• Journal of the Korean Statistical Society
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• v.23 no.2
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• pp.503-503
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• 1994

• Applied Chemistry for Engineering
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• v.20 no.1
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• pp.87-93
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• 2009

Pd/activated carbon (Pd/AC) and Pd/alumina (Pd/AO) catalysts were prepared by the impregnation of palladium into activated carbon and alumina. The catalytic characteristics according to the kinds of support materials were compared. The decomposition efficiencies of ozone according to kinds of support materials are about the same when these were compared by adding 10 g of catalysts into the water saturated with ozone. The decomposition efficiencies and the oxidation characteristics (TOC, $COD_{Cr}$) of dichloroacetic acid were compared with the ozone only process and the catalytic ozonations using Pd/activated carbon and Pd/alumina catalysts. The decomposition efficiencies of dichloroacetic acid by catalytic ozonations were better than the one by ozone only process, but there was slight difference of the one between Pd/activated carbon and Pd/alumina catalyst. The decomposition efficiency of dichloroacetic acid was increased with increasing ozone dose at a constant concentration of dichloroacetic acid, but the one was little increased with increasing ozone dose at more than 1.0 L/min of ozone dose. It was seemed that the bicarbonate and the chloric ion formed throughout the decomposition of dichloroacetic acid acted as the scavenger of hydroxyl radical.

• Journal of the Korean Society of Safety
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• v.15 no.2
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• pp.70-77
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• 2000

For hazardous air pollutants(HAP) such as NO, $NO_2$ and $SO_2$ decomposition efficiency, power consumption, and applied voltage were investigated by SPCP(Surface induced discharge Plasma Chemical Processing) reactor to obtain optimum process variables and maximum decomposition efficiencies. Decomposition efficiency of HAP with various electric frequencies(5~50 kHz), flow rates(100~1,000 mL/min), initial concentrations(100~1,000 ppm) and additive($CH_4$) were measured and the products were analyzed with FT-IR. Experimental results showed that for the frequency of 10 kHz, the highest decomposition efficiency of 94.3 % for NO, 84.7 % for $NO_2$ and 99 % far $SO_2$ were observed at the power consumptions of 19.8, 20 and 19W, respectively, and that decomposition efficiency decreased with increasing frequency above 20 kHz. And decomposition efficiency per unit power were 5.21 %/W for $SO_2$, 4.76 %/W for NO and 4.24 %/W for $NO_2$ and the highest decomposition efficiency was observed with $SO_2$. Decomposition efficiency was increased with increasing residence times and with decreasing initial concentration of pollutants. When the additive of $CH_4$ was used, decomposition efficiency was increased with increasing $CH_4$ content, and NO, $NO_2$ and $SO_2$ were almost completely decomposed with the efficiency of 99 %, 98 % and 99 %, respectively and therefore $CH_4$ was a good additive material. The optimum power for the maximum decomposition efficiency were 7.5 W for $SO_2$, 9.5 W for NO and 15.5 W for $NO_2$, respectively. Optimum power with the maximum decomposition efficiency were 9.5 W at 1,000 ppm of NO, 7~8 W at 100~500 ppm of NO and 15.5 W at all concentration range of $NO_2$ and 11.5 W at 1,000 ppm, 4.9 W at 500 ppm, 3.7 W at 100~300 ppm of $SO_2$ and power efficiency was best in these case.

• Journal of Hydrogen and New Energy
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• v.26 no.6
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• pp.507-515
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• 2015

HI decomposition reaction requires a catalyst for the efficient production of hydrogen as a key reaction for hydrogen production in sulfur-iodine thermochemical water-splitting (SI) cycle. As a catalyst used in the reaction, the performance of platinum catalyst is excellent. While, the platinum catalyst is not economical. Therefore, studies of a nickel catalyst that could replace platinum have been carried out. In this study, the characteristics of the catalytic HI decomposition on the amount of loaded nickel (Ni = 0.1, 0.5, 1, 3, 5, 10 wt%) were investigated. As the supported Ni amount increased up to 3 wt%, HI decomposition was found to increase in linear proportion. However, the conversion of $Ni/Al_2O_3$ catalyst loaded above 3 wt% was not linear. It was thought that the different HI decomposition characteristics was caused in the size and metal dispersion of Ni particles of catalyst. The physical property of catalyst before and after HI decomposition reaction was characterized by BET, chemisorption, XRD and SEM analysis.

• Journal of Environmental Science International
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• v.21 no.11
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• pp.1321-1331
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• 2012

To date, carbon and nitrogen co-doped photocatalysts (CN-$TiO_2$) for environmental application focused mainly on the aqueous phase to investigate the decomposition of water pollutants. Accordingly, the present study explored the photocatalytic performance of CN-$TiO_2$ photocatalysts for the purification of indoor-level gas-phase aromatic species under different operational conditions. The characteristics of prepared photocatalysts were investigated using X-ray diffraction, scanning emission microscope, diffuse reflectance UV-VIS-NIR analysis, and Fourier transform infrared (FTIR) analysis. In most cases, the decomposition efficiency for the target compounds exhibited a decreasing trend as input concentration (IC) increased. Specifically, the average decomposition efficiencies for benzene, toluene, ethyl benzene, and xylene (BTEX) over a 3-h process decreased from 29% to close to zero, 80 to 5%, 95 to 19%, and 99 to 32%, respectively, as the IC increased from 0.1 to 2.0 ppm. The decomposition efficiencies obtained from the CN-$TiO_2$ photocatalytic system were higher than those of the $TiO_2$ system. As relative humidity (RH) increased from 20 to 95%, the decomposition efficiencies for BTEX decreased from 39 to 5%, 97 to 59%, 100 to 87%, and 100 to 92%, respectively. In addition, as the stream flow rates (SFRs) decreased from 3.0 to 1.0 L $min^{-1}$, the average efficiencies for BTEX increased from 0 to 58%, 63 to 100%, 69 to 100%, and 68 to 100%, respectively. Taken together, these findings suggest that three (IC, RH, and SFR) should be considered for better BTEX decomposition efficiencies when applying CN-$TiO_2$ photocatalytic technology to purification of indoor air BTEX.

• Korean Journal of Materials Research
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• v.25 no.6
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• pp.274-278
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• 2015

The possibility of using the chemical precipitation method of up-cycled ammonium paratungstate (APT) was studied and compared with the thermal decomposition method. $WO_3$ particles were synthesized by chemical precipitation method using a 1:2 weight ratio of APT: Di-water. For thermal decomposition, APT powder was heated for 4h at $600^{\circ}C$ in air atmosphere. The reaction products were characterized by X-ray diffraction (XRD), X-ray fluorescence spectrometer (XRF), particle size analyzer (PSA), and field emission-scanning electron microscopy (FE-SEM). Thermogravimetric analysis (TGA) of the up-cycled APT allowed for the identification of the sequence of decomposition and reduction reactions that occurred during the heat treatment. TGA data indicated a total weight loss of 10.78% with the reactions completed in $658^{\circ}C$. The XRD results showed that APT completely decomposed to $WO_3$ by thermal decomposition and chemical precipitation. The particle size of the synthesized $WO_3$ powders by thermal decomposition with 2 h of planetary milling was around $2{\mu}m$ During the chemical precipitation process, the particle size of the synthesized $WO_3$ powders showed a round-shape with ${\sim}0.6{\mu}m$ size.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.12
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• pp.142-149
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• 2008

This paper proposes an effective decomposition method of trichloroethylene using pellet packed-bed non-thermal plasma reactor and catalyst. For that, two types of reactors filled with manganese dioxide and alumina pellets are designed. When $MnO_2$ packed reactor is used, TCE decomposition rate is high due to the generation of oxygen atom radicals at the surface of catalyst during ozone decomposition. In addition, When $Al_2O_3$ packed reactor is used, TCE is oxidized into DCAC and it did not decomposed into small molecules such as COx and $Cl_2$. However, the plasma processed gas using $Al_2O_3$ packed reactor is passed through the $MnO_2$ catalyst reactor, which is placed at the downstream of plasma reactor, the decomposition rate increased as well due to oxygen atom radicals through ozone decomposition. Therefore, the adequate use of $MnO_2$ catalyst in the plasma process is very promising way to increase the decomposition efficiency.

• Applied Science and Convergence Technology
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• v.25 no.3
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• pp.56-60
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• 2016

The ALD process is an adequate technique to meet the requirements that come with the downscaling of semiconductor devices. To obtain thin films of the desired standard, it is essential to understand the thermal decomposition properties of the precursors. As such, this study examined the thermal decomposition properties of TEMAHf precursors and its effect on the formation of $HfO_2$ thin films. FT-IR experiments were performed before deposition in order to analyze the thermal decomposition properties of the precursors. The measurements were taken in the range of $135^{\circ}C-350^{\circ}C$. At temperatures higher than $300^{\circ}C$, there was a rapid decrease in the absorption peaks arising from vibration of $Sp^3$ C-H stretching. This showed that the precursors experienced rapid decomposition at around $275^{\circ}C-300^{\circ}C$. $HfO_2$ thin films were successfully deposited by Atomic Layer Deposition (ALD) at $50^{\circ}C$ intervals between $150^{\circ}C$ to $400^{\circ}C$; the deposited films were characterized using a reflectometer, X-ray photoelectron spectroscopy (XPS), Grazing Incidence X-ray Diffraction (GIXRD), and atomic force microscopy (AFM). The results illustrate the relationship between the thermal decomposition temperature of TEMAHf and properties of thin films.

• Journal of IKEEE
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• v.23 no.2
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• pp.431-437
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• 2019

This work was carried out ozone generation and TCE decomposition characteristics using dielectric ball materials filled barrier discharge reactor and catalyst's reactor for ozone decomposition. Ozone concentration generated from $Al_2O_3$ or $TiO_2$ filled barrier discharge reactor was so high compared with non-filled discharge reactor. This reactor is good discharge structure for generating the high ozone concentration. In addition, TCE decomposition rate and COx conversion rate increased using $MnO_2$ filled discharge reactor, because ozone was decomposed at the same discharge space on the surface of $MnO_2$ catalysts. To identify the $MnO_2$ catalytic effects, TCE decomposition rate reached to 100[%] by the decomposition of ozone at $MnO_2$ catalyst's reactor by the arrangement of $Al_2O_3$ filled discharge reactor and $MnO_2$ catalyst reactor. Finally, $MnO_2$ catalyst is good materials for the decomposition of ozone and this process will be useful for decomposing VOCs such as TCE.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2244-2249
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• 2007

A directly heated $SO_3$ decomposer for the sulfur-iodine and hybrid-sulfur processes has been introduced and analyzed by using a computational fluid dynamics code(CFD) with the CFX 5.7.1. The use of a directly heated decomposition reactor in conjunction with a VHTR allows higher decomposition reactor operating temperature. However, the thermochemical and hybrid hydrogen production processes accompanied with the high temperature and strongly corrosive operating conditions basically have material problems. In order to resolve these problems, we carried out the development of a structural material and equipment design technologies. The results show that the maximum temperature of the structural material (RA330) could be maintained at 800$^{\circ}C$ or less. Also, it can be seen that the mean temperature of the reaction region packed with catalysts in the $SO_3$ decomposition reactor could satisfy the temperature condition of around 850 $^{\circ}C$ which is the target temperature in this study.