• Journal of Korean Society for Atmospheric Environment
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• v.14 no.4
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• pp.313-320
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• 1998

The most desirable diesel oxidation catalyst (DOC) should have the properties of oxidibing CO and HC effectively at low exhaust gas temperature while minimizing the formation of sulfate at high exhaust gas temperature. Precious metals such as platinum and palladium have been known to be sufficiently active for oxidizing CO and HC and also to have high activity for the oxidation of sulfur dioxide (SO2) to sulfor trioxide (SO3). There is a need to develop a highly selective catalyst which can promote the oxidation of CO and HC efficiently, but, on the other hand, suppress the oxidation of SO2. One approach to solve this problem is to load a base metal such as vanadium in Pt-based catalyst to suppress sulfate formation. In this study, a Pt-V catalyst was prepared by impregnating platinum and vanadium onto a Ti-Si wash coated catalyst in a laboratory reactor by changing the formulations and reaction temperatures.

• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.806-812
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• 2008

The ammonia decomposition reaction has been of increasing interest as a means of treating ammonia in flue gas in the presence of precious metal catalyst. Various catalysts, $Pt-Rh/Al_2O_3$, $Pt-Rh/TiO_2$, $Pt-Rh/ZrO_2$, $Pt-Pd/Al_2O_3$, $Pd-Rh/Al_2O_3$, $Pd-Rh/TiO_2$, $Pd-Rh/ZrO_2$, $Pt-Pd-Rh/Al_2O_3$, $Pd/Ga-Al_2O_3$, $Rh/Ga-Al_2O_3$, and Ru/Ga-$Al_2O_3$, were synthesized by using excess wet impregnation method. Using a homemade 1/4" reactor at $10,000{\sim}50,000hr^{-1}$ of space velocity in the presence of precious metal catalyst ammonia decomposition reactions were carried out to investigate the catalyst activity. The inlet ammonia concentration was maintained at 2,000 ppm, with an air balance. Both $T_{50}$ and $T_{90}$, defined as the temperatures where 50% and 90% of ammonia, respectively, are converted, decreased significantly when alumina-supported catalysts were applied. In terms of catalytic performance on the ammonia conversion in the presence of hydrogen sulfide, $Pt-Rh/Al_2O_3$ catalyst showed no effect on the poisoning caused by hydrogen sulfide. These results indicate that platinum-rhodium bimetallic catalyst is a useful catalyst for ammonia decomposition.

• Applied Chemistry for Engineering
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• v.10 no.6
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• pp.917-922
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• 1999

The transesterification of dimethyl terephthalate(DMT) with ethylene glycol(EG) was kinetically investigated in the temperature range from 190 to $240^{\circ}C$ with and without a zinc acetate(Zn) as a catalyst. The degree of reaction was calculated by the measurement of the quantity of methanol which distilled from the reaction vessel. This distillation made corrections of reactant and catalyst concentrations necessary. The effects of catalyst concentration, molar ratio of DMT and EG, types of metal compounds, and temperature on kinetics were studied. The catalytic activity of various metal compounds was excellent, in order of Ti, Zn, Sn, and Sb. Also the order of activation energy was Zn>Ti>Sn>Sb.

• Journal of Energy Engineering
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• v.28 no.4
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• pp.8-12
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• 2019

Thermal amine scrubbing is the most advanced CO₂ capture technique but its largescale application is hindered due to the large heat requirement during solvent regeneration step. The addition of a solid metal oxide catalysts can optimize the CO₂ desorption rate and thus minimize the energy consumption. Herein, we evaluate the solvent regeneration performance of Monoethanolamine (MEA) and Diethanolamine (DEA) solvents without and with two metal oxide catalysts (TiO₂ and V₂O₅) within a temperature range of 40-86℃. The solvent regeneration performance was evaluated in terms of CO₂ desorption rate and overall amount of CO₂ desorbed during the experiments. Both catalysts improved the solvent regeneration performance by desorbing greater amounts of CO₂ with higher CO₂ desorption rates at low temperature. Improvements of 86% and 50% in the CO₂ desorption rate were made by the catalysts for MEA and DEA solvents, respectively. The total amount of the desorbed CO₂ also improved by 17% and 13% from MEA and DEA solvents, respectively. The metal oxide catalyst-aided regeneration of amine solutions can be a new approach to minimize the heat requirement during solvent regeneration and thus can remove a primary shortfall of this technology.

• Bulletin of the Korean Chemical Society
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• v.28 no.5
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• pp.805-810
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• 2007

Molecular recognition for a specific cation depending on the change of the oxidation state of the metal catalyst component contained in the hydrogel network has been studied in a self-oscillating hydrogel. The selfoscillating hydrogels are synthesized by the copolymerization of N-isopropylacrylamide (NIPAAm), lead methacrylic acid (Pb(MAA)2), and Ru(bpy)3 2+ monomer as a metal catalyst component. The recognition for a specific cation (in this study, Ca2+ has been used) is characterized by the adsorbed amount of Ca2+ into the gel. The recognition of the gels for Ca2+ is higher at the temperature below the LCST, and also higher at the oxidized state than at reduced state of the metal catalyst component which corresponds to a more swollen state. Moreover, a propagating wave induced by a periodic change of the oxidation state with the diffusion phenomena in the oscillating hydrogel shows a possibility for temporal and site-specific molecular recognition due to the local swelling of the gel.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2019.10a
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• pp.83-83
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• 2019

Increasing the CO₂ concentration in the atmosphere induce high temperature and rising sea levels. So the technology that capture and reuse of the CO₂ have been recently become popular. Among other methods, CRR(CO2₂ reduction reaction) is typical method of CO₂ reusing. Electrocatalyst can show more higher efficiencies in CRR than photocatalyst because it doesn't use nature source. Nowadays, finding high efficient electrocatalyst by controlling electronic (affected by stoichiometry) and geometric (affected by atomic arrangement) factors are very important issues. Mono-atomic electro-catalyst has limitations on controlling binding energy because each intermediate has own binding energy range. So the Multi-metallic electro-catalyst is important to stabilize intermediate at the same time. Carbon monoxide(CO) which is our target product and important feedstock of useful products. Au is known for the most high CO production metal. With copper, Not only gold/copper has advantages which is they have FCC packing for easily forming solid solution regardless of stoichiometry but also presence of adsorbed CO on Cu promotes the desorption of CO on Au because of strong repulsion. And gold/copper bi-metal catalyst can show high catalytic activity(mass activity) although it has low selectivity relatively Gold. Actually, multi-metallic catalyst structure control method is limited in the solution method which is takes a lot of time. In here, we introduce CTS(carbo thermal shock) method which is using heat to make MMNP in a few seconds for making gold-copper system. This method is very simple and efficient in terms of time(very short reaction time and using carbon substrate as a direct working electrode) and increasing reaction sites(highly dispersed and mixing alloy structures). Last one is easy to control degree of mixing and it can induce 5 or more metals in one alloy system. Gold/copper by CTS can show higher catalytic activity depending on metal ratio which is altered easily by changing simple variables. The ultimate goals are making CO₂ test system by CTS which can check the selectivity depending on metal types in a very short time.

• Bulletin of the Korean Chemical Society
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• v.26 no.4
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• pp.515-522
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• 2005

Enzyme-metal combo catalysis is described as a useful methodology for the synthesis of optically active compounds. The key point of the method is the use of enzyme and metal in combination as the catalysts for the complete transformation of racemic substrates to single enantiomeric products through dynamic kinetic resolution (DKR). In this approach, enzyme acts as an enantioselective resolving catalyst and metal does as a racemizing catalyst for the efficient DKR. Three kinds of enzyme-metal combinations - lipase-ruthenium, subtilisin-ruthenium, and lipase-palladium –have been developed as the catalysts for the DKRs of racemic alcohols, esters, and amines. The scope of the combination catalysts can be extended to the asymmetric transformations of ketones, enol acetates, and ketoximes via the DKRs. In most cases studied, enzyme-metal combo catalysis provided enantiomerically-enriched products in high yields.

• Analytical Science and Technology
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• v.19 no.5
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• pp.422-432
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• 2006

The volatile organic compounds(VOCs) have been recognized as a major contributor to air pollution. The catalytic oxidation is one of the most important processes for VOCs destruction due to getting high efficiency at low temperature. In this study, monometallic Pt and bimetallic Pt-Ru, Pt-Ir were supported to ${\gamma}-Al_2O_3$. Xylene, toluene and MEK were used as reactants. The monometallic or bimetallic catalysts were prepared by the excess wetness impregnation method and were characterized by XRD, XPS, TEM and BET analysis. As a result, Pt-Ru, Pt-Ir bimetallic catalysts showed higher conversion than Pt monometallic catalyst. Pt-Ir bimetallic catalyst showed the highest conversion on the ${\gamma}-Al_2O_3$ support. In the VOCs oxidation, Pt-Ru, Pt-Ir bimetallic catalyst had multipoint active sites, so it improved the range of Pt metal state. Therefore, bimetallic catalysts showed higher conversion of VOCs than monometallic ones. In this study, the use of small amount of Ru, Ir to Pt promoted oxidation conversion of VOCs.

• Clean Technology
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• v.21 no.3
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• pp.184-190
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• 2015

Most of LNT catalysts use noble metals such as Pt for low temperature NO_x oxidation but there is an economic weakness. For the purpose of overcoming this, this study is to develop DeNO_x catalyst for LNT excluding PGM (platinum group metal) such as Pt, Pd, Rh, etc. To do so, Al/Co/Ni catalyst selected as a preliminary test is used to study fundamental property and NO_x’s conversion according to calcined temperature. Ultimately, that is, Al/Co/Ni mixed metal oxide which does not use PGM is selected and physicochemical characterization is performed by way of XRD, EDS, SEM, BET and ramp test and NO_x conversion is also analyzed. This study shows that all samples consist of mixed oxides of spinel structure of Co₂AlO₄ and NiAl₂O₄ and have enough pore volume and size for redox. But as a result of NH₃-TPD test, it is desired that calcined temperature needs to be maintained at 700 ℃ or lower. Also only samples which are processed under 500 ℃ satisfied NO and NO_x conversion simultaneously through ramp test. Based on this study’s results, optimum calcined temperature for Al/Co/Ni=1.0/2.5/0.3 mixed metal oxide catalyst is 500 ℃.

• Journal of Digital Convergence
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• v.10 no.8
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• pp.201-210
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• 2012

Because sensing odor varies depending on each person, even if the odor is released in line with the legal emission permission concentration levels, it can still become a social issue if a civil complaint is made. The purpose of this research is to study the possibility of putting Mn-Cu metallic oxide catalysts into practical use to economically eliminate acetaldehyde which produces a odor in the industrial process. An optimal operating parameter to eliminate acetaldehyde was deduced through a performance evaluation in the research laboratory and the performance was verified by applying the parameter into an actual facility as an on-the-site experiment through a Scale-up of pilot size. The operating temperature of the metallic oxide catalysts researched so far was at the minimum close to $220^{\circ}C$, and the $220^{\circ}C$ elimination efficiency was 50% or below. However, having experimented by using a Mn-Cu metallic oxide catalyst in this research, optimum elimination efficiency showed when space velocity (GHSV) was equal to or below 6,000 $hr^{-1}$. The average elimination efficiency was 61.2% when the catalyst controlling temperature was $120^{\circ}C$, 93.3% when the catalyst controlling temperature was $160^{\circ}C$, and 94.9% when catalyst controlling temperature was $180^{\circ}C$, thereby reflecting high elimination efficiency. The specific surface area of the catalyst was $200m^2/g$ before use, however, was reduced to $47.162m^2/g$ after 24 months and therefore showed that despite the decrease in specific surface area as time passed, there was no significant influence on the performance. Having operated Mn-Cu metallic oxide catalyst systems for at least two years on a site where there was no inflow of toxins like sulfur compounds and acidic gases, we were able to confirm that elimination efficiency of at least 90% was maintained.