Soo-Sun Lee

Life Cycle Assessment for Proton Conducting Ceramics Synthesized by the Sol-Gel Process

In this report, the environmental aspects of producing proton conducting ceramics are investigated by means of the environmental Life Cycle Assessment (LCA) method. The proton conducting ceramics BaZr0.8Y0.2O3-δ (BZY), BaCe0.9Y0.1O2.95 (BCY10), and Sr(Ce0.9Zr0.1)0.95Yb0.05O3-δ (SCZY) were prepared by the sol-gel process. Their material requirements and environmental emissions were inventoried, and their energy requirements were determined, based on actual production data. This latter point makes the present LCA especially worthy of attention as a preliminary indication of future environmental impact. The analysis was performed according to the recommendations of ISO norms 14040 and obtained using the Gabi 6 software. The performance of the analyzed samples was also compared with each other. The LCA results for these proton conducting ceramics production processes indicated that the marine aquatic ecotoxicity potential (MAETP) made up the largest part, followed by fresh-water aquatic ecotoxicity potential (FAETP) and Human Toxicity Potential (HTP). The largest contribution was from energy consumption during annealing and calcinations steps.

Evaluation of Hydrogen Properties on Mg2NiHx-Graphene Composites by Mechanical Alloying

Mg hydride has a high hydrogen capacity (7.6%), at high temperature, and is a lightweight and low cost material, thus it a promising hydrogen storage material. However, its high operation temperature and very slow reaction kinetics are obstacles to practical application. In order to overcome these disadvantages of Mg hydride, graphene powder was added to it. The addition of graphene has been shown to reduce the operating temperature of dehydrogenation. Moreover, in this report the environmental aspects of MgHx-Graphene composites are investigated by means of the environmental life cycle assessment (LCA) method. MgHx-Graphene mixture was prepared by hydrogen induced mechanical alloy (HIMA). The synthesized powder was characterized by XRD(X-ray Diffraction). The hydro- genation behaviors were evaluated by using a Sieverts type automatic PCT apparatus. Such evaluation of Materials also conducted in the LCA. From the result of P-C-T(Pressure-Composition-Temperature) curves, the MgHx-3wt.% graphene composite was evaluated as having a 5.86wt.% maximum hydrogen storage capacity, at 523K. From absorption kinetic testing, the MgHx-7wt.%graphene composite was evaluated as having a maximum 6.94wt.%/ms hydrogen absorption rate, at 573K. Environment evaluation results for the MgHx-graphene composites and other materials indicated environmental impact from the electric power used and from the materials themselves.

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.

Evaluations of Hydrogen Properties of MgH x -Nb 2 O 5 Oxide Composite by Hydrogen Induced Mechanical Alloying

Abstract >> Mg and Mg-based alloys are regarded as strong candidate hydrogen storage materials since their hydrogen capacity exceeds that of known metal hydrides. One of the approaches to improve kinetic is additionof metal oxide. In this paper, we tried to improve the hydrogenation properties of Mg-based hydrogen storage composites. The effect of transition metal oxides, such as Nb 2 O 5 on the kinetics of the Magnesium hydrogen absorption kinetics was investigated. MgH x -5wt.% Nb 2 O 5 composites have been synthesized by hydrogen induced mechanical alloying. The powder fabricated was characterized by X-ray diffraction (XRD), Field Emission-ScanningElectron Microscopy (Fe-SEM), Energy Dispersive X-ray (EDX), BET and simultaneous Thermo Gravimetric Analysis / Differential Scanning Calorimetry (TG/DSC) analysis. The Absorption / desorption kinetics of MgH x -5wt.%Nb 2 O 5 (type I and II) are determined at 423, 473, 523, 573 and 623 K. Key words : Hydrogen storage alloy (수소저장합금), Mechanical alloying (기계적 합금화법), Hydride (수소화물),Kinetics(반응속도)