• Carbon letters
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• 제9권4호
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• pp.303-307
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• 2008

The studies on integrated operation of fuel cell with fuel processor are very essential prior to its commercialization. In this study, Polymer Electrolyte Membrane Fuel Cell (PEMFC) was operated with a fuel processor, which is mainly composed of two parts, methanol steam reforming reaction and preferential oxidation (PROX). In fuel processor, ICI 33-5 (CuO 50%, ZnO 33%, $Al_2O_3$ 8%, BET surface area: $66\;m^2g^{-1}$) catalyst and CuO-$CeO_2$ catalyst were used for methanol steam reforming, preferential oxidation (PROX) respectively. PEMFC was operated by hydrogen fuel generated from fuel processor. The resulting gas from PROX reactor is used to operate PEMFC equipped with our prepared anode and cathode catalyst. PtRu/C catalyst gives more tolerance to CO.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2001년도 연료전지심포지움 2001논문집
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• pp.65-70
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• 2001

• 한국응용과학기술학회지
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• 제34권4호
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• pp.883-891
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• 2017

고분자 전해질 연료전지의 연료에 포함된 일산화탄소의 선택적 산화를 위하여, 귀금속 촉매를 대체하기 위한 CuO-$CeO_2$ 복합 산화물 촉매를 졸-겔법과 공침법으로 제조하였다. 졸-겔법으로 촉매 제조 시 Cu/Ce의 비와 가수분해 비를 변화시켰다. 제조한 촉매의 활성은 귀금속 촉매($Pt/{\gamma}-Al_2O_3$)와 비교하였다. Cu/Ce의 비를 변화시키면서 제조한 촉매 중 Cu/Ce의 비가 4:16인 촉매가 가장 높은 CO 전환율(90%)과 선택도(60%)를 나타내었다. 촉매의 제조에서 가수분해 비가 증가할수록 촉매 표면적이 증가하였고, 아울러 촉매 활성 또한 증가하였다. 공침법으로 제조한 촉매와 1wt% $Pt/{\gamma}-Al_2O_3$ 촉매의 가장 높은 CO 전환율은 각각 82% 및 81%인 반면, 졸-겔법으로 제조한 촉매의 경우는 90%가 얻어졌다. 이는 졸-겔법으로 제조한 촉매가 공침법으로 제조한 촉매나 귀금속 촉매보다 더 높은 촉매활성을 보임을 의미한다. CO-TPD 실험을 통하여, 낮은 온도($140^{\circ}C$)에서 CO를 탈착하는 촉매가 본 반응에서 더 높은 촉매활성을 보임을 알 수 있었다.

• 한국재료학회지
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• 제14권3호
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• pp.163-167
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• 2004

TiAl(La)N thin films were oxidized in vacuum of about 7 Pa to reduce the oxidation of WC-Co as a substrate. The oxidation rate constants of the thin films were quantified by an assumption of parabolic oxidation. Increasing AI content significantly decreased the parabolic oxidation rate constant. A simultaneous addition of AI and La was more effective to reduce the oxidation rate. The parabolic oxidation rate constant of $Ti_{0.66}$ $Al_{0.32}$ $La_{ 0.02}$N thin film at 1273 K showed about ten times lower than that of TiN. The addition of a small amount of La with Al induced the preferential formation of dense $\alpha$ $-Al_2$$O_3$ film in oxide film, leading to the abrupt reduction of oxidation rate.

• 한국분말재료학회지
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• 제18권6호
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• pp.538-545
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• 2011

This study shows that catalytic activity of bimetallic RhPt nanoparticle arrays under CO oxidation can be tuned by varying the size and composition of nanoparticles. The tuning of size of RhPt nanoparticles was achieved by changing concentration of rhodium and platinum precursors in one-step polyol synthesis. Two-dimensional RhPt bimetallic nanoparticle arrays in different size and composition were prepared through Langmuir-Blodgett thin film technique. CO oxidation was carried out on these two-dimensional nanoparticle arrays, revealing higher activity on the smaller nanoparticles compared to the bigger nanoparticles. X-ray photoelectron spectroscopy (XPS) results indicate the preferential surface segregation of Rh compared to Pt on the smaller nanoparticles, which is consistent with the thermodynamic analysis. Because the catalytic activity is associated with differences in the rates of $O_2$ dissociative adsorption between Pt and Rh, this paper suppose that the surface segregation of Rh on the smaller bimetallic nanoparticles is responsible for the higher catalytic activity in CO oxidation. This result suggests a control mechanism of catalytic activity via synthetic approaches of colloid nanoparticles, with possible application in rational design of nanocatalysts.

• Journal of Electrochemical Science and Technology
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• 제7권2호
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• pp.146-152
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• 2016

A combined system with PEMFC and reformer is introduced and optimized for the real use of this kind of system in the future. The hydrogen source to operate the PEMFC system is methanol, which needs two parts of methanol reforming reaction and preferential oxidation (PROX) for the hydrogen fuel process in the combined operation PEMFC system. With the optimized methanol steam reforming condition, we tested PROX reactions in various operation temperature from 170 to 270 ℃ to investigate CO concentration data in the reformed gases. Using these different CO concentration, PEMFC performances are achieved at the combined system. Pt/C and Ru promoted Pt/C were catalysts were used for the anode to compare the stability in CO contained gases. The alloy catalyst of PtRu/C shows higher performance and better resistance to CO than the Pt/C at even high CO amount of 200 ppm, indicating a promotion not only to the activity but also to the CO tolerance. Furthermore, in a system point of view, there is a fluctuation in the PEMFC operation due to the unstable fuel supply. Therefore, we also modified the methanol reforming by a scaled up reactor and pressurization to produce steady operation of PEMFC. The optimized system with the methanol reformer and PEMFC shows a stable performance for a long time, which is providing a valuable data for the PEMFC commercialization.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.731-734
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• 2009

KIER has been developed a compact and highly efficient fuel processor which is one of the key component of the residential PEM fuel cells system. The fuel processor uses methane steam reforming to convert natural gas to a mixture of water, hydrogen, carbon dioxide, carbon monoxide and unreacted methane. Then carbon monoxide is converted to carbon dioxide in water-gas-shift reactor and preferential oxidation reactor. A start-up time of the fuel processor is about 1h and CO concentration among the final product is maintained less than 5 vol. ppm. To achieve high thermal efficiency of 80% on a LHV basis, an optimal thermal network was designed. Internal heat exchange of the fuel processor is so efficient that the temperature of the reformed gas and the flue gas at the exit of the fuel processor remains less than $100^{\circ}C$. A compact design considering a mixing and distribution of the feed was applied to reduce the reactor volume. The current volume of the fuel processor is 17L with insulation.

• Metals and materials international
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• 제24권6호
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• pp.1432-1437
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• 2018

This work investigated edge-cracking behavior of equiatomic CoCrFeMnNi high-entropy alloy during hot rolling at rolling temperatures $500{\leq}T_R{\leq}1000^{\circ}C$. Edge cracks did not form in the material rolled at $500^{\circ}C$, but widened and deepened into the inside of plate as $T_R$ increased from $500^{\circ}C$. Edge cracks were most severe in the material rolled at $1000^{\circ}C$. Mn-Cr-O type non-metallic inclusion and oxidation were identified as major factors that caused edge cracking. The inclusions near edge region acted as preferential sites for crack formation. Connection between inclusion cracks and surface cracks induced edge cracking. Rolling at $T_R{\geq}600^{\circ}C$ generated distinct inclusion cracks whereas they were not serious at $T_R=500^{\circ}C$, so noticeable edge cracks formed at $T_R{\geq}600^{\circ}C$. At $T_R=1000^{\circ}C$, significant oxidation occurred at the crack surface. This accelerated edge crack penetration by embrittling the crack tip, so severe edge cracking occurred at $T_R=1000^{\circ}C$.

• 한국표면공학회지
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• 제52권5호
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• pp.251-257
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• 2019

Fe-9Cr-2W steels were corroded at $600-800^{\circ}C$ for up to 100 hr in ($Na_2SO_4-K_2SO_4-Fe_2O_3$)-($CO_2-0.3%SO_2-6%O_2$) mixed gas. The poor condition samples formed thick oxide scales that consisted primarily of $Fe_2O_3$ as the major oxide and $Fe_3O_4$, FeO as the minor one through preferential oxidation of Fe. Fe-9Cr-2W steels corroded fast, forming thick and non-protective scale. The scale divided into the outer and inner layer, which consisted of the outer Fe-O layer and the inner (Fe,Cr)-O layer containing some (Fe,Cr)-S.

• 청정기술
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• 제13권1호
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• pp.54-63
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• 2007

고분자 전해질 연료전지에 사용되는 개질 수소 속에는 미량의 일산화탄소가 존재할 수 있으며, 이는 연료전지의 백금 성분의 양극 전극을 비활성화로 이끌며, 그로 인하여 전기 출력이 급격히 떨어지게 된다. 본 연구는 담체의 조성을 달리한 여러 가지 $Cu/Ce_xZr_{1-x}O_2$ (x=0.0-1.0) 촉매들을 합성하고 그들 특성이 분석되었으며, 또한 일산화탄소의 산화반응과 수소 분위기에서의 일산화탄소에 대한 선택적 산화반응을 수행하였다. 이들 촉매들은 수열합성법과 침적-침전법을 조합하여 제조되었으며, XRD, XRF, SEM, TEM, BET, $N_2O$ 분해실험, 산소저장능력 측정 기법 등에 의해 그들의 물리화학적 성질들이 분석되었다. 담체의 조성과 반응물 산소의 과잉정도에 따른 영향들이 여러 반응온도에서 반응활성과 이산화탄소 선택도 등에 의해 조사되어졌다. 합성된 여러 조성을 달리한 $Cu/Ce_xZr_{1-x}O_2$ 촉매들 가운데 $Cu/Ce_{0.9}Zr_{0.1}O_2$와 $Cu/Ce_{0.7}Zr_{0.3}O_2$ 두 가지 촉매는 $170^{\circ}C$ 반응온도 부근의 PROX 반응에서 99% 이상의 CO 전환율과 50% 내외의 선택도를 나타내었다. 이와 같은 비교적 완화된 조건에서의 우수한 활성은 높은 산소저장능력을 지닌 $Ce_xZr_{1-x}O_2$ 담체를 사용함으로서 구리촉매의 산호-환원 활성이 증가한 것에 기인하며, 결국 수소분위기에서의 일산화탄소의 산화 반응에 대한 높은 활성과 선택도를 이끌었다.