Ansan, South Korea
Ansan, South Korea

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Kim Y.J.,Pohang University of Science and Technology | Kwon H.J.,Pohang University of Science and Technology | Heo I.,Pohang University of Science and Technology | Nam I.-S.,Pohang University of Science and Technology | And 4 more authors.
Applied Catalysis B: Environmental | Year: 2012

A Mn-Fe/ZSM5 catalyst has been developed for removing NOx from diesel engine exhausts and its excellent low-temperature SCR activity and N 2 selectivity demonstrated in comparison with other representative SCR catalysts including CuZSM5 and a Cu-based commercial catalyst (COM). The well-dispersed MnO 2 and the high NH 3 adsorption capacity of the Mn-Fe/ZSM5 catalyst have been identified as the primary sources for its high deNOx activity for NH 3/SCR. Hydrothermal stability and durability of the Mn-Fe/ZSM5 catalyst have been examined and compared to those of the CuZSM5 and COM catalysts. The hydrothermal stability of the catalyst improved upon the increase of Mn content and/or the addition of Er, the latter of which helps to stabilize the dispersion of MnOx on the catalyst surface during hydrothermal aging. The deNOx activity of the Mn-Fe/ZSM5 and its Er-promoted counterpart was less affected by HC poisoning, C 3H 6 poisoning in particular, compared to the CuZSM5 and COM catalysts, mainly due to the excellent C 3H 6 oxidation activity of MnO 2. No poisoning of the Mn-based ZSM5 and CuZSM5 catalysts has been observed upon the addition of 2wt.% of K + and Ca 2+ to their surface, primarily due to the high NH 3 adsorption capacity of the ZSM5 support, whereas the COM catalyst has been severely deactivated by the deposition of K + and Ca 2+. The deNOx activity of the Mn-based ZSM5 catalyst, particularly the Er-promoted one, was less affected by SO 2 compared to the CuZSM5 and COM catalysts, although it was hardly regenerated at 500°C. Formation of MnSO 4 on the catalytic surface appears to be the primary cause for the deactivation of the Mn-based ZSM5 catalysts in the presence of SO 2 in the feed gas stream. © 2012 Elsevier B.V.

Yoon D.Y.,Pohang University of Science and Technology | Park J.-H.,Pohang University of Science and Technology | Park J.-H.,Korea Advanced Institute of Science and Technology | Kang H.-C.,Pohang University of Science and Technology | And 6 more authors.
Applied Catalysis B: Environmental | Year: 2011

The effect of the calcination temperature of Ag/Al2O3 catalyst on NO removal activity by n-dodecane as a diesel simulant has been examined with respect to the Ag loading and C1/NO feed ratio under a feed gas condition containing both excess H2O and oxygen. The higher the catalyst calcination temperature and Ag loading, the higher deNOx activity that has been achieved in the reaction temperature range lower than 300°C. 56% of the NO conversion to N2 has been attained over Ag(2)-800 catalyst at 300°C when the C1/NO feed ratio to the reactor is 6. The amount of the metallic Ag formed on the catalyst surface responsible for the high deNOx performance in the temperature region lower than 300°C increases upon the increase of the catalyst calcination temperature from 550 to 800°C and of the Ag loading from 1 to 3wt.%, as determined by UV-vis and XPS. The -NCO species formed on the catalyst surface with acetate, formate and carbonate compounds produced from the partial oxidation of n-dodecane is a critical reaction intermediate for the present reaction system, as identified by in situ IR study. The formation of the -NCO species on the catalyst surface becomes apparent, particularly at 300°C as the catalyst calcination temperature increases. © 2010 Elsevier B.V.

Kim Y.J.,Pohang University of Science and Technology | Kwon H.J.,Pohang University of Science and Technology | Nam I.-S.,Pohang University of Science and Technology | Choung J.W.,Hyundai Engineering | And 4 more authors.
Catalysis Today | Year: 2010

The deNOx performance of the s-Mn/TiO2 catalyst prepared by sol-gel method has been significantly enhanced, particularly in the low temperature region. Mn is basically incorporated into the matrix of Ti and becomes a structural component of s-MnO2/TiO2 mixed oxide, whereas by impregnation method it simply exists on the surface of i-Mn/TiO2. The well-dispersed Mn over s-Mn/TiO2 catalyst is the primary cause for the high deNOx performance compared to that over i-Mn/TiO2. The addition of Fe onto the Mn/TiO2 catalyst improves the NOx removal activity by NH3 in a wide operating temperature window, including the low temperature region less than 250.C, regardless of the catalyst preparation methods. Including NO2 (NO2/NO = 1) in the feed gas stream further enhances the low temperature deNOx activity of Mn/Fe/TiO2 catalyst. © 2010 Elsevier B.V. All rights reserved.

Wang T.J.,Korea Advanced Institute of Science and Technology | Wang T.J.,Doosan Infracore | Baek S.W.,Korea Advanced Institute of Science and Technology | Kwon H.J.,Pohang University of Science and Technology | And 5 more authors.
Industrial and Engineering Chemistry Research | Year: 2011

In this work, an in-house computational code capable of simulating highly coupled physicochemical phenomena occurring in ammonia/urea SCR (selective catalytic reduction) was developed. On the basis of this computational code, the kinetic parameters of catalytic reactions were newly calibrated using the experimental results obtained over a commercial ammonia/urea SCR washcoated Fe-ion-exchanged zeolite-based catalyst. Powder-phase NH3 TPD (temperature-programmed desorption) experiments were performed to calibrate the kinetic parameters of NH3 adsorption and desorption, and core-out monolith experiments were conducted to estimate the kinetic parameters of various deNOx reactions as well as NH3 oxidation. The currently established SCR model and kinetic parameters gave a good prediction for both steady-state and transient experimental results for a wide range of operating conditions. The main objectives of this study were to develop numerical tools and their implementation methodologies that can be cost-effectively applied to the design and development of real-world ammonia/urea SCR systems. Details of the procedures and techniques in numerical modeling and kinetic parameter calibration are described step-by-step in this article. © 2011 American Chemical Society.

Jung J.-H.,University of Ulsan | Cha M.-S.,Ordeg Co. | Kim J.-B.,University of Ulsan
Journal of Nanoscience and Nanotechnology | Year: 2012

In this study, carbon nano?ber (CNF) was used as a support in which 47.5 wt% Pt/CNFs catalyst was prepared by a modi?ed polyol method. The platinum particle size and dispersion on the CNFs are approximately 2-4 nm as determined by X-ray diffractometry and transmission electron microscopy. The speci?c surface area was approximated as 55.90 m 2 /g by BET analysis. Electrodes were prepared by the spray method and have a size of 5 cm 2 . A commercial catalyst (TKK, 46 wt% Pt/C) was used as the anode and the cathode was Pt/CNFs. Different amounts of Na?on ionomer (Aldrich, 5 wt% solution, in the range of 0-20 wt%) were coated on a membrane (Dupont, Na?on 212) with 0.4 mg/cm 2 of Pt catalyst at the cathode side. The resulting polarization, ohmic and mass transfer resistances changed signi?cantly based on the Na?on ionomer content. Optimum Na?on ionomer content in the 47.5 wt% Pt/CNFs was 5 wt%. The well-dispersed Na?on ionomer was observed on the catalyst surface area using SEM-EDAX analysis. A suf?cient triple-phase boundary was formed by a small amount of Na?on ionomer due to the BET surface area of the Pt/CNFs. © 2012 American Scientific Publishers.

Jung J.H.,University of Ulsan | Park B.I.,ORDEG Co. | Kim J.,University of Ulsan
Nanoscale Research Letters | Year: 2012

In this study, a catalyst was synthesized on carbon nanofibers [CNFs] with a herringbone-type morphology. The Pt/CNF catalyst exhibited low hydrophilicity, low surface area, high dispersion, and high graphitic behavior on physical analysis. Electrodes (5 cm 2) were prepared by a spray method, and the durability of the Pt/CNF was evaluated by fuel starvation. The performance was compared with a commercial catalyst before and after accelerated tests. The fuel starvation caused carbon corrosion with a reverse voltage drop. The polarization curve, EIS, and cyclic voltammetry were analyzed in order to characterize the electrochemical properties of the Pt/CNF. The performance of a membrane electrode assembly fabricated from the Pt/CNF was maintained, and the electrochemical surface area and cell resistance showed the same trend. Therefore, CNFs are expected to be a good support in polymer electrolyte membrane fuel cells. © 2012 Jung et al.

Jung J.,University of Ulsan | Kwon M.,University of Ulsan | Kim H.-R.,Ordeg Co. | Kim J.,University of Ulsan
International Journal of Hydrogen Energy | Year: 2014

Research on membrane electrode assemblies (MEA) is focused on reducing cost and increasing durability in polymer electrolyte membrane fuel cells (PEMFC). Development of the electrode structure and reduction of platinum (Pt) contents are studied to improve the efficiency of Pt catalysts. We studied the combined effects of improved electrode structure and reduced Pt loading. To enhance the performance of an MEA, a commercial Pt/C catalyst with micro graphite (MG) was used. The 40 wt% Pt/C catalyst content was reduced about 5, 15, 30 and 60 wt% at the cathode. MG was added as a reduced weight percent of Pt/C. Cell performance was significantly dependent on the content of MG. The MEA with 15 wt% of MG was seen to best performance compare with other MEA. These results showed that the catalyst with mixed MG improved both performance and cost savings with reduced Pt content of PEMFC. Copyright © 2013, Hydrogen Energy Publications, LLC.

Choung S.-J.,Kyung Hee University | Kim J.,Kyung Hee University | Kim H.-R.,Ordeg Corporation
International Journal of Photoenergy | Year: 2011

The photocatalytic production of hydrogen from water using solar energy is potentially a clean and renewable source for hydrogen fuel. This study examines the production of hydrogen over In, P-TiO2s photocatalysts. 1mol% In-TiO2 and P-TiO2 were produced using the solvothermal method and were treated at 500 and 800°C to obtain anatase and rutile structure, respectively. The photocatalysts were characterized by X-ray diffraction, photoluminescence spectra, X-ray spectroscopy, UV-visible spectroscopy, and scanning electron microscopy. The production of H2 from methanol photodecomposition was greater over the rutile structure than over the anatase structure of TiO2. Moreover, the amount of hydrogen was enhanced over In-TiO2 and P-TiO2 compared to that over pure TiO2; the production increased by about 30%. The structural effect and the addition of In, P have significant influence on the H2 production from methanol/water decomposition. Copyright © 2011 Joonwoo Kim et al.

A zeolite catalyst for removing nitrogen oxides is provided, in which 5 to 30 wt% of manganese (Mn) and 2 to 20 wt% of iron (Fe) on the basis of the total weight of the catalyst are supported on zeolite, and a method for preparing the same, and a method for removing nitrogen oxides using the same are provided.

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