• Title/Summary/Keyword: Alkali-metal effect

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Overview of the Effect of Catalyst Formulation and Exhaust Gas Compositions on Soot Oxidation In DPF

  • Choi Byung Chul;FOSTER D.E.
    • Journal of Mechanical Science and Technology
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    • v.20 no.1
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    • pp.1-12
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    • 2006
  • This work reviews the effects of catalyst formulation and exhaust gas composition on soot oxidation in CDPF (Catalytic Diesel Particulate Filter). DOC's (Diesel Oxidation Catalysts) have been loaded with Pt catalyst (Pt/$Al_{2}O_3$) for reduction of HC and CO. Recent CDPF's are coated with the Pt catalyst as well as additives like Mo, V, Ce, Co, Fe, La, Au, or Zr for the promotion of soot oxidation. Alkali (K, Na, Cs, Li) doping of metal catalyst tends to increase the activity of the catalysts in soot combustion. Effects of coexistence components are very important in the catalytic reaction of the soot. The soot oxidation rate of a few catalysts are improved by water vapor and NOx in the ambient. There are only a few reports available on the mechanism of the PM (particulate matter) oxidation on the catalysts. The mechanism of PM oxidation in the catalytic systems that meet new emission regulations of diesel engines has yet to be investigated. Future research will focus on catalysts that can not only oxidize PM at low temperature, but also reduce NOx, continuously self-cleaning diesel particulate filters, and selective catalysts for NOx reduction.

Effect of Al Alloy Composition on Physical and Crystallographical Properties of Plasma Electrolytic Oxidized Coatings I. Physical Properties of PEO Layer (플라즈마 전해 산화 코팅에 있어서 알루미늄 합금 모재 성분의 물리적, 결정학적 영향 I. PEO 층의 물성)

  • Kim, Bae-Yeon;Lee, Deuk-Yong;Kim, Yong-Nam;Jeon, Min-Seok;Song, Jun-Kwang;Kim, Sung-Youp;Kim, Kwang-Youp
    • Journal of the Korean Ceramic Society
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    • v.47 no.3
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    • pp.256-261
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    • 2010
  • Physical properties of Plasma electrolytic oxidized 8 different types of Al alloys, A-1100, A-2024, A-5052, A-6061, A-6063, A-7075, ACD-7B and ACD-12 were investigated. The electrolyte for PEO was $Na_2SiO_3$ solutions with NaOH and some alkali earthen metal salts. Porous layer near the surface of PEO coating was not found, and surface roughness Ra50 was below 2.5 ${\mu}m$. Surface roughness was affected by growth rate of plasma electrolytic oxidized layer, not by Si content in Al alloy.

Catalytic Combustion of Carbon Particulate over LaMnO3 Perovskite-Type Oxides (LaMnO3형 페롭스카이트 산화물에서 입자상물질의 촉매연소반응)

  • Lee, Yong Hwa;Lee, Geun Dae;Park, Seong Su;Hong, Seong Su
    • Journal of Environmental Science International
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    • v.13 no.7
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    • pp.619-626
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    • 2004
  • We have studied the catalytic combustion of soot particulates over perovskite-type oxides prepared by malic acid method, The catalysts were modified to enhance the activity by substitution of metal into A or B site of perovskite oxide. In addition, the reaction conditions such as temperature and $O_2$ concentration were investigated. The partial substitution of alkali metals into A site in the $LaMnO_3$ catalyst, enhanced the catalytic activity in the combustion of carbon particulate and the activity was shown in the order: Cs > K > Na. For the $La_{1-x}Cs_{x}MnO_{3}$ catalysts, the catalytic activity showed the maximum value with x=0.3 but no more increase on the catalytic activity was shown with x > 0.3. For the $La_{0.8}Cs_{0.2}MnO_{3}$ catalyst, the substitution of Fe or Ni increased the ignition temperature. The ignition temperature decreased with an increase of $O_2$ concentration, however, no more increase in the catalytic activity was shown with $O_2$ concentration > 0.2. The introduction of NO into reactants showed no effect on the catalytic activity.

K and Cs Doped Ag/Al2O3 Catalyst for Selective Catalytic Reduction of NOx by Methane

  • Rao, Komateedi N.;Yu, Chang-Yong;Lack, Choi-Hee;Ha, Heon-Phil
    • Journal of Powder Materials
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    • v.18 no.6
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    • pp.510-516
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    • 2011
  • In the present study, potassium and caesium doped Ag/$Al_2O_3$ catalysts were synthesized by simple wet impregnation method and evaluated for selective catalytic reduction (SCR) of NOx using methane. TEM analysis and diffraction patterns demonstrated the finely dispersed Ag particles. BET surface measurements reveal that the prepared materials have moderate to high surface area and the metal amount found from ICP analysis was well matching with the theoretical loadings. The synthesized K-Ag/$Al_2O_3$ and Cs-Ag/$Al_2O_3$ catalysts exhibited a promotional effect on deNOx activity in the presence of $SO_2$ and $H_2O$. The long-term isothermal studies at $550^{\circ}C$ under oxygen rich condition showed the superior catalytic properties of the both alkali promoted samples. The crucial catalytic properties of materials are attributed to NO adsorption properties detected by the NO TPD.

Effect of Al Alloy Composition on Physical and Crystallographical Properties of Plasma Electrolytic Oxidized Coatings II. Crystallographic Analysis of PEO Layer (플라즈마 전해 산화 코팅에 있어서 알루미늄 합금 모재 성분의 물리적, 결정학적 영향 II. PEO 층의 결정상 분석)

  • Kim, Bae-Yeon;Lee, Deuk-Yong;Shin, Min-Chul;Shin, Hyun-Gyoo;Kim, Byeong-Kon;Kim, Sung-Youp;Kim, Kwang-Youp
    • Journal of the Korean Ceramic Society
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    • v.47 no.4
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    • pp.283-289
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    • 2010
  • Physical properties of Plasma electrolytic oxidized 8 different kinds of Al alloys, A-1100, A-2024, A-5052, A-6061, A-6063, A-7075, ACD-7B and ACD-12 were investigated. The electrolyte for PEO was $Na_2SiO_3$ and NaOH and some alkali earthen metal salts system solution. $\eta$-alumina, as well as $\gamma$-alumina, was main crystal phase, which were ever reported. Also, $Al_{4.95}Si_{1.05}O_{9.52}$ was found only in this research. So we can conclude that the process conditions of PEO apparatus and composition and concentration of its electrolyte affects crystal structure and physical properties of PEO layers much more than the compositions of Al alloy.

Removal of Cu and Fe Impurities on Silicon Wafers from Cleaning Solutions (세정액에 따른 실리콘 웨이퍼의 Cu 및 Fe 불순물 제거)

  • Kim, In-Jung;Bae, So-Ik
    • Korean Journal of Materials Research
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    • v.16 no.2
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    • pp.80-84
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    • 2006
  • The removal efficiency of Cu and Fe contaminants on the silicon wafer surface was examined to investigate the effect of cleaning solutions on the behavior of metallic impurities. Silicon wafers were intentionally contaminated with Cu and Fe solutions by spin coating and cleaned in different types of cleaning solutions based on $NH_4OH/H_2O_2/H_2O\;(SC1),\;H_2O_2/HCl/H_2O$ (SC2), and/or HCl/$H_2O$ (m-SC2) mixtures. The concentration of metallic contaminants on the silicon wafer surface before and after cleaning was analyzed by vapor phase decomposition/inductively coupled plasma-mass spectrometry (VPD/ICP-MS). Cu ions were effectively removed both in alkali (SC1) and in acid (SC2) based solutions. When $H_2O_2$ was not added to SC2 solution like m-SC2, the removal efficiency of Cu impurities was decreased drastically. The efficiency of Cu ions in SC1 was not changed by increasing cleaning temperature. Fe ions were soluble only in acid solution like SC2 or m-SC2 solution. The removal efficiencies of Fe ions in acid solutions were enhanced by increasing cleaning temperature. It is found that the behavior of metallic contaminants as Cu and Fe from silicon surfaces in cleaning solutions could be explained in terms of Pourbaix diagram.

Devulcanization of Vulcanized EPDM Rubber by a Chemical Method (화학적 방법에 의한 가황 EPDM 고무의 탈황처리)

  • Moon, Jae-Ho;Kim, Yang-Soo
    • Elastomers and Composites
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    • v.35 no.4
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    • pp.288-295
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    • 2000
  • It has been tried to decrease the crosslink density of vulcanized EPDM (ethylone-propylene-diene terpolymer) rubber through a chemical devulcanization treatment. Phase transfer catalyst, alkali metal (i.e., sodium), and triphenylphosphine have been used as a chemical agent ul the devulcanization treatment. Also it has been estimated the effect of the devulcanization treatment in the case of utilization of 2-butanol as a devulcanization reaction solvent. In the devulcanization treatment using quaternary ammonium salt as a phase transfer catalyst. the devulcanization effect has been studied with the variation of catalyst molecular weight and the choice of bromide or chloride cation. In the devulcanization treatment using sodium, it has been estimated the devulcanization treatment effect depending upon the variation of reaction variables such as amount of sodium used, reaction temperature, pressure of hydrogen gas, which is used as a reaction environment. The $M_c$ value (number average molecular weight between two crosslink points) has been experimentally estimated by the equilibrium swelling method and it is quantitatively related to the crosslink density. The estimation of devulcanization effect for vulcanized EPDM rubber has been carried out by the comparison of the $M_c$ values between the untreated and the treated specimens.

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Effective Treatment of Wastewater from the Electroplating Plant of Cold-mill by using Microorganism (냉연공장 도금공정에서 발생되는 폐수의 효율적인 미생물 처리에 관한 연구)

  • Kim, Sang-Sik;Kim, Hyung-Jin
    • Applied Chemistry for Engineering
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    • v.20 no.3
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    • pp.301-306
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    • 2009
  • This research was carried out to establish the effective treatment condition and characteristic of wastewater from the electroplating plant of cold rolling mill by using microorganism. Alkaline wastewater and acidic heavy metal wastewater accounted for 64%, 30%, respectively, of the total wastewater. Highly concentrated thiocyanate was 53890 mg/L as COD and it was 53% of total COD, even though it was 0.03% of wastewater from the electroplating plant. When treating mixed wastewater with microorganism, it was easy to remove when SCN concentrations of mixed wastewater was 200 mg/L or less. While the treatment effect of COD-causing materials was low at the concentration of 400 mg/L or less, it implies that highly concentrated thiocyanate contains a large amount of slowly biodegradable organics. When treating with mixed wastewater, pH was 7.33 at the beginning, but after 8 hours it increased to 7.99. This is caused by ammonia which is generated when SCN of highly concentrated thiocyanate was degraded by microorganism.

A Basic Study on the Effective Management for MSWI Fly Ash (II) - Effect of Leaching Parameter - (소각 비산재의 적정처리를 위한 기초연구(II) - 용출인자의 영향 -)

  • Kim, Jin-Beom;Lee, Woo-Keun;Shim, Yeong-Ju
    • Journal of Korean Society of Environmental Engineers
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    • v.22 no.7
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    • pp.1357-1364
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    • 2000
  • Our study was performed to evaluate the effect of leaching parameters including the physicochemical characteristics and the fractionated composition of heavy metals on the release of heavy metals in fly ash discharged from MSWI. Leaching parameters such as pH, CEC, particle size, and exchangeable fraction among the fractional composition classified by sequential extraction procedure are considered. The leaching rate of heavy metal released by KSLT method is largely dependent on the pH of fly ash. The effect of pH on the release of heavy metals is different from elements. It appears that the leaching rate of cadmium and copper decreases with increasing pH, while lead and zinc increases at the condition of neutral or strong alkali condition, which suggests that the leaching of heavy metals are limited by the solubility. It is found that the effect of CEC is similarly to that of pH, $D_{10}$ among the particle size of fly ash is negative correlated with the concentration of heavy metals leached by KSLT method. In the case of exchangeable fraction, the leaching rate of heavy metals is linearly correlated with the exchangeable fraction for the fly ash below 40 meq/l00g of CEC, but not related out of the range.

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Ion Permeation of PVA/Gelatin Blend Membrane Prepared Under High Electric Field (고전장하에서 제조된 PVA/Gelatin 블렌드막의 이온투과 특성)

  • Huh, Yang-Il;Joe, Jeong-Woong
    • Polymer(Korea)
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    • v.30 no.6
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    • pp.568-571
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    • 2006
  • Poly(vinyl alcohol) (PVA)/gelatin(GEL) blend membranes were prepared under a high electric field, and their swelling and ion permeation behaviors were investigated. For alkali metal salts such as LiCl, NaCl and KCl, the permeability coefficients were increased until the electric field of 10 kV due to the decreased tortuosity, whereas they were decreased over 10 kV owing to the increase of the degree of crystallinity. The swelling ratios of the blend membranes showed the minimum values at pH 6, while the permeability coefficients exhibited the maximum values at the same condition. The minimum swelling ratios result from the repulsion effect between charged groups in acidic or basic regions, and the maximum permeabilities result from Donnan exclusion effect in the same regions. Especially, the per-meability coefficient for KCl of the membrane increased steeply to five times at $40^{\circ}C$ than below $35^{\circ}C$.