• Journal of Korean Society for Atmospheric Environment
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• v.13 no.4
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• pp.319-325
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• 1997

The catalytic decomposition of CFC-113(1,1,2-trichloro-1,2,2-trifluoroethane) was studied over an activated carbon catalyst in a fixed-bed reactor at the temperature from 300 to 600$^\circ$C, the space velocity (SV) of 1800 $\sim 14400h^{-1}$ and the mole ratio(decomposition agent/CFC-113) of 0.25 $\sim$ 5. In the absence of a decomposition agent, the decomposition efficiency of CFC-113 was low but when a decomposition agent was added to the gas stream, it was dramatically increased with the increase of temperature. In particular, in the presence of n-hexane as the decomposition agent it showed a high decomposition efficiency compared with benzene at 400$^\circ$C. It was found that the decomposition activity of CFC-113 was very sensitive to reaction temperature. Thus it is expected that to raise the reaction temperature is more effective than to increase the residence time and the amount of decomposition agent. Over the activated carbon catalyst more than 99% decomposition was achieved at the reaction temperature of 600$^\circ$C, SV of 7200$h^{-1}$, the mole ration $(C_6H_{14}/CFC-113)$ of 1 in this study.

• The Korean Journal of Ecology
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• v.26 no.4
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• pp.203-208
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• 2003

Losses in the dry weight of leaf litter from six tree species were studied during 16 months on the forest floor in temperate deciduous forest of Mt. Cheonma in the vicinity of Seoul in Korea by using litter bag method. The decomposition rate of each leaf litter varies with each species. After 16 months elapsed, the leaf litter of Acer pseudo-sieboidianum showed the highest decomposition constant (0.82) as Olson´s decomposition constant, while that of Pinus densiflora showed the lowest decomposition constant (0.33). The decomposition constant of Quercus mongolica, Q. serrata, Betula ermani and Carpinus laxiflora showed 0.43, 0.37, 0.66 and 0.75, respectively. The decomposition constant of leaf litter was considered with temperature and precipitation which accumulated daily during each term of litter bag collection. The decomposition constant of leaf litter showed closely positive correlation with daily accumulative temperature and precipitation. The relationships between decomposition constant and the daily accumulative temperature and precipitation at each period of litter bag collection were analyzed through multi-regression analysis. The correlation coefficients as a result of multi-regression analysis in Q. mongolica, Q. serrata, P densiflora, B. ermani, C. laxiflorais and A. pseudo-sieboldianum were 0.83, 0.81, 0.69, 0.77, 0.77 and 0.62, respectively. The precipitation showed higher effect, about 10 times, on the leaf litter decomposition than the daily accumulative temperature.

• 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.

• Macromolecular Research
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• v.12 no.5
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• pp.490-492
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• 2004

We report a new method using a heating medium for the thermal decomposition of epoxy resin (EP) at temperatures ranging from 50 to 200$^{\circ}C$. EP decomposition also occurred below 50$^{\circ}C$ during a 6-day period to generate bisphenol A (BPA) at concentrations as high as 5 ppm. When polyethylene glycol was used as a heating medium, we determined the kinetics of the EP decomposition at low temperature. We determined the apparent activation energy of the overall decomposition to be 40.8 kJ/mol and the frequency factor to be 2.3${\times}$10$^3$ by monitoring the rate of BPA formation. Thus, EP is clearly unstable upon the application of heat.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.1
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• pp.21-28
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• 2011

Fe, Ni and Co, typical active components, were dispersed on $Al_2O_3$ and $TiO_2$ for $SO_3$ decomposition. $SO_3$ decomposition was conducted at the temperature ranges from $750^{\circ}C$ to $950^{\circ}C$ using the prepared catalysts. Alumina based catalysts showed the surface areas higher than Titania based catalysts, which resulted from spinel structure formation of alumina based catalysts. Catalytic $SO_3$ decomposition reaction rates were in the order of Fe>Co${\gg}$Ni. The metal sulfate decomposition temperature were in the order of Ni>Co>Fe from TGA/DTA analysis of metal sulfate. During $SO_3$ decomposition, metal sulfate can form on the catalysts. $SO_2$ and $O_2$ can be produced from the decomposition of metal sulfate. In that point of view, the less is the metal sulfate deomposition temperature, the higher can be the $SO_3$ decomposition activity of the metal component. Therefore, it can be concluded that metal component with the low metal sulfate decomposition temperature is the pre-requisite condition of the catalysts for $SO_3$ decomposition reaction.

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.157-159
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• 2015

In this study, $CF_4$ decomposition was experimentally investigated in a high temperature flow reactor. Effects of temperature, reactant composition and concentration, and residence time on its decomposition into other stable species were analyzed. Then the results were compared to numerical results obtained using Chemkin Plug Flow Reactor model with Princeton Chemistry. As a preliminary result higher decomposition rate is obtained for higher reactor temperature and long residence time when proper reactants are supplied.

• Fire Science and Engineering
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• v.30 no.6
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• pp.9-13
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• 2016

Anti-oxidation and flame resistant polyurethane nanofibers were prepared by electrospinning and aluminum hydroxide addition. Electrospinning was carried out under the following procedure conditions; applied voltage, 20 kV; polymer solution feeding rate, 1.2 ml/h; collector rolling speed, 120 rpm; and tip to collector distance, 15 cm. Aluminum hydroxide was added to the prepared polymer solution for electrospinning to enhance the oxidation and flame resistant properties. The thermal properties were investigated by thermogravimetric analysis to determine the polymer decomposition temperature, integral procedure decomposition temperature, final decomposition temperature, and remaining amount after thermal decomposition. The activated energy for polymer degradation was also investigated using the Horowitz-Metzger equation. The activation energy increased to more than 50%. The thermal properties of the polyurethane nanofibers were improved by a hydration reaction during the thermal decomposition of aluminum hydroxide around $300{\sim}500^{\circ}C$.

• Journal of Environmental Science International
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• v.11 no.7
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• pp.749-755
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• 2002

The effects of noble gas (such as helium, neon, argon, krypton, and xenon) on the sonolytic decomposition of water and 2-methyl-2-propanol(t-butanol) with 200 KHz high power ultrasound were investigated. The physical properties of the noble gas have an effect on the formation rate of products $(H_2O_2,\;H_2,\;O_2)$ and the decomposition rate on the sonolytic decomposition of water. The pyrolysis products, such as methane, ethane, ethylene, and acetylene are formed during the sonolytic decomposition of t-butanol. From the estimation of the ratio $[C_2H_4+C_2H_2] / [C_2H_6]$, the cavitation temperature would be varied by the used noble gas. In all cases for the sonolytic decomposition of water, t-butanol, and diethyl phthalate, the decomposition rates were xenon > krypton > argon > neon > helium with a significant difference and were closely correlated with the formation rate of OH radical and high temperature inside the cavitation bubble under each noble gas.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.1
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• pp.51-59
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• 2011

Sulfur-Iodine (SI) cycle, which thermochemically splits water to hydrogen and oxygen through three stages of Bunsen reaction, HI decomposition, and $H_2SO_4$ decomposition, seems a promising process to produce hydrogen massively. Among them, the decomposition of $H_2SO_4$ ($H_2SO_4=H_2O+SO_2+1/2O_2$) requires high temperature heat over $800^{\circ}C$ such as the heat from concentrated solar energy or a very high temperature gas-cooled nuclear reactor. Because of harsh reaction conditions of high temperature and pressure with extremely corrosive reactants and products, there have been scarce and limited number of data reported on the pressurized $H_2SO_4$ decomposition. This work focuses whether the $H_2SO_4$ decomposition can occur at high pressure in a noble-metal reactor, which possibly resists corrosive acidic chemicals and possesses catalytic activity for the reaction. Decomposition reactions were conducted in a Pt-lined tubular reactor without any other catalytic species at conditions of $800^{\circ}C$ to $900^{\circ}C$ and 0 bar (ambient pressure) to 10 bar with 95 wt% $H_2SO_4$. The Pt-lined reactor was found to endure the corrosive pressurized condition, and its inner surface successfully carried out a catalytic role in decomposing $H_2SO_4$ to $SO_2$ and $O_2$. This preliminary result has proposed the availability of noble metal-lined reactors for the high temperature, high pressure sulfuric acid decomposition.

• Journal of the Korean Society of Safety
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• v.24 no.6
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• pp.55-62
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• 2009

After examining the characteristics of the heat decomposition of the 80~120mesh flour using the Mini cup pressure vessel test and determining the apparent activation energy in a spontaneous combustion, the conclusion is as follows. The heat decomposition of flour occurs at around $100^{\circ}C$ and the peak for the maximum rise in pressure appears at around $290^{\circ}C$. The decomposition pressure against various temperature in the vessel shows the maximum value of $4.7kg/cm^2$ approximately at $440^{\circ}C$. When the thickness of the sample is 3cm, the maximum temperature and the critical temperature of ignition are $398^{\circ}C$ and $204.5^{\circ}C$, respectively; the critical temperature is $194.5^{\circ}C$ when the thickness of the sample is 5cm, and $182.5^{\circ}C$ when the sample is 7cm. In addition, the apparent velocity calculated using the method of least squares is 35.0407Kcal/mol.