Kyeong-Il Kim

Fabrication and Evaluation of Hydorgenation Propeties on Mg 8 Ti 2- (10, 20 wt.%)Ni Composites

The hydrogen energy had recognized clean and high efficiency energy source. The research field of hydrogen energy was production, storage, application and transport. The commercial storage method was using high pressure tanks but it was not safety. However metal hydride was very safety due to high chemical stability. Mg and Mg alloys are attractive as hydrogen storage materials because of their lightweight and high absorption capacity (about 7.6 wt%). Their range of applications could be further extended if their hydrogenation properties and degradation behavior could be improved. The main emphasis of this study was to find an economical manufacturing method for Mg-Ti-Ni-H systems, and to investigate their hydrogenation properties. In order to examine their hydrogenation behavior, a Sievert`s type automatic pressure-compositionisotherm (PCI) apparatus was used and experiments were performed at 423, 473, 523, 573, 623 and 673 K. The results of the thermogravimetric analysis (TGA) revealed that the absorbed hydrogen contents were around 2.5wt.% for (Mg8Ti2)-10 wt.%Ni. With an increasing Ni content, the absorbed hydrogen content decreased to 1.7 wt%, whereas the dehydriding starting temperatures were lowered by some 70-100 K. The results of PCI on (Mg8Ti2)-20 wt.%Ni showed that its hydrogen capacity was around 5.5 wt% and its reversible capacity and plateau pressure were also excellent at 623 K and 673 K.

Pressure-composition-isotherm behaviors of MgHx-BCY composites by reactive mechanical alloying

The aim of the present paper is to report results on hydrogenation behavior of a new composite material, MgHx-BCY10. Rare earth element-doped ABO3 perovskite oxides have been studied for their possibility use in hydrogen storage. Especially, materials based on BaCeO3 are known not only for their proton conductivity in hydrogen but also for the fact that they have higher hydrogen solubility than that of other metal oxides. So, the admixing of perovskite-type oxide in storage materials has to consider the possibility of MgHx leading to sorption kinetics. And, these materials can be new materials for hydrogen storage. This research considers Pressure-Composition-Isothermal behavior according to perovskite-type oxide powder ratio and hydrogen pressure. The effects of added amount of BCY show a temperature of dehydrogenation that has decreased.From the results shown in the P-C-T curves, the MgHx-5wt% BCY composite was evaluated as having a 2.81 wt% maximum hydrogen storage capacity at 623 K. The absorption curves show that the MgHx-10wt% BCY was composite evaluated at a maximum 0.43wt%/s hydrogen absorption rate at 623 K. From the results of the hydrogenation behavior observed, the role of BCY as a catalyst in hydrogen absorption is confirmed.

Hydrogen permeability of nanocrystallined Al 2 O 3 /ITO membrane by hot press sintering (HPS)

Hydrogen permeation membrane was well known that Pd and Pd-alloys membranes have excellent properties for hydrogen separation. However, it has hydrogen embrittlement and high cost for practical applications. Therefore, most scientists have studied new materials instead of Pd and Pd-alloys. On the other hand, ceramic materials are great in resistance to acids and chemically stable under high operating temperature. Porous ceramic membrane process high hydrogen permeability and flux which are chemically and thermally stable. Therefore, they are attractive for applications in hydrogen production reactions. The Al2O3/ITO composite membrane was evaluated high hydrogen permeability and flux.

Pressure?composition isotherm behavior of an Mg?YSZ composite synthesized by hydrogen-induced mechanical alloying

The most attractive way to store hydrogen safely and economically is by storing it in metal hydrides. In particular, magnesium has attracted much interest since its hydrogen storage capacity exceeds that of known metal hydrides. Mg and Mg-based materials are lightweight and low cost, with high hydrogen storage capacity (7.6 wt%). However, commercial applications of Mg hydrides are currently hindered by their high absorption/desorption temperature and very slow reaction kinetics. One of the ways to improve the kinetics is by the addition of transition metal oxide. In this study, we have tried to improve the hydrogen absorption properties of Mg. The effect of transition oxides, such as YSZ (Y2O3-stabilized ZrO2), on the kinetics of the Mg hydrogen absorption reaction was investigated. MgHx–YSZ composites were synthesized by hydrogen-induced mechanical alloying. The powder synthesized was characterized by XRD, SEM, EDS and simultaneous TG/DSC analysis. The hydrogenation behaviors were evaluated using a Sieverts type automatic PCT apparatus. The absorption kinetics of MgHx with 5 wt% YSZ composites were determined at 423, 473, 523, 573 and 623 K.