and, most importantly, makes the rehydrogenation of the compound feasible. The influence of both high energy ball milling and the presence of catalysts on the stability of LiAlH 4 has been the topic of several publications [77][78][79][80][81][82][83][84]. The presence of catalysts accelerates the decomposition of LiAlH 4 and complete decomposition to the hexahydride is observed already after 5 min of ball milling with TiCl 4 (3 wt.%) as catalyst [81].…”

Section: Role Of Catalystsmentioning

confidence: 99%

Complex Hydrides

and

Felderhoff

2010

Handbook of Hydrogen Storage

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Complex hydrides are salt-like materials in which hydrogen is covalently bound to the central atoms, in this way a crystal structure consisting of so-called complex anions is formed. In general, complex hydrides have the chemical formula A x Me y H z . Compounds where position A is preferentially occupied by elements of the first and second groups of the periodic table and Me is occupied either by boron or aluminum are well known and have been intensively investigated. However, another possibility is that complex hydrides are built by transition metal cations. Complex metal hydrides have been known for more than 50 years, but for many years they were not considered for reversible hydrogen storage due to the high kinetic barriers of the decomposition requiring high temperatures. The situation changed in 1997 when Bogdanovi c and Schwickardi discovered that the kinetic barrier of the decomposition of the complex metal hydride, NaAlH 4 , can be lowered by the addition of Ti catalysts and that the material becomes reversible close to acceptable technical conditions [1]. They further showed not only that catalysts can enhance the kinetics of dehydrogenation but also that rehydrogenation under moderate conditions becomes feasible. This breakthrough induced the publication of a tremendous number of papers focusing on the synthesis and the properties of complex hydrides. The major goal is to understand the basic steps of dehydrogenation and rehydrogenation and the role of catalysts. Many complex metal hydrides have high hydrogen gravimetric storage capacities and some of them are commercially available. Some complex hydride systems, such as Mg 2 FeH 6 and Al(BH 4 ) 3 , have an extremely high volumetric hydrogen density of up to 150 kg m À3 . Compared to liquid hydrogen with a volumetric density of 70 kg m À3 , the amount of hydrogen in such metal hydrides is much higher. This makes complex transition metal hydrides interesting as potential storage materials.Handbook of Hydrogen Storage. Edited by Michael Hirscher

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Catalytic effect of Zr and Hf on hydrogen desorption/absorption of NaAlH4 and LiAlH4

Cited by 63 publications

References 20 publications

NiFe₂O₄ Nanoparticles Catalytic Effects of Improving LiAlH₄ Dehydrogenation Properties

NiFe₂O₄ Nanoparticles Catalytic Effects of Improving LiAlH₄ Dehydrogenation Properties

A Revisit to the Hydrogen Desorption/Absorption Behaviors of LiAlH4/LiBH4: Effects of Catalysts

Complex Hydrides

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Catalytic effect of Zr and Hf on hydrogen desorption/absorption of NaAlH4 and LiAlH4

Cited by 63 publications

References 20 publications

NiFe2O4 Nanoparticles Catalytic Effects of Improving LiAlH4 Dehydrogenation Properties

NiFe2O4 Nanoparticles Catalytic Effects of Improving LiAlH4 Dehydrogenation Properties

A Revisit to the Hydrogen Desorption/Absorption Behaviors of LiAlH4/LiBH4: Effects of Catalysts

Complex Hydrides

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NiFe₂O₄ Nanoparticles Catalytic Effects of Improving LiAlH₄ Dehydrogenation Properties

NiFe₂O₄ Nanoparticles Catalytic Effects of Improving LiAlH₄ Dehydrogenation Properties