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연세대학교 화학공학과 이 태 규

Comparison of Mercury Removal Efficiency from a Simulated Exhaust Gas by Several Types of TiO 2 under Various Light Sources. 연세대학교 화학공학과 이 태 규. 제 4 회 광촉매 연구회 2004 년 2 월 26 일. Introduction. Mercury. Toxic properties High volatility Tendency to bio-accumulate. Emission resources.

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연세대학교 화학공학과 이 태 규

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  1. Comparison of Mercury Removal Efficiency from a Simulated Exhaust Gas by Several Types of TiO2 under Various Light Sources 연세대학교 화학공학과 이 태 규 제4회 광촉매 연구회 2004년 2월 26일

  2. Introduction Mercury • Toxic properties • High volatility • Tendency to bio-accumulate Emission resources • 80% of the total emission from the combustors (Coal Combustors, Waste Incinerators, etc.)

  3. Introduction Hg Emissions Control Methods • Oxidized mercury can be captured relatively easily because of its high solubility in weak acidic solution • Elemental mercury is difficult to capture • Unusual non-reactivity compared to other metals • 5d106s2 closed shell electronic structure for Hg atom • extremely slow or no oxidation at high temperatures • possible oxidation by strong oxidants (NO2, Cl2)

  4. Photocatalyst TiO2  high removal efficiency for low concentrations of toxic compounds Hg removal under UV light Introduction Hg removal by adsorbents Activated Carbon => most widely used disadvantage • Low applicable temperature range • Low regeneration rate & slow adsorption rate

  5. Introduction UV light • high energy strength • harmful • development of improved photocatalysts activating • under the visible light!!! Intermediate step Hg removal using a TiO2 under thefluorescent light

  6. Theory Hg capture by TiO2 Light Hg TiO2 HgO O 2 - O 2 - e H O 2 OH • + Hg HgO + + H TiO2(s) + light → TiO2·OH + Hg(g) → TiO2·HgO(complex)

  7. Experimental Apparatus

  8. Light Sources TiO2 Powder • UV black light • UV sterilizing light • fluorescent light • blue light • pure anatase (Ishihara co.) • P25 (Degussa co.) • anatase : rutile = 80 : 20 • pure rutile (Junsei co.) Experimental

  9. UV-C UV-B UV-A Visible Light Infrared Ray Experimental Wave length

  10. Results [a] UV black light

  11. Results [b] UV sterilizing light

  12. Results [c] fluorescent light

  13. Results [d] blue light

  14. Results Breakthrough Experiment

  15. Results XRD pattern of (TiO2-Hg) Complex

  16. The removal efficiency was close to 100% under most light sources tested. More than 99% of initial Hg was removed under all the light sources tested except for the blue light still achieving a Hg removal efficiency close to 80%. High efficiency was achieved even under the low concentration. Easily maintainable and cost-effective fluorescent light can be used. Conclusion

  17. Future Works • Verification of Hg adsorption mechanism under the visible light • Verification of Hg removal efficiency with crystallinity, surface area, and particle size • Hg removal by TiO2 directly coated on beads • Application of TiO2 coated ferro-powder to water treatment Hg removal by sunlight

  18. Structural Effect of In Situ Generated TiO2 on Hg0 Removal in a Simulated Combustion Flue Gas • Furnace 온도가 증가함에 따라 크기가 커지지만 open structure를 가진 입자를 생성 •입자의 크기가 증가할수록 수은의 제거효율 증가 • NH3를 이용하여 TiOx-Ny를 제조, 가시광선에의 반응성 측정 및 촉매 특성 분석

  19. Structural Effect of In Situ Generated TiO2 on Hg0 Removal in a Simulated Combustion Flue Gas

  20. Structural Effect of In Situ Generated TiO2 on Hg0 Removal in a Simulated Combustion Flue Gas Ti(OC3H7)4 + 18O2 → TiO2+12CO2 +14H2O

  21. Structural Effect of In Situ Generated TiO2 on Hg0 Removal in a Simulated Combustion Flue Gas

  22. Preparation of Column Shape TiO2 Fiber by a Diffusion Flame Reactor • Height above burner (HAB)에 따른 • particle shape / crystallinity ; fibrous / anatase • Raman Spectroscopy

  23. Apparatus

  24. SEM I <Figure 1. Pure TTIP, HAB=3cm> <Figure 2. Pure TTIP, HAB=5cm>

  25. SEM II <Figure 3. Pure TTIP, HAB=7.5cm> <Figure 4. Pure TTIP, HAB=10cm>

  26. The End

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