• Title, Summary, Keyword: Three-phase Slurry

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Synthesis of High Purity p-Phenylenediamine from p-Nitroaniline by Catalytic Hydrogenation (Pd/C촉매하 파라니트로아닐린 수소첨가에 의한 고순도 파라페닐렌디아민의 합성공정)

  • Cho, Chul Kun;Chung, Kwang Bo
    • Applied Chemistry for Engineering
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    • v.10 no.8
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    • pp.1210-1215
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    • 1999
  • Optimum conditions of the hydrogenation of PNA to pure PPD were determined in a three-phase slurry reactor with suspended Pd/C catalyst particles. Minimization of mass transfer resistances at the interfaces of both gas-liquid and liquid-catalyst particles and control of overall reaction rate on catalyst surface leaded to decrease the hydrogen starvation on reaction active sites and to reduce the side reactions during hydrogenation. The optimum temperature, pressure, and catalysst concentration were confirmed to be in the range of $60^{\circ}C$, 60~70 psig, and 1~2 g-cat/L, respectively. Reaction rate was zero order with respect to the concentration of PNA and 1st order with respect to the pressure of hydrogen(P). Overall rate expression of the reaction was $R_A=6.44{\times}10^6{\cdot}H{\cdot}P{\cdot}m{\cdot}$exp(-4659/T) where H is constant, m is concentration of catalyst, and T is temperature.

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Transformation of Endocrine Disrupting Chemicals (EDCs) by Manganese(IV) Oxide (망간산화물을 이용한 내분비계장애물질의 변환에 관한 연구)

  • Lee, Seung-Hwan;Choi, Yong-Ju;Chung, Jae-Shik;Nam, Taek-Woo;Kim, Young-Jin;Nam, Kyoung-Phile
    • Journal of Soil and Groundwater Environment
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    • v.14 no.1
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    • pp.44-50
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    • 2009
  • The occurrence of endocrine disrupting compounds (EDCs), chemicals that interfere with human hormone system, are increasing in the freshwater, waste water and subsurface as well. In this study, we determined the reactivity of three EDCs in the presence of birnessite. In aqueous phase, bisphenol A, 2,4-dichlorophenol and 17${\beta}$-estradiol, which possesses phenoxy-OH, were very rapidly transformed by birnessite: up to 99% of initial concentrations (50 mg/L for bisphenol A, 100mg/L for 2,4-dichlorophenol, and 1.5mg/L for 17${\beta}$-estradiol) were destroyed within 60 minutes. Especially, bisphenol A was the most reactive chemical, disappearing by 99% in a few minutes. The reaction occurred on the surface of birnessite, showing a linear increase of first-order kinetic constants with the increase of the surface area of birnessite. In soil slurry phase, the reactivity of birnessiteto EDCs was faster than in aqueous phase probably due to the cross coupling reaction of phenoxy radicals with soil organic matter. Considering the rapid transformation of the EDCs in the both phases, this oxidative cross coupling reaction mediated by birnessite would be an effective solution for the remediation of EDCs in environmental media, especially in soil.

Cathodic Polarization of $La_{0.5}Sr_{0.5}MnO_{3-\delta}$ on $Ce_{0.8}Gd_{0.2}O_{1.9}$ Electrolyte ($Ce_{0.8}Gd_{0.2}O_{1.9}$ 전해질에서 $La_{0.5}Sr_{0.5}MnO_{3-\delta}$ 양극의 과전압특성)

  • 윤희성;노의범;김병호
    • Journal of the Korean Ceramic Society
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    • v.35 no.9
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    • pp.981-987
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    • 1998
  • $La_{0.5}Sr_{0.5}MnO_{3-\delta}$ as air electrode for soild oxide fuel cell was synthesized by a citrate process and its cathodic polarization was determinated by the current interruption method on the Gd-doped ceria as electrolyte. The addition of citric acid increased the exothermic heat for the formation of $La_{0.5}Sr_{0.5}MnO_{3-\delta}$ perovskite oxide. The degree of the initial particle agglomeration was affected by the exothermic heat. Also the increase of cal-cination temperature enlarged the particle size and the higher sintering temperature accelerated the den-sification of $La_{0.5}Sr_{0.5}MnO_{3-\delta}$ layer after its being painted on $Ce_{0.8}Gd_{0.2}O_{1.9}$ electrolyte. In this study $La_{0.5}Sr_{0.5}MnO_{3-\delta}$ synthesized by citrate process of which the molar ratio of citric acid to metal nitrate was 2 calcined at $650^{\circ}C$ for 2hr and sintered at 1100 at $1200^{\circ}C$ for 4 hrs after slurry coating on Ce0.8Gd0.2O1.9 electrlyte showed the lowest cathodic polarization.

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