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공업화학 , 촉매 / 반응공학 : PCE ( perchloroethylene ) 제거반응에서 크롬산화물 촉매의 활성저하
임성대(Sung Dae Yim),장광현(Kwang Hyun Chang),남인식(In Sik Nam) 한국화학공학회 2001 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.39 No.3
The effect of the concentration of reactant on the deactivation of chromium oxide catalysts for the oxidation of CVOCs was investigated. Feeds with various PCE concentrations of 30, 1,000, 5,000 and 10,000 ppm were introduced into the reactor for the oxidation over CrO_χ catalysts supported on high surface area TiO₂ and Al₂O₃. Both chromium oxide catalysts exhibited stable PCE removal activities up to 100 hours of reaction time without any catalyst deactivation at the low concentration of PCE in the feed, 30 ppm. However, high concentrations of PCE, from 1,000 to 10,000 ppm, significantly deactivated the chromium oxide catalyst regardless of the support. Deactivation of the chromium oxide catalyst was neither caused by the evaporation of chromium from the catalyst surface nor the reduction of surface area by coking. It was mainly due to the phase transformation from Cr(VI), active reaction sites on the catalyst surface, to Cr(III). Although some of Cr on We catalyst surface evaporated during the course of the reaction at high feed concentrations of PCE, it was insignificant to reduce the PCE removal activity of the catalyst.
데칼법을 이용한 연속 제조 공정에서의 고분자 전해질 연료전지용 전극 개발
임성대(Yim, Sung-Dae),박석희(Park, Seok-Hee),윤영기(Yoon, Young-Gi),양태현(Yang, Tae-Hyun),김창수(Kim, Chang-Soo) 한국신재생에너지학회 2010 신재생에너지 Vol.6 No.1
Membrane electrode assemblies (MEAs) for proton exchange membrane fuel cells (PEMFCs) have been extensively studied to improve their initial performance as well as their durability and to facilitate the commercialization of fuel cell technology. To improve the MEA performance, particularly at low Pt loadings, many approaches have been made. In the present study, MEA performance improvement was performed by adding TiO₂ particles into the catalyst layer of MEA. Most of previous studies have focused on the MEA performance enhancement under low humidity conditions by adding metal oxides into the catalyst layer mainly due to the water keeping ability of those metal oxides particles such as Al₂O₃, SiO₂ and zeolites. However, this study mainly focused on the improvement of MEA performance under fully humidified normal conditions. In this study, the MEA was prepared by decal method aiming for a continuous MEA fabrication process. The decal process can make very thin and uniform catalyst layer on the surface of electrolyte membrane resulting in very low interfacial resistance between catalyst layer and the membrane surface and uniform electrode structure in the MEA. It was found that the addition of TiO₂ particles into the catalyst layer made by decal method can minimize water flooding in the catalyst layer, resulting in the improvement of MEA performance.
Effect of stack configuration on the performance of 10W PEMFC stack
임성대(Yim, Sung-Dae),김병주(Kim, Byung-Ju),손영준(Sohn, Young-Jun),윤영기(Yoon, Young-Gi),양태현(Yang, Tae-Hyun),김창수(Kim, Chang-Soo),김영채(Kim, Young-Chai) 한국신재생에너지학회 2009 한국신재생에너지학회 학술대회논문집 Vol.2009 No.06
A small PEM fuel cell has two different stack configurations such as active and passive stacks. The active stack has a distintion of high power density although it makes system complex by using alr blower and related BOPs resulting in large system volume. On the contrary, passive stack has an advantage of compact system because it doesn't need air supplying devices although it reveals relatively low stack power density. In this study we fabricated two 10W PEMFC stacks with different stack configurations, active and passive stacks, and tested their performance and stability. The active stack consists of 13cells with an active area of 5cm². The passive stack has 12cells with an active area of 16cm². When we compared the stack performance of those stacks, the active stack showed higher power density compared to the passive stack, particularly at high voltage regions. However, at low voltage and high current regions, the passive stack performance was comparable to the active stack. The stack stability was largely dependent on the fuel humidity, particularly for active stack. At low humidity conditions, the active stack performance was decreased continuously and the cell voltage distribution was not uniform showing seriously low cell voltage at center cells mainly due to the cell drying. The passive stack showed relatively stable behavior at low humidity and the stack performance was largely dependent on the atmospheric conditions.
류성관(Ryu, Sung Kwan),최영우(Choi, Young Woo),양태현(Yang, Tae Hyun),임성대(Yim, Sung Dae),김한성(Kim, Han Sung),김창수(Kim, Chang Soo) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.11
Polymer electrolyte fuel cells (PEFCs) have received a lot of attention as a power source for both stationary and mobile applications due to their attractive feature. In general, the performance of PEFCs is highly affected by the property of the electrodes. A PEFC electrode essentially consists of a gas diffusion layer and a catalyst layer. The gas difusion layer is highly porous and hydrophobicized with PTFE polymer. The catalyst layer usually contains electrocatalyst, proton conducting polymer, even PTFE as additive. Particularly, the proton conducting ionomer helps to increase the catalytic activity at three-phase boundary and catalyst utilization. Futhermore, it helps to retain moisture, resulting in preventing the electrodes from membrane dehydration. The most widely used proton conducting ionomer is perfluorinated sulfonic acid polymer, namely, Nafion from DuPont due to its high proton conductivity and good mechanical property. However, there are great demands for alternative ionomers based on non-fluorinated materials in terms of high temperature availability, environmental adaptability and production cost. In this study, the electrodes with the various content of the sulfonated poly(ether sulfone) ionomer in the catalyst layer were prepared. In addition, we evaluated electrochemical properties of the prepared electrodes containing the various amount of the ionomers by using the cyclic voltammetry and impedance spectroscopy to find an optimal ionomer composition in the catalyst layer.
Developement of a PEFC electrodes under the high temperature and low humidified conditions
류성관(Ryu, Sung-Kwan),최영우(Choi, Young-Woo),박진수(Park, Jin-Soo),임성대(Yim, Sung-Dae),양태현(Yang, Tae-Hyun),김한성(Kim, Han-Sung),김창수(Kim, Chang-Soo) 한국신재생에너지학회 2009 한국신재생에너지학회 학술대회논문집 Vol.2009 No.11
Generally, Nafion ionomer is used in the polymer electrolyte fuel cell (PEFC) electrodes to achieve high power density. At the high temperature operation of PEFC, however, ionic conductivity of Nafion remarkably decreased due to the evaporation of water in Nafion polymer. Recently, many researchers have focused on using the Ionic Liquids(ILs) instead of water in Nafion polymer. ILs have intrinsic properties such as good electrochemical stability, high ionic conductivity, and non-flammability. Especially, ILs play a crucial role in proton conduction by the Grottuss mechanism and act as water in water-free Nafion polymer. However, it was found that the ILs was leached out of the polymer matrix easily. In this study, we prepared membrane electrode assemblies with various contents of ILs. The effect of ILs in the electrode of each designed was investigated by a cyclic voltammetry measurement and the cell performance obtained through a single cell test using H2/Air gases. Electrodes with different contents of ILs in catalyst layer were examined at high temperature and low humidified condition.
이상헌(Lee, Sang-Heon),임성대(Yim, Sung-Dae),박구곤(Park, Gu-Gon),유상필(Yu, Sang-Phil),윤영기(Yoon, Young-Gi),김창수(Kim, Chang-Soo),박승빈(Park, Seung-Bin) 한국신재생에너지학회 2005 한국신재생에너지학회 학술대회논문집 Vol.2005 No.06
현재 인류가 직면하고 있는 에너지 및 환경 문제를 해결할 수 있는 최선의 대안으로서 수소 에너지 및 연료전지 기술에 대한 연구가 활발히 진행 중이다. 본 연구에서는 디메틸 에테르를 이용한 수소 생산 기술에 대한 연구를 수행하였다 디메틸 에테르(BATE)는 안정한 화합물로서 비 활성적이고 부식성이 없으며 발암성 및 마취성이 얼어 인체에 무해한 청청 연료로서 각광을 받고 있으며 특히 기존의 LPG 인프라를 그대로 사용할 수 있는 장점 등으로 수소 스테이션 및 소형 연료전지용 수소 발생기 등에의 적용을 위한 연구가 활발히 진행 중이다. 본 연구에서는 이러한 응용을 위한 수소 발생기용 DME 개질 반응기의 개발을 위하여 본 반응에 대한 촉매 종류의 영향, 공간속도의 최적화, 반응 메카니즘에 따른 촉매 선정, 반응온도 등의 다양한 반웅 조건에 대한 영향을 확인하고 실제 소형 연료전지를 위한 수소공급 장치로서 적용코자 마이크로채널 반응기에 적용하여 마이크로채널 DME 개질반응기의 컴팩트한 수소공급 장치로서의 적용 가능성을 평가하였다.
손영준(Sohn, Young-Jun),임성대(Yim, Sung-Dae),박구곤(Park, Gu-Gon),김경연(Kim, Kyoung-Youn),김민진(Kim, Min-Jin),이원용(Lee, Won-Yong) 한국신재생에너지학회 2008 한국신재생에너지학회 학술대회논문집 Vol.2008 No.10
Air-breathing polymer electrolyte membrane fuel cells (PEMFC) are highly promising particularly for small-power applications up to tens watts class. A distinctive feature of the air-breathing PEMFC is its simple system configuration in which axial fans operate for dual purposes, supplying both oxidant and coolant in a single manner. In the present study, a nominal 80W air-breathing PEMFC system is developed and investigated to determine the optimal operating strategy through parametric studies (i.e., reactant humidity, and fanblowing flow rate). The cell voltage distributions are examined as a function of time to evaluate the system performance under various operating conditions.