• Journal of the Korean Chemical Society
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• v.34 no.2
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• pp.159-164
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• 1990

Absolute configuration of optically active [Co(EDDS)]- (EDDS = ethylenediaminedisuccinate) complex was determined as Λ-form by octant rule and spectroscopic data, and the stereoselective ionic association of Λ-[Co(EDDS)]- and racemic-$[Co(en)^3]_{3+}$ occurs preferrentially between Λ$-[Co(EDDS)]-$ and Δ$-[Co(en)3]3+$. The stereoselective electron-transfer reaction between Λ-[Co(EDDS)]- and racemic-$[Co(en)_3]^{2+}$ has produced 14% e.e (e.e = enantiomeric excess) of Δ$[Co(en)_3]^{3+}$ through the stereoselective ion pairing.

• Journal of Environmental Health Sciences
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• v.34 no.3
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• pp.240-246
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• 2008

The purpose of this study was to gain basic information on the characteristics of $CO_2$ adsorption in relation to $Na_2CO_3$, $K_2CO_3$, $Li_2CO_3$-impregnated activated carbon in a Fixed Bed Reactor. From the results of this study the following conclusions were made: $Na_2CO_3$, $K_2CO_3$, $Li_2CO_3$-impregnated activated carbon had a longer breakthrough time and more enhanced adsorption capacity than activated carbon alone. When tested with isothermal adsorption and tested for $CO_2$ adsorption the amount of $CO_2$ adsorbed varied with temperature, $CO_2$ inlet concentration, gas flow rate, aspect ratio, etc. Based on the results, when Langmuir, Freundlich and Dubinin-Polanyi adsorption isotherms were used for linear regression of isothermal adsorption data, Langmuir adsorption isotherm was the most suitable. And, the optimum condition for $Na_2CO_3$ and $K_2CO_3$ impregnated activated carbon make-up was 1N and $Li_2CO_3$ was 0.1N. It could be concluded that adsorption capacity was decreased with adsorption temperature and increased gas concentration. When the aspect ratio (L/D) was varied 0.5, 1.0 and 2.0, the significant drop of adsorption amount was observed below 1.0 and breakthrough time was shortened with gas flow rate.

• Transactions of the Korean hydrogen and new energy society
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• v.18 no.1
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• pp.32-39
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• 2007

CO oxidation and selective CO oxidation of $La_xCe_{1-x}Co_yCu_{1-y}O_{3-{\alpha}}$ perovskite(x=1, 0.9, 0.7. 0.5; y=1, 0.9, 0.7, 0.5) were investigated. For CO oxidation, catalytic activities were studied according to different preparation conditions such as pH and calcination temperature. The influence of the change of the $O_2$ concentration for selective CO oxidation was studied, too. The substitution of Ce for La improved the catalytic activity for CO oxidation and selective CO oxidation and best activity was observed for $La_{0.7}Ce_{0.3}CoO_3$ prepared at pH 11 and calcined at $600^{\circ}C$. The temperature of 90% CO conversion for CO oxidation using $La_{0.7}Ce_{0.3}CoO_3$ was $230^{\circ}C$. In contrast to the enhancement effect by Ce substitution, the partial substitution of Cu for Co in $LaCo_yCu_{1-y}O_{3-{\alpha}}$ decreased catalytic activities for CO oxidation reaction compared to that using $LaCoO_3$. For selective CO oxidation, the best CO conversion was 66% at $230^{\circ}C$ for $La_{0.7}Ce_{0.3}CoO_3$. The CO conversion of $La_{0.7}Ce_{0.3}CoO_3$ was greatly increased from 66% to 91% as increasing $O_2$ concentration from 1% to 2%.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.5
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• pp.223-227
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• 2009

$BaCO_3$ crystals with various morphology were prepared using precipitation, hydrothermal and ligand-assisted methods. An irregular structure of $BaCO_3$ microparticle was obtained by simple precipitation method from $Ba(NO_3)_2$ and $Na_2CO_3$ in aqueous solution. Hexagonal pyramidals of $BaCO_3$ were synthesized using a hydrothermal method between $Ba(NO_3)_2$ and urea. Hexagonal rods of $BaCO_3$ were also synthesized using the ligand-assisted hydrothermal method. The aspect ratio of $BaCO_3$ hexagonal rods was increased with the concentration of ligand.

• Journal of the Korean Chemical Society
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• v.40 no.7
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• pp.501-508
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• 1996

The base-catalysed carbonato or oxalato ring opening of cis-${\beta}-[Co(3,2,3,-tet))CO_3\;or\;C_2O_4)]^+$(3,2,3-tet=4,7-diazadecane-1,10-diamine, $C_2O_4$=oxalate) has been investigated in aqueous solution and in mixed aqueous-organic solvent. The rearrangement of 3,2,3-tet and carbonato or oxalato ring opening of cis-${\beta}-[Co(3,2,3,-tet))CO_3\;or\;C_2O_4)]^+$ occurred via the dissociation of one of the two coordinating carbonato or oxalato oxygen atoms. The resulting product was cis-${\alpha}-[Co(3,2,3-tet)(OH)(OCO_2\;or\;OC_2O_3)_3].$ It has been suggested that the base-catalysed reaction of cis-${\beta}-[Co(3,2,3,-tet))CO_3\;or\;C_2O_4)]^+$ takes place via the Dcb(dissociative conjugated base) mechanism. The other oxygen atom of carbonato or oxalato was dissociated continuously to give cis-${\alpha}-[Co(3,2,3-tet)(OH)_2]^+.$ Cis-${\alpha}-[Co(3,2,3-tet)(OH)_2]^+$ was isomerized to cis-${\beta}-[Co(3,2,3-tet)(OH)_2]^+.$

• Bulletin of the Korean Chemical Society
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• v.15 no.6
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• pp.436-442
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• 1994

Heterobimetallic complexes have a donor-accepter metal-metal bond in which two electrons from the electron-rich metal moiety are donated to the other electron-deficient one. Based on the competition reactions, Cotton-Kraihanzel force constants, ν(CO)IR band resolution and the relative nucleophilicity comparison of the donor ligands, the following relative ligating ability of the donor ligands toward $M(CO)_5$ (M=Cr, W) is assessed: cis-HW$(CO)_4P(OMe)_3^-$, $HW(CO)_5^-$ > $HCr(CO)_5^-$-$Br^-$ > trans-HFe$(CO)_3P(OMe)_3^-$ > $Mn(CO)_5^-$ > $HFe(CO)_4^-$ > PP$h_3$

• Korean Journal of Crystallography
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• v.9 no.1
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• pp.48-52
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• 1998

The new Nd3Ba5Co4O15 phase was synthesized with Nd2O3, BaCO3, and Co3O4 by solid state reaction at 1200℃ with intermittent grinding. The crystal structure of Nd3Ba5Co4O15 has been refined on X-ray diffraction powder data by means of Rietveld method. The starting model was based on the Nd3.43Ba4.42Co2.23Al1.77O15 structure. The crystal system was hexagonal, space group P63mc(186), a=11.629(3) Å, c=6.842(2) Å. Final R values were Rwp=0.097 and Rp=0.068. The structure consists of clusters of CoVICoIV3O15 in which a CoVI octahedron shares corners with 3CoIV tetrahedra.

• The Journal of Natural Sciences
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• v.4
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• pp.85-93
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• 1991

In solid reaction of the eqimolecular mixture of $BaCO_3$ and $TiO_2$, $CO_2$ generates by the following reaction ; $BaCO_3 + TiO_2\longrightarrow$ $BaTiO_3 + CO_2$ The solid reaction is studied as the kinetics of decomposition reaction with DTA-TG. The results are as follows. 1. $BaCO_3$ with is coexisted with $TiO_2$ decompose at lower temperature than pure $BaCO_3$. The reason is decreasing free eneragy of products. 2. Carter's equation is more important than Jander's equation in solid reaction of $BaCO_3$ decomposi-tion. The activation energy obtained by Carte r's equation is 42.8 Kcal/mol.

• Bulletin of the Korean Chemical Society
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• v.11 no.2
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• pp.109-114
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• 1990

The anionic transition metal hydrides $(HW(CO)_4P(OMe)_3\;^-,\;HW(CO)_5\;^-,\;HCr(CO)_5\;^-,\;HFe(CO)_4\;^-)$ react with transition metal alkyl $(CpMo(CO)_3(CH_3)$ to yield $CH_4\;and\;CH_3CHO$ in addition to the inorganic products $(CpMo(Co)_3\;^-$, etc.). The reaction of these anionic metal hydrides with CpMo(CO)3{CH2CH(CH2)2} may lead to an elucidation of the reaction mechanisms involved; the organic product distributions are among $CH_4,\;CH_2\;=\;CHCH_2CH_3$, and $CH_3CH(CH_2)_2$, depending upon the anionic metal hydride used. These anionic metal hydrides also are reported to undergo a hydride-halide exchange reaction with organic halides; therefore, these similar reactions have been compared in terms of leaving group ability $(CpMo(CO)_3\;^-\;vs.\;Br^-)$ and the mechanistic pathways.

• Applied Chemistry for Engineering
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• v.17 no.3
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• pp.250-254
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• 2006

Reaction of $CO_2$ with $Li_{2}ZrO_{3}$ has been investigated in a TGA and the effects of $H_{2}$ and CO on the removal of $CO_{2}$ using $Li_{2}ZrO_{3}$ were evaluated in a packed bed reactor. The initial rate of $CO_{2}$ removal reaction of $Li_{2}ZrO_{3}$ increased with the increase of gas flow rate up to 100 mL/min and then was maintained, which implied the disappearance of the gas film resistance. The reaction of $CO_{2}$ with $Li_{2}ZrO_{3}$ took place as the first order and the range of optimum temperature was found to be about $500{\sim}600^{\circ}C$. XRD and SEM analysis showed the formation of crystalline $Li_{2}ZrO_{3}$ and porous $Li_{2}ZrO_{3}$/$ZrO_{2}$. The presence of $H_{2}$ did not affect the adsorption of $CO_2$ with $Li_2ZrO_3$. On the other hand, CO inhibited the sorption of $CO_{2}$ into $Li_{2}CO_{3}$(L) on $Li_{2}ZrO_{3}$.