• Clean Technology
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• v.29 no.1
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• pp.39-45
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• 2023

To investigate the effects of Mg addition at different aging times and temperatures, Cu/MgO/Al₂O₃ catalysts were synthesized for the low-temperature water gas shift (LT-WGS) reaction. The co-precipitation method was employed to prepare the catalysts with a fixed Cu amount of 30 mol% and varied amounts of Mg/Al. Synthesized catalysts were characterized using XRD, BET, and H₂-TPR analysis. Among the prepared catalysts, the highest CO conversion was achieved by the Cu/MgO/Al₂O₃ catalyst (30/40/30 mol%) with a 60 ℃ aging temperature and a 24 h aging time under a CO₂-rich feed gas. Due to it having the lowest reduction temperature and a good dispersion of CuO, the catalyst exhibited around 65% CO conversion with a gas hourly space velocity (GHSV) of 14,089 h-1 at 300 ℃. However, it has been noted that aging temperatures greater or less than 60 ℃ and aging times longer than 24 h had an adverse impact, resulting in a lower surface area and a higher reduction temperature bulk-CuO phase, leading to lower catalytic activity. The main findings of this study confirmed that one of the main factors determining catalytic activity is the ease of reducibility in the absence of bulk-like CuO species. Finally, the long-term test revealed that the catalytic activity and stability remained constant under a high concentration of CO₂ in the feed gas for 19 h with an average CO conversion of 61.83%.

• Bulletin of the Korean Chemical Society
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• v.31 no.5
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• pp.1241-1246
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• 2010

Ternary Cu/ZnO/$Al_2O_3$ catalysts were prepared by a co-precipitation method. The precursor structures were monitored during the aging. The first precipitate structure was amorphous georgeite, which transformed into the unknown crystalline structure. The transition crystalline structure was assigned to the crystalline georgeite, which was suggested with elemental analysis, IR and XRD. The final structure of precursors was malachite. The Cu surface area of the resulting Cu/ZnO/$Al_2O_3$ was maximized to be 30.6 $m^2$/g at the aging time of 36 h. The further aging rapidly decreased Cu surface areas of Cu/ZnO/$Al_2O_3$. ZnO characteristic peaks in oxide samples almost disappeared after 24 h aging, indicating that ZnO was dispersed in around bulk CuO. TOF of the prepared catalysts of the Cu surface area ranges from 13.0 to 30.6 $m^2/g_{cat}$ was to be 2.67 ${\pm}$ 0.27 mmol/$m^2$.h in methanol synthesis at the condition of $250^{\circ}C$, 50 atm and 12,000 mL/$g_{cat}$. h irrespective of the XRD and TPR patterns of CuO and ZnO structure in CuO/ZnO/$Al_2O_3$. The pH of the precipitate solution during the aging time can be maintained at 7 by $CO_2$ bubbling into the precipitate solution. Then, the decrease of Cu surface area by a long aging time can be prevented and minimize the aging time to get the highest Cu surface area.

• Economic and Environmental Geology
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• v.43 no.3
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• pp.269-278
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• 2010

We investigated characteristics of the coloring material of Dancheong pigments and hope that this study contributes the revival of traditional Dancheong pigments color. For this purpose, we collected Dancheong fragment samples that fell off naturally from old wooden buildings in Gwangju and Jeonnam and analyzed the natural coloring material by XRD and EDS-SEM analysis method. In white pigments of Dancheong fragments, it is confirmed that gypsum$(CaSO_{4}{\cdot}2H_{2}O)$, quartz$(SiO_{2})$, white lead$(PbCO_{3})$ and calcite$(CaCO_{3})$ which have been used for white pigments since ancient times and $TiO_{2}$ which is common used in modern times. In red pigments of Dancheong fragments, it is confirmed that hematite$(Fe_{2}O_{3})$ and red lead$(Pb_{3}O_{4})$, which have been used for red pigments since ancient times and C.I. pigment orange $13(C_{32}H_{24}C_{12}N_{8}O_{2})$ but there is no cinnabar(HgS) which has been used since B.C. 3000 in China. In yellow pigments of Dancheong fragments, it is confirmed that crocoite$(PbCrO_{4})$ and massicot(PbO). In blue pigments of Dancheong fragments, it is confirmed that sodalite$(Na_{4}BeAlSi_{4}O_{12}Cl)$ and nosean $(Na_{8}Al_{6}Si_{6}O_{24}SO_{4})$ as coloring material of blue pigment and C.I. pigments blue $29(Na_{7}Al_{6}Si_{6}O_{24}S_{3})$ which is used in modern times. In green pigments of Dancheong fragments, it is confirmed that calumetite$(Cu(OHCI)_{2}{\cdot}2H_{2}O)$, escolaite(Cr2O3), dichromium trioxide$(Cr_{2}O_{3})$, emerald green$(C_{2}H_{3}As_{3}Cu_{2}O_{8})$, and C.I. pigments green$(C_{32}H_{16}-XCl_{x}Cu_{8})$ which is used in modern time. In black pigments of Dancheong fragments, Chiness ink(carbon black) is confirmed.

• Clean Technology
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• v.24 no.4
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• pp.293-300
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• 2018

Sulfamethoxazole (SMX) is sulfaamide-based synthetic antibiotics, which are widely prescribed pharmaceutical compound to treat bacterial infections in both human and animals. Most of them are not completely decomposed as refractory substances. The environmental impact of pharmaceuticals as emerging contaminants has generated severe concerns. In this study, catalytic wet peroxide oxidation (CWPO) of SMX was carried out with $Cu/Al_2O_3$ catalyst and investigated the optimum reaction conditions of temperature, dosage of catalyst and concentration of $H_2O_2$ to completely decompose the SMX. It was observed that SMX was completely decomposed within 20 min using 0.79 mM $H_2O_2$ and 6 g $Cu/Al_2O_3$ catalyst at 1 atm and $40^{\circ}C$, but SMX was not fully mineralized and converted to intermediates as hydroylated-SMX, sulfanilic acid, 4-aminobenzenesulfinic acid and nitrobenzene. After that these are completely mineralized through organic acid. We proposed the decomposition reaction path ways of SMX by analyzing the behavior of these intermediates. To investigate the durability of heterogeneous catalyst, decomposition of SMX was observed by continuously recycling catalysts. When the heterogeneous catalyst of 10 wt% $Cu/Al_2O_3$ was continuously reused 5 times, decomposition of SMX was a little lowered, but the activity of catalyst was overall very stable.

• 보존과학연구
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• s.34
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• pp.102-108
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• 2013

The purpose of this investigation is to Dancheong documentary project of Tangible cultural in Jeollabukdo. The colored pigments of Nahanjeon Hall in Songkwangsa Temple analyzed and composition and repair period for each pigments were compared. The result are that blue color is Ultramarine blue($Na_6Al_6Si_6O_{24}S_4$), green color is Yangrok($Cu(C_2H_3O_2)_2{\cdot}3Cu(AsO_2)_3$), orange color is Jangdan($Pb_3O_4$), yellow color is Chrome yellow($PbCrO_4$). It is difficult to distinguishable from coloring period by analysis of pigments of Nahanjeon Hall.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.5
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• pp.423-430
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• 2015

$Cu/ZnO/Al_2O_3$ catalysts for water gas shift (WGS) reaction were synthesized by co-precipitation method with the fixed molar ratio of Cu/Zn/Al precursors as 45/45/10. Copper and zinc precursor were added into sodium carbonate solution for precipitation and aged for 24h. During the aging period, aluminum precursor was added into the aging solution with different time gap from the precipitation starting point: 6h, 12h, and 18h. The resulting catalysts were characterized with SEM, XRD, BET surface measurement, $N_2O$ chemisorption, TPR, and $NH_3$-TPD analysis. The catalytic activity tests were carried out at a GHSV of $27,986h^{-1}$ and a temperature range of 200 to $400^{\circ}C$. The catalyst morphology and crystalline structures were not affected by aluminum precursor addition time. The Cu dispersion degree, surface area, and pore diameter depended on the aging time of Cu-Zn precipitate without the presence of $Al_2O_3$ precursor. Also, the interaction between the active substance and $Al_2O_3$ became more stronger as aging duration, with Al precursor presented in the solution, increased. Therefore, it was confirmed that aluminum precursor addition time affected the catalytic characteristics and their catalytic activities.

• Korean Journal of Materials Research
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• v.26 no.3
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• pp.123-129
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• 2016

The morphology, crystal structure and size of aerosol nanoparticles generated by erosion of electrodes made of different materials (titanium, copper and aluminum) in a multi-spark discharge generator were investigated. The aerosol nanoparticle synthesis was carried out in air atmosphere at a capacitor stored energy of 6 J, a repetition rate of discharge of 0.5 Hz and a gas flow velocity of 5.4 m/s. The aerosol nanoparticles were generated in the form of oxides and had various morphologies: agglomerates of primary particles of $TiO_2$ and $Al_2O_3$ or aggregates of primary particles of $Cu_2O$. The average size of the primary nanoparticles ranged between 6.3 and 7.4 nm for the three substances studied. The average size of the agglomerates and aggregates varied in a wide interval from 24.6 nm for $Cu_2O$ to 46.1 nm for $Al_2O_3$.

• Conservation Science in Museum
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• v.24
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• pp.99-116
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• 2020

This study examines the results of analyses of the lead isotope ratio and chemical composition of lead glass and green glaze from ancient Northeast Asia in order to suggest their production sites and reveal further characteristics. The comparison of the lead isotope ratio of lead glass and green glaze from two Baekje remains in Iksan-the Wanggung-ri Site and Mireuksa Temple Site-suggests that they were produced to the west of the South Gyeonggi Massif (Zone 4) using lead extracted from the same area. With a few exceptions, it has proved difficult to identify the production sites of most of the green-glazed roof tiles from Unified Silla-period Buddhist temples across Northeast Asia. The major component of the lead glass from Baekje, Silla, China, and Japan during the seventh century is PbO, SiO₂, Al₂O₃, CuO, and Fe₂O₃, with a ratio of PbO and SiO₂ of 70 and 30 wt.%, respectively. The green-glazed roof tiles excavated from a temple from the Unified Silla period have a high proportion of lead, ranging from 64 to 90 wt.%. Green-glazed lozenge tiles excavated from the Sacheonwangsa Temple site in Gyeongju were shown to contain PbO, SiO₂, Al₂O₃, and CuO, a similar composition with lead glass. An experiment was conducted to reproduce a glaze according to the production method mentioned in the Zō hotokesho sakumotsu-chō (Buddhist statue workshop crop book) in the Shosoin Repository. In this experiment, an identical ratio of PbO was observed for Japanese green-glazed ceramics from the eighth to eleventh century as that found in Chinese lead-glazed ceramics excavated from kilns operated from the seventh to tenth century in Henan. This indicates that production methods for lead glass and glaze were shared across Northeast Asia.

• 보존과학연구
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• s.22
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• pp.93-114
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• 2001

The composition analysis of Danchung pigments at Geunjeongjeon Hall in Gyeongbokgung Palace were carried out by FXRF and MXRD. The analytical result of the inside pigments at Geunjeongjeon showed that these painted in use the mineral pigments. Gold pigment was pure gold(Au).The main composition identified in green pigments were chalcanthite($CuSO_4$.$5H_2O$) and celadonite($K(Mg, Fe, Al)_2$.$(Si, Al)_4O_10(OH)_2$ ). Red pigments werecinnnabar(HgS).The analytical result of the outside pigments at Geunjeongjeon revealed that these applied to the artificial synthetic pigment. Yellow pigment was chromeyellow($PbCrO_4$). The main composition identified in red pigments were red lead($Pb_3O_4$)and hematite($Fe_2O_3$). Green pigments were emeral green($C_2H_3A_s3Cu_2O_8$) and chromegreen($Cr_2O_3$). Blue pigment was lazurite($Na_6Ca2Al_6Si_6O_24(SO_4)_2$), titanium dioxide($TiO_2$) of white pigment.

• Resources Recycling
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• v.24 no.1
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• pp.35-42
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• 2015

To obtain the fundamental information on the dissolution of nickel into the slag in the pyrometallurgical processes for treatment of wasted PCB, the distribution ratios of nickel between CaO-$SiO_2-Al_2O_3$-MgO slag and copper-5 wt%Ni alloy were measured at 1623 K to 1823 K under a controlled $CO_2$-CO atmosphere. The distribution ratio of Ni increased linearly with increasing oxygen partial pressure. Therefore, the dissolution reaction of nickel into the slags could be described by the following equation; $$Ni(l)_{metal}+\frac{1}{2}O_2(g)NiO(l)_{slag}$$ The distribution ratio of Ni increased linearly with increasing content of basic oxides(CaO and MgO) in slag. However, the distribution ratio of Ni decreased linearly with increasing temperature. From these results, the empirical equation of distribution ratio of Ni was obtained by the following equation from the analysis of experimental conditions by multiple regression. $${\log}L_{Ni}=0.4000{\log}P_{O2}-5.1{\times}10^{-4}T+0.3375\(\frac{X_{CaO}+X_{MgO}}{X_{SiO2}}\)$$