• Journal of Hydrogen and New Energy
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• v.23 no.4
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• pp.346-352
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• 2012

The properties of methane oxidation were studied in this research over transition metal containing $CeO_2$ (TM/$CeO_2$, TM=Ni, Co, Cu, Fe) with TM content of 5 wt. % at atmospheric pressure. The characteristics of catalysts were investigated by various characterization techniques, including XRD, GC, SEM and EPMA analyses. The catalytic tests were carried out in a fixed Rmix ratio of 1.5 ($CH_4/O_2$) in a fixed-bed reactor operating isothermally at atmospheric pressure. Only the Ni/$CeO_2$ catalysts showed syngas production above $400^{\circ}C$ via typical partial oxidation reaction whereas other catalysts induced complete oxidation resulting in the production of $CO_2$ and $H_2O$ in whole reaction temperature range. From the quantitative analysis on carbon deposition after catalytic tests, Cu/$CeO_2$ was found to show the highest resistance on carbon deposition. Therefore Cu can be proposed as an efficient catalyst element which can be combined with a conventional Ni-based SOFC anode to enhance the carbon tolerance.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.379.2-379.2
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• 2016

The Ni oxide/PVP nanofibers were synthesized by sol-gel and electrospinning technique. The obtained Ni oxide/PVP (polyvinylpyrrolidone) nanofibers were calcined to remove the PVP compound at 873 and 1173 K. The Ni oxide/PVP nanofibers were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The SEM images showed that the mat form was prepared by calcination of Ni oxide/PVP nanofibers at 873 K. And the crystal structure of Ni oxide at 1173 K was also confirmed by SEM images. XRD results shows the crystallinity of metallic Ni and NiO. TEM images also verified the crystal phase of Ni and Ni oxide. XP spectra revealed that the oxidation state of Ni to conclude the chemical composition of Cu oxide nanofibers.

• Korean Journal of Materials Research
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• v.14 no.11
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• pp.813-820
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• 2004

The electrolytic reduction of spent oxide fuel involves the liberation of oxygen in a molten LiCl electrolyte, which is a chemically aggressive environment that is very corrosive for typical structural materials. So, it is essential to choose the optimum material for the process equipment handling molten salt. In this study, corrosion behavior of Haynes 263, 75, and Inconel X-750, 718 in molten salt of $LiCl-Li_{2}O$ under oxidation atmosphere was investigated at $650^{\circ}C\;for\;72\sim360$ hours. At $3\;wt\%\;of\;Li_{2}O$, Haynes 263 alloy showed the highest corrosion resistance among the examined alloys, and up to $8\;wt\%\;of\;Li_{2}O$, Haynes 75 exhibited the highest corrosion resistance. Corrosion products were formed $Li(Ni,Co)O_2,\;LiNiO_2\;and\;LiTiO_2\;and\;Cr_{2}O_3$ on Haynes 263, $Cr_{2}O_3,\;NiFe_{2}O_4,\;LiNiO_2,\;Li_{2}NiFe_{2}O_4,\;Li_{2}Ni_{8}O_10$ and Ni on Haynes 75, $Cr_{2}O_3,\;(Al,Nb,Ti)O_2,\;NiFe_{2}O_4,\;and\;Li_{2}NiFe_{2}O_4$ on Inconel X-750 and $Cr_{2}O_3,\;NiFe_{2}O_4\;and\;CrNbO_4$ on Inconel 718, respectively. Haynes 263 showed local corrosion behavior and Haynes 75, Inconel X-750, 718 showed uniform corrosion behavior.

• Journal of Hydrogen and New Energy
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• v.21 no.6
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• pp.526-532
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• 2010

The anode may inevitably undergo a number of reduction.oxidation (redox) cycles during solid oxide fuel cells (SOFCs) operation. The re-oxidation of Ni to NiO causes significant mechanical stress to be developed across the anode, which may destroy the integrity of the whole cell. In this study, the redox behavior of Ni-YSZ composite was examined at $800^{\circ}C$ using various characterization techniques.

• Journal of Hydrogen and New Energy
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• v.3 no.2
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• pp.45-54
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• 1992

An applicability microencapsulation, using electroless copper plating, of hydrogen storage alloy powder as an anode material for nickel-hydrogen secondary batteries was investigated. Alloys employed were $LaNi_{4.7}Al_{0.3}$ and $MmNi_{4.5}Al_{0.5}$(Mm=mischmetal) which have an appropriate equilibrium pressure and capacity. The microencapsulation of the alloy powder was found to accelerate initial activation of electrodes and to increase capacity which is about 285mAh/g for $LaNi_{4.7}Al_{0.3}$. In addition, other charge and discharge characteristics, such as polarization and flatness of charge and discharge potential, were improved due to the role of copper layer as a microcurrent collector and an oxidation barrier of the alloy powder. $MmNi_{4.5}Al_{0.5}$ alloy showed lower capacity than $LaNi_{4.7}Al_{0.3}$ because of higher equilibrium pressure. Cyclic characteristics of both alloys were somewhat poor because of mainly shedding and partial oxidation of alloy powder during the cycling. However, it was considered that the microencapsulation method is effective to improve the performances of the hydrogen storage alloy electrodes.

• Journal of the Korean Ceramic Society
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• v.44 no.11
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• pp.639-644
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• 2007

Spinel pigments, developing black color in high temperature glazes at oxidation or reduction atmosphere, without CoO because of its high price were synthesized by solid solution method. Ten mixed compositions consisted of NiO, MnO, $Fe_2O_3 and $Mn_2O_3$ were fired at $1250^{\circ}C$ for 1h. The resulting pigments were characterized by using XRD, FT-IR, SEM and UV-vis spectrometer. Structure of the pigments are spinel and particles' shape are spherical or cubic. Glazed tiles containing 5 wt% pigments were fired at $1260^{\circ}C$ and $1240^{\circ}C$ in reduction atmosphere. Color in glazes were analyzed by UV-vis spectrometer. Colors of NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.4875{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0125 mole% and NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.3875{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.1125 mole% in lime glaze showed black in oxidation, in reduction NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.4875{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0125 mole% and NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.4375{\cdot}Cr_2O_3$ $0.55{\cdot}Mn_2O_3$ 0.0125 mole% showed black. In case of lime-barium glaze, NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.3875{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.1125 mole%, NiO 0.975 MnO $0.075{\cdot}Fe_2O_3$ $0.4375{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0625 mole% and NiO 0.925 MnO $0.075{\cdot}Fe_2O_3$ $0.4375{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0625 mole% showed black color in oxidation and NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.3875{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.1125 mole%, NiO 0.925 MnO $0.075{\cdot}Fe_2O_3$ $0.4375{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0625 mole% and NiO 0.725 MnO $0.275{\cdot}Fe_2O_3$ $0.4375{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0625 mole% showed black one in reduction.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.4
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• pp.431-439
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• 2006

Catalytic oxidation of benzene, toluene and xylene (BTX) using regenerated metal oxide catalysts (ZnO-CuO, NiO, $Fe_2O_3$, ZnO, CrO) were investigated in a fixed bed flow reactor to evaluate their feasibility for the purpose of removing volatile organic compounds (VOCs). Four kinds of pre-treatment methods such as gas (air and hydrogen), acid aqueous solution, alkali aqueous solution and cleaning agent were used to find out the optimal regeneration conditions. The physico-chemical properties of the used and regenerated catalysts were characterized by BET and TPR (Temperature Programmed Reduction). The used catalysts showed high conversion ratio and the catalytic ability of toluene oxidation was in the order of ZnO-CuO>$Fe_2O_3$>NiO>ZnO>CrO. We found that the acid aqueous pre-treatment (0.1 N HNO$_3$) was the best way to enhance the catalytic activity of $Fe_2O_3$. In addition, air and hydrogen gas treatment were optimal for NiO and ZnO-CuO catalysts, respectively. Furthermore, the decomposition of BTX depends on the type of a catalyst and a gas molecule.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.11
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• pp.934-940
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• 2001

Magnetic properties were investigated for Si/SiO$_2$/NiFe(300 )/A1$_2$O$_3$(t)/Co(200 ) junction related with the parameters of $Al_2$O$_3$. Insulating $Al_2$O$_3$ layer was formed by depositing a 5~40 thick Al layer, followed by a 90~120s RF plasma oxidation in an $O_2$ atmosphere. Magnetoresistance was not observed for tunnel junction with 5~10 thick Al layer, but magnetoresistance was observed large for tunnel junction with 15~40 thick Al layer. Oxidation time did not largely influence magnetoresistance. Tunnel magnetoresistance effect depended on magnetization behavior of two ferromagnetic layers. Tunneling junction was confirmed through nonlinear I-V curve. In this work, tunneling magnetoresistance(TMR) up to 30 % was observed. This apparent TMR is an artifact of the nonuniform current flow over the junction in the cross geometry of the electrodes.

• Korean Journal of Materials Research
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• v.23 no.2
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• pp.128-134
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• 2013

A study on the corrosion behavior of Inconel alloys and Incoloy 800H in molten salt of LiCl-$Li_2O$ was investigated at $650^{\circ}C$ for 24-312 hours in an oxidation atmosphere. The order of the corrosion rate was Inconel 600 < Inconel 601 < Incoloy 800H < Inconel 690. Inconel 600 showed the best performance suggesting that the content of Fe, Cr and Ni are the important factor for corrosion resistance in hot molten salt oxidation conditions. The corrosion products of Inconel 600 and Inconel 601 were $Cr_2O_3$ and $NiFe_2O_4$, In case of Inconel 690, a single layer of $Cr_2O_3$ was formed in the early stage of corrosion and an outer layer of $NiFe_2O_4$ and inner layer of $Cr_2O_3$ were formed with an increase of corrosion time. In the case of Incoloy 800H, $Cr_2O_3$ and $FeCr_2O_4$ were observed. Most of the outer scale of the alloys was observed to be spalled from the results of the SEM analysis and the unspalled scale which adhered to the substrate was composed of three layers. The outer layer, the middle one, and the inner one were Fe, Cr, and Ni-rich, respectively. Inconel 600 showed localized corrosion behavior and Inconel 601, 690 and Incoloy 800H showed uniform corrosion behavior. Ni improves the corrosion resistance and too much Cr and/or Fe content deteriorates the corrosion resistance.

• Applied Chemistry for Engineering
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• v.21 no.1
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• pp.63-70
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• 2010

Transition metal based spent catalysts (Ni-Mo and Co-Mo), which were scrapped from the petrochemical industry, were reused for the removal processes of volatile organic compounds (VOCs). Especially the optimum regeneration procedures were determined using the removal efficiency of VOCs. In this work, the spent Ni-Mo and spent Co-Mo catalysts were pretreated with different physic-chemical treatment procedure: 1) acid aqueous solution, 2) alkali solution, 3) chemical agent and 4) steam. The various characterization methods of spent and its regenerated catalysts were performed using nitrogen adsorption, X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with an energy dispersive spectrometry (EDS). It was found that all spent catalysts were found to be potentially applicable catalysts for catalytic oxidation of benzene. The experimental results also indicated that among the employed physico-chemical pretreatment methods, the oxalic acid aqueous (0.1 N, $C_2H_2O_4$) pretreatment appeared to be the most efficient in increasing the catalytic activity, although the catalytic activity of spent Ni-Mo and spent Co-Mo catalysts in the oxidation of benzene were greatly dependent on the pretreatment conditions. The pretreated spent catalysts at optimum condition could be also applied for removing other aromatic compounds (Toluene/Xylene).