• Proceedings of the Korean Nuclear Society Conference
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• 1995.05a
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• pp.747-752
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• 1995

핵융합로 증식재용 ${\gamma}$-LiAlO$_2$ 분말을 자발착화 연소반응법을 적용하여 합성하였다. LiAlO$_2$분말을 합성하는데 이 방법을 적용하면 다른 분말 합성법과 달리 짧은 시간 내에 미세한 ${\gamma}$상을 쉽게 형성할 수 있었다. 최적의 ${\gamma}$-LiAlO$_2$ 분말을 합성하려면 구연산과 우레아의 혼합연료가 가장 적절하다고 판단되며, 이 연료로 합성된 ${\gamma}$-LiAlO$_2$ 분말을 24시간 볼분쇄하면 비표면적 값이 15.8 m$^2$/g인 미세한 분말을 얻을 수 있었다.

• Journal of the Korean Ceramic Society
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• v.38 no.8
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• pp.765-770
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• 2001

광촉매용 ZnO 나노크기의 분말은 시작원료와 연료의 종류에 따라 용액연소법에 의해 제조되었다. 결정상은 XRD로부터 확인할 수 있었으며 분말의 하소온도는 TG 분석으로부터 결정되었다. 분말의 비표면적은 BET 법에 의해 측정되었으며 평균입자크기와 형태를 SEM과 TEM으로부터 조사하였다. 또한 분말의 순도를 조사하기 위해 적외선 흡수스펙트럼을 측정하였으며 광촉매 효율로서 은이 첨가된 사진현상액을 이용하여 은의 수거율을 측정하였다. 용액연소법으로 제조한 경우 시작원료와 연료에 관계없이 단상의 ZnO 분말을 쉽게 얻을 수 있었다. 그러나 합성된 ZnO 분말의 입자크기와 형태는 연료의 종류에 따라 서로 다르게 보였다. 특히, 연료로 glycine을 사용한 경우, ZnO 분말의 입자 형태는 균일한 나노 크기의 구형이었으나 carbohydrazide을 사용한 경우에는 판상과 같은 형태를 보였다. 이러한 결과를 기초로 하여 시작원료와 연료로 Zn(OH)$_2$와 glycine을 사용하여 합성된 ZnO 분말이 우수한 분말 특성을 보였으며 75nm의 입자크기와 94$m^2$/g의 비표면적을 보였다. 또한 사진현상액에 존재하는 은이 3분 이내에 완전히 제거되는 우수한 광촉매 성질을 보였다.

• Korean Chemical Engineering Research
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• v.56 no.2
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• pp.156-161
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• 2018

$TiO_2$ photocatalyst powders were prepared by chlorination method and sol-gel method. Specific surface area and crystalline (i.e., anatase and rutile) of the catalyst varied depending on manufacture conditions and method. TTIP-sol photocatalyst had higher methylene blue (MB) decomposition characteristics than photocatalyst from chlorination method and TBOT-sol. MB removal efficiency from aqueous solution with TTIP-sol photocatalyst was over 90%. Experimental results showed that the $TiO_2$ photocatalyst with a single anatase phase and a large specific surface area had high decomposition characteristics of organic materials.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.462-462
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• 2009

$CeO_2$는 고체 산화물 연료전지 (SOFC, soild oxide fuel cell)의 전해질 재료와 CMP(Chemical Mechanical Polishing) 슬러리 재료, 자동차의 3원 촉매, gas sensor, UV absorbent등 여러 분야에서 사용되고 있다. 본 연구에서는 위의 활용범위 외에 $CeO_2$의 구조적 안정성과 빠른 $Ce^{3+}/Ce^{4+}$의 전환 특성을 이용하여 lithium ion battery의 anode 재료로서 전기화학적 특성을 알아보고자 실험을 실시하였다. $CeO_2$ 합성에 사용되는 전구체인 cerium carbonate의 형상 및 크기, 비표면적과 같은 물리화학적 특성이 $CeO_2$ 분말의 특성에 직접적인 영향을 주기 때문에 전구체의 합성 단계에서 입자의 특성을 조절하였다. 전구체 합성의 출발원료로 cerium nitrate hexahydrate 와 ammonium carbonate를 사용하였고 반응온도 및 농도 등을 변화시켜 입자의 형상 및 결정상을 fiber형태의 orthorombic $Ce_2O(CO_3)_2{\cdot}H_2O$와 구형의 hexagonal $CeCO_3OH$의 세리아 전구체를 합성하였다. 이를 $300^{\circ}C$에서 30분 동안 하소하여 전구체의 입자형상을 유지하는 cubic $CeO_2$를 합성하고 X-ray diffraction, FE-SEM, micropore physisorption analyzer 분석을 통하여 입자의 결정상과 형상, 비표면적 등을 비교 분석하고 $Li/CeO_2$ couple의 충,방전 용량과 수명특성을 비교 분석하여 $CeO_2$의 전기화학적 특성을 알아보았다.

• Clean Technology
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• v.22 no.1
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• pp.9-15
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• 2016

xAl-yZr mixed oxide catalysts with different molar ratios of Al/(Al+Zr) were prepared by a co-precipitation method and its catalytic performance was compared in the iso-propanol dehydration as a model reaction. The catalysts were characterized by X-ray diffraction (XRD), differential thermal analysis (DTA), N₂ adsorprion-desorption, NH₃ temperature programmed desorption (NH₃-TPD), and iso-propanol TPD analyses. The addition of Al into ZrO₂ promoted the formation of relatively small particles with large surface areas and retarded the transformation of teragonal phase to monoclnic phase. NH₃-TPD results revealed that the relative acidity of the catalysts increased along with the increase of Al molar ratio. The catalytic activity for the dehydration of iso-propanol to propylene was also increased with the same tendency. The catalytic activity could be correlated with high surface area, acidity and easy desorption of iso-propanol.

• Resources Recycling
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• v.12 no.6
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• pp.38-46
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• 2003

In this study, nano-sized Ni-ferrite and $Fe_2$$O_3$＋NiO powder was fabricated by spray pyrolysis process in the condition of 1kg/$\textrm{cm}^2$ air pressure using the Fe-Ni complex waste acid solution generated during the manufacturing process of shadow mask. The average particle size of the produced powder was below 100 nm. The effects of the reaction temperature, the concentration of raw material solution and the nozzle tip size on the properties of powder were studied. As the reaction temperature increased from $800 ^{\circ}C$ to $1100^{\circ}C$, the average particle size of the powder increased from 40 nm to 100 nm, the structure of the powder gradually became solid, yet the distribution of the particle size appeared more irregular. Along with the increase of the reaction temperature, the fraction of the Ni-ferrite phase were also on the rise, and the surface area of the powder was greatly reduced. As the concentration of Fe in solution increased from 20g/l to 200g/l, the average particle size of the powder gradually increased from 30 nm to 60 nm, while the distribution of the particle size appeared more irregular. Along with the increase of the concentration of solution, tie fraction of the Ni-ferrite phase was on the rise, and the surface area of the powder was greatly reduced. Along with the increase of the nozzle tip size, the distribution of the particle size appeared more irregular, yet the average particle size of the powder showed no significant change. As the nozzle tip size increased from 1 mm to 2 mm, the fraction of the Ni-ferrite phase showed no significant change, while the surface area of the powder slightly reduced. As the nozzle tip size increased to 3 mm and 5 mm, the fraction of the Ni-ferrite phase gradually reduced, and the surface area of the powder slightly increased.

• Resources Recycling
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• v.8 no.4
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• pp.11-19
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• 1999

Fly ash generated from (he pulverized coal power plant have caused the serious ocean pollution due to the disposal in the ash pond, the life reduction of a power plant and the waste of re-utilizable resource The research to reuse the unburned carbon and mineral composing of the ash has been progressed. In this study. the physical and chemical characteristics of high grade ash and unburned carbon particles obtained from countercurrent column flotation are investigated. The cleaned ash of the less 0,5% loss on Ignition(LOI) in carbon content is a spherical sphere and 39.8${\mu}m$ in size of MMD(Mass Median Diameter). 2.22 $m^2/g$ of specific area. The morphology of high LOI carbon particles is a amorphousness, 76.6 ${\mu}m$ of particle size and 15.2 $m^2/g$ of specific The high grade cleaned ash and the high LOI ash have some difference in the light of physical. chemical and morphological characteristics

• Journal of the Korean Ceramic Society
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• v.40 no.5
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• pp.468-474
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• 2003

Activated carbon fibers were prepared from stabilized PAN fibers by physical and chemical activation to compare their characteristics. In this study, stabilized PAN fibers were activated by physical activation with steam and CO$_2$, and by chemical activation with KOH. The fabricated activated carbon fibers were evaluated and compared such as specific surface area, pore size distribution, pore volume, and amount of iodine adsorption. In the steam activation, a specific surface area of 1635 m$^2$/g was obtained after heat treatment at 990$^{\circ}C$. Otherwise, in the CO$_2$ activation, produced activated carbon fibers had been a specific surface area of 671 m$^2$/g after heat treatment at 990$^{\circ}C$. In chemical activation using KOH, a specific surface area of 3179 m$^2$/g was obtained with a KOH/ stabilized PAN fiber ratio of 1.5 : 1 at 900$^{\circ}C$. Nitrogen adsorption isotherms for fabricated activated carbon fibers showed type I and transformation from type I and II in the Brunauer-Deming-Deming-Teller (B.D.D.T) classification. Increasing specific surface area Increased the amount of iodine adsorption in both activation methods. Because the ionic radius of iodine was smaller than the interior micropore size of activated carbon fibers.

• Journal of the Korean Ceramic Society
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• v.38 no.10
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• pp.928-935
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• 2001

In this study, two kinds of activated carbon fibers were prepared from PAN-based stabilized fibers by physical activation with steam. The variations in specific surface area, amount of iodine adsorption and pore size distribution of the activated carbon fibers after the activation process were discussed. The activated carbon fibers were prepared by two different methods, namely a 1- and 2-step method. For the 2-step method, carbonization of fibers in $N_2$ atmosphere was carried out to make carbon fibers and then activated by steam. In normal two step steam activation, BET surface area of about $1019m^2/g$ was obtained in the study. In the 1-step steam activation process, the carbonization and activation were simultaneously carried out. In the one step steam activation, BET surface area of $1635m^2/g$ was obtained after heat-treatment at $990^{\circ}C$. However, nitrogen adsorption isotherms for oxidized PAN based activated carbon fibers that were prepared by both methods were type I in the Brunauer-Deming-Deming-Teller (BDDT) classification even though they have different BET surface areas, amounts of iodine adsorption and pore size distributions.

• Clean Technology
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• v.24 no.4
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• pp.280-286
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• 2018

In this study, the adsorption performance of vapor phase VOCs under dry conditions was evaluated by using two metal oxides, $TiO_2$ powder and $Al_2O_3$ powder. BET analysis and ammonia in-situ FT-IR analysis were used to analyze specific surface area and surface acid site. As a result, $TiO_2$ powder and $Al_2O_3$ powder had a specific surface area of $317.6m^2\;g^{-1}$ and $64m^2\;g^{-1}$, respectively. In the case of $TiO_2$ powder, many acid sites were observed on the surface. As a result of evaluating the vapor phase VOCs adsorption performance using two metal oxide powders, $TiO_2$ powder having a relatively large specific surface area and a large number of acid sites exhibited relatively good adsorption performance. In particular, it is considered that the specific surface area directly affects the adsorption performance, and further study on the effect of the acid site is required. Based on the $TiO_2$ exhibited excellent adsorption performance, it manufactured into various forms of honeycomb, hollow fiber and disc. As a result, the adsorption performance was lower than that of the powder, but it is advantageous in view of applicability. In addition, it was confirmed that the disc adsorbent having excellent thermal durability due to the characteristics of the manufacturing process stably maintains adsorption performance even at a high temperature desorption process several times.