• 한국정밀공학회지
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• 제27권9호
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• pp.58-66
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• 2010

This study examines thermal safety on three-way catalyst that dominates 70 % among whole exhaust gas purification device in 2003. Three-way catalyst durability in the Korea requires 5 years/80,000 km in 1988 but require 10 years/120,000 km after 2002. Three-way catalyst durability in the USA requires 7 years/120,000 km but require 10 years/160,000 km after 2004. Three-way catalyst maintains high temperature in interior domain but maintains low temperature on outside surface. Therefore this device shows tensile stress on outside surface. Temperature distribution of three-way catalyst was acquired by thermal flow analysis for predicted thermal flow parameter. Thermal stress analysis for three-way catalysis was performed based on this temperature distribution. Thermal safety of three-way catalyst was estimated by power law dynamic fatigue life estimation and strength reduction methods for thermal stress.

• 동력기계공학회지
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• 제17권5호
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• pp.13-22
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• 2013

This paper reports the investigation of the physical and chemical characteristics of the prepared 3Pt-2MgO-$3ZrO_2$-$2CeO_2/Al_2O_3$ DOC, based on its hydrothermal aging. As a result of impregnating and reducing the $H_2PtCl_6$ $6H_2O$ precursor on a ${\gamma}-Al_2O_3$ basis, it was well dispersed into small particles with the range 2-3nm. This was because the $Al_2O_3$ acted as a barrier to prevent movement of the catalyst particles. For a hydrothermally aged catalyst for 9h at $700^{\circ}C$, its performance when purifying harmful gases decreased compared to a fresh catalyst, but its specific surface area was at the same level. This was because the performance of the catalyst was reduced by the sintering of the precious metal Pt, rather than by washcoat sintering and pore clogging. For an excessively hydrothermally aged catalyst for 9h at $850^{\circ}C$, Pt grew into an approximately 50nm class, formed a cluster compared to a fresh catalyst. The $CeO_2$ promoters also formed clusters among components of the same type, reducing their specific surface area to $114m^2/g$, which was 14% less than a fresh catalyst.

• 한국수소및신에너지학회논문집
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• 제23권3호
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• pp.256-263
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• 2012

We studied the degradation phenomenon of Pt catalyst in PEMFC. We used the electron microscope analysis technique including the ultra-microtome pretreatment method, FEG-SEM and TEM analysis methods for analysis of Pt nanoparticles. The Pt catalyst degradation is observed not only in electrode site but also in membrane site. We investigated these various degradation phenomena. The cathode electrode layer thickness is reduced. The size of the catalyst is increased much larger than initial size in membrane site. The catalyst moved from electrode layer to the electrolyte membrane. The rounded shape of catalyst was changed to the polygon. As a result, we found that the catalyst degradation processes of migration and coarsening occurred by the followings mechanisms; (1) dissolution of Pt ; (2) diffusion of Pt ion ; (3) Pt ion chemical reduction in membrane; (4) Coarsening of Pt particles (Ostwald ripening) ; (5) polygon shape change of Pt by {111} plane growth.

• 한국기계기술학회지
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• 제13권2호
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• pp.123-128
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• 2011

It has been stand high in estimation to converse from Carbon dioxide to Dimethyl Ether in new alternative fuel energy division in 21C, especially Using of DME in point of view of transportation fuel has been discussed of a new clean energy which is very lower of exhaust gas than gasoline and diesel energy. In this paper it is used ZSM-5 and I developed new catalyst by addition of cerium to control acidity. The new catalyst was proved high conversion rate, when it was conversed from methanol to DME, there wasn't any additional material except DME and water, and I overlooked reaction temperature, reaction time, amount of catalyst, amount of added cerium, effect of water content in methanol, reaction temperature by making change of reaction time. I have conclude that conversion rate to DME was increased as increased of catalyst amounts. The best catalyst condition of without additional product was treated poisoning from ZSM-5 to 5% cerium and new catalyst was not effected in purity of fuel methanol.

• Bulletin of the Korean Chemical Society
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• 제20권12호
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• pp.1413-1417
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• 1999

Chemical poisoning of Ni/MgO catalyst was induced by hot alkali carbonate vapor in molten carbonate fuel cell (MCFC), and the poisoned (or contaminated) catalyst was characterized by TPR/TPO, FTIR, and XRD analysis. Carbonate electrolytes such as K and Li were transferred to the catalyst during DIR-MCFC operation at 650 ℃. The deposition of alkali species on the catalyst consequently led to physical blocking on catalytic active sites and structural deformation by chemical poisoning. TPR/TPO analysis indicated that K species enhanced the reducibility of NiO thin film over Ni as co-catalyst, and Li species lessened the reducibility of metallic Ni by chemical reaction with MgO. FTIR analysis of the poisoned catalyst did not exhibit the characteristic ${\vector}_1$$(D_{3h})$ peaks (1055 $cm^{-1},\;1085\;cm{-1})$ for pure crystalline carbonates, instead a new peak (1120 $cm^{-1})$ was observed proportionally with deformed alkali carbonates. From XRD analysis, the oxidation of metallic Ni into $Ni_xMg_{1-x}O$ was confirmed by the peak shift of MgO with shrinking of Ni particles. Conclusively, hot alkali species induced both chemical poisoning and physical deposition on Ni/MgO catalyst in DIR-MCFC at 650 ℃.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제31회 추계학술대회논문집
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• pp.109-112
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• 2008

초소형 추력기의 최적화를 위한 연구로 촉매 담지 조건을 변화시키면서 성능 평가를 실시하였다. 촉매의 담지 조건 중 촉매 전구체를 용해시키는 전해물질의 산성도를 변화시켰다. 또한 각각의 경우에 대해 건조 조건을 달리하면서 이에 따른 성능 평가를 실시하였다. 이를 통해 촉매 담지 조건이 추력기 성능에 미치는 영향을 알아보았다. 추진제로는 90wt% 과산화수소를 사용하였으며, 높은 분해성능을 보이는 백금을 촉매로 사용하였다. 초소형 추력기의 목표 추력은 0.1N이며 성능 평가를 위해서 특성속도 효율과 온도 효율을 사용하기로 하였다.

• 한국수소및신에너지학회논문집
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• 제26권2호
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• pp.96-104
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• 2015

Reactivity of commercial WGS catalyst and four new catalysts(RMC-3, PC-73, PC-67SU, PC-59) manufactured with various compositions by Korea Electric Power Research Institute(KEPCO RI) were compared to select suitable WGS catalyst for SEWGS system. Steam/CO ratio, gas velocity, flow rates of syngas, and temperature were considered as operating variables. As a result, commercial catalyst showed the highest CO conversion and RMC-3 catalyst showed also high CO conversion. Therefore, commercial and RMC-3 catalysts were selected as applicable catalysts. However, PC-73 catalyst showed low CO conversion at low temperature($200^{\circ}C$) but showed good reactivity at high temperature($225{\sim}250^{\circ}C$), and therefore, PC-73 catalyst was selected as applicable catalyst for high temperature operation. Continuous operations up to 24 hours for those three catalysts(commercial, RMC-3, PC-73) were conducted to check reactivity decay of catalysts. All three catalysts maintained their original reactivity.

• 한국수소및신에너지학회논문집
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• 제26권6호
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• pp.507-515
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• 2015

HI decomposition reaction requires a catalyst for the efficient production of hydrogen as a key reaction for hydrogen production in sulfur-iodine thermochemical water-splitting (SI) cycle. As a catalyst used in the reaction, the performance of platinum catalyst is excellent. While, the platinum catalyst is not economical. Therefore, studies of a nickel catalyst that could replace platinum have been carried out. In this study, the characteristics of the catalytic HI decomposition on the amount of loaded nickel (Ni = 0.1, 0.5, 1, 3, 5, 10 wt%) were investigated. As the supported Ni amount increased up to 3 wt%, HI decomposition was found to increase in linear proportion. However, the conversion of $Ni/Al_2O_3$ catalyst loaded above 3 wt% was not linear. It was thought that the different HI decomposition characteristics was caused in the size and metal dispersion of Ni particles of catalyst. The physical property of catalyst before and after HI decomposition reaction was characterized by BET, chemisorption, XRD and SEM analysis.

• 한국환경과학회지
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• 제15권3호
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• pp.193-201
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• 2006

Advanced oxidation processes involving $O_3/H_2O_2$ and $O_3/catalyst$ were used to compare the degradability and the effect of pH on the oxidation of 1,4-dioxane, Oxidation processes were carried out in a bubble column reactor under different pH. Initial hydrogen peroxide concentration was 3.52 mM in $O_3/H_2O_2$ process and 115 g/L (0.65 wt.%) of activated carbon impregnated with palladium was packed in $O_3/catalyst$ column. 1,4-dioxane concentration was reduced steadily with reaction time in $O_3/H_2O_2$ oxidation process, however, in case of $O_3/catalyst$ process, about $50{\sim}75%$ of 1,4-dioxane was degraded only in 5 minutes after reaction. Overall reaction efficiency of $O_3/catalyst$ was also higher than that of $O_3/H_2O_2$ process. TOC and $COD_{cr}$ were analyzed in order to examine the oxidation characteristics with $O_3/H_2O_2\;and\;O_3/catalyst$ process. The results of $COD_{cr}$ removal efficiency and ${\Delta}TOC/{\Delta}ThOC$ ratio in $O_3/catalyst$ process gave that this process could more proceed the oxidation reaction than $O_3/H_2O_2$ oxidation process. Therefore, it was considered that $O_3/catalyst$ advanced oxidation process could be used as a effective oxidation process for removing non-degradable toxic organic materials.

• 청정기술
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• 제5권2호
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• pp.63-68
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• 1999

The activities of Ni(20wt%)/$La_2O_3$, Ni(20wt%)/${\gamma}-Al_2O_3$, and Ni(20wt%)/$SiO_2$ catalyst for $CO_2$ reforming of $CH_4$ were investigated in a fixed bed flow reactor under atmospheric condition. Catalyst characterization using XRD, TEM, SEM, BET analysis were also conducted. The catalytic activity of Ni(20wt%)/$La_2O_3$ catalyst has relatively superior to that of Ni(20wt%)/${\gamma}-Al_2O_3$ and Ni(20wt%)/$SiO_2$ catalyst. The good activity of Ni(20wt%)/$La_2O_3$ catalyst seems to depend on reduced $Ni^{\circ}$ phases of NiO($\rightarrow$ Ni + O), $LaNiO_3$($\rightarrow$ $Ni+La_2O_3$), Ni crystalline phases, and decoration of Ni phases by lanthanum species is also an important factor. Ni(20wt%)/${\gamma}-Al_2O_3$ and Ni(20wt%)/$SiO_2$ catalyst due to surface acidity resulted in the deposition of wisker type and encapsulate carbon on the surface of catalyst, but Ni(20wt%)/$La_2O_3$ catalyst did not show carbon on the surface of catalyst up to 8.5hr reaction.