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ELEC 7730 02’

Application of Nonthermal Plasma to Chemical Reactions Abstract authors: S. Futamura, H. Kabashima, and H. Einaga National Institute of Advances Science and Technology Presented by Yu-Chun Chen November 11, 2002. ELEC 7730 02’. Introduction.

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ELEC 7730 02’

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  1. Application of Nonthermal Plasma to Chemical Reactions Abstract authors: S. Futamura, H. Kabashima, and H. Einaga National Institute of Advances Science and Technology Presented by Yu-Chun Chen November 11, 2002 ELEC 7730 02’

  2. Introduction • Applicability of non-thermal plasma (NTP) to chemical reactions: 1. Removal of hazardous air pollutants (HAPs) 2. Hydrogen production from small molecules 3. Hydrocarbon reformimg ELEC 7730 02'

  3. Outline • From the authors • NTP • FPR • SDR • Results • Conclusions ELEC 7730 02'

  4. From The Authors • Plasma-generating methods greatly affect average • electron temperature and distribution of active • species formed in NTP. • Hybridization of NTP with catalyst/ photocatalyst • is mandatory to increase the energy efficiency of • the reaction system. • This paper: Comparison of reactor effect between • FPR and SDR of conversions of trichloroethylene • (TCE) and CH3Br , and H2 production from H2O • and CH4 (both in N2) ELEC 7730 02'

  5. NTP • NTP has been investigated in control of 1. Volatile organic compounds (VOCs) 2. Nitrogen oxides (NOx) 3. Hydrogen production 4. Syntheses of methanol, synthesis gas • Merit: Gas temperature kept at ambient temperature in spite of large magnitudes of electron energies ELEC 7730 02'

  6. NTP • Even without gaseous oxygen, many of VOCs can be easily decomposed. • Amount of active oxygen species in NTP are not necessarily large, depending on the plasma-generating method. • Reason: The short lifetime of the high-energy electron and the partial decomposition of active oxygen species caused by local temperature inside NTP. ELEC 7730 02'

  7. FPR (1)(Ferroelectric Packed-bed Reactor) Ref.: S. Futamura, H. Einaga, and A. Zhang, “Behavior of N2 and nitrogen oxides in non-thermal plasma chemical processing of hazardous air pollutants ”, IEEE transactions on industry applications, Vol. 36, No. 6, November/December 2000. ELEC 7730 02'

  8. FPR (2) • Ferroelectric pellet packed-bed reactor • Operated with a relatively small volume fraction of plasma that could catalytically activated by free radicals or UV irradiation from the plasma • Employed an AC power supply in conjunction with a ferroelectric pellet layer • Coaxial reactor: the inner cylindrical electrode: 16.6 mm the outer electrode: 47.3 mm resulting in a gap distance of 15.4 mm ELEC 7730 02'

  9. FPR (3) • The BaTiO3 pellets (=5000 at room temperature): 1. 1mm in diameter 2. packed between two electrodes with a high ac voltage applied in the radial direction 3. held by a notched perforated Teflon plate at both ends • Effective reactor length: 127 mm • The gas: passed through the entry tube (6.4mm in diameter) and dispersed into the plasma zone • Gas flow rate: 0.25 to 0.5 L/min (nitrogen) ELEC 7730 02'

  10. FPR (4) • When an external ac voltage was applied across the high dielectric layer in a radial direction, the pellets were polarized, and an intense electric field was formed around each pellet contact point, resulting in partial discharge. • Maximum applied voltage: 50-Hz ac at up to 8-kV rms. ELEC 7730 02'

  11. SDR (1)(Silent Discharge Plasma Reactor) AC power supply Al foil Cu-coated stainless steel electrode Gas out Gas in Ref.: S. Futamura, H. Einaga, and A. Zhang, “Comparsion of reactor performance in the non-thermal plasma chemical processing of hazardous air pollutants”, IEEE transacitons on industry applications, Vol. 37, No. 4, August 2001. ELEC 7730 02'

  12. SDR (2) • Reactor: a tubular type consisting of a stainless steel rod coated with copper (OD 8.6mm) and an encircling glass tube (ID 10.6mm ), which was wrapped with Al foil (100 mm wide) • The effective reaction length: 100 mm • Gas flow rate: 0.1 to 0.25 L/min • Maximum applied voltage: 10 kV ELEC 7730 02'

  13. Result (1) Reactor effect on the conversions of TCE and CH3Br in N2 Ref.: S. Futamura, H. Kabashima, and H. Einaga, “Application of non-thermal plasma to chemical reactions ”, IEEE transactions on industry applications, 202nd meeting of the electron-chemical society, Oct. 20-24, 2002. ELEC 7730 02'

  14. Result (2) Reactor effect on H2 production from H2O and CH4 in N2 Ref.: S. Futamura, H. Kabashima, and H. Einaga, “Application of non-thermal plasma to chemical reactions ”, IEEE transactions on industry applications, 202nd meeting of the electron-chemical society, Oct. 20-24, 2002. ELEC 7730 02'

  15. Conclusion • From result (1): FPR and SDR are comparable with each other for the decomposition of halogenated VOCs. • From result (2): FPR and SDR are quite different for hydrogen production from water. • Use of a pertinent reactor is important for a specific purpose. ELEC 7730 02'

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