• 공업화학
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• 제19권6호
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• pp.668-673
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• 2008

본 연구의 목적은 니켈-몰리브데늄 성분계 폐촉매로부터 니켈 성분의 선택적 회수를 위한 습식 침출 및 추출공정에서의 반응조건 최적화이다. 폐촉매로부터 니켈 성분의 선택적 회수를 위한 과정으로 침출제를 사용하여 폐촉매로부터 니켈 성분을 용액으로 용해시키는 침출공정과 니켈 성분을 포함한 다양한 금속 성분들의 용액으로부터 니켈 성분의 선택적 추출공정으로 이루어진 2단계 공정이다. 침출공정에서는 필요한 다양한 침출제로 질산($HNO_3$), 탄산나트륨($Na_2CO_3$) 및 탄산암모늄($(NH_4)_2CO_3$) 수용액 등이 사용되었으며, 추출제로 옥살산 수용액이 사용되었다. 침출공정에서 니켈성분을 효과적으로 용해시킬 수 있는 침출제는 질산 수용액이었으며, 최적화된 온도, 침출제농도, 반응시간 등은 각각 $90^{\circ}C$, 6.25 vol%, 3 h이었다. 이러한 최적화된 침출공정 및 추출공정으로부터 얻어진 니켈 화합물은 니켈 옥살레이트로 확인되었으며, 니켈 성분의 회수율 및 순도는 각각 88.7% 및 100%였다.

• 한국분말재료학회지
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• 제21권4호
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• pp.266-270
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• 2014

Metal foams have a cellular structure consisting of a solid metal containing a large volume fraction of pores. In particular, open, penetrating pores are necessary for industrial applications such as in high temperature filters and as a support for catalysts. In this study, Fe foam with above 90% porosity and 2 millimeter pore size was successfully fabricated by a slurry coating process and the pore properties were characterized. The Fe and $Fe_2O_3$ powder mixing ratios were controlled to produce Fe foams with different pore size and porosity. First, the slurry was prepared by uniform mixing with powders, distilled water and polyvinyl alcohol(PVA). After slurry coating on the polyurethane(PU) foam, the sample was dried at $80^{\circ}C$. The PVA and PU foams were then removed by heating at $700^{\circ}C$ for 3 hours. The debinded samples were subsequently sintered at $1250^{\circ}C$ with a holding time of 3 hours under hydrogen atmosphere. The three dimensional geometries of the obtained Fe foams with an open cell structure were investigated using X-ray micro CT(computed tomography) as well as the pore morphology, size and phase. The coated amount of slurry on the PU foam were increased with $Fe_2O_3$ mixing powder ratio but the shrinkage and porosity of Fe foams were decreased with $Fe_2O_3$ mixing powder ratio.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.86-86
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• 2012

The new approaches for silicon solar cell of new concept have been actively conducted. Especially, solar cells with wire array structured radial p-n junctions has attracted considerable attention due to the unique advantages of orthogonalizing the direction of light absorption and charge separation while allowing for improved light scattering and trapping. One-dimenstional semiconductor nano/micro structures should be fabricated for radial p-n junction solar cell. Most of silicon wire and/or pillar arrays have been fabricated by vapour-liquid-solid (VLS) growth because of its simple and cheap process. In the case of the VLS method has some weak points, that is, the incorporation of heavy metal catalysts into the growing silicon wire, the high temperature procedure. We have tried new approaches; one is electrochemical etching, the other is noble metal catalytic etching method to overcome those problems. In this talk, the silicon pillar formation will be characterized by investigating the parameters of the electrochemical etching process such as HF concentration ratio of electrolyte, current density, back contact material, temperature of the solution, and large pre-pattern size and pitch. In the noble metal catalytic etching processes, the effect of solution composition and thickness of metal catalyst on the etching rate and morphologies of silicon was investigated. Finally, radial p-n junction wire arrays were fabricated by spin on doping (phosphor), starting from chemical etched p-Si wire arrays. In/Ga eutectic metal was used for contact metal. The energy conversion efficiency of radial p-n junction solar cell is discussed.

• 한국생산제조학회지
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• 제21권4호
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• pp.575-581
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• 2012

The electrochemical oxygen demand (ECOD) is an additional sum parameter, which has not yet found the attention it deserves. It is defined as the oxygen equivalent of the charge consumed during an electrochemical oxidation of the solution. Only one company has yet developed an instrument to determine the ECOD. This instrument uses $PbO_2$-electrodes for the oxidation and has been successfully implemented in an automatic on-line monitor. A general problem of the ECOD determination is the high overpotential of electrochemical oxidations of most organic compounds at conventional electrodes. Here we present a new approach for the ECOD determination, which is based on the use of a solid composite electrodes with highly efficient electro-catalysts for the oxidation of a broad spectrum of different organic compounds. Lead dioxide as an anode material has found commercial application in processes such as the manufacture of sodium per chlorate and chromium regeneration where adsorbed hydroxyl radicals from the electro-oxidation of water are believed to serve as the oxidizing agent. The ECOD sensors based on the Au/$PbO_2$ electrode were operated at an optimized applied potential, +1.6 V vs. Ag/AgCl/sat. KCl, in 0.01 M $Na_2SO_4$ solution, and reduced the effect of interference ($Cl^-$ and $Fe^{2-}$) and an expended lifetime (more than 6 months). The ECOD sensors were installed in on-line auto-analyzers, and used to analyze real samples.

• Korean Chemical Engineering Research
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• 제43권5호
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• pp.566-570
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• 2005

이중고리형 불포화탄화수소 화합물인 methylcyclopentadiene dimer(MCPD)의 수소화 및 이성화반응에 관한 연구를 행하였다. Exo 화합물은 2단계의 수소화반응 후에 이성화반응에 의해 제조되었다. 수소 1몰이 첨가되는 1차 수소화 반응은 $100^{\circ}C$이상의 반응온도에서는 다이머가 분해되어 모노머가 생성이 증가되었다. 1차 수소화 반응에 의하여 DHDMCPD[dihydrodi(methylcyclopentadiene)]가 생성된 후 2차 수소화반응을 진행하여 THDMCPD[tetrahydrodi (methylcyclopentadiene)]를 제조하였는데, 2차 반응온도조절에 의해 exo와 endo 비율이 변화되었다. 공정개선을 위하여 2단 가열반응기를 사용함으로 연속식 1, 2차 수소화 조건을 확립하였고 또한 endo THDMCPD로부터 exo 형태로 의 이성화반응에 할로겐화 알루미늄과 같은 할로겐화 금속촉매와 고체산 촉매를 사용하여 촉매의 활성을 비교하였다.

• Korean Chemical Engineering Research
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• 제49권2호
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• pp.155-160
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• 2011

디메틸 에테르(DME)는 최근 청정 연료로서 주목을 받고 있다. 본 연구에서는 메탄올 탈수반응을 통한 디메틸 에테르(DME)의 제조에 대하여 조사하였다. 이때 촉매는 제올라이트 계열인 고체산 촉매를 이용하였다. 조촉매로서 세리아가 반응전환율뿐만 아니라 DME 생성 선택도도 증가시키는 것을 발견하였다. 실리카/알루미나의 조성비와 촉매 표면의 세리아의 무게함량을 변화시켜 최적의 촉매를 선정하였다. 5 wt%의 세리아가 첨가된 ZSM5-30의 DME에 대한 반응선택성이 가장 뛰어났으며, 이 촉매는 메탄올 내에 포함되어 있는 수분의 영향을 거의 받지 않았다. 마이크로 반응기에서 얻은 데이터를 가지고 반응 속도식을 구하였다.

• The Korean Journal of Ceramics
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• 제5권4호
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• pp.379-385
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• 1999

Minute boehmite crystals with high aspect rations, which were hydrothermally synthesized from gibbsite in $Ba(OH)_2$ solution, occluded Ba with the Ba/Al molar ratio of about 0.03 in their interlayers. Their surface areas were about 14$\m^2$/g. The Ba-intercalated bohemite samples were partly used for producing $BaAl_{12}O){19}$ with low sinterability by externally supplementing $Ba(OH)_2$, and for forming transient aluminas. The surface area of $BaAl_{12}O){19}$ obtained by firing at $1500^{\circ}C$ for 3 h was 5.3$\m^2$/g, which was significantly lower than 12$\m^2$/g of the sol-gel origin. While a mixture ${\gamma}$-alumina and BaO is known to from $BaAl_{12}O){19}$ at $1200^{\circ}C$, solid state reaction between η-alumina transformed from the Ba-intercalated boehmite and BaO formed from $Ba(OH)_2$ deposited on the boehmite started above $1300^{\circ}C$. This suggests that large sized $Ba^{2+}$ ion occluded in η-alumina considerably suppresses the diffusion of $Al^{3+}$ ion. The surface area of the Ba-intercalated boehmite fired at $1400^{\circ}C$ for 3h was as high as 14$\m^2$/g indicative of its potential applicability to combustion catalysts. But it was decreased to 5.0$\m^2$/g after firing at $1500^{\circ}C$ for 3 h, accompanied by abrupt formations of $\alpha$-alumina and $BaAl_{12}O){19}$ as main products. The suppression of $\alpha$-alumina formation up to $1400^{\circ}C$ also suggests the significant blocking effect of $Ba^{2+}$ ion on the diffusion of the component ions.

• 한국재료학회지
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• 제12권12호
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• pp.941-946
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• 2002

Both Cu and Cu-oxide nanopowders have great potential as conductive paste, solid lubricant, effective catalysts and super conducting materials because of their unique properties compared with those of commercial micro-sized ones. In this study, Cu and Cu-oxide nanopowders were prepared by Pulsed Wire Evaporation (PWE) method which has been very useful for producing nanometer-sized metal, alloy and ceramic powders. In this process, the metal wire is explosively converted into ultrafine particles under high electric pulse current (between $10^4$ and $10^{ 6}$ $A/mm^2$) within a micro second time. To prevent full oxidations of Cu powder, the surface of powder has been slightly passivated with thin CuO layer. X-ray diffraction analysis has shown that pure Cu nanopowders were obtained at $N_2$ atmosphere. As the oxygen partial pressure increased in $N_2$ atmosphere, the gradual phase transformation occurred from Cu to $Cu_2$O and finally CuO nanopowders. The spherical Cu nanopowders had a uniform size distribution of about 100nm in diameter. The Cu-oxide nanopowders were less than 70nm with sphere-like shape and their mean particle size was 54nm. Smaller size of Cu-oxide nanopowders compared with that of the Cu nanopowders results from the secondary explosion of Cu nanopowders at oxygen atmosphere. Thin passivated oxygen layer on the Cu surface has been proved by XPS and HRPD.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.199-199
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• 2011

The addition of a carbanion to ${\yen}{\acute{a}}{\yen}{\hat{a}}$-unsaturated carbonyl compounds is of importance in the C-C bond formation reactions for modern pharmaceuticals and organic synthesis. Recently, heterogeneous asymmetric catalysis became more attractive area of research because of the easy recovery and separation of the catalyst from the reaction system. Most of synthetic methods for heterogeneous catalysts were grafting or immobilization of homogeneous catalyst onto the solid supports. Trans-1,2-Diaminocyclohexane(DACH) and L-proline ligands have been enormously used as chiral ligands in several catalytic transformation under homogenous conditions. Our group prepared l-proline functionalized mesoporous silica was synthesized under acidic condition using a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer template (EO20PO70EO20, Pluronic P-123, BASF). Furthermore, we successfully directly synthesized trans-1,2 diaminocyclohexane functionalized mesoporous silica by using microwave method. The direct functionalization of chiral ligand into the framework of mesoporous materials is expected to be useful for the heterogeneous asymmetric catalysis. So, we adopt the direct synthesis of chiral ligand functionalized mesoporous silica by using thermal and microwave irradiation. Then, chiral ligand functionalized mesoporous silicas were applied to enantioselective asymmetric catalytic reactions.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2012년도 춘계학술발표대회
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• pp.88.1-88.1
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• 2012

Silicon nanowires (SiNWs), due to their unusual quantum-confinement effects that lead to superior electrical and optical properties compared to those of the bulk silicon, have been widely researched as a potential building block in a variety of novel electronic devices. The conventional means for the synthesis of SiNWs has been the vapor-liquid-solid method using chemical vapor deposition; however, this method is time consuming, environmentally unfriendly, and do not support vertical growth. As an alternate, the electroless etching method has been proposed, which uses metal catalysts contained in aqueous hydrofluoric acids (HF) for vertically etching the bulk silicon substrate. This new method can support large-area growth in a short time, and vertically aligned SiNWs with high aspect ratio can be readily synthesized with excellent reproducibility. Nonetheless, there still are rooms for improvement such as the poor surface characteristics that lead to degradation in electrical performance, and non-uniformity of the diameter and shapes of the synthesized SiNWs. Here, we report a facile method of SiNWs synthesis having uniform sizes, diameters, and shapes, which may be other than just cylindrical shapes using a modified nanosphere lithography technique. The diameters of the polystyrene nanospheres can be adjustable through varying the time of O2 plasma treatment, which serve as a mask template for metal deposition on a silicon substrate. After the removal of the nanospheres, SiNWs having the exact same shape as the mask are synthesized using wet etching technique in a solution of HF, hydrogen peroxide, and deionized water. Different electrical and optical characteristics were obtained according to the shapes and sizes of the SiNWs, which implies that they can serve specific purposes according to their types.