• Journal of the Korean Electrochemical Society
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• v.12 no.2
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• pp.131-141
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• 2009

The conversion of carbon dioxide to value-added compounds has been attracted to solve the environmental problems due to the climate change caused by greenhouse effect in addition to recycle the abundant and renewable carbon source. For utilizing carbon dioxide to useful compounds, the development of catalysts and optimization of experimental conditions are indispensable since carbon dioxide is the most stable one among carbon compounds and the a certain amount of energy is required for the carbon dioxide conversion. The technologies developed for the electrochemical carbon dioxide conversion were reviewed in terms of electrocatalyst which can be electrode material, inorganic complex, and enzyme. This field should be developed further since no good catalyst having selectivity, efficiency, and stability all together.

• 한국연소학회:학술대회논문집
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• 2002.06a
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• pp.212-219
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• 2002

Waste fuels, which originate from different sources, have unique combustion characteristics. The characteristics should be considered in applying FBC(fluidized bed combustor) technology to those fuels. The effects of fuel properties and operating conditions on FBC reactivity were investigated by means of carbon based parameter called mean carbon conversion time, rate of carbon conversion, fraction of carbon conversion and carbon recovery. And the basic physical and chemical mechanisms taking place in a fluidized bed were summarized. Major parameters in designing and operating FBC were evaluated in terms of the fuel properties and the combustion environment.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.229-230
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• 2012

Platinum (Pt) has been commonly used as a counter electrode material in dye-sensitized solar cells, because it has high catalytic activity and electric conductivity as well as chemical inertness with iodide electrolyte. However, Pt is too expensive to be commercialized. Therefore, in the present study, carbon black counter electrode with Pt and carbon nano tube (CNT) was investigated. The power conversion efficiency with Pt added carbon black electrode was lower than hat of pure Pt electrode which was 6.47 %. By adding 3 wt% Pt to the carbon black counter electrode, the power conversion efficiency was maximized at 5.88 %. On them, additional adding of 1 wt % CNT, the power conversion efficiency (${\eta}$)wasincreasedupto6.21%. The reason of power conversion efficiency improvement with a proper amount of Pt and CNT was examined by comparing the impedance properties measured using EIS.

• The Korean Journal of Ceramics
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• v.4 no.3
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• pp.245-248
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• 1998

Porous carbon fiber composites (CFCs) having variable specific surface area ranging 35~1150 $\m^2$/g were reacted to produce silicon carbide fiber composites with SiO vapor generated from a mixture of Si and $SiO_2$ at 1673 K for 2 h under vacuum. Part of SiO vapor generated during conversion process condensed on to the converted fiber surface as amorphous silica. Chemical analysis of the converted CFCs resulting from reaction showed that the products contained 27~90% silicon carbide, 7~18% amorphous silica and 3~63% unreacted carbon, and the composition depended on the specific carbide, 7~18% amorphous silica and 3~63% unreacted carbon, and the composition depended on the specific surface area of CFCs. CFC of higher specific surface area yielded higher degree of conversion of carbon to silicon and conversion products of lower mechanical strength due to occurrence of cracks in the converted caron fiber. As the conversion of carbon to silicon carbide proceeded, pore size of converted CFCs increased as a result of growth of silicon carbide crystallites, which is also linked to the crack formation in the converted fiber.

• Korean Chemical Engineering Research
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• v.54 no.3
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• pp.425-430
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• 2016

p-Phenylenediamine (PPD) was synthesized by aromatic amination of p-diiodobenzene (PDIB) using liquid ammonia and Cu-catalysts. The effects of the catalyst, reductant, ammonia quantity and reaction temperature on PPD production were investigated. Cu(I) compounds and Cu powder were selected as catalyst due to a higher selectivity than Cu(II) compounds. As the catalyst quantity increased, rate of PPD production as well as side reaction of aniline decreased with increasing the quantity of ammonia. Reductants such as ascorbic acid, hydrazine and dihydroxyfumaric acid were tested to lower the catalyst loading. The use of reductants resulted in increasing the reaction rate but also increased the amount of aniline The rate of reaction using ascorbic acid or dihydroxyfumaric acid was faster than that using hydrazine. The lowest side reaction of aniline was found in dihydroxyfumaric acid of reductants investigated.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.3
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• pp.301-308
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• 2006

The present work explores the effect of carbon-supported platinum catalyst on the HI decomposition using gas adsorption analyzer, thermogravimetry, X-ray diffractometry, scanning electron microscopy, and gas chromatography. For this purpose, three types of activated carbon (C), Pt/C-1 wt.%, and Pt/C-5 wt.% were prepared. The HI gas conversion is crucially influenced by the amount of Pt on the carbon support. The more the amount of Pt was, the higher results in the HI gas conversion. For three types of catalysts, HI conversion increased with increasing the decomposition temperature but with decreasing the space velocity. The increase of HI conversion with temperature was more pronounced in activated carbon than that in Pt/C. From EDX result, it was found that the activated carbon comprised higher amount of iodine than the Pt/C after the decomposition reaction. This implies that the HI conversion is closely related to the amount of Iodine.

• 한국연소학회:학술대회논문집
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• 2004.11a
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• pp.117-123
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• 2004

The burning characteristics of interacting coal particles in a convective flow are numerically investigated at various Reynolds numbers. The transient combustion of 2-dimensionally arranged particles, both the fixed particle distances of 5 radii to 20 radii horizontally and 3 radii to 24 radii vertically, is studied. The results obtained from the present numerical analysis reveal that the transient flame configuration and retardation of particle temperature augmentation with the horizontal or vertical particle spacing substantially influence devolatilization process and carbon conversion ratio of interacting particles. Volatile release and carbon conversion ratio of the second particle with decreasing horizontal and vertical particle spacing decrease gradually, whereas those of the first particle with decreasing vertical particle spacing increases due to flow acceleration. When the vertical particle spacing is smaller than $6R_{o}$, volatile release and carbon conversion ratio of the second particle decrease greatly due to reduction of flame penetration depth.

• Carbon letters
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• v.9 no.2
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• pp.121-126
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• 2008

High modulus pitch based carbon fibers (HM) were exposed to isothermal oxidation using tube furnace in carbon dioxide gas to study the oxidation kinetics under the temperature of $800-1100^{\circ}C$. The kinetic equation $f=1-{\exp}(-at^b)$ was introduced and the constant b was obtained in the range of 1.02~1.42. The oxidation kinetics were evaluated by the reaction-controlling regime (RCR) depending upon the apparent activation energies with the conversion increasing from 0.2 to 0.8. The activation energies decrease from 24.7 to 21.0 kcal/mole with the conversion increasing from 0.2 to 0.8, respectively. According to the RCR, the reaction was limited by more diffusion controlling regime for the HM fibers with the conversion increasing. Therefore, it seems that the oxidation which is under the diffusion controlling regime takes place continuously from the skin to the core of the fiber.

• Carbon letters
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• v.17 no.1
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• pp.1-10
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• 2016

Lignocellulosic biomass conversion to biofuels such as ethanol and other value-added bio-products including activated carbons has attracted much attention. The development of an efficient, cost-effective, and eco-friendly pretreatment process is a major challenge in lignocellulosic biomass to biofuel conversion. Although several modern pretreatment technologies have been introduced, few promising technologies have been reported. Microwave irradiation or microwave-assisted methods (physical and chemical) for pretreatment (disintegration) of biomass have been gaining popularity over the last few years owing to their high heating efficiency, lower energy requirements, and easy operation. Acid and alkali pretreatments assisted by microwave heating meanwhile have been widely used for different types of lignocellulosic biomass conversion. Additional advantages of microwave-based pretreatments include faster treatment time, selective processing, instantaneous control, and acceleration of the reaction rate. The present review provides insights into the current research and advantages of using microwave-assisted pretreatment technologies for the conversion of lignocellulosic biomass to fermentable sugars in the process of cellulosic ethanol production.

• New & Renewable Energy
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• v.2 no.4 s.8
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• pp.70-77
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• 2006

The butane decomposition over the catalyst is an attractive method for the hydrogen production. The objective of the work was investigated the catalysis of carbon black in butane decomposition reaction. The Butane decomposition was performed over carbon black catalyst in a range of $500-1100^{\circ}C$. The butane conversion of thermal decomposition and catalytic decomposition were increased with increasing the reaction temperature The butane conversion of the thermal decomposition was higher than the butane conversion of the catalytic decomposition. Hydrogen and methane were mostly observed in the butane decomposition over $1000^{\circ}C$. Especially, the hydrogen yield was steadily increased with raising the reaction temperature, It could be known that the hydrogen yield of the catalytic decomposition was higher than one of the thermal cracking because the hydrogen productivity was improved by the catalyst. The deactivation of the catalyst was not observed in the reactivity test. The surface and crystalline of the fresh and used catalysts were characterized by TEM, BET surface area and XRD analysis, respectively. The fresh carbon black particles had mostly smoothly round-shaped surfaces. In the surface of the carbon black after the reaction, the deposited carbon was formed as the protrusion-shaped carbon and the cone-shaped. The proper peaks of carbon black appeared in XRD analysis.