• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1378-1379
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• 2006

Carbon nanotubes (CNTs) with few defects and very small amount of amorphous carbon coating have been synthesized by catalytic decomposition of acetylene in $H_2$ over well-dispersed metal particles supported on MgO. The yield, quality and diameters of CNTs were obtained by control of catalyst metal compositions to be used. The optimization condition of carbon nanotubes with high yield is when Co and Mo are in a 1:1 ratio and Fe metal contents to Co is increased on magnesium oxide support. It is also found that the diameter of the as-prepared CNTs can be controlled mainly by adjusting the molar ratio of Fe-Mo, Co-Fe, and Co-Mo versus the MgO support. Our results indicated that desired diameter distribution of CNTs is obtained by choosing or combining the catalyst to be employed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.162-163
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• 2005

Singlewalled carbon nanotubes are largely synthesized on Fe-Mo/MgO catalysts by catalytic decomposition of CH4 in H2. Raman data revel that the as-prepared SWNTs have a diameter of about 0.7-1.2nm. It is found that the diameter of the as-prepared SWNTs can be controlled mainly by adjusting the molar ratio of Fe-MO versus the MgO support. The experimental results was documented with scanning electron microscopy(SEM), X-ray Diffractometer(XRD) and Raman spectroscopy.

• Bulletin of the Korean Chemical Society
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• v.6 no.3
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• pp.138-140
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• 1985

Hydroxylation of anisole with $H_2O_2$ was investigated by employing Fe(III) ion and N-dodecyl-3,4-dihydroxybenzamide (DDHB) as a catalyst. The study was aimed at obtaining an insoluble catalyst with a long catalytic life, in view of the inactivation of the catechol portion of the catalyst during the reaction. The rate of decomposition of $H_2O_2$ under various conditions indicated that the reaction proceeds through the catalytic participation of $Fe(III){\cdot}DDHB$. Yield of the hydroxylation products under various conditions revealed that $Fe(III){\cdot}DDHB$ is not inactivated during the reaction.

• Journal of the Korean Chemical Society
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• v.68 no.2
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• pp.87-92
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• 2024

The commercialization of rechargeable metal-air batteries is extremely desirable but designing stable oxygen reduction reaction (ORR) catalysts with non-noble metal still has faced challenges to replace platinum-based catalysts. The nonnoble metal catalysts for ORR were prepared to improve the catalytic performance and stability by the thermal decomposition of ZIF-8 with optimum cobalt loading. The porous carbon was obtained by the calcination of ZIF-8 and different loading amounts of Co nanoparticles were anchored onto porous carbon forming a Co/PC catalyst. Co/PC composite shows a significant increase in the ORR value of current and stability (500 h) due to the good electronic conductive PCN support and optimum cobalt metal loading. The significantly improved catalytic performance is ascribed to the chemical structure, synergistic effects, porous carbon networks, and rich active sites. This method develops a new pathway for a highly active and advantageous catalyst for electrochemical devices.

• New & Renewable Energy
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• v.20 no.1
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• pp.126-134
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• 2024

Biogas, composed mainly of methane (CH₄) and carbon dioxide (CO₂), is a renewable gas that can serve as an alternative energy source. In this study, we developed a new microwave reformer and analyzed its reforming characteristics. We observed that higher temperatures of the microwave receptor led to increased reforming efficiency. By supplying appropriate amounts of methane and steam, we could prevent carbon generated from the thermal decomposition reaction of carbon dioxide from depositing on the catalytic active layer, thus avoiding the inhibition of catalytic activity. Hydrogen generation was enhanced when maintaining the biogas ratio and steam supply at adequate levels. Increasing the SiC ratio in the receptor improved the uniformity of temperature distribution and growth rate, resulting in higher conversion rates of the reforming process.

• Polymer(Korea)
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• v.37 no.3
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• pp.379-386
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• 2013

SAPO-11 was applied for the first time to the catalytic pyrolysis of miscanthus and random polypropylene (random PP). Thermogravimetric analysis confirmed that SAPO-11 promoted the dehydration of miscanthus while suppressing the formation of char. In the pyrolysis of random PP, the decomposition temperature and activation energy were reduced by using a catalyst. A large fraction of levoglucosan, which was the main oxygenate product from the non-catalytic pyrolysis of miscanthus, was converted to high value-added products, such as furans, phenolics and aromatics using SAPO-34. The catalytic pyrolysis of random PP produced gasoline- and diesel-range hydrocarbons.

• Journal of Aerospace System Engineering
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• v.11 no.2
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• pp.9-15
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• 2017

In order to verify the possiblity of improving the combustion performance of ethanol using zeolite catalyst and the characteristics of nitrogen oxides and carbon monoxide emission, micro gas turbine experiments were performed using catalytic reaction products, ethanol and kerosene as fuels and the results were compared. The thrust of the catalytic reaction product was lower than that of kerosene, but it was improved by 5% on average compared with the use of ethanol. Nitrogen oxides and carbon monoxide emissions of the catalytic reaction products were measured to be very low overall compared to kerosene. As a result, when the ethanol was reformed using the zeolite catalyst, the engine performance could be improved while maintaining the environment friendliness of the ethanol.

• Transactions of the Korean hydrogen and new energy society
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• v.19 no.3
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• pp.199-208
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• 2008

HI decomposition was conducted using Pt/C-based catalysts with a fixed-bed reactor in the range of 573 K to 773 K. To examine the change of the characteristic properties of the catalysts, $N_2$ adsorption analyser, a X-ray diffractometer(XRD), and a scanning electron microscopy(SEM) were used before and after the HI decomposition reaction. the effect of Pt loading on HI decomposition was investigated by $CO_2$-TPD. HI conversion of all catalysts increased as decomposition temperature increased. The XRD analysis showed that the sizes of platinum particle became larger and agglomerated into a lump during the reaction. From $CO_2$-TPD, it can be concluded that the cause for the increase in catalytic activity may be attributed to the basic sites of catalyst surface. The results of both b desorption and gasification reaction showed the restriction on the use of Pt/C-based catalyst.

• Applied Chemistry for Engineering
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• v.19 no.1
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• pp.17-26
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• 2008

With the effectuation of Kyoto Protocol on the United Nations Framework Convention on the Climate Change, the emission reduction of greenhouse gases became an urgent issue and has been competitively secured among countries as the form of certificates through clean development mechanism (CDM) or joint implementation (JI). Nitrous oxide ($N_2O$) is one of the major greenhouse gases along with carbon dioxide ($CO_2$) and methane ($CH_4$) having warming potential 310 times that of carbon dioxide and chemically very stable in the atmosphere to give a life time of more than 120 years so that it reaches to the stratosphere to act as an ozone depleting substance. $N_2O$ hardly decomposes and thus, besides to the adoption of thermal decomposition at high temperature, selective catalytic reduction methods are usually used at temperatures over $400^{\circ}C$ in which the presence of NOx acts as a major impeding material in the decomposition process. In this article, the sources of various $N_2O$ generation, catalytic reduction processes and the status and trends of emission trade with CDM projects for greenhouse gas reduction are summarized and discussed on a condensed basis.

• Korean Chemical Engineering Research
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• v.43 no.2
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• pp.206-214
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• 2005

Heterogeneously-catalyzed oxidation of aqueous phase trichloroethylene (TCE) over supported metal oxides has been conducted to establish an approach to eliminate ppm levels of organic compounds in water. A continuous flow reactor system was designed to effect predominant reaction parameters in determining catalytic activity of the catalysts for wet TCE decomposition as a model reaction. 5 wt.% $CoO_x/TiO_2$ catalyst exhibited a transient period in activity vs. on-stream time behavior, suggesting that the surface structure of the $CoO_x$ might be altered with on-stream hours; regardless, it is probable to be the most promising catalyst. Not only could the bare support be inactive for the wet decomposition reaction at $36^{\circ}C$, but no TCE removal also occurred by the process of adsorption on $TiO_2$ surface. The catalytic activity was independent of all particle sizes used, thereby representing no mass transfer limitation in intraparticle diffusion. Very low TCE conversion appeared for $TiO_2$-supported $NiO_x$ and $CrO_x$ catalysts. Wet oxidation performance of supported Cu and Fe catalysts, obtained through an incipient wetness and ion exchange technique, was dependent primarily on the kinds of the metal oxides, in addition to the acidic solid supports and the preparation routes. 5 wt.% $FeO_x/TiO_2$ catalyst gave no activity in the oxidation reaction at $36^{\circ}C$, while 1.2 wt.% Fe-MFI was active for the wet decomposition depending on time on-stream. The noticeable difference in activity of the both catalysts suggests that the Fe oxidation states involved to catalytic redox cycle during the course of reaction play a significant role in catalyzing the wet decomposition as well as in maintaining the time on-stream activity. Based on the results of different $CoO_x$ loadings and reaction temperatures for the decomposition reaction at $36^{\circ}C$ with $CoO_x/TiO_2$, the catalyst possessed an optimal $CoO_x$ amount at which higher reaction temperatures facilitated the catalytic TCE conversion. Small amounts of the active ingredient could be dissolved by acidic leaching but such a process gave no appreciable activity loss of the $CoO_x$ catalyst.