• Journal of Powder Materials
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• v.12 no.2 s.49
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• pp.146-150
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• 2005

An optimum route to synthesize $Al_2O_3$-based composite powders with homogeneous dispersion of carbon nanotubes (CNTs) was investigated. CNTs/Metal/$Al_2O_3$ nanocomposite powders were fabricated by thermal chemical vapor deposition of $C_2H_2$ gas over metal/$Al_2O_3$ nanocomposite catalyst prepared by selective reduction of metal oxide/$Al_2O_3$ powders. The FT-Raman spectroscopy analysis revealed that the CNTs have single- and multi-walled structure. The CNTs with the diameter of 25-43 nm were homogeneously distributed in the metal/$Al_2O_3$ powders, and their characteristics were strongly affected by a kind of metal catalyst and catalyst size. The experimental results show that the composite powder with required size and dispersion of CNTs can be realized by control of synthesis condition.

• Journal of the Korean Applied Science and Technology
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• v.37 no.4
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• pp.723-732
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• 2020

The spent RHDS (Residue HydroDeSulfurization) catalyst is deactivated mainly by deposition of various contaminants such as coke, sulfur and vanadium on the surface of catalyst. To eliminate those contaminants, the following remanufacturing process was conducted. The first, heavy oil on the surface of the spent RHDS catalyst was removed by kerosene and dehydrated. The second, the high temperature incineration was carried out to eliminate coke and sulfur components deposited on the surface of spent RHDS catalyst. The third, the excessive quantity of Vanadium deposited on the surface of catalyst was removed by leaching process as follows: ultrasonic agitation was carried out at 50℃, for 10 seconds with 0.5% and 1% oxalic acid solution. The purpose of this process is to find out regenerated RHDS catalyst can be used as SCR catalyst for NOx reduction by controlling the vanadium residual content of the regenerated RHDS catalyst through leaching process. The composition of regenerated RHDS catalyst was analyzed by XRF and the NOx reduction efficiency was also measured by continuous catalytic fixed bed reactor. As the result, regenerated catalyst, with 0.5% oxalic acid, ultrasonic agitation in 10 seconds, showed the most stable NOx reduction efficiency. Also, in comparison with commercial SCR catalyst, the NOx reduction performance of regenerated catalyst was similar to that of commercial SCR catalyst at the temperature 375℃ and higher whereas was lower than commercial SCR catalyst at the temperature range between 200~250℃. Therefore, it was confirmed that the regenerated catalyst as powder form wash coated on the surface of metal corrugated substrate can be used for commercial SCR catalyst.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.6
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• pp.397-405
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• 2012

In this study, performance evaluation of newly developed technology for the economical and safe removal of volatile organic compounds (VOCs) coming out from electronic devices washing operation and offensive odor induction materials was made. Metal oxidization catalyst has shown 50% of removal efficiency at the temperature of $220^{\circ}C$. Composite metal oxidization catalyst applied in this study has shown that the actual catalysis has started at the temperature of $100^{\circ}C$. Comprehensive analysis on the catalyst property using Mn-Cu metal oxidization catalyst in the pilot-scale unit was made and the removal efficiency was variable with temperature and space velocity. Full-scale unit developed based on the pilot-scale unit operation has shown 95% of removal efficiency at the temperature of $160^{\circ}C$. Optimum elimination effective rates for the space velocity was found to be $6,000hr^{-1}$. The most appropriate processing treatment range for the inflow concentration of VOCs was between 200 ppm to 4,000 ppm. Catalyst control temperature showed high destruction efficiency at $150{\sim}200^{\circ}C$ degrees Celsius in 90~99%. External heat source was not necessary due to the self-heat reaction incase of VOCs inflow concentration is more than 1,000 ppm. Equipment and fuel costs compared to the conventional RTO/RCO method can be reduced by 50% and 75% respectively. And it was checked when there was poisoning for sulfide and acid gas.

• Korean Journal of Materials Research
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• v.15 no.3
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• pp.189-194
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• 2005

[ $SiO_2$ ] nanowires were synthesized using the catalyst evaporation method. Grown nanowires had different shapes by kind of used metal catalyst. Mean diameters of grown $SiO_2$ nanowire were about 30 nm. The kind of catalysts affected microstructure of grown $SiO_2$ nanowire because of its typical growth reactions through the liquid state metal catalysts. Optical property were measured by photoluminescence spectroscopy. Relatively broad peak was obtained and mean peak positioned at 450 nm.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.514-517
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• 2008

Water gas shift(WGS) is an important step in fuel process for fuel cells, and improperness of commercial WGS catalysts for use in fuel cell systems has prompted numerous researches on noble metal catalysts. A selected noble metal catalyst for water gas shift reaction(WGS) was prepared with various metal loadings. The prepared catalysts were tested under two feeding conditions. At moderate residence time, carbon monoxide conversion was much higher on the noble metal catalysts as compared to commercial high-temperature shift catalyst. Effects of metal loading were examined by activity tests at short residence time. Higher metal loading effected higher reaction rate. The kinetic data was fitted to simple reaction equations and effectiveness factor was estimated. The results suggest the necessity of a structural design for the highly active noble metal catalysts.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.5
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• pp.529-537
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• 2000

Several Pt-based oxidation catalysts with different loading were prepared with various metal precursor solutions and characterized with H$_2$ chemisorption and TEM for Pt particle size. V was added to Pt-based catalyst for inhibiting SO$_2$oxidation reaction, as result, Pt-V/Ti-Si catalyst prepared by ERMS(Free Reduced Metal in Solution) method showed high enough activity and better inhibition on SO$_2$oxidation than Pt only catalyst. Optimum Pt particle size for diesel oxidation reaction turned out to be the size of around 20 nm. A prototype catalyst was prepared for light=duty diesel passenger car, and teated for the emission reduction performance with Korean regulation test mode(CVS-75 mode) on chassis dynamometer. The catalyst shows the performance reduction of 75~94% for CO, 53~67% for HC and 10~31% for PM. In the case of heavy-duty diesel catalyst, the domestic formal regulation teat mode D-13 was adopted for both Na engine and Turbo engine. The conversions of CO and THC are high enough(86% and 41%) while the reductions of NOx and PM are relatively low(3~11%).

• Resources Recycling
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• v.10 no.3
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• pp.23-28
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• 2001

Zinc ion could be recovered from metal plating wastewater with the spent iron oxide catalyst which was used in the plant of Styrene Monomer(SM) production. The zinc was recovered more than 98.7% at higher than pH 2.0. The saturation magnetization of the spent catalyst is enough high as 59.4 emu/g to apply in the solid-liquid separation after treating the wastewater. The mechanism of zinc recovery with the iron oxide catalyst could be a electro-chemical adsorption at pH 3.0~8.5, and a precipitation as $Zn(OH)_2$ at higher than pH 8.5.

• Environmental Engineering Research
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• v.18 no.3
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• pp.145-150
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• 2013

Optimal preparation guidelines of a cathode catalyst layer by non-precious metal catalysts were evaluated based on electrochemical performance in single-chamber microbial fuel cells (MFCs). Experiments for catalyst loading rate revealed that iron(II) phthalocyanine (FePc) can be a promising alternative, comparable to platinum (Pt) and cobalt tetramethoxyphenylporphyrin (CoTMPP), including effects of substrate concentration. Results showed that using an optimal FePc loading of $1mg/cm^2$ was equivalent to a Pt loading of $0.35mg/cm^2$ on the basis of maximum power density. Given higher loading rates or substrate concentrations, FePc proved to be a better alternative for Pt than CoTMPP. Under the optimal loading rate, it was further revealed that 40 wt% of FePc to carbon support allowed for the best power generation. These results suggest that proper control of the non-precious metal catalyst layer and substrate concentration are highly interrelated, and reveal how those combinations promote the economic power generation of single-chamber MFCs.

• Journal of the Korean Applied Science and Technology
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• v.31 no.2
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• pp.313-319
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• 2014

This study was performed to obtain high conversion efficiency of $NH_3$ and minimize generation of nitrogen oxides using metal-supported catalyst with Ag : Cu ratio. Through structural analysis of the prepared catalyst with Ag : Cu ratio ((10-x)Ag-xCu ($0{\leq}x{\leq}6$)), it was confirmed that the specific surface area was decrease with increasing metal content. A prepared catalysts showed Type II adsorption isotherms regardless of the ratio Ag : Cu of metal content, and crystalline phase of $Ag_2O$, CuO and $CuAl_2O$ was observed by XRD analysis. In the low temperature($150{\sim}200^{\circ}C$), a conversion efficiency of AC_10 recorded the highest(98%), whereas AC_5 (Ag : Cu = 5 : 5) also showed good conversion efficiency(93.8%). However, in the high temperature range, the amounts of by-products(NO, $NO_2$) formed with AC_5 was lower than that of AC_10. From these results, It is concluded that AC_5 is more environmentally and economically suitable.

• Journal of Environmental Science International
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• v.15 no.7
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• pp.635-642
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• 2006

Present study evaluated the low-temperature destruction of n-hexane and benzene using mesh-type transition-metal platinum(Pt)/stainless steel(SS) catalyst. The parameters tested for the evaluation of catalytic destruction efficiencies of the two volatile organic compounds(VOC) included input concentration, reaction time, reaction temperature, and surface area of catalyst. It was found that the input concentration affected the destruction efficiencies of n-hexane and benzene, but that this input-concentration effect depended upon VOC type. The destruction efficiencies increased as the reaction time increased, but they were similar between two reaction times for benzene(50 and 60 sec), thereby suggesting that high temperatures are not always proper for thermal destruction of VOCs, when considering the destruction efficiency and operation costs of thermal catalytic system together. Similar to the effects of the input concentration on destruction efficiency of VOCs, the reaction temperature influenced the destruction efficiencies of n-hexane and benzene, but this temperature effect depended upon VOC type. As expected, the destruction efficiencies of n-hexane increased as the surface area of catalyst, but for benzene, the increase rate was not significant, thereby suggesting that similar to the effects of the re- action temperature on destruction efficiency of VOCs, high catalyst surface areas are not always proper for economical thermal destruction of VOCs. Depending upon the inlet concentrations and reaction temperatures, almost 100% of both n-hexane and benzene could be destructed, The current results also suggested that when applying the mesh type transition Metal Pt/SS catalyst for the better catalytic pyrolysis of VOC, VOC type should be considered, along with reaction temperature, surface area of catalyst, reaction time and input concentration.