• 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.

• Bulletin of the Korean Chemical Society
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• v.19 no.12
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• pp.1342-1346
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• 1998

The dehydrogenation of ethylbenzene with carbon dioxide has been carried out over ZSM-5 zeolite-supported iron oxide catalyst as well as commercial catalyst (K-Fe2O3) and unsupported iron oxide (Fe3O4) for comparison. In the dehydrogenation over the ZSM-5 zeolite-supported iron oxide catalyst, ethylbenzene is predominantly converted to styrene by an oxidative pathway in the presence of excess carbon dioxide. Carbon dioxide in this reaction is found to play a role as an oxidant for promoting catalytic activity as well as coke resistance of catalyst. On the other hand, both of commercial catalyst and unsupported Fe2O4 exhibit considerable decrease in catalytic activity under the same condition. It is suggested that an active phase for the dehydrogenation with carbon dioxide over ZSM-5 zeolite-supported iron oxide catalyst would be rather a reduced and isolated magnetite (Fe3O4)-like phase having oxygen deficiency in the zeolite matrix.

• Bulletin of the Korean Chemical Society
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• v.16 no.7
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• pp.661-666
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• 1995

The surface structure of the adsorption site for the identification of active sites involved in the Ziegler-Natta catalyst was studied by surface science techniques. As an example of a real catalyst, TiCl3 single crystals were prepared in a gradient furnace designed for this study and characterized by Auger Electron Spectroscopy (AES) and Low Energy Electron Diffraction (LEED) under ultrahigh vacuum condition. The chlorine covered Ti (0001) surface was employed as a model catalyst for the study of Ziegler-Natta catalyst. The diffuse LEED (DLEED) technique for the surface structural determination was applied to this disordered chlorine adsorbed on Ti (0001) surface. The diffuse scattering intensities were measured by a TV-computer method using a low light level video camera. From an analysis of two catalyst systems, the informations for the surface structure of the model catalyst surfaces were derived.

• Applied Chemistry for Engineering
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• v.9 no.1
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• pp.115-120
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• 1998

The surface chemistry of $Re_2(CO)_{10}$ deposition for preparing highly dispersed rhenium catalysts and the formation of active site for the metathesis were studied. Alumina as support was treated at 1223K(DA) and 773k(PDA), respectively. The metathesis activity of the catalysts at 298K was measured by using pure propene under atmospheric pressure. The oxidation number of rhenium on PDA was very high, and that on DA was zero-valent with highly dispersed state. The prepared Re/DA catalyst was easily activated by treating with oxygen gas at low temperatures after thermal decomposition at high temperatures. The activity of Re/DA catalyst, even with very low rhenium loading, was much higher than that of Re/PDA or conventional $Re_2O_7/Al_2O_3$ catalysts. Therefore, rhenium carbonyl was effective for preparing a highy active metathesis catalyst with very low rhenium loading. Rhenium ion on Re/DA catalyst seemed to be bonded to two oxygen atoms on DA surface, that is, two-valent. The two-valent rhenium ion was changed to about six-valent by treating with oxygen. It could be considered that propene metathesis occurred through carbene complex which was formed on the six-valent rhenium ions.

• 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.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.172-175
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• 2006

Steam reforming of methane using Xe-arc solar simulator was studied for converting solar radiation into energy foam that one can readily utilize. The Xe-arc lamp produce a spectrum similar to that of the sun. SiC ceramic foam, resist high temp.$(>900^{\circ}C)$, is used to catalytically active foam absorber, and to support of reforming catalyst. The catalyst on the surface of foam were directly irradiated with solar simulated xe-light in order to carry out the steam reforming of methane. The reactor was made of stainless steel and quartz window was located on a place of the xe-light irradiation and temperature was controlled using K-type thermocouple in contact with catalyst located inside the reactor. The result show that a possibility of solar reforming using catalytically active foam absorber is exist.

• Bulletin of the Korean Chemical Society
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• v.26 no.6
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• pp.887-891
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• 2005

Novel nickel catalyst deposited on nanoporous carbon was found to be an efficient catalyst for the epoxidation of simple alkenes with $O_2$ and isobutyraldehyde under mild conditions. Alkenes exhibited different reactivities towards Ni-catalyst and epoxidation with stilbene proceeds stereospecifically. This may be rationalized with the mechanism involving coordinated acylperoxy radical intermediate. Nickel contents depend on the preparative methods and the KNI-3 catalyst, which was synthesized by wet impregnation of $Ni(NO_3)_2$ into nanoporous carbon, shows the highest activity. The activity of the catalyst is well correlated with contents of nickel. Recycled catalysts suffer considerable loss of activity due to leaching of catalytic active species, nickel.

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1589-1595
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• 2010

In order to effective degradation of organic dye both under visible light or ultrasonic irradiation, the MWCNTs (multiwalled carbon nanotube) deposited with Fe and $TiO_2$ were prepared by a modified sol-gel method. The Fe/$TiO_2$-MWCNT catalyst was characterized by surface area of BET, scanning electron microscope (SEM), Transmission Electron Microscope (TEM), X-ray diffraction (XRD), and energy dispersive X-ray (EDX) and ultraviolet-visible (UV-vis) spectroscopy. The low intensity visible light and low power ultrasound was as an irradiation source and the methylene blue (MB) was choose as the model organic dye. Then degradation experiments were carried out in present of undoped $TiO_2$, Fe/$TiO_2$ and Fe/$TiO_2$-MWCNT catalysts. Through the degradation of MB solution, the results showed the feasible and potential use of Fe/$TiO_2$-MWCNT catalyst under visible light and ultrasonic irradiation due to the enhanced formation of reactive radicals as well as the possible visible light and the increase of ultrasound-induced active surface area of the catalyst. After addition of $H_2O_2$, the MB degradation rates have been accelerated, especially with Fe/$TiO_2$-MWCNT catalyst, in case of that the photo-Fenton reaction occurred. The sonophotocatalysis was always faster than the respective individual processes due to the more formation of reactive radicals as well as the increase of the active surface area of Fe/$TiO_2$-MWCNT catalyst.

• Korean Chemical Engineering Research
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• v.45 no.4
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• pp.410-413
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• 2007

The effect of internal donor(ID) in the heterogeneous Ziegler-Natta catalyst on the ethylene-1-butene copolymerization and the molecular structure of the resulting copolymer was investigated. $SiO_2$-supported $TiCl_4$ catalysts having ID/Ti molar ratio of 0.5 were prepared with ethyaluminium dichloride, magnesium alkyl, 2-ethyl-1-hexanol and $TiCl_4$. Three different IDs were employed such as ethylbenzoate(EB), diisobuylphthalate(DIBP) and dioctylphthalate(DOP). ID-added catalyst showed a larger fraction of Ti(+3) compared to that of no ID-added catalyst. The EB-added catalyst showed the highest activity in copolymerization. Xylene soluble value decreased by more than 50 % with ID-added catalysts compared to that of no ID-added catalyst. Crystaf analysis showed the chemical compositional distribution of PE copolymer was improved in the case of DIBP-added catalyst significantly. It could be explained that the presence of ID could make more even active sites and block the non-stereospecific active sites.

• Korean Journal of Materials Research
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• v.28 no.11
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• pp.646-652
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• 2018

During a long-term operation of polymer electrolyte membrane fuel cells(PEMFCs), the fuel cell performance may degrade due to severe agglomeration and dissolution of metal nanoparticles in the cathode. To enhance the electrochemical durability of metal catalysts and to prevent the particle agglomeration in PEMFC operation, this paper proposes a hybrid catalyst structure composed of PtCo alloy nanoparticles encapsulated by porous carbon layers. In the hybrid catalyst structure, the dissolution and migration of PtCo nanoparticles can be effectively prevented by protective carbon shells. In addition, $O_2$ can properly penetrate the porous carbon layers and react on the active Pt surface, which ensures high catalytic activity for the oxygen reduction reaction. Although the hybrid catalyst has a much smaller active surface area due to the carbon encapsulation compared to a commercial Pt catalyst without a carbon layer, it has a much higher specific activity and significantly improved durability than the Pt catalyst. Therefore, it is expected that the designed hybrid catalyst concept will provide an interesting strategy for development of high-performance fuel cell catalysts.