Papers by Author: Mie Won Jung

Abstract: In order to enhance the hydrogen permeation, Silicon carbide (SiC) was prepared with CeO₂-NiO mixed oxides via sol-gel process and the SiC membranes with various contents of χ wt% mixed oxides (χ = 20, 40, 60 and 80) were fabricated by hot-press sintering (HPS) at 1173 K under vacuum condition. The effect of the CeO₂-NiO mixed oxides was studied in terms of properties on hydrogen permeation. All the membranes were characterized by XRD, FE-SEM and BET instrument. The hydrogen permeation test was carried out at various temperatures under 0.1 MPa. Hydrogen permeation flux of the 80 wt% CeO₂-NiO/SiC membrane, which has the highest value, was obtained at 2.92×10^-6 mol/m²sPa, 323 K. The reaction enthalpy (ΔH°) was calculated as - 4.95 J/mol by Arrhenius’s plot.

Abstract: NiO-doped Al₂O₃ was synthesized with 20 wt% of nickel nitrate using the sol-gel process. P123 as an organic additive added to increase surface area of powder. The phase transformation, thermal evolution and surface morphology of the powder were characterized by XRD, TG-DTA and FE-SEM. The 20 wt% NiO-doped Al₂O₃ /10 wt% Ni composite membrane was prepared by hot press sintering (HPS) following with a mechanical alloying process. Hydrogen permeation flux for 20 wt% NiO-doped Al₂O₃ /10 wt% Ni membrane was obtained as 0.1 mol/m² s at 673K.

Abstract: Hydrogen energy had recognized clean systems and high energy carrier. Mg and Mg-based materials have been lightweight and low cost materials which had been 7.6wt.% hydrogen capacity. However, Mg and Mg-alloys were currently hinder by its high absorption/desorption temperature, and very slow reaction kinetics. Therefore, one of the most methods to improve kinetics focused on addition transition metal oxide. Addition to transition metal oxide in MgH_x powder produce MgH_x-metal oxide composition by mechanical alloy and it analyze XRD, EDS, TG/DSC, SEM, and PCI. This report considers kinetics by transition metal oxide rate and hydrogen pressure. In this research, we can see behavior of hydriding/dehydriding profiles by addition catalyst (transition metal oxide). MgH_x-5wt.%Fe₂O₃ composite was measured most high hydrogen capacity and fast kinetics.

Abstract: The Al₂O₃-CuO-ZnO (ACZ) was synthesized from sol-gel process with aluminum isopropoxide, copper (II) nitrate hemi pentahydrate, Zn (II) nitrate hexahydrate and primary distilled water. The ACZ synthesized powders were analyzed by TG/DTA, XRD, BET and FE-SEM. The ACZ-Co composites membrane was prepared by hot press sintering (HPS). Hydrogen permeability was characterized by Sievert's type hydrogen permeation membrane equipment. The hydrogen permeation rate was measured 0.0496 mol m^-2 s^-1 at room temperature under 2 bar of H2 atmosphere.

Abstract: Hydrogen has attracted clean energy media as a high-quality and renewable energy source in recent years. On the one hand, a ceramic catalyst and/or catalyst support such as Al2O3 has often been a preferred choice due to their specific properties such as thermal stability and high surface area. Al2O3-CuO-ZnO was synthesized by using the sol-gel process with aluminum isopropoxide and primary distilled water as the precursor and solvent. In this synthesized process, metal oxides caused to precursors such as copper and zinc nitrate were added. To prepare membranes, cobalt metal powder was used to increase the strength and durability. The Al2O3-CuO-ZnO/Co composite membranes were produced using hot press sintering for consolidation of powders following reactively mechanical alloying process. The characterizations of membrane were measured XRD, FE-SEM and EDS. Hydrogen permeation evaluations were examined at a room temperature to 773 K under increasing pressure. Hydrogen permeation rate was obtained with 0.18 mol m-2 s-1 at 773 K result from complex diffusion mechanism such as Sievert’s type, Knudsen diffusion and/or molecular sieving.

Abstract: The purpose of this work was hydrogen permeation of ceramic or metal/ceramic membrane using γ-Al2O3 by synthesizing. The γ-Al2O3 was synthesized by using the sol-gel process with aluminum isopropoxide and primary distilled water as the precursor and solvent. The γ-Al2O3-based membranes were prepared using HPS. The phase transformation, thermal evolution, surface are and morphology of γ-Al2O3 and γ-Al2O3-based membranes were characterized by XRD, TG-DTA, BET and FE-SEM. The hydrogen permeation of γ-Al2O3-based membranes was examined at room temperature comparing with other paper using nickel composited membrane on alumina ceramic support.