• 한국분말재료학회지
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• 제10권4호
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• pp.281-287
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• 2003

Ultrafine TiC-15%Co powders were synthesized by a thermochemical process, including spray drying, calcination, and carbothermal reaction. Ti-Co oxide powders were prepared by spray drying of aqueous solution of titanium chloride and $Ti(OH)_2$ slurry, both containing cobalt nitrate, fellowed by calcination. The oxide powders were mixed with carbon powder to reduce and carburize at 1100~125$0^{\circ}C$ under argon or hydrogen atmosphere. Ultrafine TiC particles were formed by carbothermal reaction at 1200~125$0^{\circ}C$, which is significantly lower than the formation temperature (~1$700^{\circ}C$) of TiC particles prepared by conventional method. The oxygen content of TiC-15%Co powder synthesized under hydrogen atmosphere was lower than that synthesized under argon, suggesting that hydrogen accelerates the reduction rate of Ti-Co oxides. The size of TiC-15%Co powder was evaluated by FE-SEM and TEM and Identified to be smaller than 300 nm.

• 공업화학
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• 제17권4호
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• pp.414-419
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• 2006

연소 배기가스 중의 수분, 탄화수소 및 CO가 저온 플라즈마 및 $NH_{3}$ SCR (Selective Catalytic Reduction)공정이 복합된 탈질공정에 미치는 영향에 대한 연구가 수행되었다. 실험결과 일반적인 SCR 반응에 비해 매우 빠른 반응속도를 갖는 fast SCR 반응은 $150{\sim}200^{\circ}C$의 저온조건에서 탈질율의 상승을 가져다주지만, 처리가스 중에 탄화수소가 있는 경우 fast SCR 반응의 역할이 상당히 감소되는 것을 확인할 수 있었다. 이는 저온 플라즈마 반응기에서 부분산화반응을 통해 탄화수소 중 일부가 알데히드로 전환되며, 알데히드는 fast SCR 반응에 있어 중요한 변수인 $NO_{2}/NO_{x}$ 비율에 영향을 주기 때문인 것으로 설명되었다. 한편, 수분 및 CO가 fast SCR 반응에 미치는 영향은 탄화수소에 비해 상대적으로 적음을 확인할 수 있었다.

• 한국수소및신에너지학회논문집
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• 제24권6호
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• pp.518-523
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• 2013

This paper describes the reduction of a hydrogen sulfide ($H_2S$) generated from a biogas plant. Micro bubble system is adopted to supply air into the water in the reaction chamber, which can increase the contact area of the supplied air to the reserving water. Two stage reaction chambers having two reaction rooms are designed and manufactured to enhance the reduction rate of a hydrogen sulfide. Sodium hydroxide (NaOH) is also considered to get rid of a hydrogen sulfide. Air volume rate to the water in a reaction chamber is maintained between 0.5 and $1.0m^3/min$. Throughout experimental measurement of the concentration of a hydrogen sulfide by changing the volume of supplied air into the water, reduction rate of a hydrogen sulfide increases as air volume increases. Adding sodium hydroxide to the water with the air supply can reduce effectively a hydrogen sulfide up to 99.5% from biogas. It is noted that a hydrogen sulfide generated by a biogas plant can reduce by supplying micro bubble air and sodium hydroxide effectively.

• Korean Chemical Engineering Research
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• 제48권3호
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• pp.316-321
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• 2010

본 연구에서는 고압조건에서 $SO_2$를 원소 황으로 전환하기 위한 촉매환원반응이 수행되었다. $SO_2$ 환원을 위한 촉매로 Sn-Zr계 금속복합산화물 촉매를 사용하였으며, 환원제로 CO가 사용되었다. 촉매환원반응성을 조사하기 위하여 반응온도, 반응물의 몰비([CO]/[$SO_2$]), 공간속도에 따른 $SO_2$ 전화율과 원소 황 수율 그리고 COS의 선택도를 상압조건과 20기압조건에서 비교되었다. 상압조건에서 $SO_2$ 전화율은 반응온도가 증가될수록 함께 증가되었으며, $CO/SO_2$ 몰비가 높을수록 증가되었다. 또한 $SO_2$ 전화율의 증가와 함께 COS의 선택도도 함께 증가되어, 원소 황 수율은 오히려 낮아졌다. 그러나 20 atm의 고압조건에서는 높은 $SO_2$ 전화율과 낮은 COS의 선택도가 얻어졌다. 이와 같은 결과는 높은 압력으로 인한 반응속도의 증가와 함께 생성된 원소 황이 응축되어 CO에 의한 COS 생성이 억제되었기 때문이라 판단된다. 이와 같은 결과로부터 $SO_2$ 촉매환원반응으로 높은 황 수율은 고압조건에서 더 유리하게 얻을 수 있다.

• 한국수소및신에너지학회논문집
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• 제35권2호
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• pp.162-167
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• 2024

Fossil fuels have been main energy source to people. However, enormous amount of CO₂ was emitted over the world , resulting in global climate crisis today. Recently, solid oxide electrolyzer cell (SOEC) is getting attention as an effective way for producing H₂, a clean energy resource for the future. Also, SOEC could be applicable to reverse water-gas shift reaction process due to its high-temperature operating condition. Here, SOEC system was utilized for both H₂ production and CO₂ reduction process, allowing product gas composition change by controlling operating conditions.

• 한국분말재료학회지
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• 제31권2호
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• pp.163-168
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• 2024

As the demand for lithium-ion batteries for electric vehicles is increasing, it is important to recover valuable metals from waste lithium-ion batteries. In this study, the effects of gas flow rate and hydrogen partial pressure on hydrogen reduction of NCM-based lithium-ion battery cathode materials were investigated. As the gas flow rate and hydrogen partial pressure increased, the weight loss rate increased significantly from the beginning of the reaction due to the reduction of NiO and CoO by hydrogen. At 700 ℃ and hydrogen partial pressure above 0.5 atm, Ni and Li₂O were produced by hydrogen reduction. From the reduction product and Li recovery rate, the hydrogen reduction of NCM-based cathode materials was significantly affected by hydrogen partial pressure. The Li compounds recovered from the solution after water leaching of the reduction products were LiOH, LiOH·H₂O, and Li₂CO₃, with about 0.02 wt% Al as an impurity.

• Bulletin of the Korean Chemical Society
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• 제17권3호
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• pp.269-273
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• 1996

Alkyl halides were reduced to the corresponding alkanes by the homonuclear bridging hydride, (μ-H)[(η5-MeCp)Mn(CO)2]2-PPN+ in THF at the elevated temperatures (40-60 ℃) under the pseudo first order reaction conditions where excess of alkyl halide was employed under nitrogen atmosphere. The reaction is of overall second order; first order with respect to [bridging hydride] and first order with respect to [alkyl halide] with the activation parameters, ΔH≠=28.93 kcal/mol and ΔS≠=17.95 e.u. The kinetic data, the ESR evidence and the reaction with cyclopropyl canbinyl bromide ensure that two possible reaction pathways are operable in this reaction: (1) concerted mechanism, and (2) single electron transfer pathway are in competition leading to the same product, the corresponding alkane.

• Journal of Electrochemical Science and Technology
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• 제6권4호
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• pp.121-130
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• 2015

The micro emulsion method has been successfully used for preparing perovskite LaCoO₃ with uniform, fine-shaped nanoparticles showing high activity as electro catalysts in oxygen reduction reactions (ORRs). They are, therefore, promising candidates for the air-cathode in metal-air rechargeable batteries. Since the activity of a catalyst is highly dependent on its specific surface area, nanoparticles of the perovskite catalyst are desirable for catalyzing both oxygen reduction and evolution reactions. Herein, LaCoO₃ powder was also prepared by sol-gel method for comparison, with a broad particle distribution and high agglomeration. The electro catalytic properties of LaCoO₃ and LaCoO₃-carbon Super P mixture layers toward the ORR were studied comparatively using the rotating disk electrode technique in 0.1 M KOH electrolyte to elucidate the effect of carbon Super P. Koutecky-Levich theory was applied to acquire the overall electron transfer number (n) during the ORR, calculated to be ~3.74 for the LaCoO₃-Super P mixture, quite close to the theoretical value (4.0), and ~2.7 for carbon-free LaCoO₃. A synergistic effect toward the ORR is observed when carbon is present in the LaCoO₃ layer. Carbon is assumed to be more than an additive, enhancing the electronic conductivity of the oxide catalyst. It is suggested that ORRs, catalyzed by the LaCoO₃-Super P mixture, are dominated by a 2+2-electron transfer pathway to form the final, hydroxyl ion product.

• Journal of Mechanical Science and Technology
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• 제18권12호
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• pp.2303-2309
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• 2004

Flue gas recirculation (FGR) is a method widely adopted to control NOx in combustion system. The recirculated flue gas decreases flame temperature and reaction rate, resulting in the decrease in thermal NO production. Recently, it has been demonstrated that the recirculated flue gas in fuel stream, that is, the fuel induced recirculation (FIR), could enhance a much improved reduction in NOx per unit mass of recirculated gas, as compared to the conventional FGR in air. In the present study, the effect of FGR/FIR methods on NOx reduction in turbulent swirl flames by using N$_2$ and CO$_2$ as diluent gases to simulate flue gases. Results show that CO$_2$ dilution is more effective in NO reduction because of large temperature drop due to the larger specific heat of CO$_2$ compared to N$_2$ and FIR is more effective to reduce NO emission than FGR when the same recirculation ratio of dilution gas is used.

• 한국수소및신에너지학회논문집
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• 제27권5호
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• pp.471-477
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• 2016

In this research, the Ir supported $TiO_2$ (P25) catalyst was prepared by precipitation method for oxygen evolution reaction. The $Ir/TiO_2$ catalyst was synthesised by reduction reaction using reducing agent. Physiochemical characterizations of synthesized $Ir/TiO_2$ catalyst was studied by means of SEM, EDS mapping, TEM and XRD. The Electrochemical characterizations were tested by using the technique of CV and LSV by RDE and Potentiostat. Physicochemical properties were characterized with XRD where Iridium metal morphology and Ir(111) and Ir(222) peaks were founded. $Ir0.2Ru0.8O_2$ exhibited higher OER activity than $Ir0.5Ru0.5O_2$ followed by $Ir/TiO_2$ and $IrO_2$.