Principles of plasma based VOC reduction

Transcription

1 Principles of plasma based VOC reduction R. Brandenburg 1, D. Cameron 2, A. Haljaste 3, T. Hoder 1, M. Hołub 4, T. Ivanova 2, I. Jõgi 3, M.-L. Kääriäinen 2, and M. Schmidt 1 1 INP Greifswald (Germany) 2 Lappeenranta University of Technology (Finland) 3 University of Tartu (Estonia) 4 West Pomeranian University of Technology, Szczecin (Poland)

2 Content European Environment Agency Introduction Plasmas for VOC-removal Chances and prospects of plasma based VOC-removal / Examples Advantage of plasma based exhaust treatment Plasma enhanced catalysis Plasma assisted adsorption Plasma assisted scrubbing Outlook Open questions and future prospects PlasTEP+ WS Poznan

3 Introduction Gas discharges for gas treatment Gas flows through an electrode structure utilizing a gas discharges with a non-thermal plasma Discharge types (cross sectional views): - Barrier discharges (a) - Corona discharges (b) - Packed bed reactors (c) Plasma enables chemical conversion in the treated gas Plasma Chemistry (a) (b) (c) PlasTEP+ WS Poznan 2

4 Introduction VOC removal in air (a) Free electrons generate radicals (collisions) (O, OH, OH 2 ) and O 3 Oxidative reactions resulting in CO 2 and H 2 O and other by-products Efficacy and selectivity depend on gas composition, pollutant and its concentration, temperature, specific energy etc. Plasma as oxidation stages in combination with other processes like adsorption, catalysis, scrubbing, (b) (c) PlasTEP+ WS Poznan 3

5 Introduction Dielectric Barrier Discharge Stack Reactor (PlasTEP) Electrode Isolator plate S. Müller, R.-J. Zahn; Contributions to Plasma Physics 47 (2007) PlasTEP+ WS Poznan 4

6 Chances and prospects of plasma based VOC-removal / Examples Advantage of plasma based exhaust treatment Chemical conversion without increase of gas temperature Effects an gas particles and particulate matter (aerosols) Effects in gas phase and on surfaces Controllable by electrical operation parameters Regardless of how strictly we define environmental plasma, the history and future potential of this technology are quite remarkable. Alexander Gutsol In: The 2012 Plasma Roadmap J. Phys. D: Appl. Phys. 45 (2012) (37 pp) PlasTEP+ WS Poznan 5

7 Chances and prospects of plasma based VOC-removal / Examples State-of-the-art: plasma deodorization H.H. Kim et al. International Journal of Plasma Environmental Science & Technology Vol.1, 2007 PlasTEP+ WS Poznan 6

8 Plasma Science Filamentary Plasma (e.g. DBD) Engineering Assignement of Tasks Type and Level of Contamination Gas Composition and Temperature Electrical Breakdown (Microdischarge) Instateneous Parameters Ions Plasma Parameters Radicals Efficacy Chemical reactions Upscaling Selectivity Plasma-Enhanced Processes Catalysis, Adsorption, Scrubbing, By-Products Synergies Electrical Characterization Cost and Technical Benefit PlasTEP+ WS Poznan 7

9 Chances and prospects of plasma based VOC-removal / Examples Implementation of catalyst (ASTRaL) Activity of TiO 2 catalysts, pure porous filters and plasma during (2500 ppm of toluene at 336 J/L) 1000 ALD layers of TiO 2 catalyst on glass filters deposited on mesh electrodes (Atomic Layer Deposition) Amount of removed toluene depends on applied catalyst and porosity of glass filters Improved selectivity of CO X by catalyst application PlasTEP+ WS Poznan 8

10 Chances and prospects of plasma based VOC-removal / Examples Synergy between plasma and adsorber (I) Surface Barrier Discharge Undersized Active Carbon Sample Model VOC Ethanol C 2 H 5 OH CO 2 + H 2 O + C 2 H 4 O PlasTEP+ WS Poznan 9

11 Chances and prospects of plasma based VOC-removal / Examples Plasma supported adsorption Cont. air Plasma stage Adsorber sample Gasphase Oxidation (Removal) Physisorption (Filtering) Adsorptive Adsorbate 10 Adsorbent Reduction of resorbed ethanols with plasma treatment before active carbon = reduction of the absorptive & oxidation of adsorbate Removal of pollutant & Regeneration of adsorbent PlasTEP+ WS Poznan 10

12 Chances and prospects of plasma based VOC-removal / Examples Falling water reactor Water flows up through vertical hollow cylindrical electrode (inner electrode of a concentric barrier discharge) and flows down making thin water film over inner electrode treatment of water (dye removal) demonstrated Gas inlet Water film Glass vessel High voltage electrode Power supply treatment of gas phase? Filamentary plasma Gas outlet Grounded tube electrode V. Kovacevic, M. Kuraica et al.; Belgrade University Water resevoir Peristaltic pump PlasTEP+ WS Poznan 11

13 Chances and prospects of plasma based VOC-removal / Examples Plasma assisted scrubbing C 11 H 26 reduced by plasma more effective without water film by-product: Formic acid HCOOH C 11 H 26 non-soluble in water HCOOH soluble in water With water w/o water PlasTEP+ WS Poznan 12

14 Outlook Plasma used mainly for deodorization issues Role of oxidation stage synergy with adsorption, catalysis and scrubbing Plasmas offer compact systems with a direct (instantaneous) control via electrical operation parameters Potential to expanded use of plasmas To understand more the physical and chemical processes of combined action, e.g., - quantitative description of plasma-supported adsorption - interplay discharge physics, surface processes and plasma chemistry To explore other fields of application of plasma chemistry PlasTEP+ WS Poznan 13