• Title/Summary/Keyword: 선택적환원

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A Study on the Electrochemical Behavior of Au and Pd in Hydrochloric Acidic Solution (염산 수용액 중에서 Au와 Pd의 전기화학적 거동에 관한 연구)

  • Yu, Yeon-Tae;Kim, Chi-Kwon
    • Korean Journal of Materials Research
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    • v.11 no.2
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    • pp.76-81
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    • 2001
  • In order to recover Au and Pd from the leaching solution of various electronic wastes by electrowinning, the electrochemical behavior of Au and Pd in hydorchloric acidic solution was investigated by means of voltammetry. The reduction potential of Au ion was 800mV and the limiting current appeared at 470mV in electrolytic solution of gold. The reduction potential of Pd ion was 500mv and the limiting current appeared at 150mV in electrolytic solution of Palladium. However, in Au-Pd electrolytic solution, the Potentials for reduction and the limiting current of Au decreased as the content of Pd in electrolyte increased, and the potentials for the limiting current of Au and Pd closed nearest together when percentage of Pd electrolytic solution was 37v71% in Au-Pd electrolyte.

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학부제 시행은 대학의 자율에 맡겨야 한다

  • Yun, Pyeong-Hyeon
    • 대학교육
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    • s.142
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    • pp.14-18
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    • 2006
  • '99학년도 부터 본격적으로 시행된 학부제는 현재 많은 문제에 직면해 있으며 특히 학생들에 의한 전공 학과 선택권 보장은 실질적인 허구임이 드러났다. 학부제가 당초의 취지를 제대로 살리지 못하고 있다면 지체 없이 학과별 모집 단위로 환원되어야 하며 학문 분야의 성격과 각 대학의 특성에 맞추어 해당 대학에서 학부제 실시 여부를 판단할 수 있게 해야 한다. 더불어 그에 따른 책임 또한 각 대학이 스스로 질 수 있게 해야 할 것이다.

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New Selective Tungsten Deposition Process by the alternating Cyclic Hydrogen Reduction of $WF_6$ using LPCVD (LPCVD을 사용하여 $WF_6$의 교번적 수소환원 반응에 의한 새로운 선택적 텅스텐 박막 증착)

  • ;Arnold Reisman;Christopher Berry
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.39 no.7
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    • pp.692-701
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    • 1990
  • New selective tungsyen deposition deposition on silicon process is described which makes use of a previously unreported, alternating cyclic,

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A Study of the Reaction Characteristics on Hydrocarbon Selective Catalytic Reduction of NOx Over Various Noble Metal Catalysts (다양한 귀금속 촉매를 이용한 NOx의 탄화수소 선택적촉매환원 반응 특성에 관한 연구)

  • Kim, Sung-Su;Jang, Du-Hun;Hong, Sung-Chang
    • Clean Technology
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    • v.17 no.3
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    • pp.225-230
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    • 2011
  • Characteristics of hydrocarbon selective catalytic reduction of NOx using various noble metal catalysts were investigated. The best active metal is Pt, supports are $CeO_2$ and $TiO_2$ by strong interactions between active metals, and 55% of conversion rate of NOx is shown. Pd, Rh and Ag catalysts presented a conversion of less than 20% as active metals, and supports also showed the poor activity compared to $SiO_2$ and $ZrO_2$. Experiments were performed with different types of reducing agents, amount, concentration of oxygen and space velocity in order to investigate the performance of catalysts according to operating conditions. The results confirm that the methane is better than propane as a reducing agent, and as the ratio of methane/nitrogen oxide increases, the catalytic activity increased, as the concentration of oxygen increases and space velocity decreases, the performance of catalysts increased.

Spatially Selective Immobilization of Functional Materials onto Silicon Surfaces Using Electrochemical Method (전기화학을 이용한 실리콘 표면상으로 기능성 물질의 공간 선택적 고정화 연구)

  • Park, Soo-Hyoun;Ah, Chil-Seong;Kim, Kyu-Won
    • Journal of the Korean Electrochemical Society
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    • v.12 no.1
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    • pp.40-46
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    • 2009
  • We present a method for spatially selective immobilization of functional materials, such as proteins and nanoparticles, onto pre-activated silicon surfaces by electrochemical reaction. Carboxymethylbenzendiazonium (CMBD) cations, being adsorbable on silicon surfaces through electrochemically reductive deposition, is used as an anchor molecule to prepare the pre-activated silicon surfaces. It is demonstrated that the use of BD reaction is very efficient for the selective immobilization because the functional materials are immobilized exclusively onto the pre-adsorbed CMBD region. The method is applied to immobilize gold nanoparticles on the selected nanowire of the nanowire array.

$DeNO_{x}$ Performance of Activated Carbon Catalysts Regenerated by Surfactant Solution (계면활성제 수용액에 의해 재생된 활성탄 촉매의 탈질 성능)

  • Park, Hye-Min;Park, Young-Kwon;Jeon, Jong-Ki
    • Korean Chemical Engineering Research
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    • v.49 no.6
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    • pp.739-744
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    • 2011
  • Activated carbon SCR(CSCR) catalyst that is used to remove $NO_x$ in exhaust gas including boron discharged from the production process of liquid crystal display(LCD) shows deactivation when boron is deposited to block the pores within the catalyst or to cover its active sites. The spent carbon catalyst is regenerated by washing with various surfactants, drying and calcination. For comparison of the physical and chemical properties before and after the regeneration with the variables, type of surfactants and calcination condition, element analysis by ICP, $N_{2}$ adsorption were conducted. $DeNO_{x}$ in SCR with $NH_3$ was carried out in a fixed bed reactor at $120^{\circ}C$. The activated carbon catalyst regenerated through washing with a non-ionic surfactant in $H_{2}O$ at $90^{\circ}C$ and calcination under $N_{2}$ gas at $550^{\circ}C$ shows similar level of surface area and $NO_x$ removal efficiency with those of fresh catalyst.

Effect of Intermittent Plasma Discharge on the Hydrocarbon Selective Catalytic Reduction of Nitrogen Oxides (간헐적 플라즈마 방전이 질소산화물의 탄화수소 선택적 촉매환원에 미치는 영향)

  • Kyeong-Hwan Yoon;Y. S. Mok
    • Applied Chemistry for Engineering
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    • v.34 no.5
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    • pp.507-514
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    • 2023
  • The selective catalytic reduction (SCR) of nitrogen oxides (NOx) was investigated in a catalyst (Ag/γ-Al2O3) packed dielectric barrier discharge plasma reactor. The intermittent generation of plasma in the catalyst bed partially oxidized the hydrocarbon reductant for NOx removal to several aldehydes. Compared to using the catalyst alone, higher NOx conversion was observed with the intermittent generation of plasma due to the formation of highly reductive aldehydes. Under the same operating conditions (temperature: 250 ℃; C/N: 8), the NOx reduction efficiencies were 47.5%, 92%, and 96% for n-heptane, propionaldehyde, and butyraldehyde, respectively, demonstrating the high NOx reduction capability of aldehydes. To determine the optimal condition for intermittent plasma generation, the high voltage on/off cycle was adjusted from 0.5 to 3 min. The NOx reduction performance was compared between continuous and intermittent plasma generation on the same energy density basis. The highest NOx reduction efficiency was achieved at 2-min high voltage on/off intervals. The reason that the intermittent plasma discharge exhibited higher NOx reduction efficiency even at the same energy density, compared to the continuous plasma generation case, is that the intermediate products, such as aldehydes generated from hydrocarbon, were more efficiently utilized for the reduction of nitrogen oxides.

Reduction of AgCl to Ag by $Na_2CO_3$ ($Na_2CO_3$에 의한 AgCl의 Ag 환원)

  • 박경호;노범식;손정수
    • Resources Recycling
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    • v.5 no.1
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    • pp.29-33
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    • 1996
  • The cominnn plocesses lor rccoremg silver irom silvcr conlaincd waster are the lcachmg silver hy HNO;. the srlcctive precipilillion of sliver ion lo AgCl and thc rcduchon of Ag wrfh ;I proper reductant. In this sludy, thc reduction of AgCI lo Ag was invesllngated by using Na, CO, as a rcd\icta~lt. The variations wcic reaction time. ttmpcrarure thc amount of NalCO, . and the resulls %, ere analyzcd by using sialist~c:d tecl~niques such as the ]polynomial rcgressiun analysis and the response surh~ce method. More than Yh% Ag analyzed was rcduced 1rtm AgCI at 62UT. I hour ullder condillon of 2 stnlchio~nctric ratio of Na iCO, !AgCI.

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Low-Temperature SCR of NO over Physical Mixture of MnO2 and Metal-Loaded Activated Carbon (MnO2와와 금속담지활성탄의 물리적 혼합물을 이용한 NO의 저온 선택적 촉매 환원 반응)

  • Choi, Jong Cheol;Cho, Chul-Hoon;Jeong, Kwang-Eun;Jeon, Jong-Ki;Yim, Jin-Hyeong;Park, Young-Kwon
    • Applied Chemistry for Engineering
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    • v.19 no.1
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    • pp.92-97
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    • 2008
  • Selective catalytic reduction (SCR) of NO with ammonia was carried out over the physical mixture of $MnO_2$ and K or Cu-loaded activated carbons (AC) at low temperature. Introduction of oxygen affected positively the reduction of NO. Metal-impregnated AC showed significantly enhanced catalytic activity. Without water, the mixed catalyst of $MnO_2$ and K-loaded AC exhibited the best activity in the reduction of NO at $120^{\circ}C$. On the contrary, the activities of all the catalysts were significantly diminished in the presence of water. The mixed catalyst of $MnO_2$ and Cu-loaded AC treated with nitric acid and heat (1 : 1, w/w) exhibited the better activity for the reduction of NO than each single catalyst in presence of water.

Computational Study on Design of the AIG for the Enhancement of Ammonia Injection in the SCR System (SCR 시스템 내 암모니아 분사 균일도 개선을 위한 AIG 설계에 관한 해석적 연구)

  • Seo, Moon-Hyeok;Chang, Hyuksang
    • Clean Technology
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    • v.18 no.4
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    • pp.410-418
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    • 2012
  • The performance of the ammonia injection gun (AIG) used for maximizing the utilization of reducing agent in the selective catalytic reduction (SCR) system is decided by several parameters such as the pattern of flow distribution, geometry of the air distribution manifold (ADM) and the array and geometry of nozzles. In the study, the uniformity of jet flows from the nozzles in AIG was analyzed statistically by using the computational fluid dynamics (CFD) method to evaluate the role of design parameters on the performance of the SCR system. The uniformity of jet flows from the nozzles is being deteriorated with increasing the supplying flow rate to the AIG. Distribution rates to each branch pipe become lower with decreasing distance to the header, and flow rates from nozzle are also reduced with decreasing distance to the header. The uniformity of jet flows from nozzles becomes stable significantly when the ratio of summative area of nozzles to each sectional area of the branch pipe is below 0.5.