• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.245-245
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• 2012

Syntheses of oxide supported metal catalysts by wet-chemical routes have been well known for their use in heterogeneous catalysis. However, uniform deposition of metal nanoparticles with controlled size and shape on the support with high reproducibility is still a challenge for catalyst preparation. Among various synthesis methods, arc plasma deposition (APD) of metal nanoparticles or thin films on oxide supports has received great interest recently, due to its high reproducibility and large-scale production, and used for their application in catalysis. In this work, Au and Pt nanoparticles with size of 1-2 nm have been deposited on titania powder by APD. The size of metal nanoparticles was controlled by number of shots of metal deposition and APD conditions. These catalytic materials were characterized by x-ray diffraction (XRD), inductively coupled plasma (ICP-AES), CO-chemisorption and transmission electron microscopy (TEM). Catalytic activity of the materials was measured by CO oxidation using oxygen, as a model reaction, in a micro-flow reactor at atmospheric pressure. We found that Au/$TiO_2$ is reactive, showing 100% conversion at $110^{\circ}C$, while Pt/$TiO_2$ shows 100% conversion at $200^{\circ}C$. High activity of metal nanoparticles suggests that APD can be used for large scale synthesis of active nanocatalysts. We will discuss the effect of the structure and metal-oxide interactions of the catalysts on catalytic activity.

• Applied Chemistry for Engineering
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• v.25 no.3
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• pp.281-285
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• 2014

$Pd/TiO_2$ particles were prepared by wet impregnation for aerobic benzyl alcohol oxidation. Catalysts were prepared by the impregnation of 10 wt% palladium on $TiO_2$ after calcination at various temperatures. The surface areas of the catalysts were changed with calcination temperature. The catalyst calcined at $300^{\circ}C$ possessed the highest surface areas. Catalytic activity of the prepared samples was examined for aerobic benzyl alcohol oxidation. Among the samples, $Pd/TiO_2$ calcined at $300^{\circ}C$ showed the highest catalytic activity. Moreover, the catalysts with various Pd concentrations from 5 wt% to 15 wt% were prepared to investigate an optimum catalyst. 10 wt% $Pd/TiO_2$ was the most active in this reaction due to its higher surface areas and metal dispersion.

• Applied Chemistry for Engineering
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• v.28 no.2
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• pp.193-197
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• 2017

In this study, we report on the catalyst process installed in conjunction with a wet plasma electrostatic precipitator to remove the oil mist and fine dust emitted from large-size grill restaurants. The multi-stage catalyst module reduced odor through catalytic reaction of acetaldehyde on catalysts even at an ambient temperature with ozone as an oxidant readily produced in a wet plasma electrostatic precipitator. Two types of manganese-based catalysts, $Mn_2O_3$ and $CuMnO_x$ were fabricated by extrusion molding for structured catalysts in practical applications, and the optimum conditions for high removal efficiencies of acetaldehyde and ozone were determined. When two optimized catalysts were applied in a two-stage catalyst module, the removal efficiency of acetaldehyde and ozone were ${\geq}85%$ and 100% respectively at the space velocity of $10,000h^{-1}$ and the reaction temperature of $100^{\circ}C$.

• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.808-814
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• 2010

Activities of nanostructure HZSM-5 and Co-ZSM-5 catalysts (with different Co-loading) for catalytic conversion of ethyl acetate and toluene were studied. The catalysts were prepared by wet impregnation method and were characterized by XRD, BET, SEM, TEM and ICP-AES techniques. Catalytic studies were carried out inside a U-shaped fixed bed reactor under atmospheric pressure and different temperatures. Toluene showed lower reactivity than ethyl acetate for conversion on Co-ZSM-5 catalysts. The effect of Co loading on conversion was prominent at temperatures below $400^{\circ}C$ and $450^{\circ}C$ for ethyl acetate and toluene respectively. In a binary mixture of organic compounds, toluene and ethyl acetate showed an inhibition and promotional behaviors respectively, in which the conversion of toluene was decreased at temperatures above $350^{\circ}C$. Inhibition effect of water vapor was negligible at temperatures above $400^{\circ}C$. An artificial neural networks model was developed to predict the conversion efficiency of ethyl acetate on Co-ZSM-5 catalysts based on experimental data. Predicted results showed a good agreement with experimental results. ANN modeling predicted the order of studied variable effects on ethyl acetate conversion, which was as follows: reaction temperature (50%) > ethyl acetate inlet concentration (25.085%) > content of Co loading (24.915%).

• Applied Chemistry for Engineering
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• v.25 no.4
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• pp.425-429
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• 2014

Pd on charcoal particles were prepared by wet impregnation to develop commercial catalyst for aerobic benzyl alcohol oxidation. Especially, one of room temperature ionic liquids, [Hmim][$PF_6$], was used as an effective solvent in the synthesis to improve the metal dispersion of the catalysts. Among the Pd/Charcoal with various Pd concentrations, 7.5 wt% catalyst showed the higher catalytic activity and stability. Moreover, Ag was used as a promoter with various ratios in catalyst preparation. Under identical reaction conditions, the catalyst with 9 : 1 of Pd and Ag weight ratios was most active due to higher metal dispersion.

• Clean Technology
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• v.17 no.2
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• pp.166-174
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• 2011

The xAl-yCe oxide catalysts with different mol ratios of Al/(Al+Ce) were prepared by a co-precipitation method and Pt supported on xAl-yCe oxide catalysts were synthesized by an incipient wetness impregnation method. The catalysts were characterized by X-ray Diffraction (XRD), $N_2$ sorption, and $H_2$/CO-temperature programmed reduction ($H_2$/CO-TPR) to correlate with catalytic activities in co oxidation. Among the catalysts studied here, Pt/1Al-9Ce oxide catalyst showed the highest activity in dry and wet reaction conditions and the catalytic activity showed a typical volcano-shape curve with respect to Al/(Al+Ce) mol ratio. When the presence of 5% water vapor in the feed, the temperature of $T_{50%}$ was shifted ca. $30^{\circ}C$ to lower temperature region than that in dry condition. From CO-TPR, the desorption peak of $CO_2$ on Pt/1Al-9Ce oxide catalyst showed the highest value and well correlated the catalytic performance. It indicates that the Pt/1Al-9Ce oxide catalyst has a large amount of active sites which can be adsorbed by co and easy to supplies the needed oxygen. In addition, the amount of pentacoordinated $Al^{3+}$ sites obtained through $^{27}Al$ NMR analysis is well correlated the catalytic performance.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.720-725
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• 2011

Gold catalysts supported on metal-oxides were prepared by co-precipitation using the various metal nitrates and chloroauric acid as precursors, and effect of water addition on the catalytic activity in CO oxidation was investigated. Among the various supported gold catalysts, Au/$Co_{3}O_{4}$ and Au/ZnO catalysts showed the excellent activity for CO oxidation. Water in the reactant gas had a negative effect on the oxidation activity over Au/$Co_{3}O_{4}$ catalysts and a positive effect on that over Au/ZnO, which means the activity depends strongly on the nature of support. It was also confirmed that no significant change in the particle size of gold was observed after reaction both in dry and wet conditions. This fact suggested that the deactivated catalyst due to a carbonate species could be regenerated by water addition in the reactant gas.

• Applied Chemistry for Engineering
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• v.32 no.3
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• pp.237-242
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• 2021

Simultaneous removal technologies of multi-pollutants such as particulate matters (PMs), NOx, SOx, VOCs and ammonia have received consistent attention due to the enhancement of pollutant abatement efficiency in addition to the stringent environmental regulation and emission standard. Pretreatment of insoluble NO by an ozone oxidation can be considered to be more effective route for saving space occupation as well as operation cost in comparison with that of traditional selective catalytic reduction (SCR) process. Moreover the primary advantage of ozone oxidation process is that the simultaneous removal with acidic gas including SOx is also available. Herein, we highlight recent studies of multi-pollutant abatement via ozone oxidation process and the promising research topics for better application in industrial sectors.

• Applied Chemistry for Engineering
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• v.28 no.1
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• pp.64-72
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• 2017

A series of Pt-based ${\gamma}-Al_2O_3$ catalysts promoted with several alkali and alkaline earth metals were prepared by a wet impregnation method. We confirmed that the addition of Na to $Pt/{\gamma}-Al_2O_3$ could cause a change in the oxidation state of Pt through an electronegative gap between Pt and Na atom, and increase the ratio of the metallic Pt. The metallic Pt species made by adding an optimum Na content improved the adsorption of NO species on the catalyst surface and restrained the oxidation of $CH_4$ to $CO_2$. When molar ratio of Na/Pt was 4.0, the highest catalytic activity could be obtained.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.77.2-77.2
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• 2013

In this talk, I will briefly review recent results of my group related to application of atomic layer deposition (ALD) for fabricating environmental catalysts and organic solar cells. ALD was used for preparing thin films of TiO2 and NiO on mesporous silica with a mean pore size of 15 nm. Upon depositing TiO2 thin films of TiO2 using ALD, the mesoporous structure of the silica substrate was preserved to some extent. We show that efficiency for removing toluene by adsorption and catalytic oxidation is dependent of mean thickness of TiO2 deposited on silica, i.e., fine tuning of the thickness of thin film using ALD can be beneficial for preparing high-performing adsorbents and oxidation catalysts of volatile organic compound. NiO/silica system prepared by ALD was used for catalysts of chemical conversion of CO2. Here, NiO nanoparticles are well dispersed on silica and confiend in the pore, showing high catalytic activity and stability at 800oC for CO2 reforming of methane reaction. We also used ALD for surface modulation of buffer layers of organic solar cell. TiO2 and ZnO thin films were deposited on wet-chemically prepared ZnO ripple structures, and thin films with mean thickness of ~2 nm showed highest power conversion efficiency of organic solar cell. Moreover, performance of ALD-prepared organic solar cells were shown to be more stable than those without ALD. Thin films of oxides deposited on ZnO ripple buffer layer could heal defect sites of ZnO, which can act as recombination center of electrons and holes.