• Bulletin of the Korean Chemical Society
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• 제28권11호
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• pp.2029-2033
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• 2007

Hydrotalcite, layered double hydroxides (LDH), with hexagonal morphology has been rapidly synthesized by microwave reaction within 1 hour by urea hydrolysis from homogeneous solution. Different synthesis parameters, Mg/Al molar ratio, microwave reaction temperature and microwave power were systematically investigated. Pure hydrotalcite phase was obtained for Mg/Al ratios of 2:1 and 3:1, and higher reaction temperature gave higher crystallinity. The hydrotalcite synthesized at 600W power shows the highest crystallinity and more homogeneous crystal size distribution. The hydrotalcite samples were characterized by powder X-ray diffraction (XRD), simultaneous thermogravimetric/differential thermal analysis (TG/DTA), Fourier Transform Infrared (FT-IR) and Scanning electron micrograph (SEM).

• 한국가스학회:학술대회논문집
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• 한국가스학회 2007년도 춘계학술발표회 논문집
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• pp.33-36
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• 2007

합성가스는 C1화학을 시작하는 반응원료 물질로 최근 DME(dimethyl-ether), 메탄올, GTL(gas to liquid), CTL(coal to liquid), 암모니아 생성 공정 등 많은 화학공정에 사용되고 있다. 합성가스를 생산하는 방법은 천연가스 개질반응과 석탄의 가스화반응, 그리고 원유의 정제 등을 통해 얻을 수 있다. 삼중개질반응은 천연가스와 산소, 수증기, 이산화탄소를 원료로 $1000^{\circ}C$ 이상의 고온에서 반응시켜 합성가스를 생산하며, 균일반응계와 불균일반응계로 이루어져 있다. 균일반응계에서는 천연가스와 산소가 주로 반응하며, 원료로 투입된 대부분의 산소는 균일반응계에서 소모되어 일산화탄소와 이산화탄소를 생성한다. 삼중개질반응의 균일반응계에서는 산소와 천연가스와의 반응으로 많은 발열이 발생하여 전체 반응계의 온도를 유지할 수 있도록 해준다. 본 연구에서는 산소로 인한 삼중개질반응의 온도 조절과 균일반응계의 온도 분포를 위치에 따라 관찰해 보았으며, 실험과 모사를 통해 비교해 보았다.

• 한국결정성장학회지
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• 제14권3호
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• pp.110-114
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• 2004

반응온도 $75^{\circ}C$에서 $Ca(OH)_2$ slurry 및 NaOH의 혼합용액에 $Na_2CO_3$ 수용액의 농도 및 첨가방법을 변화시키면서 아라고나이트 침강성 탄산칼슘의 생성거동을 관찰하였다. 이 반응에서 $Na^+$ 이온은 탄산칼슘 격자내의 $Ca^{2+}$ 이온 자리에 치환되어 칼사이트의 성장을 지연시키고, 특정방향으로의 결정성장이 진행되어 침상형 아라고나이트의 생성을 유리하게 하는 것을 알 수 있었다. 또한, $CO_3^{2-}$ 이온농도 조절에 의한 반응속도의 감소는 균일침전반응을 유도하고, $Na^+$ 이온의 치환능력을 증대시켜 아라고나이트의 생성 및 성장을 촉진하는 것으로 판단되었다.

• 대한화학회지
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• 제57권6호
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• pp.703-711
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• 2013

In the present investigation, kinetic studies of oxidation of formic acid with and without catalyst and promoter in aqueous acid media were studied under the pseudo-first order conditions [formic acid]T ${\gg}[Cr(VI)]_T$ at room temperature. In the 1,10-phenanthroline (phen) promoted path, the cationic Cr(VI) phen complex is the main active oxidant species undergoes a nucleophilic attack by the substrate to form a ternary complex which subsequently experiences a redox decomposition through several steps leading to the products $CO_2$ and $H_2$ along with the Cr(III) phen complex. The anionic surfactant (i.e., sodium dodecyl sulfate, SDS) and neutral surfactant (i.e., Triton X-100, TX-100) act as catalyst and the reaction undergo simultaneously in both aqueous and micellar phase with an enhanced rate of oxidation in the micellar phase. Whereas the cationic surfactant (i.e., N-cetyl pyridinium chloride, CPC) acts as an inhibitor restricts the reaction to aqueous phase. The observed net enhancement of rate effects has been explained by considering the hydrophobic and electrostatic interaction between the surfactants and reactants. The neutral surfactant TX-100 has been observed as the suitable micellar catalyst for the phen promoted chromic acid oxidation of formic acid.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.328-334
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• 2000

The hybrid catalytic(catalytic+thermal) combustor of a lean methane-air mixture on platinum catalyst was investigated numerically using a 2-D boundary layer model with detailed homogeneous and heterogeneous chemistries. For the more accurate calculations, the actual surface site density of monolith coated with platinum was decided by the comparison with experimental data. It was found that the homogeneous reactions in the monolith had little effect on the change of temperature profile, methane conversion rate and light off location. However, the radicals such as OH and CO were produced rapidly at exit by homogeneous reactions. Thus the homogeneous reactions were important to predict the productions of CO and NOx exactly. In thermal combustor, the production of $N_2O$ was more dominant than that of NO due to the relative important of the reaction $N_2+O(+M){\to}N_2O(+M)$. Finally the production of CO and NOx by amount of methane addition were studied.

• Bulletin of the Korean Chemical Society
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• 제28권11호
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• pp.1902-1909
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• 2007

This account reports an overview of our findings in homogeneous Pd-catalyzed reactions. Herein we describe the new design in reactions of Group 14 element compounds and in homogeneous nanosize Pd catalysts. In the early stages of our study, we developed Pd-catalyzed transformations of allylic esters with disilanes, silylcyanides and acylsilanes to the corresponding silylation, cyanation and acylation products, respectively. We also developed a Pd-catalyzed three component coupling reaction of Group 14 element compounds involving 1,3-diene and acid chlorides to form β,γ-unsaturated ketone as a single product. Recently, we focus our attention on modifying the catalytic environment by nanosize Pd in order to improve the performance of Pd catalysts. These nanosystems realize efficient catalytic environment with remarkable enhancement in catalytic activity and unprecedented selectivity.

• 대한화학회지
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• 제57권4호
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• pp.525-528
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• 2013

• Journal of Electrochemical Science and Technology
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• 제8권4호
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• pp.344-355
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• 2017

In this study, a numerical approach is adopted to investigate the effectiveness factors for distributed electrochemical reactions in thin active reaction layers of solid oxide fuel cells (SOFCs), taking into account the Butler-Volmer reaction kinetics. The mathematical equations for the electrochemical reaction and charge conduction process were formulated by assuming that the active reaction layer has a small thickness, homogeneous microstructure, and high effective electronic conductivity. The effectiveness factor is defined as the ratio of the actual reaction rate (or equivalently, current generation rate) in the active reaction layer to the nominal reaction rate. From extensive numerical calculations, the effectiveness factors were obtained for various charge transfer coefficients of 0.3-0.8. These effectiveness data were then fitted to simple correlation equations, and the resulting correlation coefficients are presented along with estimated magnitude of error.

• 대한수학회지
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• 제44권4호
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• pp.779-786
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• 2007

In this note, we consider a system of two reaction-diffusion equations with absorption, under homogeneous Dirichlet boundary. Using scaling methods, we establish the blow-up rate estimates.

• Bulletin of the Korean Chemical Society
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• 제31권11호
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• pp.3238-3240
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• 2010

A new and efficient method for the preparation of substituted 3,4-dihydropyrimidin-2(1H)-ones via Biginelli synthesis using catalytic amounts of 1,3-dichloro-5,5-dimethylhydantoin is presented. Short reaction times, easy work-up, high yields of products and stability, easy-handling, non-toxicity and cheapness of the catalyst are noteworthy advantages of the present work.