• Title/Summary/Keyword: 피독

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The deactivation behavior of SCR catalyst by alkali and alkali earth metal (알칼리 및 알칼리 토금속에 의한 SCR 촉매 비활성 거동)

  • Han, Seungyun;Shin, Min-Chul;Lee, Heesoo
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.26 no.6
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    • pp.238-242
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    • 2016
  • The effect of the alkali, alkali earth metal elements on selective catalytic reduction(SCR) catalyst deactivation behavior were investigated in terms of microstructure, surface area, pore volume and De-NOx test. Poisoned SCR catalyst were manufactured by injection of $K_2CO_3$, $Na_2CO_3$, $Ca(CH_3COO)_2{\cdot}H_2O$, $C_4H_6MgO_4{\cdot}4H_2O$, $H_3PO_4$ solutions in the new SCR catalyst at $350^{\circ}C$ for 6 hours. New and poisoned catalysts surface were similar. But specific surface area, pore volume decrease from Na, Mg, K, Ca, P compared to new SCR catalyst. Especially, Na poisoned catalyst surface area and pore size extremely decreased by $10.20m^2/g$, $0.061cm^2/g$. De-NOx test results of new and poisoned catalysts at $150{\sim}450^{\circ}C$ indicated that alkali metal (K, Na) poisoned SCR catalysts have the lowest De-NOx efficiency, alkali earth metal poisoned SCR catalysts (Ca, Mg) De-NOx efficiency are higher than alkali metal poisoned SCR catalysts. P poisoned SCR catalyst De-NOx efficiency is similar new SCR catalyst. It were considered that physical deactivation of SCR catalyst was affected by SCR catalyst surface area and pore volume change.

A Study on the Performance Recovery of $H_2S$ Poisoned PEMFC ($H_2S$ 피독 고분자 전해질막 연료전지의 연료극 성능 회복 연구)

  • Lee, Soo;Jin, Seok-Hwan
    • Journal of the Korean Applied Science and Technology
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    • v.29 no.1
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    • pp.102-107
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    • 2012
  • The recovery of a Pt anode in a PEMFC through 30 ppm $H_2S/H_2$ exposure was evaluated by using a cyclic voltametry(CV) scan. First, the PEMFC unit cell performanc loss was measured three times under an anode feeding with 30 ppm $H_2S/H_2$ for 1hr at $0.5A/cm^2$ of current density. The initial cell performance was $1.16A/cm^2$ at 0.6 V without $H_2S$ poisoning. After first poisoning step for 1hr the cell performance was decrease to $0.77A/cm^2$, and the further poisoning steps decreased up 0.57 V. Finally, the recovery of the cell performance of $H_2S$ poisoned PEMFC was achieved up to 90.3% by applying CV scan. Moreover, we also found out that another possible approach for over 80% recovery of the cell performance of $H_2S$ poisoned anode Pt catalyst layer was to just inject fresh hydrogen into the anode feeding stream.

A Study on the Characteristics of CO Oxidation by NO Poisoning in Pt/TiO2 Catalyst (Pt/TiO2 촉매에서의 NO 피독에 의한 CO 산화반응특성 연구)

  • Kim, Min Su;Kim, Se Won;Hong, Sung Chang
    • Clean Technology
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    • v.25 no.4
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    • pp.296-301
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    • 2019
  • This study was conducted to investigate the characteristics of CO oxidation by NO poisoning in Pt/TiO2 catalyst prepared by wet impregnation method and calcined at 400 ℃. In order to confirm the NO poisoning effect of the Pt/TiO2 catalyst, the change of reaction activity was observed when NO was injected during the CO+O2 reaction where it was ascertained that the CO conversion rate rapidly decreased below 200 ℃. Also, CO conversion was not observed below 125 ℃. Recovery of initial CO conversion was not verified even if NO injection was blocked at 125 ℃. Accordingly, various analyses were performed according to NO injection. First, as a result of the TPD analysis, it was confirmed that NO pre-adsorption in catalyst inhibited CO adsorption and conversion desorption from adsorbed CO to CO2. When NO was pre-adsorbed, it was confirmed through H2-TPR analysis that the oxygen mobility of the catalyst was reduced. In addition, it was validated through FT-IR analysis that the redox cycle (Pt2+→Pt0→Pt2+) of the catalyst was inhibited. Therefore, the presence of NO in the Pt/TiO2 catalyst was considered to be a poisoning factor in the CO oxidation reaction, and it was determined that the oxygen mobility of the catalyst is required to prevent NO poisoning.

A Study on Poisoning of the Reforming Catalysts on the Position of Anode in the Direct Internal Reforming Molten Carbonate Fuel Cell (직접 내부개질형 용융탄산염 연료전지의 음극판 위치에 따른 개질 촉매 피독에 관한 연구)

  • Wee, Jung Ho;Chun, Hai Soo
    • Applied Chemistry for Engineering
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    • v.10 no.5
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    • pp.652-659
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    • 1999
  • The trend of poisoning of reforming catalyst along with the position of anodic catalyst bed was studied. Keeping the conditions that steam to carbon ratio was 2.5, operating voltage was 0.75 V, current density was $140mA/cm^2$, the unit cell was operated during 24 hrs at a steady state. And then the cell was stopped, the catalysts packed in the position of inlet, middle and outlet were sampled individually and then the amount of carbon, Li and K poisoned were analysed. After 100 hrs operated, the catalysts at the same positions were analysed at the same manner. The result of this experiment was as followings. After 24 hrs operated, the poisoning amounts of Li and K in the catalyst were 0.27 wt% at inlet, 0.23 wt% at middle and the highest value 1.59 wt% at outlet. After 100 hrs, the amount of poisoning is the highest in the catalyst packed at the inlet of unit cell. The performance simulation of unit cell explained these trends of poisoning catalysts. The simulation told that the catalyst in the region of the inlet of unit cell treated the 90% of initial methane flow rate and the highest electrochemical reaction happened in this region. So the catalysts of this region were the most poisoned with carbon, Li and K and also the rate of poisoning is faster than that of the catalyst at other regions. The temperature at the region of outlet of unit cell was $30^{\circ}C$ higher than that of other regions, so more Li, and K vaporized than at other regions and little reforming reaction at this region made the catalysts poisoning rate low.

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The Measurement Method Using Hydrogen Peroxide for Quantification of Phosphate Ion Poisoning of Pt Based Catalyst (과산화수소를 이용한 Pt계 촉매의 인산 이온 피독 특성 정량 평가 방법)

  • Yang, Seungwon;Park, Jeongjin;Chung, Yongjin;Kwon, Yongchai
    • Korean Chemical Engineering Research
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    • v.57 no.3
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    • pp.438-443
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    • 2019
  • A new measurement method is suggested to quantify the phosphate poisoning of cathodic Pt catalyst for HT-PEMFC. To do that, hydrogen peroxide was used as an indicator to reduce the error which has been occurred in conventional electrochemical measurement such as CV or ORR RDE with high concentration of phosphate ions. As a result, the current density induced from the reaction of hydrogen peroxide decomposition increased proportionally to the concentration of phosphate ion while the conventional methods show has a significant error with high concentration of phosphate ion. Thus, it is confirmed that the suggested way is superior to the conventional measurement method for the quantification of phosphate ion poisoning in an atmosphere similar to the actual operation condition of HT-PEMFC.

Operation Characteristics of 5 kW Class Proton-Exchange-Membrane Fuel Cell(PEMFC) Stack (5 kW급 고분자 전해질 연료전지 스택의 운전 특성)

  • Kim, Jae-Dong;Lee, Jung-Woon;Park, Dal-Ryung
    • Journal of the Korean Institute of Gas
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    • v.11 no.1 s.34
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    • pp.51-54
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    • 2007
  • 78-cell proton exchange membrane fuel cell(PEMFC) stack with an effective electrode area of $295cm^{2}$ were investigated its operational characteristics and effects of CO poisoning. When power output, 5.4 kW, was released at current density of $325mA/cm^{2}$ for 6 hours, stablility of each cell was showed the small deviation of 2.3%. Carbon monoxide is a conventional contaminant in the fuel obtained from reforming processes with an important influence on the performance of the PEMFC. The studies of continuous injection of CO presented (5-20 ppm) with the time gave information about poisoning and recovery processes of the stack.

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Numerical analysis of chromium deposition through the SOFC cathode channel (고체 산화물 연료전지의 공기극 유로내 크롬 피독에 관한 전산해석)

  • Park, Joon-Guen;Bae, Joong-Myeon;Lee, Shin-Ku;Nabielek, Heinz
    • 한국신재생에너지학회:학술대회논문집
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    • 2006.11a
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    • pp.372-375
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    • 2006
  • SOFC is a high temperature fuelcell with many advantages, but it also have several demerits. One of the Issues is cathode poisoning of Cr coming from stainless steel interconnects. Diffusion process of Cr evaporated from the surface of interconnect steel was calculated by using CFD technique to understand factors for Cr deposition. It has been cleared that factors concerned in Cr deposition and how they affect Cr deposition. Major variables for Cr deposit ion are diffusion coefficient, air velocity and temperature If diffusion coefficient decreases, Cr concentration increases in the air but decreases on the cathode surface. Increasing in air velocity, Cr concentration decreases in the air and on the cathode surface. Increase in temperature leads to rising Cr concentration on the cathode surface because of diffusion coefficient increment.

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Energy conservation by catalytic combustion on low temperature drying process (촉매연소에 의한 저온 건조공정에서의 에너지 절약효과)

  • 강성규;유인수;하영옥;원장묵
    • Proceedings of the Korea Society for Energy Engineering kosee Conference
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    • 1994.05a
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    • pp.98-102
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    • 1994
  • 천연가스의 주성분인 순수 메탄에 대한 촉매 산화반응은 Pd촉매가 가장 양호하나 LP가스의 주성분인 프로판에 대해서는 Pt촉매가 가장 양호한 결과를 보였다. 그러나 유황 피독된 Pd촉매는 메탄에 대해 영구피독 현상을 보였고, fresh한 Pd촉매는 연료 중 미량의 유황분량에 의해 반응 개시온도가 지연되는 경향을 보였다. 이와 같은 촉매독 영향이 적은 Rh촉매버너를 개발하여 8000시간 이상 성공적인 연소 실험을 하고 있으며 C 방적의 염색 시험기에 적응 실험한 결과 기존의 적외선 전기 건조기에 비해 에너지 절감은 약30-40%를 기하였고 연료비는 70-80%의 절약효과를 얻었다.

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The Performance Degradation of PEMFCs Fabricated with Different GDLs During Exposure to Simultaneous Sulfur Impurity Poisoning Condition (서로 다른 GDL을 이용한 고분자전해질 막 연료전지의 황불순물 복합피독에 의한 성능 저하)

  • Lee, Soo;Kim, Jae-Hyun;Jin, Seok-Hwan
    • Journal of the Korean Applied Science and Technology
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    • v.30 no.1
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    • pp.146-151
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    • 2013
  • This paper reveals the performance decrease and recovery of PEMFC when the contaminated fuel gas and air source with sulfur impurities such as hydrogen sulfide and sulfur dioxide were simultaneously introduced to anode and cathode, respectively. Three different GDLs were fabricated with different carbon black and activated carbon to prevent an introduction of sulfur compound impurities into MEA. components. The severity of $SO_2$ and $H_2S$ poisoning was depended on concentrations(3 ppm - 10 ppm) of sulfur impurities. Especially, cell performance degradation rate was rapid when MEA fabricated with CN-2 GDL because it had little porosity on GDL surface. Moreover, the cell performance can be recovered up to 90%-95% only with neat hydrogen and fresh air feeding.. Conclusively, MEA fabricated with porous CN-1 GDL showed the best cell performance and recovery efficiency during exposure to poisoning condition by simultaneous sulfur impurities.

The performance of PEMFC during exposure to simultaneous sulfur impurity poisoning on cathode and anode (공기극과 연료극의 복합 황불순물에 의한 고분자 전해질막 연료전지의 성능에 미치는 영향)

  • Lee, Soo;Jin, Seok-Hwan
    • Journal of the Korean Applied Science and Technology
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    • v.29 no.4
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    • pp.594-598
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    • 2012
  • Polymer electrolyte membrane fuel cell(PEMFC) performance degrades seriously when sulfur dioxide and hydrogen sulfide are contaminated in the fuel gas at anode and air source at cathode, respectively. This paper reveals the effect of the combined sulfur impurity poisoning on both PEMFC cathode and anode parts through measuring electrical performance on single FC operated under 1 ppm to 10 ppm impurity gases. The severity of $SO_2$ and $H_2S$ poisoning depended on concentrations of impurity gases under optimum operating conditions($65^{\circ}C$ of cell temperature and 100 % relative humidity). Sulfur adsorption occured on the surface of Pt catalyst layer on MEA. In addition, MEA poisoning by impurity gases were cumulative. After four consecutive poisonings with 1, 3, 5 to 10 ppm, the fuel cell performance of PEMFC was decrease upto 0.54 V(76 %) from 0.71 V.