• Applied Chemistry for Engineering
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• v.9 no.6
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• pp.878-883
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• 1998

The methane combustion reaction was conducted over Pb-ZSM-5 catalysts. ZSM-5 synthesized at low temperature and atomospheric pressure was used as a support. The change of methane conversion with $SiO_2/Al_2O_3$ molar ratio was tested. The methane conversions of the synthesized Pb-ZSM-5 catalyst was compared with those of a commercial Pd-ZSM-5(PQ Co.) and $PdO/{\gamma}-Al_2O_3$. The methane conversion increased with the decrease in $SiO_2/Al_2O_3$ molar ratio. The combustion rate of methane also increased with the decrease in $SiO_2/Al_2O_3$ molar ratio. The synthesized Pb-ZSM-5 showed better methane conversion than that of the commercial one. It is found that a crucial factor in methane combustion reaction is oxygen adsorption strength on the catalysts.

• Applied Chemistry for Engineering
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• v.23 no.2
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• pp.190-194
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• 2012

10 wt% Mn supported on various commercial $TiO_2$ catalysts were prepared by wet-impregnation method for the low temperature selective catalytic reduction (SCR) of NO with $NH_3$. A combination of various physico-chemical techniques such as BET, XRD, XPS and TPR were used to characterize these catalysts. MnOx surface densities on MnOx/$TiO_2$ catalyst were related to surface area. As MnOx surface density lowered with high dispersion, the SCR activity for low temperature was increased and the reduction temperature ($MnO_2$ ${\rightarrow}$ $Mn_2O_3$) of surface MnOx was lower. For a high SCR, MnOx could be supported on a high surface area of $TiO_2$ and should be existed a high dispersion of non-crystalline species.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.1
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• pp.32-44
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• 2002

Selective catalytic reduction of nitric oxide by methane in the presence of excess oxygen was investigated over copper and cobalt ion-exchanged ZSM-5 zeolites. Copper ion-exchanged ZSM-5(Cu-ZSM-5) has the limitations for commercial applications to lean-bum gasoline and diesel engines due to low thermal stability and resistance to water vapor and sulfur dioxide. But cobalt ion-exchanged ESM-5(Co-ZSM-5) is more active at high temperatures and also stable to water vapor and sulfur dioxide for catalytic reduction of nitric oxide by methane. The catalytic activity of Cu-ZSM-5 for NO reduction increases with increasing temperatures, reaches the maximum conversion of 23.0% at 350\"C. and then decreases with higher temperatures. In the meantime catalytic activities of Co-ZSM-5 show the maximum conversion of 25.8% at $500^{\circ}C$ Therefore Co-ZSM-5 catalysts have higher thermal stability at high temperatures. Catalytic activities of both zeolites were remarkably enhanced with the existence of oxygen in the exhaust. It is noted that the catalytic activity of Cu-ZSM-5 decreases with the increasing concentration of methane while the catalytic activity of Co-ZSM-5 decreases with increasing contents of methane in the exhaust. This may imply the existence of different paths of NO reduction by methane in the presence of excess oxygen fur Cu-ZSM-5 and Co-ZSM-5 catalysts. For binary metal ionexchanged ZSM-5, the primary ion-exchanged metal may be masked by secondary ion-exchanged component, which plays the important role for catalytic activities of binary metal ion-exchanged ZSM-5, Therefore CuCo-ZSM-5 catalysts show the similar volcano-shaped curves to Cu-ZSM-5 catalysts between the activity and temperature. It Is interesting that the activities of CoCu-ZSM-5 catalysts indicate almost no dependence on the concentration of methane in the exhaust.aust.

• Journal of the Korean Applied Science and Technology
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• v.35 no.1
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• pp.163-172
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• 2018

In this study, selective catalytic reductions (SCR) of NO commercial catalysts were used to investigate the effect of ammonia gasification from urea solution. The effects of catalytic chemical composition on the reaction temperature and space velocity were studied. $V_2O_5/TiO_2$ catalysts, which are widely used as SCR catalysts for removal of nitrogen oxides, have better ammonia formation compare to $TiO_2$ and $WO_3-V_2O_5/TiO_2$ catalysts. The $TiO_2$ catalyst not supporting the active metal was not affected by the space velocity as compared with the catalyst supporting $V_2O_5$ or $WO_3-V_2O_5$. The active metal supported catalysts decreased in the ammonia formation as the space velocity increased.

• Transactions of the Korean hydrogen and new energy society
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• v.19 no.1
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• pp.71-76
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• 2008

CuFeOx/$Al_2O_3$ catalysts are developed for the use in sulfuric acid decomposition which is a subcycle in thermochemical iodine-sulfur cycle to split water into hydrogen and oxygen. Both Cu and Fe components are co-precipitated with Al component to enhance distribution of active components. Developed catalysts are improved in the capability of sulfuric acid decomposition and endurance under highly acidic environment compared to commercial catalysts such as Pt/$Al_2O_3$ and $2CuO{\cdot}Cr_2O_3$. Developed CuFeAlOx catalysts exhibited higher sulfuric acid decomposition ability than $2CuO{\cdot}Cr_2O_3$ and longer endurance trends than Pt/$Al_2O_3$ maintaining comparable performance, respectively.

• Transactions of the Korean hydrogen and new energy society
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• v.15 no.4
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• pp.274-282
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• 2004

This study focused on the development of high performance catalyst for autothermal reforming (ATR) of gasoline to produce hydrogen. The ATR was carried out over MgO/Al2O3 supported metal catalysts prepared under various experimental conditions. The catalysts before and after reaction were characterized by N2-physisorption, CO-chemisorption, SEM and XRD. The performance of supported multi-metal catalysts were better than that of supported mono-metal catalysts. Especially, it was observed that the conversion of iso-octane over prepared Ni/Fe/MgO/Al2O3 catalyst was 99.9 % comparable with commercial catalyst (ICI) and the selectivity of hydrogen over the prepared catalyst was 65% higher than ICI catalyst. Furthermore, it was identified that the sulfur tolerance of prepared catalyst was much better than ICI catalyst based on the ATR reaction of iso-octane containing sulfur of 100 ppm. Therefore, Ni/Fe/MgO/Al2O3 catalyst can be applied for a fuel reformer, hydrogen station and on-board reformer in furl cell powered vehicles.

• Journal of the Korean Electrochemical Society
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• v.8 no.1
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• pp.12-16
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• 2005

Diesel is one of the best hydrogen systems, which has very high volumetric density $[kg\;H_2/m^3]\;(>100)\;and\;gravimetric\;density[\%\;H_2]\;(>\;15)$Several catalysts were selected for diesel reforming. 3 catalysts of our group (NECS-1, NECS-2, NECS-3) and 2 commercial catalysts (Sud-Chemie, Inc, FCR-HCl4, FCR-HC35) were used to reform diesel. NECS-1 showed the best performance to reform diesel. In addition to these results, we studied on reaction characteristics for better understanding about auto thermal reforming of diesel by investigating product gas concentrations and temperature Profiles along the catalyst bed. We found technological issues such as fuel delivery and thermal configuration between front exothermic part and rear endothermic part.

• Applied Chemistry for Engineering
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• v.23 no.6
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• pp.561-566
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• 2012

PtRuW/C catalysts were prepared with the different molar ratios of Pt : Ru : W and their compositions were analyzed by energy dispersive X-ray (EDX). The uniform distribution of particles was observed using transmission electron microscopy (TEM). An average crystalline size of 3.5~5.5 nm was calculated based on x-ray diffraction (XRD) data. The electrochemical properties such as electrochemically active surface areas, current densities, specific activities and poisoning rates, were analyzed via CO stripping, linear sweep voltammetry and chronoamperometry. From the analysis, we observed that ternary alloy catalysts, except $PtRu_2W_2/C$, have higher current densities, specific activities and stabilities than those of commercial binary catalysts. Among all in-house catalysts, Pt5Ru4W/C showed the highest specific activity of $121.05mA{\cdot}m^{-2}$ and the lowest poisoning rate of $0.01%{\cdot}s^{-1}$.

• 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.

• Clean Technology
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• v.19 no.1
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• pp.59-64
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• 2013

Pt/carbon Electrode catalysts for PEMFC were synthesized using colloidal method. PSA (platinum sulfite acid) was used as a Pt precursor and CPA (chloroplatinic acid) was also used to replace relatively expensive PSA. Electrode catalysts prepared using PSA showed Pt particle size less than 3.5 nm and Pt yield higher than 90% in 10~40 wt% Pt loading. Electrode catalysts prepared using CPA also showed Pt particle size less than 4.4 nm and Pt yield higher than 80% in 10~40 wt% Pt loading. The MEA (membrane electrode assembly) using 20 wt% Pt/VXC72 showed equivalent I-V curve comparing with commercial electrode catalyst in single cell test.