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        검색결과 146

        82.
        2011.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Esterification reaction between succinic acid[SA] and 1,4-butanediol [BD] was kinetically investigated in the presence of organometallic catalysts (ESCAT-100Ag18, MBTO) at 150~180℃. The reaction followed from the measurement of the quantity of water which was distilled from the reaction vessel. The esterification reaction was carried out under the first order kinetics with respect to the concentration of reactants and catalyst, respectively. The overall reaction order was 2nd. From the examination of relationship between apparent reaction rate constants and reciprocal absolute temperature, the activation energy has been calculated as 146.70 kJ/mol(ESCAT-100Ag18) and 87.57 kJ/mol(MBTO), respectively.
        4,000원
        83.
        2010.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The transesterification of rapeseed oil, soybean oil, and mixed fat were conducted at 65℃ with Al2O3-supported CaO, 0.8 wt% KOH, 1 wt% NaOH and mixed catalyst. The overall conversion(%) of rapeseed oil indicated to be 96% at the 12:1 molar ratio of methanol to oil, 8 wt% CaO and 2 wt% water. The pH ranges of biodiesel for mixed fat using four catalysts and for three fats using 8wt% CaO were 7.3-9.1, 7.3-7.5, respectively. The volumes of water needed to wash biodiesel from rapeseed oil using 0.8 wt% KOH and 8 wt% CaO were 15 mL and 3 mL.
        4,000원
        84.
        2010.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Nickel recovery method was studied by the wet process from the catalyst used in hydrogenation process. Nickel content in waste catalyst was about 16%. At the waste catalyst leaching system by the alkaline solution, selective leaching of nickel was possible by amine complex formation reaction from ammonia water and ammonium chloride mixed leachate. The best leaching condition of nickel from mixed leachate was acquired at the condition of pH 8. LIX65N as chelating solvent extractant was used to recover nickel from alkaline leachate. The purity of recovered nickel was higher than 99.5%, and the whole quantity of nickel was recovered from amine complex.
        4,000원
        85.
        2010.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        On cold start operation of an SI engine, a catalyst shows poor performance before it reaches activation temperature. Therefore, fast warmup of the catalyst is very crucial to reduce harmful emissions. In this study, an appropriate control strategy is investigated to increase exhaust gas temperature through changes of spark timing and exhaust valve timing. Combustion stability is also considered at the same time. Experiments showed that retarded spark timing promotes the combustion at the end of expansion stroke and increases exhaust gas temperature during cold start.An advance of exhaust valve timing decreases residual gas in cylinders due to decrease of valve overlap period. It helps improvement combustion stability by virtue of reduced residual gas. A control strategy of proper valve timing and spark timing is suggested in order to achieve fast light-off of the catalyst and stable operation of the engine in a cold start and idle operation
        4,000원
        86.
        2010.02 구독 인증기관 무료, 개인회원 유료
        The potassium permanganate was used for manganese oxide catalyst with various methods and various processes, which manganese oxide wasused for removal of formaldehyde in flow gas. Experiments indicate that these catalyst materials are difference from each other because of raw materials used and pH values in catalysts preparation when used for formaldehyde removal. And when catalyst was prepared by using potassium permanganate and GLU or PEAunder different pH values respectively, it could have good performance in formaldehyde oxidizing purification. In this thesis, when the ratio of potassium permanganate and GLU was 5:1 for catalyst preparation, and 5 mL of nitric acid was added, the formaldehyde elimination efficiency could be maintained at 100% longer than 600 minutes. And when the ratio of potassium permanganate and PEA was 10:1 for catalyst preparation, and 5 mL of nitric acid was added, the formaldehyde elimination efficiency could be maintained at 100% longer than 705 minutes.
        4,200원
        87.
        2010.02 구독 인증기관 무료, 개인회원 유료
        Oxidation characteristics of benzene as a VOC were investigated using a fixed bed reactor system over transition metal catalysts. The transition metal catalysts were made by using transition metal nitrate reagent and various support materials such as γ-Al2O3, and TiO2. The parametric tests were conducted at the reaction temperature range of 200~500℃, benzene concentration of 2,000~3,000 ppm with space velocity of 10000 hr-1. The property analyses such as BET, SEM, TGA and the conversions of catalytic oxidation of VOC were examined. The experimental results showed that the BET surface areas of catalyst are 86.4∼167.7m2/g, the pore volumes are 0.049∼0.056cm3/g, and the average pore sizes of catalyst are 27∼44Å, which mean the meso pore. It was also found that the conversion of benzene oxidation reaction at 400∼500℃ with Cu/γ-Al2O3+TiO2 catalyst showed 90∼100%, which indicate that the transition metal catalyst with composite supports is very effective for the oxidation of benzene.
        4,000원
        88.
        2009.12 KCI 등재후보 구독 인증기관 무료, 개인회원 유료
        In this study, toluene catalytic oxidation was investigated using various metal components (Cu, Ce, Ni, La and Zr) supported on Used FCC zeolite for the application of the waste recycling and odor reduction. Among the metals, 5 wt% Cu/zeolite showed the best catalytic activity. 100 % conversion was achieved at 300℃ which was 50℃ lower than that of other metal components. As increasing the amount of doped Cu, the CuO was formed and the surface area and pore size were decreased. By the reduction treatment before toluene oxidation, the catalytic activity of the oxidation below 250℃ was improved. No decrease of conversion was observed during the continuos reaction at 300℃ for 48 h.
        4,000원
        89.
        2009.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The electrochemical deposition of Pt nanoparticles on carbon nanotubes (CNTs) supports and their catalytic activities formethanol electro-oxidation were investigated. Pt catalysts of 4~12nm average crystalline size were grown on supports bypotential cycling methods. Electro-plating of 12min time by potential cycling method was sufficient to obtain smallcrystalline size 4.5nm particles, showing a good electrochemical activity. The catalysts’ loading contents were enhanced byincreasing the deposition time. The crystalline sizes and morphology of the Pt/support catalysts were evaluated using X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). The electrochemical behaviors of the Pt/support catalystswere investigated according to their characteristic current-potential curves in a methanol solution. In the result, theelectrochemical activity increased with increased plating time, reaching the maximum at 12min, and then decreased. Theenhanced electroactivity for catalysts was correlated to the crystalline size and dispersion state of the catalysts.
        3,000원
        90.
        2009.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Esterification reaction between succinic acid and 1,4-butanediol was kinetically investigated in the presence of monobutyl tinoxide catalysts at 150~190℃. The reaction rates measured by the amount of distilled water from the reaction vessel. The esterification reaction was carried out under the first order conditions with respect to the concentration of reactants, respectively. The overall reaction order was 2nd. The linear relationship was shown between apparent reaction rate constant and reciprocal absolute temperature. By the Arrhenius plot the activation energy have been calculated as 87.567 kJ/mol under monobutyl tinoxide catalyst and also apparent reaction rate constant, k' was found to obey first kinetics with respect to the concentration of catalyst.
        4,000원
        91.
        2009.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        On cold start operation of a gasoline engine, a catalyst shows poor performance before it reaches activation temperature. Therefore, fast warmup of the catalyst is very crucial to reduce harmful emissions. In this study, an appropriate control strategy is investigated to increase exhaust gas temperature through changes of exhaust valve timing. An advance of exhaust valve timing decreases residual gas in cylinders due to decrease of valve overlap period. A control strategy of proper valve timing is suggested in order to achieve fast light-off of the catalyst and stable operation of the engine in a cold start and idle operation.
        4,000원
        92.
        2008.09 KCI 등재후보 구독 인증기관 무료, 개인회원 유료
        The importance of indoor air environment gets higher because time of staying in indoor such as house or car become longer due to a change of the life pattern on human society. One of major pollution sources, VOCs or odor could be reduced or controlled by using adsorbent. It may be valuable for used catalyst to be applied in the adsorption of VOCs or odor. This could reduce the cost of adsorbent. In this work, the potential of used zeolites such as HZSM-5 catalyst and FCC catalyst as an adsorbent for removing acetaldehyde was investigated. Their adsorptive performances were compared with those of active carbon and MCM-41. The removal performace of used HZSM-5 was similar to that of active carbon due to its higher surface area. But used-FCC catalyst showed the lowest performance. These results suggest that used HZSM-5 can be applied to cheap adsorbent for acetaldehyde removal.
        4,000원
        93.
        2008.02 구독 인증기관 무료, 개인회원 유료
        Characteristics of VOC(benzene) treatment were investigated using a fixed bed reactor system over copper base catalyst and photocatalyst/adsorbent blending material. The copper base catalysts were made by using copper nitrate reagent and various support materials such as γ-Al2O3, TiO2. The parametric tests were conducted at the reaction temperature range of 200~400℃, benzene concentration of 1,000~2,000 ppm, and space velocity range of 5,000~10,000 hr-1. The property analyses such as BET, SEM and the removal efficiency(conversion) of VOC were examined. The experimental results showed that the VOC removal efficiency of hybrid method was higher than that of single method. It was also found that the comprehensive feasibility study of hybrid method would need with considering various factors including additional expenses.
        4,500원
        94.
        2007.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Carbon nanofiber (CNF) grown catalytically was chemically activated with KOH to attain structural change of CNF. The structural changes of CNF through KOH activation were investigated by using BET and SEM. From the results of BET, it was found that KOH activation was effective to develop particular sizes of pores on the CNF surface, increasing the surface area of CNF. Activated CNF was applied as an anode catalyst support of fuel cell. The effects of different activation conditions including the activation temperature and the activation time on the specific surface area of the CNF activated with KOH were investigated to obtain appropriate structure as a catalyst support. The 60 wt% Pt-Ru catalyst prepared was observed by using TEM and XRD.
        4,000원
        95.
        2007.02 구독 인증기관 무료, 개인회원 유료
        Oxidation characteristics of benzene as a VOC was investigated using a fixed bed reactor system over copper base catalysts. The copper base catalysts were made by using copper nitrate reagent and various support materials such as γ-Al2O3, TiO2, and zeolite. The parametric tests were conducted at the reaction temperature range of 200~500℃, benzene concentration of 1,000~2,000 ppm, and space velocity range of 5,000~20,000 hr-1. The property analyses such as BET, SEM, XRD and the conversions of catalytic oxidation of VOC were examined. XRD analysis on copper catalysts showed CuO crystal forms and the peak intensity of CuO increased as the impregnation weight of copper grew. The experimental results showed that the conversion was increased with decreasing space velocity. It was also found that Cu/γ-Al2O3+TiO2 catalyst showed the highest activity for the oxidation of benzene and 15% metal loading was the optimum impregnation level.
        4,800원
        96.
        2006.04 구독 인증기관·개인회원 무료
        This paper described the preparation method for composing high-grade synthetic diamond by water atomizing using FeNi30 powder catalyst. The objective of this article is about powder making process using super high water atomizing in the atmosphere of inert gas, and then corroded the powder with a corrosion inhibitor. Finally, FeNi30 catalyst powder with lower oxygen content and good sphericity is produced. The experiment of making diamonds by using cubic press and the performance of the diamonds are also discussed.
        97.
        2005.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The work reported in this paper relates to preparation and characterization of carbon nanomaterials by CVD method on different substrates by decomposition of certain hydrocarbons at 550-800℃ using a horizontal quartz tube reactor. Monometallic and bimetallic catalyst system of iron and nickel were used for the preparation of different carbon nanomaterials. The influence of various parameters such as substrate/catalyst preparation parameters, the nature of substrate, catalyst concentration, reaction time and temperature on the growth, yield and alignment of carbon nanotubes has been studied. The characterization of carbon nanomaterials has been carried out using SEM, TEM and TGA. The carbon nanomaterials developed were vertically aligned on a large area of flat quartz substrate.
        4,000원
        99.
        2005.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Platinum catalysts for the DMFC (Direct Methanol Fuel Cell) were impregnated on several carbon supports and their catalytic activities were evaluated with cyclic voltammograms of methanol electro-oxidation. To increase the activities of the Pt/C catalyst, carbon supports with high electric conductivity such as mesoporous carbon, carbon nanofiber, and carbon nanotube were employed. The Pt/e-CNF (etched carbon nanofiber) catalyst showed higher maximum current density of and lower on-set voltage of 0.54 V vs. NHE than the Pt/Vulcan XC-72 in methanol oxidation. Although the carbon named by CNT (carbon nanotube) series turned out to have larger BET surface area than the carbon named by CNF (carbon nanofiber) series, the Pt catalysts supported on the CNT series were less active than those on the CNF series due to their lower electric conductivity and lower availability of pores for Pt loading. Considering that the BET surface area and electric conductivity of the e-CNF were similar to those of the Vulcan XC-72, smaller Pt particle size of the Pt/e-CNF catalyst and stronger metal-support interaction were believed to be the main reason for its higher catalytic activity.
        4,000원
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