• Title/Summary/Keyword: metal catalyst

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A Facile and Efficient Synthesis of Dronedarone Hydrochloride

  • Li, Feng;Jin, Chunhua;Zou, Jianwei;Wu, Jun
    • Bulletin of the Korean Chemical Society
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    • v.35 no.7
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    • pp.1970-1972
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    • 2014
  • A facile and efficient synthesis of dronedarone hydrochloride starting from commercially available 4-nitrophenol is described. This approach features a tandem-type synthesis of 3-carbonylated benzofuran involving cyclization of 2-ethynylphenol followed by $CO_2$ fixation at the 3-position of the benzofuran ring mediated by potassium carbonate without the addition of any transition metal catalyst.

THERMAL PLASMA SYNTHESIS OF NANO-SIZED POWDERS

  • Seo, Jun-Ho;Hong, Bong-Guen
    • Nuclear Engineering and Technology
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    • v.44 no.1
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    • pp.9-20
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    • 2012
  • A brief review on the thermal plasma synthesis of nano-sized powders is presented according to the application materials, such as, metals, ceramics, glasses, carbonaceous materials and other functional composites, such as, supported metal catalyst and core-shell structured nano materials. As widely adopted plasma sources available for thermal plasma synthesis of nanosized powders, three kinds of plasma torches, such as transferred and non-transferred DC and RF plasma torches, are introduced with the main features of each torch system. In the basis of the described torch features and the properties of suggested materials, application results including synthesis mechanism are reviewed in this paper.

Ammonia Decomposition Over Tantalum Carbides of Hydrogen Fuel Cell (수소연료전지용 탄탈륨 탄화물에 대한 암모니아 분해반응)

  • Choi, Jeong-Gil
    • New & Renewable Energy
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    • v.9 no.1
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    • pp.51-59
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    • 2013
  • Tantalum carbide crystallites which is to be used for $H_2$ fuel cell has been synthesized via a temperature-programmed reduction of $Ta_2O_5$ with pure $CH_4$. The resultant Ta carbide crystallites prepared using two different heating rates and space velocity exhibit the different surface areas. The $O_2$ uptake has a linear relation with surface area, corresponding to an oxygen capacity of $1.36{\times}10^{13}\;O\;cm^{-2}$. Tantalum carbide crystallites are very active for hydrogen production form ammonia decomposition reaction. Tantalum carbides are as much as two orders of magnitude more active than Pt/C catalyst (Engelhard). The highest activity has been observed at a ratio of $C_1/Ta^{{\delta}+}=0.85$, suggesting the presence of electron transfer between metals and carbon in metal carbides.

Synthesis of Vertically Aligned SiNW/Carbon Core-shell Nanostructures

  • Kim, Jun-Hui;Kim, Min-Su;Kim, Dong-Hwan
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.488.2-488.2
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    • 2014
  • Carbon-based materials such as carbon nanotubes and graphene have emerged as promising building blocks in applications for nanoelectronics and energy devices due to electrical property, ease of processability, and relatively inert electrochemistry. In recent years, there has been considerable interest in core-shell nanomaterials, in which inorganic nanowires are surrounded by inorganic or organic layers. Especially, carbon encapsulated semiconductor nanowires have been actively investigated by researchers in lithium ion batteries. We report a method to synthesize silicon nanowire (SiNW) core/carbon shell structures by chemical vapor deposition (CVD), using methane (CH4) as a precursor at growth temperature of $1000{\sim}1100^{\circ}C$. Unlike carbon-based materials synthesized via conventional routes, this method is of advantage of metal-catalyst free growth. We characterized these materials with FE-SEM, FE-TEM, and Raman spectroscopy. This would allow us to use these materials for applications ranging from optoelectronics to energy devices such as solar cells and lithium ion batteries.

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Synthesis of Graphene Oxide Based CuOx Nanocomposites and Application for C-N Cross Coupling Reaction

  • Choi, Jong Hoon;Park, Joon B.
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.176.1-176.1
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    • 2014
  • Graphene has attracted an increasing attention due to its extraordinary electronic, mechanical, and thermal properties. Especially, the two dimensional (2D) sheet of graphene with an extremely high surface to volume ratio has a great potential in the preparation of multifunctional nanomaterials, as 2D supports to host metal nanoparticles (NPs). Copper oxide is widely used in various areas as antifouling paint, p-type semiconductor, dry cell batteries, and catalysts. Although the copper oxide(II) has been well known for efficient catalyst in C-N cross-coupling reaction, copper oxide(I) has not been highlighted. In this research, CuO and Cu2O nanoparticles (NPs) dispersed on the surface of grapehene oxide (GO) have been synthesized by impregnation method and their morphological and electronic structures have been systemically investigated using TEM, XRD, and XAFS. We demonstrate that both CuO and Cu2O on graphene presents efficient catalytic performance toward C-N cross coupling reaction. The detailed structural difference between CuO and Cu2O NPs and their effect on catalytic performance are discussed.

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Properties of CNT field effect transistors using top gate electrodes (탑 게이트 탄소나노튜브 트랜지스터 특성 연구)

  • Park, Yong-Wook;Yoon, Seok-Jin
    • Journal of Sensor Science and Technology
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    • v.16 no.4
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    • pp.313-318
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    • 2007
  • Single-wall carbon nanotube field-effect transistors (SWCNT FETs) of top gate structure were fabricated in a conventional metal-oxide-semiconductor field effect transistor (MOSFET) with gate electrodes above the conduction channel separated from the channel by a thin $SiO_{2}$ layer. The carbon nanotubes (CNTs) directly grown using thin Fe film as catalyst by thermal chemical vapor deposition (CVD). These top gate devices exhibit good electrical characteristics, including steep subthreshold slope and high conductance at low gate voltages. Our experiments show that CNTFETs may be competitive with Si MOSFET for future nanoelectronic applications.

Photocatalytic Epoxidation of Olefins Using Molecular O2 by TiO2 Incorporated in Hydrophobic Y Zeolite

  • Kuwahara, Yasutaka;Magatani, Yasuhiro;Yamashita, Hiromi
    • Rapid Communication in Photoscience
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    • v.4 no.1
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    • pp.19-21
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    • 2015
  • Zeolite is an ideal host material for encapsulating nano-size metal catalyst species because of its defined microporous structure, prominent adsorption/condensation properties, high surface area, chemical/thermal stability, and transparency to light. In this study, $TiO_2$ photocatalyst was incorporated in highly hydrophobic Y zeolite and its photocatalytic activity was examined in the photocatalytic oxidation of olefins under UV-light irradiation using molecular oxygen as an oxygen source. $TiO_2$ nanoparticles incorporated in hydrophobic Y zeolite exhibited a markedly enhanced photocatalytic activity compared with bare $TiO_2$ owing to its excellent affinity toward organic moieties, which facilitates the mass transfer of organic substrates and allows them to efficiently access to the neighboring active $TiO_2$ surface.

Water-spliting on ultrathin MgO(100) film on Ag(100)

  • Jo, Seong-Beom;Jo, Jun-Hyeong;Jeong, Yong-Jae
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.02a
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    • pp.317-317
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    • 2011
  • Water dissociation on oxide surface has been researched in many fields because of its importance as fundamental phenomenas. MgO(001) is a good model system to understand heterogeneous catalysis, gas sensors, ground-water contaminants, and atmosphere chemistry. Over decades, ultrathin film of MgO on Ag(100) have attracted research activities thanks to its enhanced catalytic property. Correlation of the oxide and the metal, potential screening, charge fluctuation from interface reconstruction makes different energetics of hydroxylation of waters on film. We calculate the water-spliting energetics under the vacuum system.

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Electrochemical Reduction of High Pressure Carbon Dioxide on Metal Electrodes and Gas Diffusion Electrodes

  • Hara, Kohjiro;Sakata, Tadayoshi
    • Analytical Science and Technology
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    • v.8 no.4
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    • pp.683-689
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    • 1995
  • Electrochemical reduction of carbon dioxide under high pressure on Fe electrodes and a gas diffusion electrode containing Pt catalyst (Pt-GDE) had been investigated. Formic acid was formed on Fe electrode with a faradaic efficiency of 60% at a current density of $120mA\;cm^{-2}$ under 30 atm of $CO_2$. Hydrocarbons such as $CH_4$, $C_2H_6$, $C_3H_6$, $1-C_4H_8$, and $n-C_5H_{12}$ are also formed. The distribution of hydrocarbons followed well the Schultz-Flory distribution. $CH_4$ was formed efficiently as the main reduction product on Pt-GDE.

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A Study on reaction kinetics of HC-SCR of metal/zsm-5 catalyst (금속/ZSM-5 촉매의 HC-SCR 반응속도 연구)

  • Cho, Sae-Jung;Lee, Hye-Min;Lee, Min-Joo;Lee, Ju-Hun;Han, Seung-Tak;Kim, Jin-Gul
    • Proceedings of the KAIS Fall Conference
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    • 2006.05a
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    • pp.565-568
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    • 2006
  • Fe, Co, Zn, Cu, Pt 등의 전이금속과 ZSM-5 2종($SiO_2/Al_2O_3$ 몰비: 23, 50)과 ${\gamma}-alumina$를 담체로 사용하여 촉매를 합성하였다. 합성방법은 CVD(화학기상증착법) 과 Dry Impregnation (건식함침법), Incipient Wetness Impregnation방법이 있다. CVD 방법으로 얻은 Fe/ZSM-5과 Dry Impregnation방법으로 얻은 Cu/ZSM-5은 NO저감효율에 있어 거의 비슷하였다. 지지체로 사용된 ZSM-5의 $SiO_2/Al_2O_3$의 몰 비가 작을수록, 즉 산점의 수가 많을수록 우수한 것으로 보인다.

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