scholarly journals Influence of Synthesis Gas Components on Hydrogen Storage Properties of Sodium Aluminum Hexahydride

Hydrogen ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 147-159
Author(s):  
Tai Sun ◽  
Kateryna Peinecke ◽  
Robert Urbanczyk ◽  
Michael Felderhoff

A systematic study of different ratios of CO, CO2, N2 gas components on the hydrogen storage properties of the Na3AlH6 complex hydride with 4 mol% TiCl3, 8 mol% aluminum and 8 mol% activated carbon is presented in this paper. The different concentrations of CO and CO2 in H2 and CO, CO2, N2 in H2 mixture were investigated. Both CO and CO2 gas react with the complex hydride forming Al oxy-compounds, NaOH and Na2CO3 that consequently cause serious decline in hydrogen storage capacity. These reactions lead to irreversible damage of complex hydride under the current experimental condition. Thus, after 10 cycles with 0.1 vol % CO + 99.9 vol %H2 and 1 vol % CO + 99 vol %H2, the dehydrogenation storage capacity of the composite material decreased by 17.2% and 57.3%, respectively. In the case of investigation of 10 cycles with 1 vol % CO2 + 99 vol % H2 gas mixture, the capacity degradation was 53.5%. After 2 cycles with 10 vol % CO +90 vol % H2, full degradation was observed, whereas after 6 cycles with 10 vol % CO2 + 90 vol % H2, degradation of 86.8% was measured. While testing with the gas mixture of 1.5 vol % CO + 10 vol % CO2 + 27 vol % H2 + 61.5 vol % N2, the degradation of 94% after 6 cycles was shown. According to these results, it must be concluded that complex aluminum hydrides cannot be used for the absorption of hydrogen from syngas mixtures without thorough purification.

2021 ◽  
Vol 77 (5) ◽  
pp. 227-234
Author(s):  
Volodymyr Pavlyuk ◽  
Wojciech Ciesielski ◽  
Damian Kulawik ◽  
Nazar Pavlyuk ◽  
Grygoriy Dmytriv

The multicomponent alumosilicide Li12Mg3Si3Al (cubic, space group I\overline{4}3d, cI76) belongs to the structural family based on the Cu15Si4 type. The Li atoms are ordered and occupy the site with symmetry 1 and the Mg atoms occupy the site with \overline{4}.. symmetry. The Si/Al statistical mixture occupies the site with .3. symmetry. The coordination polyhedra around the Li atoms are 13-vertex distorted pseudo-Frank–Kasper polyhedra. The environments of the Mg and Si/Al atoms are icosahedral. The hydrogen storage characteristics of Li12Mg3Si3Al were investigated. The reversible hydrogen storage capacity of the title compound is excellent and the gravimetric storage capacity of this new material, corresponding to 9.1 wt% H2, is higher compared to Li12Mg3Si4 (8.8 wt%). The enthalpy of hydrogen desorption is 86 kJ mol−1 and is lower compared to known lithium-based hydrides.


2021 ◽  
Vol 21 (8) ◽  
pp. 4353-4361
Author(s):  
Myoung Youp Song ◽  
Seong Ho Lee ◽  
Young Jun Kwak ◽  
Eunho Choi

TiCl3 was chosen as an additive to increase hydriding and dehydriding rates of Mg. In our previous works, we found that the optimum percentage of additives that improved the hydriding and dehydriding features of Mg was approximately ten. Specimens consisting of 90 wt% Mg and 10 wt% TiCl3 (named Mg–10TiCl3) were prepared by high-energy ball milling in hydrogen. The specimens’ hydriding and dehydriding properties were then studied. Mg–10TiCl3 had an effective hydrogenstorage capacity (the quantity of hydrogen absorbed in 60 min) of approximately 7.2 wt% at 593 K under 12 bar H2 at the second cycle. After high-energy ball milling in hydrogen, Mg–10TiCl3 contained Mg, β-MgH2, and small amounts of γ-MgH2 and TiH1.924. TiH1.924 remained undercomposed even after dehydriding at 623 K in a vacuum for 2 h. The hydriding and dehydriding properties of Mg–10TiCl3 were compared with those of other specimens such as Mg–10Fe2O3, Mg–10NbF5, and Mg–5Fe2O3–5Ni, for which the hydrogen-storage properties were previously reported.


Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1574
Author(s):  
Ruochen Shen ◽  
Chaohui Pu ◽  
Xiaoou Xu ◽  
Youpeng Xu ◽  
Zhilin Li ◽  
...  

The research aims to study the effect of adding mischmetal (Mm) to the TiFe0.86Mn0.07Co0.07 alloy on its hydrogen storage performance and cyclic stability. The results show that TiFe0.86Mn0.07Co0.07 + x% Mm (x = 0,4,6,8) alloys can be easily activated. The hydrogen absorption capacity of TiFe0.86Mn0.07Co0.07 + 4% Mm reaches 1.76 wt% (mass fraction) at 298 K. With the increase of Mm addition, the hydrogen storage capacity decreases slightly. Furthermore, after 40 absorption and desorption cycles in hydrogen containing 250 ppm O2, the alloy still has 36% of its initial hydrogen storage capacity, and the alloy can recover 93% of its hydrogen storage capacity through heat treatment.


2006 ◽  
Vol 971 ◽  
Author(s):  
Yasuhiro Munekata ◽  
Kota Washio ◽  
Takanori Suda ◽  
Naoyuki Hashimoto ◽  
Somei Ohnuki ◽  
...  

ABSTRACTOne of impotent materials issues of Ti-Cr-V based hydrogen storage alloys is to improve cyclic degradation of storage capacity, which has been assumed to be the effect of internal stress. We focused on the sub-micron structure of this material, which can be accumulated during cyclic use. We used 24Ti-36Cr-40V alloy for the specimens, after FZ melting. Powered samples were fabricated by mechanical grinding under Ar environment. Vacuum annealing was carried out for reducing residual stress and lattice defects. PCT properties were tested at 293 K under 4.5 MPa. XRD and TEM were carried out for important samples. In the first cycle, the annealing resulted in the increasing of storage capacity, but in the second cycle the improving was disappeared. Comparing microstructures with and without annealing, complex dislocation structures were observed after cyclic hydrogenation. It is notable that dislocation free structure was some time observed in the fine grains of less than 0.1 micron, which suggests the possibility of fine structure without defect accumulation.


2008 ◽  
Vol 1098 ◽  
Author(s):  
Young Joon Choi ◽  
Jun Lu ◽  
Hong Yong Sohn ◽  
Zak Fang

AbstractLithium based complex hydrides, including lithium aluminum hydrides and lithium borohydride (LiAlH4, Li3AlH6 and LiBH4), are among the most promising materials due to their high hydrogen contents. In the present work, we investigated the hydrogen storage properties of a new combined system of Li3AlH6-LiBH4. The samples were made with small amounts of catalyst under low energy milling conditions. Thermogravimetric analysis (TGA) of a Ti-doped Li3AlH6/2LiBH4 indicated that the degree of hydrogen release reached 7.3 wt. % by the time the sample reached 450iÆc under a heating rate of 2iÆC/min. This increased to 8.8 wt. % when the sample was held at 450iÆCfor additional 8 hours minutes under this condition. The dehydrogenation product was a mixture of LiH and AlB2. This product could be rehydrogenated up to 3.8 wt. % under 24.1 MPa hydrogen pressure and 450iÆC.


2010 ◽  
Vol 156-157 ◽  
pp. 1146-1150
Author(s):  
Zhi Qiang Lan ◽  
Shu Bo Li ◽  
Zhao Lu ◽  
Jin Guo

Mg76Ti12Ni12-xCrx(x=0,3,6,9) alloys were synthesized by mechanical alloying(MA) approach and hydrogen storage properties of the alloys were investigated by X-ray diffraction, thermal analysis and pressure-composition isotherm measurement. It is found that Ti2Ni phase and Mg2Ni phase exist as the main phases in Mg76Ti12Ni12-xCrx(x=0,3,6,9) alloys. The Mg76Ti12Ni12-xCrx(x=0,3,6,9) alloys exhibit the hydrogen storage capacity of 4.61,4.30,4.21 and 4.12wt%, and the decomposition enthalpies of the alloy hydrides are 928.4, 898.3, 831.2 and 851.4J/g H2, respectively. Mg76Ti12Ni6Cr6 alloy shows small hysteresis and fast hydrogen absorption rate. Proper Cr content can improve the performance of the Mg76Ti12Ni12-xCrx(x =0,3,6,9) alloys.


2001 ◽  
Vol 704 ◽  
Author(s):  
Jeremy Lawrence ◽  
Gu Xu

AbstractSafe, lightweight, and cost-effective materials are required to practically store hydrogen for use in portable fuel cell applications. Compressed hydrogen and on-board hydrocarbon reforming present certain advantages, but their limitations must ultimately render them insufficient. Storage in hydrides and adsorption systems show promise in models and experimentation, but a practical medium remains unavailable. To study hydrogen storage properties a new volumetric testing apparatus was designed and constructed. Adsorption conditions are evaluated up to pressures exceeding 250 bar and a broad range of temperatures. RF sputtering was used to introduce metals to carbon nanotubes with the aim to enhance hydrogen storage. Here we show a significant improvement in the gravimetric storage density over that of as-prepared single-wall nanotube samples that may be due to the unique interface introduced.


2021 ◽  
Vol 422 ◽  
pp. 130101
Author(s):  
Xiong Lu ◽  
Liuting Zhang ◽  
Haijie Yu ◽  
Zhiyu Lu ◽  
Jiahuan He ◽  
...  

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