Composite Materials based on Light Elements for Hydrogen Storage

Abstract

In this paper, we review our recent experimental results on hydrogen storage properties of light elements Li, C and Mg based nanocomposite materials. The results are summarized as follows: In the Li-N-H system, such as the ball milled 1:1 mixture of Li amide and Li hydride containing a small amount of TiCl 3 (1 mol%), a large amount of hydrogen ($6 mass%) is absorbed and desorbed in the temperature range from 150 to 250 C with good reversibility and high reaction rate. Furthermore, in the ball milled mixture of 3Mg(NH 2 ) 2 and 8LiH, $7 mass% of hydrogen is reversibly stored in the temperature from 140 to 220 C, indicating one of the suitable hydrogen storage materials. In graphite containing a small amount of nanometer sized Fe ($2 at.%), a large amount of hydrogen ($7 mass%) is chemisorbed by ball milling for 80 h under less than 1 MPa of H 2 -gas pressure. However, the chemisorbed hydrogen capacity decreases with increase in the milling pressure for the 80 h ball milled graphite (down to $4:1 mass% at 6 MPa), while the physisorbed hydrogen capacity in graphite increases with increase in the milling pressure, reaching up to 0:5$1:0 mass% at 6 MPa. Unfortunately, the desorption temperature of chemisorbed hydrogen is higher than 300 C. Therefore, some break-through is necessary for the development of carbon-based materials as one of the hydrogen storage systems. On the other hand, some nano-composite Mg catalyzed by Ni nano-particle or Nb oxide reveals superior reversible hydrogen storage properties: $6:5 mass% of hydrogen is reversibly stored in the temperature range from 150 to 250 C. Especially, the Nb metals uniformly dispersed in nanometer scale on the surface of MgH 2 , which was produced by reduction of Nb 2 O 5 , is the best catalyst we have studied so far. Thus, it seems that some Mg nano-composites catalyzed by nano-particles of d-electron transition metals is acceptable for practical applications.

Guidelines for Developing Amide-Based Hydrogen Storage Materials

“…For this purpose, the hydriding and dehydriding properties of various related systems, e.g. Li-Na-N-H, 6) Li-Mg-N-H, [7][8][9][10][11][12] Li-Ca-N-H, 11) Na-Mg-N-H 13) and Ca-N-H, 5,11,14) have been extensively investigated. Another important research direction is to clarify the method for preventing ammonia release.…”

Effects of SWNT and Metallic Catalyst on Hydrogen Absorption/Desorption Performance of MgH2.

“…However, the practical application of magnesium as a hydrogen storage medium is greatly hindered by its high desorption temperature and slow absorption/desorption kinetics. Various additives with potential catalytic effect for H 2 absorption/desorption in Mg, including transition metals, [9][10][11][12][13][14] H-storage alloys, 15 metal oxides, [16][17][18] metal hydrides, 19 and graphite, [20][21][22][23][24] have been utilized to prepare Mg-based composites by mechanical milling.…”

Efektifitas Penggunaan Silika dari Abu Sekam Padi sebagai Katalis pada Material Penyimpan Hidrogen Sistem MgH2

“…Beberapa upaya telah dilakukan secara intensif untuk memperbaiki sifat-sifat Mg. Misalnya mereduksi ukuran butir material hingga skala nanokristal dengan teknik mechanical alloying, membentuk material komposit, demikian juga upaya menambahkan katalis tertentu, seperti logam dan oksida logam [3][4][5]. Selanjutnya, Norton dkk [6] Proses selanjutnya adalah pencampuran MgH2 dengan SiO2 (1 wt%, 3 wt% dan 5 wt%) hasil ekstraksi menggunakan ball milling tipe planetary (Fritsch, P6) dengan ball to powder ratio (BPR) adalah 10:1 pada kecepatan 400 rpm selama 5 jam.…”