• Title/Summary/Keyword: 선택적 환원촉매

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A Study on Characterization for Low Temperature SCR Reaction by $Mn/TiO_2$ Catalysts with Using a Various Commercial $TiO_2$ Support (다양한 상용 $TiO_2$ 담체를 이용한 $Mn/TiO_2$ 촉매의 저온 SCR 반응 특성 연구)

  • Kwon, Dong Wook;Choi, Hyun Jin;Park, Kwang Hee;Hong, Sung Chang
    • Applied Chemistry for Engineering
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    • v.23 no.2
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    • pp.190-194
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    • 2012
  • 10 wt% Mn supported on various commercial $TiO_2$ catalysts were prepared by wet-impregnation method for the low temperature selective catalytic reduction (SCR) of NO with $NH_3$. A combination of various physico-chemical techniques such as BET, XRD, XPS and TPR were used to characterize these catalysts. MnOx surface densities on MnOx/$TiO_2$ catalyst were related to surface area. As MnOx surface density lowered with high dispersion, the SCR activity for low temperature was increased and the reduction temperature ($MnO_2$ ${\rightarrow}$ $Mn_2O_3$) of surface MnOx was lower. For a high SCR, MnOx could be supported on a high surface area of $TiO_2$ and should be existed a high dispersion of non-crystalline species.

Effect of Steam-Treated Zeolite BEA Catalyst in NH3-SCR Reaction (NH3-SCR 반응에서 스팀 처리된 zeolite BEA 촉매의 영향)

  • Park, Ji Hye;Cho, Gwang Hee;Hwang, Ra Hyun;Baek, Jeong Hun;Yi, Kwang Bok
    • Clean Technology
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    • v.26 no.2
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    • pp.145-150
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    • 2020
  • Nitrous oxide (N2O) is one of the six greenhouse gases, and it is essential to reduce N2O by showing a global warming potential (GWP) equivalent to 310 times that of carbon dioxide (CO2). Selective catalytic reduction (SCR) is a technology that converts ammonia into harmless N2 and H2O by using ammonia as a reducing agent to remove NOx, one of the air pollutants; the process also produces high denitrification efficiency. In this study, the Fe-BEA catalyst was steam-treated at 100 ℃ for 2 h before Fe ion exchange in the fixed bed reactor in order to investigate the effect of the steam-treated Fe-BEA catalyst on the NH3-SCR reaction. NH3-SCR reaction test of synthesized catalysts was performed at WHSV = 180 h-1, 370 to 400 ℃ in the fixed bed reactor. The Fe-BEA(100) catalyst steam-treated at 100 ℃ showed a somewhat higher activity than the Fe-BEA catalyst at 370 to 390 ℃. The catalysts were characterized by BET, ICP, NH3-TPD, H2-TPR, and 27Al MAS NMR in order to determine the cause affecting NH3-SCR activity. The H2-TPR result confirmed that the Fe-BEA(100) catalyst had a higher reduction of isolated Fe3+ than the Fe-BEA catalyst, and that the steam treatment increased the amount of isolated Fe3+ as an active species, thus increasing the activity.

Asymmetric Hydrogenation of Ethyl Pyruvate over Bimetallic Rh-Pt/Al2O3 Catalysts Modified with Dihydrocinchonidine (Dihydrocinchonidine으로 개질된 Rh-Pt/Al2O3 이원금속 촉매를 이용한 Ethyl Pyruvate의 비대칭 수소화)

  • Cho, Hong-Baek;Kang, Joon-seok;Park, Yeung-Ho
    • Applied Chemistry for Engineering
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    • v.17 no.4
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    • pp.369-374
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    • 2006
  • $Rh-Pt/Al_{2}O_{3}$ catalysts were used for the first time to study its reaction characteristics in the asymmetric hydrogenation of ethyl pyruvate. The catalysts were prepared either by impregnation of Rh on a commercial $Pt/Al_{2}O_{3}$ or by sequential impregnation of Rh followed by impregnation of Pt on $Al_{2}O_{3}$. Reaction rate and enantiomeric excess (ee%) were compared according to the preparation method, Rh contents, and the reduction temperature of the catalyst. The physical characteristics of the catalysts were analyzed using XRD and TEM. Bimetallic $Rh-Pt/Al_{2}O_{3}$ catalysts showed an improved reaction rate and optical purity (63.6 ee%) with increasing the reduction temperature. The variation of the Rh contents as well as the preparation method elicited a big difference on the reaction rate, while enantiomeric excess (ee%) was lower (56~60%) with all bimetallic catalysts than with monometallic $Pt/Al_{2}O_{3}$ catalyst.

A CFD Study on Aerodynamic Performances by Geometrical Configuration of Guide Vanes in a Denitrification Facility (탈질 설비 내 안내 깃의 기하학적 형상에 따른 공력 성능에 대한 전산 해석적 연구)

  • Chang-Sik, Lee;Min-Kyu, Kim;Byung-Hee, Ahn;Hee-Taeg, Chung
    • Clean Technology
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    • v.28 no.4
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    • pp.316-322
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    • 2022
  • The flow pattern at the inlet of the catalyst layer in a selective catalytic reduction (SCR) system is one of the key parameters influencing the performance of the denitrification process. In the curved diffusing parts between the ammonia injection grids and the catalyst layers, guide vanes are installed to improve flow uniformity. In the present study, a numerical simulation has been performed to investigate the effect of the geometrical configuration of the guide vanes on the aerodynamic characteristics of a denitrification facility. This application has been made to the existing SCR process in a large-scaled coal-fired power plant. The flow domain to be solved covers the whole region of the flow passages from the exit of the ammonia injection gun to the exit of the catalyst layers. ANSYS-Fluent was used to calculate the three-dimensional steady viscous flow fields with the proper turbulence model fitted to the flow characteristics. The root mean square of velocity and the pressure drop inside the flow passages were chosen as the key performance parameters. Four types of guides vanes were proposed to improve the flow quality compared to the current configuration. The numerical results showed that the type 4 configuration was the most effective at improving the aerodynamic performance in terms of flow uniformity and pressure loss.

Recovery of the Vanadium and Tungsten from Spent SCR Catalyst Leach Solutions by Hydrometallurgical Methods (SCR 폐촉매 침출액으로부터 습식제련법에 의한 바나듐, 텅스텐의 회수)

  • Choi, In-Hyeok;Moon, Gyeonghye;Jeon, Jong-Hyuk;Lee, Jin-Young;Jyothi, Rajesh Kumar
    • Resources Recycling
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    • v.29 no.2
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    • pp.62-68
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    • 2020
  • In new millennium, wide-reaching demands for selective catalytic reduction (SCR) catalyst have been increased gradually in new millennium. SCR catalyst can prevent the NOx emission to protect the environment. In SCR catalyst the main composition of the catalyst is typically TiO2 (70~80%), WO3 (7~10%), V2O5 (~1%) and others. When the SCR catalysts are used up and disposed to landfills, it is problematic that those should exist in the landfill site permanently due to their extremely low degradability. A new advanced technology needs to be developed primarily to protect environment and then recover the valuable metals. Hydrometallurgical techniques such as leaching and liquid-liquid extraction was designed and developed for the spent SCR catalyst processing. In a first stage, V and W selectively leached from spent SCR catalyst, then both the metals were processed by liquid-liquid extraction process. Various commercial extractants such as D2EHPA, PC 88A, TBP, Cyanex 272, Aliquat 336 were tested for selective extraction of title metals. Scrubbing and stripping studies were tested and optimized for vanadium and tungsten extraction and possible separation. 3rd phase studies were optimized by using iso-decanol reagent.

A Study on Hybrid DeNOx Process Using Selective Catalytic Reduction and Adsorption (선택적촉매환원과 흡착을 이용한 복합 탈질공정 연구)

  • Moon, Seung-Hyun;Jeon, Dong-Hwan;Park, Sung-Youl
    • Journal of Korean Society of Environmental Engineers
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    • v.29 no.12
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    • pp.1329-1336
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    • 2007
  • This study was carried out to develop an efficient process abating high NO concentration. A hybrid process of selective catalytic reduction(SCR) and activated carbon fiber(ACF) adsorption was newly designed and tested. Used ACF in NO adsorption was regenerated by simultaneously applying heat and vacuum. The result of ACF regeneration was for superior in the desorption condition at $140^{\circ}C$ and vacuum 600 mmHg. A commercial catalyst was used at the conditions of reaction temperature at $300^{\circ}C$, $NH_3/NO$ mole ratio = 1.0 for SCR process. NO evolved from ACF regeneration reactor could be removed by SCR reactor up to 98%. But high concentration of NO was exhausted from SCR reactor for one minute when the flue gas of NO 300 ppm and deserted NO from ACF regeneration were simultaneously treated by the same SCR reactor. Therefore, it is necessary to use additional small sized SCR reactor or to increase $NH_3$ concentration for a short time along with NO concentration rather than to mix flue gas with the gas evolving from ACF regeneration at fixed $NH_3$ inlet concentration. The hybrid process of SCR and ACF showed high NO removal efficiency over 80% at any time courses. Through the repeated cycles, stable DeNOx efficiency was maintained, indicating that the hybrid process would be a good countermeasure to the spotaneously high NO concentration instead of increasing the SCR capacity.

Fabrication of Long Metal Nanowire by Electrospinning Process for the Transparent Electrode (고종횡비 금속 나노튜브 기반 투명전극 제조기술)

  • Lee, Chang-Myeon;Heo, Jin-Yeong;Lee, Hong-Gi
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2017.05a
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    • pp.132.1-132.1
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    • 2017
  • 본 연구에서는 투명전극 제조를 목적으로 전기방사법을 이용하여 미세구리 패턴을 형성하는 방법에 대하여 연구하였다. $Ag^+$이온이 용해된 폴리비닐부티랄(PVB) 고분자 용액을 폴리에틸렌 테레프탈레이트(PET)와 같은 투명기판 위에 전기방사 하여 $Ag^+$이온/PVB 복합나노와이어를 제조한 후 이를 UV 조사로 환원하여 선택적으로 촉매를 형성하였다. 이후 연속적인 무전해 구리 도금을 통하여 촉매 위에 미세구리배선을 형성함으로써, 투명전극을 제조하였다. 개발 공정을 통해 제조된 투명전극은 기존 Ag나노와이어 기반 투명전극에서 발생하던 접촉저항에 대한 문제를 해결함으로써 전기적, 광학적 특성이 우수한 차세대 유연 디스플레이에 적용 가능성을 보여주었다.

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Effects of Calcium on the Activity of V2O5/TiO2 Catalysts in SCR Processes (SCR 공정에서 Calcium 성분이 V2O5/TiO2 촉매 활성에 미치는 영향)

  • Kim, Jin-Kil;Park, Kwang-Hee;Hong, Sung-Chang;Lee, Eui-Dong;Kang, Yong
    • Korean Chemical Engineering Research
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    • v.50 no.5
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    • pp.772-777
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    • 2012
  • Factors acting on the deactivation of $V_2O_5/TiO_2$ catalysts were investigated in the selective catalytic reduction(SCR) process for long term operation. The activity of $V_2O_5/TiO_2$ catalysts was decreased rapidly after 8 months from the starting of operation in the selective catalytic reaction processes. From ICP-AES analysis, the deactivation of the used catalysts could be caused from the calcium component included in urea solution as a reducing agent. It was found from the $NH_3$-TPD experiments that the strong basic element like Ca component drastically affected the acidity of the $V_2O_5/TiO_2$ catalyst. The results gave an explanation on the reason why the component of Ca, even though its concentration is very low, could lead to the deactivation of $V_2O_5/TiO_2$ catalyst in the selective catalytic reaction processes.

A Reaction Kinetic for Selective Catalytic Reduction of NOx with NH3 over Manganese Oxide (NMO, MnO2, Mn2O3) at Low Temperature (망간산화물(NMO, MnO2, Mn2O3)을 이용한 저온에서의 NH3-SCR의 반응속도 연구)

  • Kim, Min Su;Hong, Sung Chang
    • Clean Technology
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    • v.24 no.4
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    • pp.307-314
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    • 2018
  • In this study, NMO (Natural Manganese Ore), $MnO_2$, and $Mn_2O_3$ catalysts were used in the selective catalytic reduction process to remove nitrogen oxides (NOx) using $NH_3$ as a reducing agent at low temperatures in the presence of oxygen. In the case of the NMO (Natural Manganese Ore), it was confirmed that the conversion of nitrogen oxides in the stability test did not change even after 100 hours at 423 K. The Kinetics experiments were carried out within the range where heat and mass transfer were not factors. From a steady-state Kinetics study, it was found that the low-temperature SCR reaction was zero order with the respect to $NH_3$ and 0.41 ~ 0.57 order with the respect to NO and 0.13 ~ 0.26 order with the respect to $O_2$. As temperature increases, the reaction order decreases as a result of $NH_3$ and oxygen concentration. It was confirmed that the reaction between the $NH_3$ dissociated and adsorbedon the catalyst surface and the gaseous nitrogen monoxide (E-R model) and the reaction with the adsorbed nitrogen monoxide (L-H model) occur.