• Title/Summary/Keyword: Oxidation/Reduction

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Characteristics of Mercury Oxidation by an SCR Catalyst with Gas Composition (가스조성에 따른 선택적 환원촉매의 수은 산화 특성)

  • Lee, Sang-Sup;Kim, Kwang-Yul;Oh, Kwang-Joong;Jeon, Jun-Min;Kim, Do-Jeung;Kim, Ju-Yeong
    • Particle and aerosol research
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    • v.8 no.4
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    • pp.125-132
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    • 2012

  • Mercury oxidation in an SCR(selective catalytic reduction) catalyst was tested in this study with the conditions simulating the SCR system in full-scale coal-fired flue gas. A commercially available SCR catalyst was located in a temperature-controlled reactor system, and simulated gas was injected into the reactor. Mercury oxidation efficiency was determined from the difference between inlet and outlet elemental mercury concentrations. A control experiment was carried out with the gas composition of 12% $CO_{2}$, 5% $H_{2}O$, 5% $O_{2}$, 500 ppm $SO_{2}$, 400 ppm NO, 400 ppm $NH_{3}$, 5 ppm HCl, and 20 ${\mu}g/m^{3}$ Hg. Additional tests were conducted with different gas composition from the control condition to investigate the effect of gas composition on mercury oxidation in the SCR catalyst.

  • https://doi.org/10.11629/jpaar.2012.8.4.125 인용 KSCI

Oxidation Behavior of Oxide Particle Spray-deposited Mo-Si-B Alloys

  • Park, J.S.;Kim, J.M.;Kim, H.Y.;Perepezko, J.H.
    • Journal of the Korean Society for Heat Treatment
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    • v.20 no.6
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    • pp.299-305
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    • 2007

  • The effect of spray deposition of oxide particles on oxidation behaviors of as-cast Mo-14.2Si-9.6B (at%) alloys at $1200^{\circ}C$ up to for 100 hrs has been investigated. Various oxide powders are utilized to make coatings by spray deposition, including $SiO_2,\;TiO_2,\;ZrO_2,\;HfO_2$ and $La_2O_3$. It is demonstrated that the oxidation resistance of the cast Mo-Si-B alloy can be significantly improved by coating with those oxide particles. The growth of the oxide layer is reduced for the oxide particle coated Mo-Si-B alloy. Especially, for the alloy with $ZrO_2$ coating, the thickness of oxide layer becomes only one fifth of that of uncoated alloys when exposed to in air for 100 hrs. The reduction of oxide scale growth of the cast Mo-Si-B alloy due to oxide particle coatings are discussed in terms of the change of viscosity of glassy oxide phases that form during oxidation at high temperature.

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The Development of a Biofilter to Reduce Atmospheric Methane Emissions from MSW Landfills

  • Park, Soyoung;K.W. Brown;J.C. Thomas
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2002.04a
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    • pp.73-76
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    • 2002

  • Biofilter performance to reduce C $H_4$ emissions from MSW landfills was tested under a variety of environmental and design conditions. The optimum soil moisture content for C $H_4$ oxidation in a loamy sand was 13% by weight. The addition of N $O_3$-N did not affect the C $H_4$ oxidation rate. Soil depths of 30cm and 60cm were equally efficient in C $H_4$ oxidation. When the C $H_4$ loading rate was decreased, the percentage of C $H_4$ oxidized increased. The maximum C $H_4$ oxidation rate was 27.2 mol $m^{-2}$ $d^{-1}$ under optimum conditions (loamy sand soil, 13% moisture content, 30cm soil depth, and an loading rate of 32.8 mol $m^{-2}$ $d^{-1}$). Based on the above results, the installation of a properly sized and managed biofilter above a landfill cover should be capable of achieving a major reduction in atmospheric methane emissions from MSW landfills built with RCRA covers.

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Decomposition of PVC and Ion exchange resin in supercritical water

  • Lee, Sang-Hwan;Yasuyo, Hosgujawa;Kim, Jung-Sung;Park, Yoon-Yul;Hiroshi, Tomiyasu
    • Proceedings of the Korean Environmental Sciences Society Conference
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    • 2005.05a
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    • pp.267-271
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    • 2005

  • This experiment was carried out at 450"C, which is relatively lower than the temperature for supercritical water oxidation (600-650$^{\circ}C$). In this experiment, the decomposition rates of various incombustible organic substances were very high. In addition, it was confirmed that hetero atoms existed in organic compounds and chlorine was neutralized by sodium(salt formation).However, to raise the decomposition rate, relatively large amount of sodium nitrate(3-4 times the equivalent weight) was required. When complete oxidation is intended as in the case with PCB, the amount of oxidizer and decomposition cost is important. But when vaporization reduction is required as in the case with nuclear wastes, the amount of radioactive wastes increases instead. But as can be seen in the result of XRD measurement, unreacted sodium nitrate remained unchanged. If oxidation reaction of organic substance simply depends on collision frequency, unreacted sodium nitrate can be recovered and reused, then oxidation equivalent weight would be sufficient. In the gas generated, toxic gas was not found. As the supercritical water medium has high reactivity, it is difficult to generate relatively low energy level SO$_{X}$, and NO$_{X}$.

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