• Applied Biological Chemistry
• /
• v.37 no.3
• /
• pp.210-215
• /
• 1994

${\underline{O}},{\underline{O}}-Diethyl-{\underline{S}}-phenyl\;phosphorothiolate-^{18}O$ and other related compounds were prepared and oxidized with m-chloroperbenzoic acid (MCPBA). Each reaction was followed by $^{31}P$ NMR and the products were analyzed by GC-MS. ${\underline{O}},{\underline{O}}-Diethyl-{\underline{S}}-phenyl\;phosphorothiolate-^{18}O$ was converted to diethyl methyl phosphate in methanol by MCPBA and it was confirmed to contain $^{18}O$, which proved that the originally proposed mechanism of Segall and Casida operates in the oxidative reaction.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.411.2-411.2
• /
• 2016

직접 메탄올 연료전지 (DMFCs)는 친환경적이고 낮은 작동 온도로 인한 빠른 구동, 높은 에너지 밀도 등 다양한 장점을 가지고 있어 차세대 에너지 변환소자로 많은 관심을 받고 있다. 직접 메탄올 연료전지는 메탄올을 연료로 사용하며, 메탄올이 보유하고 있는 화학적 에너지를 전기 에너지로 변환하는 장치로써 음극에서는 백금 촉매로 인한 메탄올 산화반응, 양극에서는 환원 반응이 일어나며 전기화학적 구동을 하게 된다. 하지만 일산화탄소 피독으로 인한 촉매 활성 저하, 메탄올의 cross over, 백금 촉매 사용으로 인한 고비용 등의 문제점을 가지고 있다. 따라서 많은 연구자들이 백금 사용량을 줄이고 백금 촉매를 고르게 분포하기 위해 값이 저렴하고 넓은 비표면적을 갖는 탄소계 (graphite, graphene, carbon nanotube, carbon nanofiber 등) 지지체 재료를 도입하고 있다. 이 중 탄소나노섬유 (carbon nanofibers, CNFs)는 우수한 전기전도도와 열적/화학적 안정성을 가지고 있으며, 특히 넓은 비표면적을 가지고 있어 백금 촉매의 지지체로서 많은 연구가 진행되고 있다[1]. 따라서 우리는 전기방사법을 활용하여 넓은 비표면적을 보유하는 다공성 탄소나노섬유를 성공적으로 합성하였다. 또한, 이를 백금 촉매의 지지체로 도입하여 직접 메탄올 연료전지를 위한 다공성 탄소나노섬유에 담지된 고분산성 백금 촉매를 제조하였다. 제조한 다공성 탄소나노섬유의 형상 및 구조 분석은 주사전자 현미경 (field-emission scanning electron microscopy)와 투과전자 현미경 (transmission electron microscopy)를 이용하여 분석하였고, 결정구조와 화학적 결합상태는 X-선 회절분석 (X-ray diffraction) 및 X-선 광전자 분광법 (X-ray photoelectron spectroscopy)를 이용하여 규명하였다. 전기화학적 특성은 순환 전압 전류법 (cyclic voltammetry)를 이용하였다. 이러한 실험 결과들을 바탕으로 다공성 탄소나노섬유에 담지된 고분산성 백금 촉매의 자세한 특성을 본 학회에서 다루도록 하겠다.

• Korean Chemical Engineering Research
• /
• v.49 no.6
• /
• pp.732-738
• /
• 2011

Effect of metal oxide catalysts and ionic liquids on the synthesis of methyl carbamate(MC) and dimethyl carbonate (DMC) from urea and methanol was investigated in a high pressure reaction system. In closed system, MC yield from urea and methanol reached almost 100% at reaction temperature over $150^{\circ}C$ without catalyst, whereas DMC yield of 1.5% under was obtained irrespective of catalysts used. In DMC synthesis from MC and methanol, $ZnCl_{2}$ showed the highest catalytic activity and led to the DMC yield of 16.3% under optimal conditions. Furthermore, DMC yield can be enhanced by the simultaneous application of ionic liquids with nano-sized catalysts in semi-continuous reaction system.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.14 no.4
• /
• pp.93-103
• /
• 2006

Biogas is a byproduct after anaerobic digestion of organic materials and has been used as an energy source for heating and generating electricity. Demands of methanol for fuel mixed with gasoline and reactant in biodiesel production are steadily being increased. In this review, we summarized recent advancements in direct partial oxidation of methane to methanol with the brief history of methanol synthesis. The steam reforming and the catalytic oxidation of methane to methanol were compared, the former of which are mainly used in industrial scale and the latter in a stage of research and development. On the basis of this review, the possibility of methanol conversion from biogas was proposed in the aspects of the technological feasibility and the economical practicability.

• Journal of Life Science
• /
• v.6 no.1
• /
• pp.66-71
• /
• 1996

Antioxidative activity of various solvent extracts from freeze dried Kimchi was studied during the oxidation process of linoleic acid mixture system. The aqueous model systems were used for the evaluation of antioxidative activity of solvent extracts during the oxidative reaction at 37$^{\circ}C$ by the determination of peroxide value. The linoleic acid mixture for the aqueous model systems was consisted of linoleic acid (64.6%), oleic acid(27.4%), and other acids in ethanolic phosphate buffer (pH 7.0). Water and methanol extracts of Kimchi had a considerable antioxidative activity with the inhibition of peroxides formation during the autoxidation of linoleic acid mixture in aqueous model systems. Antioxidative activity of 75% methanol extract of 7 day-fermented-Kimchi was relatively higher than that of others, however lower than alpa-tocopherol and butylated hydroxyanisol. The antioxidative effect of 75% methanol extract of 7 day-fermented-Kimchi was increased by the its concentration from 0.5% to 2.5% in the oxidation reactions of aqueous model systems.

• Journal of the Korean Chemical Society
• /
• v.38 no.4
• /
• pp.302-308
• /
• 1994

Homogeneous catalytic oxidation of hydrazobenzene was investigated by employing pentadentate Schiff base complexes such as [Co(II)(Sal-DPT)(H$_2$O)] and [Co(II)(Sal-DET)(H$_2$O)] in oxygen-saturated methanol solvent. The oxidation product of hydrazobenzene(H$_2$AB) was trans-azobenzene(trans-AB). The rate constants of oxidation reaction measured by UV-visible spectrophotometry were observed as $6.06{\times}10^{-3}sec^{-1}$ for [Co(II)(Sal-DPT)(H$_2$O)] and $2.50{\times}10^{-3}sec^{-1}$ for [Co(II)(Sal-DET)(H$_2$O)]. The mechanism of oxidation reaction for H$_2$AB by homogeneous activated catalysts has been proposed as following. H$_2$AB + Co(II)(L)(H$_2$O) + O$_2$ $\rightleftharpoons^K_{MeOH}Co(III)(L)O_2{\cdot}H_2AB + H_2O\longrightarrow^{k}Co(II)(L) + trans-AB + H_2O_2$ (L: Sal-DPT and Sal-DET)

• Applied Chemistry for Engineering
• /
• v.21 no.4
• /
• pp.435-439
• /
• 2010

Pt-$MoO_3$ electrodes were fabricated on ITO-coated glass by electrodeposition method using 20 mM hydrogen hexachloroplatinate ($H_2PtCl_6$) and 10 mM Mo-peroxo electrolyte. Deposition order was varied, and catalytic activities of synthesized electrodes were compared with that of pure Pt electrode. Scanning Electron Microscopy (SEM) was utilized to examine surface morphology. The crystallinity of synthesized films was analyzed by X-ray Diffraction (XRD), and the oxidation state of both the platinum and molybdenum were determined by X-ray Photoelectron Spectroscopy (XPS) analyses. The catalytic activity and stability for methanol oxidation were measured using cyclic voltammetry (CV) and chronoamperometry (CA) in a mixture of 0.5 M $H_2SO_4$ and 0.5 M $CH_3OH$ aqueous solution. $MoO_3$ electrodeposited on the surface of Pt showed much higher catalytic acitivity and stability than pure Pt electrode due to the good contact between Pt and $MoO_3$.

• Journal of the Korean Chemical Society
• /
• v.46 no.3
• /
• pp.219-224
• /
• 2002

The oxidation reaction between 2,6-di-tert-butylphenol (DTBP) and oxygen adducted Co(III) complexes as a catalysis has been studied by UV-visible spectrophtometry. According to the results, main product is 2,6-di-tert-butylbenzoquinone(BQ) and the activity of the complexes is bigger in [Co(III)2(SMPD)2(Py)2]2O2 than in [Co(III)2(SPPD)2(Py)2]2O2. The rate constant is 4.55~2.12${\times}$10$-3}$s. It was found that the oxidation reaction is primary reac-tion or concentration of catalysis, O2 molecule and substance. The reasult is far from Arrhenius properties because acti-vationenergy is 10.38 kJ/mol.

• Korean Chemical Engineering Research
• /
• v.56 no.1
• /
• pp.119-124
• /
• 2018

The production of methyl N-phenyl carbamate by an oxidative carbonylation method of aniline and methanol is of great interest as an environmentally friendly process that can replace the monomer production process of a polymer produce using conventional phosgene. In this study, heterogeneous catalysts were prepared by using Y-zeolite, $SiO_2$, $Al_2O_3$ as support, and oxidative carbonylation continuous operation from aniline and methanol was attempted using the prepared heterogeneous catalyst. Batch reactor was used to determine the support, and various reaction conditions such as reaction temperature, reaction pressure, and effect of promoter were established using palladium catalyst. A reaction kinetics study was conducted under optimum reaction conditions. The basic data for carbamate process development were obtained by performing continuous operation for a long time under established reaction condition.

• Journal of Life Science
• /
• v.14 no.2
• /
• pp.269-274
• /
• 2004

Using heterogeneous catalyst, esterification reaction of soybean oil (SBO) with methanol was investigated. Distributions of components in mixtures of soybean oil and methanol were measured at temperatures ranging from 40 to $65^{\circ}C$. Glycerine contents of reaction mixtures were measured for the different kinds of catalysts, such as NaOH, CaO, Ca(OH)$_2$, MgO, Mg(OH)$_2$, and Ba(OH)$_2$. Based on the measured glycerine concentrations, conversions of the reaction mixtures were calculated. The effects of dose of catalyst, cosolvent and reaction temperature on final conversion were examined. Solubility of methanol in soybean oil was substantially greater than that of soybean oil in methanol. When the esterification reaction of soybean oil was catalyzed by heterogeneous catalyst, final conversion was strongly dependent on the alkalinity of the heterogeneous catalyst, and increased with the alkalinity of the catalyst material. Hydroxides from the alkali metals were more effective than oxides, which actually had no catalytic effects. When Ca(OH)$_2$ was used for the esterification catalyst, maximum value of final conversion was measured at dose of 4%. The final conversion and reaction rate increased with reaction temperature, and showed substantial increment at reaction temperature of 5$0^{\circ}C$. When cosolvent, CHCl$_3$, was added into the reaction mixture of soybean oil which catalyzed by Ba(OH)$_2$, maximum value of final conversion was appeared at dose of 3%.