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        검색결과 25

        21.
        2013.08 KCI 등재 서비스 종료(열람 제한)
        Alumina-supported catalysts containing different transition metals such as Cu, Cr, Mn, Zn, Co, W were investigated for their activity in the selective oxidation of toluene. Catalytic oxidation of toluene was investigated at atmospheric pressure in a fixed bed flow reactor system over transition metals with Al2O3 catalyst. The result showed the order of catalytic activities for the complete oxidation of toluene was Mn > Cu> Cr> Co> W> Zn for 5wt.% transition metals/Al2O3. Mn/Al2O3 catalysts containing different amount of Mn were characterized by X-ray diffraction spectroscopy for decision of loading amount of metal to alumina. 5 wt.%Mn/Al2O3 catalyst exhibits the highest catalytic activity, over which the toluene conversion was up to 90% at a temperature of 289℃.
        22.
        2012.07 KCI 등재 서비스 종료(열람 제한)
        The purpose of this study is to synthesize transition metal doped mesoporous silica catalyst and to characterize its surface in an attempt to decomposition of N2O. Transition metal used to surface modification were Ru, Pd, Cu and Fe concentration was adjusted to 0.05 M. The prepared mesoporous silica catalysts were characterized by X-ray diffraction, BET surface area, BJH pore size, Scanning Electron Microscopy and X-ray fluorescence. The results of XRD for mesoporous silica catalysts showed typical the hexagonal pore system. BET results showed the mesoporous silica catalysts to have a surface area of 537 ∼973 m2/g and pore size of 2∼4 nm. The well-dispersed particle of mesoporous silica catalysts were observed by SEM, the presence and quantity of transition metal loading to mesoporous surface were detected by XRF. The N2O decomposition efficiency on mesoporous silica catalysts were as follow: Ru>Pd>Cu>Fe. The results suggest that transition metal doped mesoporous silica is effective catalyst for decomposition of N2O.
        23.
        2009.07 KCI 등재 서비스 종료(열람 제한)
        Hydrochloric acid salt of a new N2O3 pentadentate ligand, N,N'-Bis(2-Hydroxybenzyl)-1,3-diamino-2-propanol(H-BHDP․2HCl) was synthesized. Br-BHDP․2HCl, Cl-BHDP․2HCl, CH3-BHDP․2HCl and CH3O- BHDP․2HCl having Br, Cl, CH3 and CH3O substituents at 5-position of the phenol group of H-BHDP․2HCl were also synthesized. The potentiometry study in aqueous solution revealed that the proton dissociations of the synthesized ligands occurred in four steps and their order of the calculated overall proton dissociation constants(logβp) was Br-BHDP〈 Cl-BHDP〈 H-BHDP〈 CH3O-BHDP〈 CH3-BHDP. The order showed a similar trend to that of Hammett substituent constants(δp). The order of the stability constants(logKML) was Co(Ⅱ)〈 Ni(Ⅱ)〈 Cu(Ⅱ)〈 Zn(Ⅱ)〈 Cd(Ⅱ)〈 Pb(Ⅱ). The order in their stability constants (logKML) of each transition metal complex agreed with that of the overall proton dissociation constants (logβp).
        24.
        2006.08 KCI 등재 서비스 종료(열람 제한)
        Hydrobromic acid salts of new N, N, O tridentate ligands containing phenol, 2-[(2-Methylamino- ethylamino)-methyl]-phenol(H-MMP․2HBr), 5-Bromo-2-[(2-Methylamino-ethylamino)-methyl]-phenol (Br- MMP․2HBr), 5-Chloro-2-[(2-Methylamino-ethylamino)-methyl]-phenol(Cl-MMP․2HBr), 5-Methyl-2-[(2-Methylamino- ethylamino)-methyl]-phenol(Me-MMP․2HBr), 5-Methoxy-2-[(2-Methylamino-ethylamino)- methyl]-phenol(MeO- MMP․2HBr) and 1-[(2-Methylamino-ethylamino)- methyl]-naphthalen-2-ol(Nap- MMP․2HBr) were synthesized. The synthesized ligands were confirmed by C. H. N. atomic analysis, UV-visible and IR spectroscopies, 1H NMR, 13C NMR and mass analysis. The potentiometry study revealed that the proton dissociation constants(logKnH) of the synthesized ligands and stability constants (logKML, logKML2) of transition metal complexes of Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II) ions occurred in three steps and the order of the calculated overall proton dissociation constants(logβp) and stability constants (logKML) of ligands was Br-MMP․2HBr < Cl-MMP․2HBr < H-MMP․2HBr < Nap-MMP․2HBr < Me-MMP․2HBr < MeO-MMP․2HBr. The order showed a similar trend to that of Hammett substituent constants(δp). The synthesized ligands usually form 2:1(ML2) complexes with transition metal ions. The order of the stability constants of each transition metal ions was Co(II) < Ni(II) < Cu(II) > Zn(II) > Cd(II) > Pb(II).
        25.
        2004.09 KCI 등재 서비스 종료(열람 제한)
        N,N-bis(2-salicylaldehyde)dipropylenetriamine(5-Hsaldipn), N,N-bis(5-bromosalicyl-aldehyde) dipropylenetriamine (5-Brsaldipn), N,N-bis(5-chlorosalicylaldehyde)dipropylene-triamine(5-Clsaldipn), N,N-bis(2-hydroxy-5-methoxybenzaldehyde)dipropylenetriamine(5-OCH3saldipn) and N,N-bis (2-hydroxy-5-nitrobenzaldehyde)dipropylenetriamine (5-NO2saldipn) were synthesized and characterized by elemental analysis, infrared spectrometry, NMR spectrometry and mass spectrometry. Their proton dissociation constants were determined in 70% dioxane/30% water solution by potentiometric. Stability constants of the complexes between these ligands and the metal ions such as Cu(Ⅱ), Ni(Ⅱ) and Zn(Ⅱ) were measured in dimethyl sulfoxide by a polarographic method. Stability constants for the ligands were in the order of 5-OCH3 > 5-H > 5-Br > 5-Cl > 5-NO2saldipn. Enthalpy and entropy changes were obtained in negative values.
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