• Korean Chemical Engineering Research
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• v.46 no.5
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• pp.868-874
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• 2008

The Ni based adsorbent was prepared by co-precipitation method and its performance for removing carbon monoxide was investigated. Here, silica, aluminium silicate and ${\gamma}$-alumina were used for carriers of catalyst. $Ni(NO_3)_2{\cdot}6H_2O$ and $Ni(CH_3COO)_2{\cdot}4H_2O$ were utilized for Ni precursors. Precipitants were urea and citric acid. After precipitation of Ni salt on the carrier and following reduction using $H_2$ gas, adsorbent was prepared and its performance was analyzed based on EDS, TPR and XRD experiments. In accordance with change of precipitation agents, Ni salts on carrier, carriers and reduction condition. Adsorbent performance for removing carbon monoxide was investigated. The adsorbent with 54.8 wt% Ni prepared using urea precipitant under reduction condition at $500^{\circ}C$ for 3 h exhibited the best CO removal performance.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.1
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• pp.26-34
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• 2010

The electrocatalystic prperties of Pt-Co and Pt-Ni with heteropolyacids (HPAs) entrapped in covalently cross-linked sulfonated poly(ether ether ketone) (CL-SPEEK)/HPA membranes were investigated for water electrolysis. The HP As, including molybdophosphoric acid (MoPA), and tungstophosphoric acid (TPA) were both used as membrane additives and electrocatalysts. The membrane electrode assembly (MEA) was prepared by a nonequilibrium impregnation-reduction (I-R) method. $Pt(NH_3)_4Cl_2$, $NiCl_2$ and $CoCl_2$ as electrocatalytic materials and $NaBH_4$ as reducing agent were used. I order to enhance electrocatalytic activity, the catalyst layer prepared above was electrodeposited (Dep) with HP A. Surface morphologies and physico-chemical properties of MEA were investigated by means of SEM, EDX and XRD. The electrocatalytic properties of composite membranes such as the cell voltage and coulombic charge in CV were in the order of magnitude: CL-SPEEK/MoPA40 (wt%) > CL-SPEEK/TPA30 > Nafion117. In the optimum cell applications for water electrolysis, the cell voltage of Pt/CL-SPEEK-MoPA40/Pt-Co (Dep-MoPA) and Pt/CL-SPEEK-TPA30/Pt-Co (Dep-TPA) was 1.75 Vat $80^{\circ}C$ and $1\;A/cm^2$ and voltage efficiency was 87.1%. Also, the observed activity of Pt-Co (84:16 atomic ratio by EDX) is a little higher than that of Pt-Ni (86: 14). The current density peak of electrodeposited electrodes were better a little than those of unactivated electrodes based on the same membranes.

• Journal of Soil and Groundwater Environment
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• v.20 no.4
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• pp.1-7
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• 2015

The degradation of off-flavors which is 2-Methylisoborneol (2-MIB) and geosmin by means of ultrasound (US) and pulsed ultraviolet (PUV) irradiation and its combination with catalyst (wire mesh, wire mesh coated TiO₂, and TiO₂) and additive (H₂O₂) were investigated via water system. A combination treatment of TiO₂ and H₂O₂ heterogeneity with US (24 kHz) and PUV (6000 W) has shown improved results in destroying 2-MIB and geosmin, which may be attributed to chain reactions by the enhanced formation of hydroxyl radicals (·OH) through H₂O₂ dissociation and reactive oxide ions of TiO₂ addition. Rapid degradation of off-flavors occurred within 2 min under PUV process with H₂O₂ 100 mg/L (81.5% for 2- MIB; 79.3% for geosmin) and TiO₂ 100 mg/L (83.7% for 2-MIB; 79.8% for geosmin), while compared with H2O2 100 mg/L (58.4% for 2-MIB; 58.0% for geosmin) and TiO₂ 100 mg/L (59.2% for 2-MIB; 38.5% for geosmin) within 5 min under US process. Surprisingly, the emphasis was given on the comparison with the same injected energies between PUV and US on degradation efficiency. Based on the injected energy comparison, the US provided better degradation performance under equal input power of 200 kJ with H₂O₂ 100 mg/L, while compared with H₂O₂ 100 mg/L under PUV process. Our findings suggest that US can be more effective compared to PUV for the degradation of off-flavors in aspect of energy consumptions.

• Korean Chemical Engineering Research
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• v.61 no.3
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• pp.362-367
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• 2023

Recently, research and development of proton exchange membrane fuel cells (PEMFC) membranes are progressing in the direction of thinning to reduce prices and improve performance. Demand for hydrogen-powered vehicles for commercial vehicles is also increasing, and their durability should be five times greater than those for passenger vehicles. Despite the thinning of the membranes, the durability of the membranes must be increased five times, so the improvement of the durability of the membranes has become more important. Since the acceleration durability evaluation time also needs to be shortened, the protocol using oxygen instead of air in the existing protocol was applied to a 10 ㎛ thin membrane to evaluate durability. The accelerated durability test (Open circuit voltage holding) was terminated at 720 hours. If the air-based department of energy (DOE) protocol was used, a lifespan of 450,000 km of driving hours would be expected, with a durability of about 1,500 hours. During the chemical durability evaluation, the active area of the electrode decreased by 51%, suggesting that catalyst degradation had an effect on membrane durability. Reducing the catalyst degradation rate is expected to increase membrane durability.

• Journal of Information Display
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• v.2 no.3
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• pp.78-85
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• 2001

The growth of carbon nanotubes(CNTs) in anodic aluminum oxide(AAO) template and their application to a field emitter are described. AAO templates were fabricated by anodizing bulk aluminum and sputtered thin Al film on Nb-coated Si wafers. After Co catalyst had been electrochemically deposited into the bottom of the pores in AAO template, CNTs were grown by pyrolyzing $C_2H_2$. Depending on the reaction conditions, CNTs grew up to or over the top of the pores in AAO template with different structures. The morphology and structure of CNTs were observed with a scanning electron microscope and a transmission electron microscope. The diameter of CNTs strongly depended on the size of the pores in AAO template and the growing conditions. The electron field emission measurement of the samples resulted in the turn-on field of 1.9-2.2 $V/{\mu}m$ and the field enhancement factor of 2450-5200. The observation of high field enhancement factors is explained in terms of low field screening effect.

• Journal of the Korean Chemical Society
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• v.54 no.1
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• pp.23-26
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• 2010

A Schiff base ligand (Z)-N-((Z)-2-(sec-butylimino)-1,2-diphenylethylidene)butan-2-amine was synthesized by condensation of benzil with sec-butyl amine. Complexation of the ligand was carried out with first row transition elements, manganese(II) and nickel(II). Ligand and complexes were characterized by FTIR, elemental analysis and thermogravimetric analysis in solid state and by NMR ($^1H,\;^{13}C$) in solution form. Both the complexes demonstrate good catalytic activity for butadiene oligomerization under mild conditions with methylaluminoxane (MAO) as co-catalyst.

• Journal of the Korean Electrochemical Society
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• v.13 no.4
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• pp.240-245
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• 2010

This work explored the catalytic effect of Pt in multi-wall carbon nanotube and poly-pyrrole conductive polymer electrocatalysts (Pt/PPy/MWCNT). A home-made Pt/PPy/MWCNT catalyst was first evaluated by comparing its electrochemical active surface area (ESA) with E-Tek commercial catalysts by cyclic voltammetry in $H_2SO_4$ solution. Then, the methanol oxidation currents of Pt/PPy/MWCNT and the hydrogen peaks in $H_2SO_4$ solution were serially measured with microporous electrode. This provided the current density of methanol oxidation based on the ESA, allowing a quantitative comparison of catalytic activity. The current densities were also measured for Pt/C catalysts of E-Tek and Tanaka Precious Metal Co. The current densities for the different catalysts were similar, implying that catalytic activity depended directly on the ESA rather than charge transfer or electronic conductivity.

• Bulletin of the Korean Chemical Society
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• v.33 no.10
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• pp.3177-3183
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• 2012

The carbon nanofibers (CNFs) used in this study were synthesized with an iron catalyst and ethylene as a carbon source. A concentration of 30 wt % iron(III) acetylacetonate was dissolved in resol type phenol resin and polyurethane foam was put into the solution. The sample was calendered after being cured at $80^{\circ}C$ in air for 24 h. Stabilization and carbonization of the resol type phenol resin and reduction of the $Fe^{3+}$ were completed in a high-temperature furnace by the following steps: 1) heating to $600^{\circ}C$ at a rate of $10^{\circ}C/min$ with a mixture of $H_2/N_2$ for 4 h to reduce the $Fe^{3+}$ to Fe; 2) heating to $1000^{\circ}C$ in $N_2$ at a rate $10^{\circ}C/min$ for 30 minutes for pyrolysis; 3) synthesizing CNFs in a mixture of 20.1% ethylene and $H_2/N_2$ at $700^{\circ}C$ for 2 h using a CVD process. Finally, the structural characterization of the CNFs was performed by scanning electron microscopy and a synthesis analysis was carried out using energy dispersive spectroscopy and X-ray photoelectron spectroscopy. Specific surface area analysis of the CNFs was also performed by $N_2$-sorption.

• Proceedings of the KAIS Fall Conference
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• 2006.05a
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• pp.561-564
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• 2006

Fe, Co, Zn, Cu, Pt 등의 전이금속과 ZSM-5 2종($SiO_2/Al_2O_3$ 몰비: 23, 50)과 ${\gamma}-alumina$를 담체로 사용하여 촉매를 합성하였다. 합성방법은 CVD(화학기상증착법) 과 Dry Impregnation (건식함침법)방법이었다. CVD 방법으로 얻은 Fe/ZSM-5는 지지체로 사용된 ZSM-5의 $SiO_2/Al_2O_3$의 몰 비가 작을수록, 즉 산점의 수가 많을수록 Fe 담지 량이 증가하는 것으로 보인다. 등온 환원 온도 $400^{\circ}C$에서 수소 환원 양이 최대로 나타나며, 이는 보고되는 $400^{\circ}C$에서의 최대 NOx 제거 반응 속도와 비례하는 것으로 나타난다.

• Korean Journal of Materials Research
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• v.11 no.9
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• pp.727-732
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• 2001

The cure kinetics of diglycidyl ether of bisphenol A (DGEBA)/4,4'- methylene dianiline (MDA) system with synthesized phenyl glycidyl ether-dimethylurea (PGE-DMU) was studied by Kissinger and Ozawa equations with DSC analysis in the temperature range of $20~300^{\circ}C$ To investigate the reaction mechanism between epoxy group of PGE and urea group of DMU, FT-lR spectroscopy analysis was used. The epoxide group of PGE reacted with the urea group of DMU and formed a hydroxyl group which acted as a catalyst on the cure reaction of other epoxide and amine groups. The activation energy of DGEBA/MDA system without PGE-DMU was 46.5 kJ/mol and those of the system with 5 and 10 phr of PGE- DMU were 43.4 and 37.0 kJ/mol, respectively. Ozawa method also showed the same tendency.