• Journal of the Korean Society of Industry Convergence
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• v.6 no.4
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• pp.269-275
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• 2003

A non-thermal plasma process combined with $Cr_2O_3/TiO_2$ catalyst was applied to the decomposition of trichloroethylene (TCE). A dielectric barrier discharge reactor operated with AC high voltage was used as the non-thermal plasma reactor. The effects of reaction temperature and input power on the decomposition of TCE and the formation of byproducts including HCl, $Cl_2$, CO, NO, $NO_2$ and $O_3$ were examined. At an identical input power, the increase in the reaction temperature from 373 K to 473 K decreased the decomposition of TCE in the plasma reactor. The presence of the catalyst downstream the plasma reactor not only enhanced the decomposition of TCE but also affected the distribution of byproducts, significantly. However, synergistic effect as a result of the combination of non-thermal plasma with catalyst was not observed, i.e., the TCE decomposition efficiency in this plasma-catalyst combination system was almost similar to the sum of those obtained with each process.

• Carbon letters
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• v.5 no.4
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• pp.180-185
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• 2004

Thermolysis of $Cu(NO_3)_2{\cdot}3H_2O$ impregnated activated carbon fiber (ACF) was studied by means of XRD analysis to obtain Cu-impregnated ACF. $Cu(NO_3)_2{\cdot}3H_2O$ was converted into $Cu_2O$ around $230^{\circ}C$. The $Cu_2O$ was reduced to Cu at $400^{\circ}C$, resulting in ACF-C(Cu). Some Cu particles have a tendency to aggregate through the heat treatment, resulting in the ununiform distribution in ACF. Catalytic decomposition of NO gas has been performed by Cu-impregnated ACF in a column reactor at $400^{\circ}C$. Initial NO concentration was 1300 ppm diluted in helium gas. NO gas was effectively decomposed by 5~10 wt% Cu-impregnated ACF at $400^{\circ}C$. The concentration of NO was maintained less than 200 ppm for 6 hours in this system. The ACF-C(Cu) deoxidized NO to $N_2$ and was reduced to ACF-$C(Cu_2O)$ in the initial stage. The ACF-$C(Cu_2O)$ also deoxidized NO to $N_2$ and reduced to ACF-C(CuO). This ACF-C(CuO) was converted again into ACF-C(Cu) by heating. There was no consumption of ACF in mass during thermolysis and catalytic decomposition of NO to $N_2$ by copper. The catalytic decomposition was accelerated with increase of the reaction temperature.

• Journal of Energy Engineering
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• v.6 no.1
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• pp.26-33
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• 1997

Highly crystalline Cu-ZSM5 was prepared without using organic templates. Several ion exchange treatments between Na$\^$＋/ and Cu$\^$2＋/ brought about excess loading of copper ions on the ZSM5 zeolite and the resultant zeolite was active for the decomposition of NO. This indicates that the copper ions excessively loaded on the ZSM5 zeolite are effective for the NO decomposition. When oxygen was added to a reactants, the conversion of NO decreased. NO, O$_2$TPD experiments explained that the active sites for NO decomposition and the adsorption sites of O$_2$, were the same. O$_2$, at the surface of ZSM5 zeolite was desorbed incompletely after pretreatment at 500$^{\circ}C$, and CU-ZSM5 pretreated with H$_2$at 500$^{\circ}C$ showed promoted activity at the start of reaction. Thus, it seems clear that O$_2$, adsorbed ai the surface of catalyst inhibits the catalytic activity.

• Macromolecular Research
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• v.11 no.2
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• pp.87-91
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• 2003

Thermal decomposition reactions of polystyrene using a new heating medium were carried out by a batch system at 190-280 $^{\circ}C$ to clarify the manner in which decomposition is initiated. Polystyrene obtained from a commercial source and low molecular weight compounds obtained from the thermal decomposition were analyzed by GC, GPC, IR, $^{13}$ C-NMR and GC-MS. The main chain underwent virtually no change by heat application. Polystyrene underwent decomposition below its molding temperature and the major decomposition products were 2,4,6-triphenyl-1-hexene (trimer), 2,4-diphenyl-1-butene(dimer) and styrene (monomer). Ethylbenzene, propylbenzene, naphthalene, benzaldehyde, biphenyl and 1,3-diphenylpropane were detected as minor products. This paper presents a new method for examining the decomposition of polystyrene at low temperature into volatile low molecular weight compounds.

• The Korean Journal of Soil Zoology
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• v.2 no.2
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• pp.83-91
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• 1997

One year study with litter bags(mesh size - 0.4mm, 0.8mm, 1.7mm and 5.0mm) was carried out to investigate the soil invertebrate community in the process of leaf decomposition in Namsan and Kwangreung deciduous forests, which were considered to be under different degrees of environmental selective pressure. Soil animals collected from litter bags were classified into the class of order or higher taxa. Acari and Collembola were major groups: Acari and Collembola were about 60% and 30% of total soil animals in their numbers, respectively. Among minor groups, Dipteria, Araneae, Diplopoda, Coleoptera and Chilopoda were comparatively dominant. In Namsan forest which was considered to be under higher environmental selective pressure than Kwangreung, the densities of Acari and Collembola were somewhat higher than in Kwangreung, although there was no statistically significant difference between two sites. The densities of Chilopoda, Enchytraeidae and Nematoda were much higher in Namsan than in Kwangreung but Diplopoda and Symphyla were much more in Kwangreung. It was expected that those groups could be used as bioindicators. The densities of Acari and Collembola were very low until March and then showed the peak in May. But they decreased slowly until November. There was no significant difference among the mesh sized of litter bags in the densities of Acari and Collembola but other groups of soil invertebrates seemed to be prevented from immigrating into the litter bag of mesh size 0.4mm. Decomposition rate of litter in the litter bag was low in early stage of decomposition. The % residual mass over initial mass at 8 months after litter bag introduction in the field was over 80%. Thereafter, % residual mass decreased more fast and was about 60% at 1 year after bag introduction. There was little evidence for the effects of soil invertebrates upon the litter decomposition in the period of this study. And there was no significant difference between Namsan and Kwangreung or among mesh sizes of litter bags in the decomposition rate.

• Applied Chemistry for Engineering
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• v.7 no.2
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• pp.321-325
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• 1996

Quantum chemical calculations are used to characterize the decomposition of nitrogenmonoxide over $Cu^{n+}$-Y zeolite. The method of theoretical calculations, such as CNDO/2, have been applied to cluster models representing cation sites in zeolite to obtain total energies, LUMO energies, and Wiberg bond orders. The calculated total energies and bond orders of cluster models showed the reaction mechanism of NO decomposition over $Cu^{n+}$ site in zeolite framework. The suggested cluster models of varying Si/Al ratios studied with exchange cations in the $Cu^+$ and in the $Cu^{2+}$ states. And the calculated LUMO energies can predict L acidifies of cluster models. The results from these experiments showed the possibility of the mechanism of NO decomposition, progressing adsorption of NO, conversion to $N_2$ and $O_2$, desorption of $N_2$ and $O_2$ in sequence. The L acidity of $Cu^{2+}$ ion in cation site is more strong than $Cu^+$.

• Applied Chemistry for Engineering
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• v.29 no.5
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• pp.541-548
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• 2018

In this work, the $N_2O$ decomposition catalyst and reaction characteristics to control the $N_2O$ removal were described. Experiments were carried out by using Rh as an active metal catalyst on various supports and the $Rh/CeO_2$ catalyst with $CeO_2$ support showed the best activity for the $N_2O$ decomposition when it was prepared under the constant heat treatment condition ($500^{\circ}C$-4 hr). $H_2-TPR$ and XPS analyzes were performed to confirm the effect of the physical and chemical properties of the catalyst on $N_2O$ decomposition. As a result, it was found that the increase of the oxygen transfer capacity of the catalyst due to the increase of both the redox property and $Ce^{3+}$ amount affected the decomposition reaction of $N_2O$. In addition, the future work will include a treatment process capable of decomposition $N_2O$ and NO under the condition that $N_2O$ and NO are simultaneously generated and its characteristics of $N_2O$ decomposition reaction.

• Clean Technology
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• v.8 no.3
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• pp.111-117
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• 2002

Catalytic decomposition and reduction of NO have been carried out on copper loaded mordenites in a packed bed flow reactor. For the decomposition of NO, $Cu^{\circ}/HM$ exhibited higher activities than CuO/HM at high copper content, which may be related to the difference in the amount of $Cu^{2+}$ ions and the reducibility of CuO between $Cu^{\circ}/HM$ and Cuo/HM. However, $Cu^{\circ}/HM$ showed higher reduction activities than CuO/HM at low copper content. This result may be dependent on the difference in the amount of high-reducibility CuO between $Cu^{\circ}/HM$ and CuO/HM.

• 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.

• Carbon letters
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• v.1 no.1
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• pp.31-35
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• 2000

[ $SO_2$ ]and NO gases that come from the flue gases of most of all industrial combustion processes are harmful to everything include person and industrial facilities. For the simplification of the environmental clean-up processes, we studied the decomposition process by microwave. The microwave can destroy molecules into elementary atoms and offers energy to the atoms to react with carbons. Since the microwave is not absorbed into quartz tube and metallic chamber, the air pollution gases can be removed with much lower energy than in the case of conventional methods. We studied the decomposition of $SO_2$ and NO gases on the carbon beds by microwave. In the microwave field, the gases can be decomposed to form other compounds, such as elementary sulfur, nitrogen, carbon monoxide and carbon dioxide. It was found that CO gas is formed at higher temperature than is $CO_2$ gas, so it needs to control the bed temperature depend on products that we want to get.