• Applied Chemistry for Engineering
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• v.3 no.1
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• pp.24-34
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• 1992

Recent studies dealing with the fundamental understanding and applications of bimetallic catalysts are discussed. Bimetallic catalysts have had a major industrial impact, specifically for the reforming of petroleum naphtha, for the hydrogen reduction of carbon monoxide, and for the three way catalytic converter system. The action of the bimetallic catalysts in these reactions may be interpreted in terms of ensembles, electronic influences and surface structure. Various combinations of metal pairs have been considered in order to evaluate the role played by the added metals. For catalyst selectivity control, the possibility of surface enrichment of one element has been recognised. More generally, the influence of preparative variables on the formation of supported catalysts has been clarified, In particular by temperature programmed reduction (TPR). Information on the structure of bimetallic catalysts has been obtained with chemical probes, such as chemisorption and reaction rate measurement and physical probes, such as extended X-ray absorption fine structure (EXAFS), scanning transmission electron microscopy (STEM) and Xe-NMR.

• Journal of the Korean Electrochemical Society
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• v.17 no.4
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• pp.209-215
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• 2014

We report on the electrocatalytic activities at Pt nanostructure surfaces electrodeposited with different deposition charges on indium tin oxide electrodes for oxygen reduction and methanol oxidation reactions. The surface properties of Pt nanostructures depending on deposition charges were characterized by scanning electron microscopy, electrochemical surface area measurement, X-ray diffraction, and CO stripping analysis, which were correlated to the electrocatalytic activities. Pt nanostructures with deposition charge of 0.03 C exhibited the highest electrocatalytic activity for oxygen reduction and methanol oxidation. The sharp sites of Pt nanostructure and the presence of highly active facet play a key role, whereas the electrochemical surface area does not significantly affect the electrocatalytic activity. The results obtained in this work with regard to the dependence of electrocatalytic activity on the variation of the Pt nanostructures will give insights into the development of advanced electrocatalytic systems.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.4
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• pp.387-392
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• 2015

A method for measuring and analyzing the $NO_x$ in ships is described in $NO_x$ Technical Code 2008. The analysis device, as required by the Code, has been to use a Chemi-luminescence detection method or Heated Chemi-luminescence detection. on the other hand, selective catalytic reduction using $NH_3$ as a reducing agent has an interference effect on the analyzer, and causes measurement error. In this study, the Chemi-luminescence detection method was examined according to how it affects the concentration of $O_2$, CO, $SO_2$, $NH_3$. Fourier transform infrared spectrometry analysis equipment and measurement methods were compared. In order to confirm the effect of the physical interference of the measuring device, it was confirmed by decomposing a measuring device. Consequently, white precipitate and moisture were generated inside the chemiluminescence detection system and I found that affecting interference. The influence of interference highlights the need to consider the minimized $NO_x$ measurement method.

• Journal of the Korean Institute of Gas
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• v.14 no.2
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• pp.7-14
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• 2010

Synthesis gas was produced by the partial oxidation of methane. For the preparation of catalysts, Ni, known to be active in this reaction and cheap, was used as the active component and $CeO_2$, having high oxygen storage capability and high redox ability, was used as the support. The catalysts were prepared by the impregnation and urea methods. The catalyst prepared by the urea method showed about 11 times higher surface area and finer particle size than that prepared by the impregnation method. The catalysts prepared by the urea method showed higher methane conversion and synthesis gas selectivity than that prepared by the impregnation method. In this reaction, carbon deposition is a problem to be solved, so La was added to the catalyst system to reduce the carbon deposition. TGA analysis results showed that there was 2% carbon deposition with La-added catalysts and 16% with La-free catalysts. It was found that the addition of La decreases the amount of carbon deposition and prevents catalyst deactivation.

• Journal of the Korean Chemical Society
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• v.34 no.6
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• pp.561-568
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• 1990

Voltammetric behavior of some light lanthanide ions (La$^{3+}$, Pr$^{3+}$, Nd$^{3+}$, Sm$^{3+}$, and Eu$^{3+}$) in various supporting electrolytes has been investigated by several electrochemical techniques. The peak potentials and the peak currents, their dependency on the concentration, temperature and pH effects, the reversibility of the electrode reactions are described. The reduction of La$^{3+}$, Pr$^{3+}$ and Nd$^{3+}$ in 0.1 M lithium chloride proceeds by a three-electron change directly to the metallic state (Ln$^{3+}$ ＋ 3e- → Ln$^0$) and charge transfer is totally irreversible. However, the reduction of Sm$^{3+}$ in 0.1 M tetramethylammonium iodide and Eu$^{3+}$ in 0.1 M lithium chloride proceeds in two stages (Ln$^{3+}$ ＋ e- → Ln$^{2+}$ and Ln$^{2+}$ ＋ 2e- → Ln$^0$). At pH values lower than ca.4 the hydrated lanthanide species (Ln(OH)$^{2+}$) reduced before the lanthanide ions (Ln$^{3+}$) due to the catalytic effect of hydrogen ions, and peak current increase with in the order Eu$^{3+}$ < Sm$^{3+}$ < Nd$^{3+}$ < Pr$^{3+}$ < La$^{3+}$ in differential pulse polarography. Some representative plots of $i_{pc}V^{-1/2} (proportional to current function) vs. V show considerable influence of hydrogen ion/lanthanide ion concentration in cyclic voltammetry. It is shown that a reaction of lanthanide ions with proton and/or water and catalytic reaction is enhanced at lower pH and at decreased lanthanide ion concentration.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.371.2-371.2
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• 2014

가스 센서분야에서 특정 가스종에 대한 선택성과 감응도 향상을 위해 금속 촉매 등을 센서 물질 표면이나 내부 등에 형성시키는 방안이 많이 연구되고 있다. 1차원 구조 반도성 물질인 나노섬유 내에 금속 촉매를 형성시켜 특정 가스에 대한 선택성과 감응도를 향상시키는 연구가 보고된 바 있다. 선행연구에 의하면 Au와 Pt입자가 형성된 나노섬유의 경우, 각각 CO와 toluene가스에 대하여 선택적인 감응을 나타내는 것으로 확인되었다. 본 연구에서는 전기방사법과 광환원법을 동시에 이용하여 Au와 Pt 입자가 포함된 $SnO_2$ 나노섬유를 합성하고, 이들 나노섬유의 가스감응 특성을 연구하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.132.1-132.1
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• 2017

본 연구에서는 투명전극 제조를 목적으로 전기방사법을 이용하여 미세구리 패턴을 형성하는 방법에 대하여 연구하였다. $Ag^+$이온이 용해된 폴리비닐부티랄(PVB) 고분자 용액을 폴리에틸렌 테레프탈레이트(PET)와 같은 투명기판 위에 전기방사 하여 $Ag^+$이온/PVB 복합나노와이어를 제조한 후 이를 UV 조사로 환원하여 선택적으로 촉매를 형성하였다. 이후 연속적인 무전해 구리 도금을 통하여 촉매 위에 미세구리배선을 형성함으로써, 투명전극을 제조하였다. 개발 공정을 통해 제조된 투명전극은 기존 Ag나노와이어 기반 투명전극에서 발생하던 접촉저항에 대한 문제를 해결함으로써 전기적, 광학적 특성이 우수한 차세대 유연 디스플레이에 적용 가능성을 보여주었다.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.1
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• pp.92-100
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• 2000

The model gas reaction tests were carried out to investigate the purification characteristics of methane on the exclusive catalyst for NGV. The experiment was conducted with the factors which affect the conversion efficiency of methane, such as Redox ratio, coexistence components of CO, MO, $H_2$O, precious metals and additives. The catalyst loaded with larger amount of pd and with additive La showed lower light-off temperature. In the presence of CO and NO, the conversion efficiency of methane was varied according to the kind of additive loaded. The conversion efficiency of methane was dropped for the catalyst loaded with La under lean air-fuel ratio, while it increased for the one loaded with Ti+Zr for the same condition. It was shown that the water vapor inhibited methane from oxidation by its poisoning on the surface of catalyst.

• Clean Technology
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• v.23 no.4
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• pp.429-434
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• 2017

To investigate the effect of magnesium oxide addition, $Cu/ZnO/MgO/Al_2O_3$ (CZMA) catalysts were prepared using co-precipitation method with fixed molar ratio of Cu/Zn/Mg/Al as 45/45/5/5 mol% for low-temperature water gas shift reaction. Synthesized catalysts were characterized by using BET, $N_2O$ chemisorption, XRD, $H_2-TPR$ and $NH_3-TPD$ analysis. The catalytic activity tests were carried out at a GHSV of $28,000h^{-1}$ and a temperature range of $200{\sim}320^{\circ}C$. At the same condition, magnesium oxide added catalyst (CZMA 400) showed that the lowest reduction temperature and stable presence of $Cu^+$, that is active species and abundant weak acid site. Also magnesium oxide added catalysts (CZMA) showed higher catalytic activity at temperature range above $240^{\circ}C$ than the catalyst without magnesium oxide (CZA). Consequently, CZMA 400 catalyst is considered to be excellent catalyst showing CO conversion of 77.59% without deactivation for about 75 hours at $240^{\circ}C$, GHSV $28,000h^{-1}$.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2002.05a
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• pp.187-191
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• 2002

The exhaust gas from electric power stations, incinerators and industrial boilers contains considerable amount of harmful nitric oxide which causes air pollution. Selective catalytic reduction system with ammonia as a reductant(NH$_{3}$ SCR) have been applied to remove NOx since 1970. it is widely accepted that the NH$_{3}$ SCR process is the best method for the removal of NOx. In this paper the design of SCR reactor based on the NOx displacement is considered and the design program of SCR reactor is developed. The newly developed design program for de-NOx system maybe used in practice.