• Title, Summary, Keyword: metal catalyst

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Synthesis and Microstructure Analysis of NiO Catalysts Coated on the FeCrAl Metal Alloy Foam for Hydrogen Production (수소제조를 위한 다공성 FeCrAl 금속 합금 Foam의 NiO 촉매 담지 및 미세구조 분석)

  • Lee, Yu-Jin;An, Geon-Hyoung;Park, Man-Ho;Lee, Chang-Woo;Choi, Sang-Hyun;Jung, Ju-Yong;Jo, Sung-Jong;Lee, Kun-Jae;Ahn, Hyo-Jin
    • Korean Journal of Materials Research
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    • v.24 no.8
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    • pp.393-400
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    • 2014
  • NiO catalysts were successfully coated onto FeCrAl metal alloy foam as a catalyst support via a dip-coating method. To demonstrate the optimum amount of NiO catalyst on the FeCrAl metal alloy foam, the molar concentration of the Ni precursor in a coating solution was controlled, with five different amounts of 0.4 M, 0.6 M, 0.8 M, 1.0 M, and 1.2 M for a dip-coating process. The structural, morphological, and chemical bonding properties of the NiO-catalyst-coated FeCrAl metal alloy foam samples were assessed by means of field-emission scanning electron microscopy(FESEM), scanning electron microscopy-energy dispersive spectroscopy(SEM-EDS), X-ray diffraction(XRD), and X-ray photoelectron spectroscopy(XPS). In particular, when the FeCrAl metal alloy foam samples were coated using a coating solution with a 0.8 M Ni precursor, well-dispersed NiO catalysts on the FeCrAl metal alloy foam compared to the other samples were confirmed. Also, the XPS results exhibited the chemical bonding states of the NiO phases and the FeCrAl metal alloy foam. The results showed that a dip-coating method is one of best ways to coat well-dispersed NiO catalysts onto FeCrAl metal alloy foam.

Growth of SiO2 Nanowire by Catalyst Evaporation Method (촉매의 휘발법에 의한 이산화규소 나노와이어의 성장)

  • Rho, Dae-Ho;Kim, Jae-Soo;Byun, Dong-Jin;Lee, Jae-Hoon;Yang, Jae-Woong;Kim, Na-Ri
    • Korean Journal of Materials Research
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    • v.15 no.3
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    • pp.189-194
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    • 2005
  • [ $SiO_2$ ] nanowires were synthesized using the catalyst evaporation method. Grown nanowires had different shapes by kind of used metal catalyst. Mean diameters of grown $SiO_2$ nanowire were about 30 nm. The kind of catalysts affected microstructure of grown $SiO_2$ nanowire because of its typical growth reactions through the liquid state metal catalysts. Optical property were measured by photoluminescence spectroscopy. Relatively broad peak was obtained and mean peak positioned at 450 nm.

The deactivation behavior of SCR catalyst by alkali and alkali earth metal (알칼리 및 알칼리 토금속에 의한 SCR 촉매 비활성 거동)

  • Han, Seungyun;Shin, Min-Chul;Lee, Heesoo
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.26 no.6
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    • pp.238-242
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    • 2016
  • The effect of the alkali, alkali earth metal elements on selective catalytic reduction(SCR) catalyst deactivation behavior were investigated in terms of microstructure, surface area, pore volume and De-NOx test. Poisoned SCR catalyst were manufactured by injection of $K_2CO_3$, $Na_2CO_3$, $Ca(CH_3COO)_2{\cdot}H_2O$, $C_4H_6MgO_4{\cdot}4H_2O$, $H_3PO_4$ solutions in the new SCR catalyst at $350^{\circ}C$ for 6 hours. New and poisoned catalysts surface were similar. But specific surface area, pore volume decrease from Na, Mg, K, Ca, P compared to new SCR catalyst. Especially, Na poisoned catalyst surface area and pore size extremely decreased by $10.20m^2/g$, $0.061cm^2/g$. De-NOx test results of new and poisoned catalysts at $150{\sim}450^{\circ}C$ indicated that alkali metal (K, Na) poisoned SCR catalysts have the lowest De-NOx efficiency, alkali earth metal poisoned SCR catalysts (Ca, Mg) De-NOx efficiency are higher than alkali metal poisoned SCR catalysts. P poisoned SCR catalyst De-NOx efficiency is similar new SCR catalyst. It were considered that physical deactivation of SCR catalyst was affected by SCR catalyst surface area and pore volume change.

Noble metal catalysts for Water Gas Shift reaction (귀금속계열 WGS 촉매 연구)

  • Lim, Sung-Kwang;Bae, Joong-Myeon;Kim, Sun-Young
    • Proceedings of the KSME Conference
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    • pp.2228-2231
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    • 2007
  • Water gas shift reactor in fuel processing is an important part that converts carbon monoxide into hydrogen. Fuel processing system for PEMFC usually has two stages of WGS reactors, which are high temperature and low temperature shifter. In this study we prepared noble metal catalysts and compared their performances with that of a commercial iron chromium oxide catalyst. Noble metal catalysts and the commercial catalyst showed quite different temperature dependence of carbon monoxide conversion. The conversion of carbon monoxide at the commercial catalyst was very low at medium temperature(${\sim}300^{\circ}C$) and increased rapidly as temperature increased while the conversion at noble metal catalysts was high in the medium temperature range and decreased as temperature increased, which is thermodynamically expected. Their characteristics agreed well with the literature published, and we are accomplishing further study for improvement of the noble metal catalysts.

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Metal organic framework derived Cu-carbon composite: An efficient non-noble metal catalyst for reduction of hexavalent chromium and pendimethalin

  • Hasan, Zubair;Cho, Jinwoo;Rinklebe, Jorg;Ok, Yong Sik;Cho, Dong-Wan;Song, Hocheol
    • Journal of Industrial and Engineering Chemistry
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    • v.52
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    • pp.331-337
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    • 2017
  • A Cu-carbon composite was facilely synthesized via one step calcination of a Cu-based metal organic frameworks (MOF), HKUST-1, under $N_2$ atmosphere. Physicochemical characteristics of the composite were examined with a series of spectroscopy and surface analyzer. The composite was used as a catalyst in the reduction of Cr(VI) and pendimethalin using HCOOH and $NaBH_4$ as reductants, respectively. The composite was very efficient in both reduction reactions, completing the reactions in several minutes. The composite also exhibited a robust reusability in the completion of four repeated Cr(VI) reduction cycles, demonstrating its potential utility as an alternative to noble-metal catalysts.

Development of Micro-Tubular Perovskite Cathode Catalyst with Bi-Functionality on ORR/OER for Metal-Air Battery Applications

  • Jeon, Yukwon;Kwon, Ohchan;Ji, Yunseong;Jeon, Ok Sung;Lee, Chanmin;Shul, Yong-Gun
    • Korean Chemical Engineering Research
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    • v.57 no.3
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    • pp.425-431
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    • 2019
  • As rechargeable metal-air batteries will be ideal energy storage devices in the future, an active cathode electrocatalyst is required with bi-functionality on both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) during discharge and charge, respectively. Here, a class of perovskite cathode catalyst with a micro-tubular structure has been developed by controlling bi-functionality from different Ru and Ni dopant ratios. A micro-tubular structure is achieved by the activated carbon fiber (ACF) templating method, which provides uniform size and shape. At the perovskite formula of $LaCrO_3$, the dual dopant system is successfully synthesized with a perfect incorporation into the single perovskite structure. The chemical oxidation states for each Ni and Ru also confirm the partial substitution to B-site of Cr without any changes in the major perovskite structure. From the electrochemical measurements, the micro-tubular feature reveals much more efficient catalytic activity on ORR and OER, comparing to the grain catalyst with same perovskite composition. By changing the Ru and Ni ratio, the $LaCr_{0.8}Ru_{0.1}Ni_{0.1}O_3$ micro-tubular catalyst exhibits great bi-functionality, especially on ORR, with low metal loading, which is comparable to the commercial catalyst of Pt and Ir. This advanced catalytic property on the micro-tubular structure and Ru/Ni synergy effect at the perovskite material may provide a new direction for the next-generation cathode catalyst in metal-air battery system.

A Method for Suppression of Active Metal Leaching during the Direct Synthesis of H2O2 by Using Polyelectrolyte Multilayers (고분자 전해질 다층박막을 이용한 과산화수소 직접제조 반응 중 활성금속 용출 억제 방법)

  • Chung, Young-Min
    • Korean Chemical Engineering Research
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    • v.53 no.2
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    • pp.262-268
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    • 2015
  • In this study, two types of catalysts were prepared via conventional metal supporting method and encapsulation of metal nanoparticles in the polyelectrolyte multilayers constructed on support. The resulting catalysts were applied to the direct synthesis of hydrogen peroxide, and the effect of catalyst preparation method on the catalyst life as well as hydrogen peroxide productivity was investigated. The catalytic activity was strongly dependent upon the acid strength of support regardless of the catalyst preparation methods and HBEA (SAR=25) with strong acidity was superior to other supports to promote the reaction. In the case of metal supported catalyst, while hydrogen peroxide productivity was higher than that of polyelectrolyte multilayered counterpart, the reaction performance was sharply decreased during catalyst recycling due to the metal leaching. On the other hand, construction of polyelectrolyte multilayers on support weakened the influence of acid support on the reaction medium and therefore resulted in the decrease of catalytic activity and the increase of hydrogen peroxide decomposition as well. It is noted, however, that the catalytic activity was maintained after 5 recycles, which suggests that the introduction of polyelectrolyte multilayers on the support is very effective to suppress the unfavorable metal leaching phenomenon during a reaction.

The Influence of a Second Metal on the Ni/SiC Catalyst for the Methanation of Syngas

  • Song, Lanlan;Yu, Yue;Wang, Xiaoxiao;Jin, Guoqiang;Wang, Yingyong;Guo, XiangYun
    • Korean Chemical Engineering Research
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    • v.52 no.5
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    • pp.678-687
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    • 2014
  • The catalytic performance of silicon carbide supported nickel catalysts modified with or without second metal (Co, Cu and Zn) for the methanation of CO has been investigated in a fixed-bed reactor using a feed consisting of 25% CO and 75% $H_2$ without any diluent gas. It has been found that the introduction of Co species can clearly improve the catalytic activity of Ni/SiC catalyst, whereas the addition of Cu or Zn can result in a significant decrease in the catalytic activity. The characterizations by means of XRD, TEM, XPS, CO-TPD and $H_2$-TPR indicate that the addition of Co could decrease the particle size of active metal, increase active sites on the surface of methanation catalyst, improve the chemisorption of CO and enhance the reducibility of methanation catalysts. Additionally, the special interaction between Co species and Ni species is likely favorable for the dissociation of adsorbed CO on the surface of catalyst, and this may also contribute to the high activity of 5Co-Ni/SiC catalyst for CO methanation reaction. For 5Cu-Ni/SiC catalyst and 5Zn-Ni/SiC catalyst, Cu and Zn species could cover partial nickel particles and decrease the chemisorption amount of CO. These could be responsible for the low methanation activity. In addition, a 150h stability test under 2 MPa and $300^{\circ}C$ showed that 5Co-Ni/SiC catalyst was very stable for CO methanation reaction.

Recent Research Progress on the Atomic Layer Deposition of Noble Metal Catalysts for Polymer Electrolyte Membrane Fuel Cell (고분자 전해질 연료전지용 촉매 소재 개발을 위한 원자층증착법 연구 동향)

  • Han, Jeong Hwan
    • Journal of Korean Powder Metallurgy Institute
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    • v.27 no.1
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    • pp.63-71
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    • 2020
  • It is necessary to fabricate uniformly dispersed nanoscale catalyst materials with high activity and long-term stability for polymer electrolyte membrane fuel cells with excellent electrochemical characteristics of the oxygen reduction reaction and hydrogen oxidation reaction. Platinum is known as the best noble metal catalyst for polymer electrolyte membrane fuel cells because of its excellent catalytic activity. However, given that Pt is expensive, considerable efforts have been made to reduce the amount of Pt loading for both anode and cathode catalysts. Meanwhile, the atomic layer deposition (ALD) method shows excellent uniformity and precise particle size controllability over the three-dimensional structure. The research progress on noble metal ALD, such as Pt, Ru, Pd, and various metal alloys, is presented in this review. ALD technology enables the development of polymer electrolyte membrane fuel cells with excellent reactivity and durability.

Decomposition of Eco-friendly Liquid Propellants over Ruthenium/Al2O3/metal foam Catalysts (Ru/Al2O3/메탈폼 촉매를 이용한 친환경 액체추진제 분해)

  • Yoo, Dalsan;Jeon, Jong-Ki
    • Clean Technology
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    • v.25 no.3
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    • pp.256-262
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    • 2019
  • Hydroxylammonium nitrate (HAN)-based liquid propellants are attracting attention as environmentally friendly propellants because they are not carcinogens and the combustion gases have little toxicity. The catalyst used to decompose the HAN-based liquid propellant in a thruster must have both low temperature activity and high heat resistance. The objective of this study is to prepare an Ru/alumina/metal foam catalyst by supporting alumina slurry on the surface of NiCrAl metal foam using a washing coating method and then to support a ruthenium precursor thereon. The decomposition activity of a HAN aqueous solution of the Ru/alumina/metal foam catalyst was evaluated. The effect of the number of repetitive coatings of alumina slurry on the physical properties of the alumina/metal foam was analyzed. As the number of alumina wash coatings increased, mesopores with a diameter of about 7 nm were well-developed, thereby increasing the surface area and pore volume. It was optimal to repeat the wash coating alumina on the metal foam 12 times to maximize the surface area and pore volume of the alumina/metal foam. Mesopores were also well developed on the surface of the Ru/alumina/metal foam catalyst. It was found that the metal form itself without the active metal and alumina can promote the decomposition reaction of the HAN aqueous solution. In the case of the Ru/alumina/metal foam-550 catalyst, the decomposition onset temperature was significantly lowered compared with that of the thermal decomposition reaction, and ${\Delta}P$ could be greatly increased in the decomposition of the HAN aqueous solution. However, when the catalyst was calcined at $1,200^{\circ}C$, the catalytic activity was lowered inevitably because the surface area and pore volume of the catalyst were drastically reduced and Ru was sintered. Further research is needed to improve the heat resistance of Ru/alumina/metal foam catalysts.