• Title, Summary, Keyword: Ceramic catalysts

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Modification of Thermal Degradation of Oligo(methylsilene) Catalyzed by Group 4 and 6 Transition Metal Complexes

  • 우희권;양수연;황택성;김동표
    • Bulletin of the Korean Chemical Society
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    • v.19 no.12
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    • pp.1310-1314
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    • 1998
  • The oligo(methylsilene) (1) was treated with the group 4 metallocene Cp2MCl2/Red-Al (M = Ti, Zr, Hf) combination catalysts and with the group 6 metal carbonyl M(CO)6 (M = Cr, W) catalysts, producing the modified, cross-linked polymers. The average molecular weights and percent ceramic residue yields of modified polymers increase as the catalyst goes down from Ti to Hf and similarly as the catalyst goes down from Cr to W. An interrelationship between average molecular weights and percent ceramic residue yield is found within the respective group of catalysts, but is not observed as the catalyst goes down from Ti to W. The polymers modified with the group 4 metallocene combination catalysts have higher molecular weights and similar percent ceramic residue yields as compared to the polymers modified with the group 6 metal carbonyl catalysts. The catalytic activities of group 4 metallocene combinations appear to be higher -100 ℃, but to be lower at very high temperature than those of group 6 metal carbonyls.

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A Study on the Removal of SOx and NOx Using Catalytic Ceramic Filters (촉매담지 세라믹 필터를 이용한 황산화물과 질소산화물의 제거에 관한 연구)

  • 홍민선;이동섭
    • Journal of Korean Society for Atmospheric Environment
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    • v.14 no.5
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    • pp.455-464
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    • 1998
  • Removal teals of Soxmox were performed using low density ceramic filters doped with various catalysts. Disc type (50 mmO.Dx10 mmt) low density ceramic filters were doped with three different catalysts such as Cu to remove SOx and NOx, and Mn and Co to remove NOx. The air permeabilities and specific surface areas were 40~50cc/min.cm2.cmH2O and 4.1~8.88 m2/g, respectively. Also, the peak pore sizes of catalyst support were 3~5nm. Tests were focused to search optimum operating temperatures for different catalysts. It was found that as the CuO content increases, SOx removal efficiency was increased. NOx removal efficiencies for Mn, Cu and Co, were 85% at 30$0^{\circ}C$, 90% at 40$0^{\circ}C$ and 90% at 45$0^{\circ}C$, respectively.

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The Effects of Catalyst on the Hydrolysis and Polymerization of TEOS (Tetra Ethyl Ortho Silicate의 수화 및 중합에 미치는 촉매의 영향)

  • ;;S. Sakka
    • Journal of the Korean Ceramic Society
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    • v.27 no.1
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    • pp.86-90
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    • 1990
  • The shape and characteristics of polymers in hydrolzed and polymerized sol were affected by the types of catalysts. In our research, the contents of water and catalysts were constant and the types of catalyst were varied. In the case of acid catalysts, polymers in sol were linear and spinnable. The shapes of polymer were affected by the types of anions in acid catalysts. In the case of catalyst having anions, F, Cl, in the same period, the effects were similar. But in the case of base catalysts polymers were rigid rod like and not spinnable.

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Catalytic Effects of Barium Carbonate on the Anodic Performance of Solid Oxide Fuel Cells

  • Yoon, Sung-Eun;Ahn, Jae-Yeong;Park, Jong-Sung
    • Journal of the Korean Ceramic Society
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    • v.52 no.5
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    • pp.350-355
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    • 2015
  • To develop ceramic composite anodes of solid oxide fuel cells without metal catalysts, a small amount of barium carbonate was added to an $(La_{0.8}Sr_{0.2})(Cr_{0.5}Mn_{0.5})O_3(LSCM)$ - YSZ ceramic composite anode and its catalytic effects on the electrode performance were investigated. A barium precursor solution with citric acid was used to synthesize the barium carbonate during ignition, while a barium precursor solution without citric acid was used to create hydrated barium hydroxide. The addition of barium carbonate to the ceramic composite anode caused stable fuel cell performance at 1073 K; this performance was higher than that of a fuel cell with $CeO_2$ catalyst; however, the addition of hydrated barium hydroxide to the ceramic composite anode caused poor stability of the fuel cell performance.

The Study on the Supported Oxide Catalysts for Reducing CO Gas in Automotive Exhaust Gas (자동차 배기가스 중의 CO 가스 제거를 위한 촉매장치의 개발에 관한 연구)

  • Kim, Hwan
    • Journal of the Korean Ceramic Society
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    • v.17 no.4
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    • pp.179-187
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    • 1980
  • Perovskite-type oxide catalysts in the $\textrm{LaMnO}_3$ family were prepared by both freeze drying and precipitation technique, and their catalytic activities with respect to the oxidation of CO with $O_2$ were measured in the composite gases. Freeze drying is a new technique for the prevention of migration of the solutes during drying. Therefore, the corrugated cordierite monolith fabricated with the Ø 1mm stainless steel bar was directly impregnated with nitrate solutions containing the appropriate cations, freeze dried and calcined. Precipitation was done by using $\textrm{(NH_4)}_2\textrm{CO}_3$ but the precipitated catalysts gave lower catalytic than the freeze dried samples due to, in part, relatively high calcining temperature. In this study, freeze dried composition had high catalytic activity, and their apparent activation energy for oxidation of CO was calculated by the rate plots using the data where the percent conversion of CO was less than 20%.

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Effect of Catalysts on Preparation of Mullite Precursor Using Silicic Acid Extracted by THF from Sodium Silicate (규산 나트륨으로부터 THF에 의해 추출된 규산을 이용한 Mullite 전구체 제조시 촉매에 대한 영향)

  • 정흥호;박은희;김도수;정호승;노재성
    • Journal of the Korean Ceramic Society
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    • v.37 no.6
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    • pp.517-523
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    • 2000
  • Effect of catalysts, which was catalyzed by acid(HCl and HNO3) and base(NH4OH), on characteristics of the mullite powders prepared by sol-gel methdo wa sinvestigated by XRD, TGA, SEm AND BET. As a result, weight loss as a function of catalysts was in order of HCl=32.6%>HNO3=25.44%>Non=24.0%>NH4OH=22.5%. The mullite powder dried at 100$^{\circ}C$ appeared spherical shape in acid catalyst and different shape in base catalyst, but sintering powder at 1400$^{\circ}C$ appeared very fine particle of 0.05∼0.1$\mu\textrm{m}$ regardless of catalysts. In all cae, the pore quantity, which was capable to adsoprtion, was decreased with increasing temperature. In base catalyst, no change of special surface area in mullite appeared.

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Selective Catalytic Reduction of Nitric Oxide over Metal Exchanged ZSM-5 Catalysts (금속을 이온교환시킨 ZSM-5 촉매 상에서 Nitric Oxide의 환원반응)

  • Ahn, Sung-Hwan;Kim, Tae-Ok;Hahm, Hyun-Sik
    • Journal of the Korean Applied Science and Technology
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    • v.17 no.1
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    • pp.1-5
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    • 2000
  • The selective catalytic reduction(SCR) of nitric oxide by ethane in the presence of oxygen was investigated on Cu-ZSM-5, Co-ZSM-5 and Ga-ZSM-5 catalysts over a range of 400, 450 and $500^{\circ}C$. The catalysts were prepared by ion-exchange method. The composition of the reactant gases were 1000 ppm of NO, 1000 ppm of $C_{2}H_{6}$ and 2.5% of $O_{2}$, and the reaction was conducted in a fixed-bed reactor at 1 atm. For the 20wt% Co-ZSM-5(50) catalyst, the NO conversion reached up to 100%, while the $C_2H_6$ conversion and the CO selectivity were about 50% and 25%, respectively, at $450^{\circ}C$. For the 20wt% Cu-ZSM-5(50) catalyst, the NO conversion and the C2H6 conversion were about 80% and 100%, respectively, but there was no CO produced. The metal ion-exchanged ZSM-5 catalysts exhibited a tendency to increase the NO conversion with the Si/Al ratio of the ZSM-5, that is, NO conversion was inversely proportional to the acidity of the catalysts. But, the effect of the acidity on NO conversion was not so large. From the XRD results of the catalysts before and after SCR reaction it was found that there was no structural change.

Preparation of 27Ni6Zr4O143M(M=Mg, Ca, Sr, or Ba)O/70 Zeolite Y Catalysts and Hydrogen-rich Gas Production by Ethanol Steam Reforming

  • Kim, Dongjin;Lee, Jun Su;Lee, Gayoung;Choi, Byung-Hyun;Ji, Mi-Jung;Park, Sun-Min;Kang, Misook
    • Bulletin of the Korean Chemical Society
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    • v.34 no.7
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    • pp.2073-2080
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    • 2013
  • In this study the effects of adding alkaline-earth (IIA) metal oxides to NiZr-loaded Zeolite Y catalysts were investigated on hydrogen rich production by ethanol steam reforming (ESR). Four kinds of alkaline-earth metal (Mg, Ca, Sr, or Ba) oxides of 3.0% by weight were loaded between the $Ni_6Zr_4O_{14}$ main catalytic species and the microporous Zeolite Y support. The characterizations of these catalysts were examined by XRD, TEM, $H_2$-TPR, $NH_3$-TPD, and XPS. Catalytic performances during ESR were found to depend on the basicity of the added alkaline-earth metal oxides and $H_2$ production and ethanol conversion were maximized to 82% and 98% respectively in 27($Ni_6Zr_4O_{14}$)3MgO/70Zeolite Y catalyst at $600^{\circ}C$. Many carbon deposits and carbon nano fibers were seen on the surface of $30Ni_6Zr_4O_{14}$/70Zeolite Y catalyst but lesser amounts were observed on alkaline-earth metal oxide-loaded 27($Ni_6Zr_4O_{14}$)3MO/70Zeolite Y catalysts in TEM photos after ESR. This study demonstrates that hydrogen yields from ESR are closely related to the acidities of catalysts and that alkaline-earth metal oxides reduce the acidities of 27($Ni_6Zr_4O_{14}$)3MO/70Zeolite Y catalysts and promote hydrogen evolution by preventing progression to hydrocarbons.

Catalytic Detoxication of Coal Combustion Gases (연탄 연소가스의 촉매제독에 관한 연구)

  • Tuwon Chang;Young Sun Uh;Youn Soo Sohn
    • Journal of the Korean Chemical Society
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    • v.29 no.6
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    • pp.656-663
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    • 1985
  • A catalytic conversion of carbon monoxide has been studied in a coal combustion system. Three different catalysts were prepared by impregnating 0.2% platinum on three different types of supports, ${\gamma}-Al_2O_3$ pellets, ceramic foam and honeycomb. These catalysts have shown an excellent initial activities in the coal combustion system, but they were rapidly deactivated in repeated uses. Among these catalysts ceramic foam has shown to be better than others both in activities and durabilities. The main cause of deactivation seems to be ascribed to poisoning by zinc metal and sulfur compounds and to decrease in platinum surface area by sintering.

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The Synthesis of Aluminum Alkoxides (알루미늄 알콕사이드의 합성)

  • 정재식;박원규
    • Journal of the Korean Ceramic Society
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    • v.35 no.9
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    • pp.953-957
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    • 1998
  • The effects of catalysts and reactive conditions on the synthesis of aluminum alkoxides are investigated. HgCl2 and I2 as catalysts are used in the synthesis reaction for comparing to no addtion. The absorption peak in IR spectra according to Al-O-L bond of aluminum isopropoxide and aluminum sec-butoxide appear at near 1030cm-1 and 1060cm-1 respectively regardless of kinds of catalysts. The synthesis yield of alu-minum-isopropoxide was 90% in case of no catalyst addition and increased to all of 95% by addition of HgCl2 and I2 The synthesis yield of aluminum sec-butoxide is increased to 95% by addition of I2 catalyst com-paring to no addition.

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