Effect of Oxygen Content on Effect of Oxygen Content on Toluene Decomposition in Toluene Decomposition in

Wire-Plate Dielectric Barrier Wire-Plate Dielectric Barrier Discharge ReactorDischarge Reactor

Guo YufangGuo YufangPh.D candidatePh.D candidate

South China University of TSouth China University of Technologyechnology

IntroductionIntroduction

1. Emission of various volatile organic compounds (VOCs) pollutes the air seriously.

Dielectric barrier discharges (DBDs) processing has been considered as one

of the most hopeful methods to remove VOCs.

2.In this study, an optimal oxygen content was tested for the removal of toluene from gas streams.Operational parameters:Operational parameters: applied voltage applied voltage gas flow rate gas flow rate gas concentration gas concentration with/without catalyst with/without catalyst

Experimental apparatusExperimental apparatus A Dielectric barrier discharge （ DBD)

reactor :wire-plate

Figure 1. Simplified structure of the wire-plate DBD reactorFigure 1. Simplified structure of the wire-plate DBD reactor

Experimental setup Experimental setup

Figure 2.Schematics of the experimental setupFigure 2.Schematics of the experimental setup

ResultsResults 1.The effect of oxygen concentration in the background ga1.The effect of oxygen concentration in the background ga

ss

Figure 3. Dependences of toluene removal Figure 4. Dependences of input power

efficiency on oxygen content on oxygen content

(Q=500ml/min, 200ppm toluene)

0 2 4 6 8 10 120

5

10

15

20

25

30

35

40

45

50

Rem

oval

Effi

cien

cy(%

)

Applied Voltage(kV)

0 5% 10% 15% 20%

2. The Effect of Gas Flow Rates 2. The Effect of Gas Flow Rates

Figure 5. Dependences of toluene removal Figure 6. Dependences of ozone concentration

efficiency on gas flow rates on gas flow rates

([O2]=5%, 1300ppm toluene)

3. 3. The Effect of Initial Concentration of Toluene inThe Effect of Initial Concentration of Toluene in Background Gas Background Gas

Figure 7a. Dependences of toluene removal efficiency on gas concentration ([O2]=5%, Q=500ml/min)

0 2 4 6 8 10 120

10

20

30

40

50

Rem

oval

Effi

cien

cy(%

)

Applied Voltage(kV)

200ppm 600ppm

Figure 7b. Dependences of toluene removal efficiency on gas concentration ([O2]=10%, Q=500ml/min)

0 2 4 6 8 10 120

10

20

30

40

Rem

ova

l Effic

iency

(%)

Applied Voltage(kV)

200ppm 600ppm

Figure 7c. Dependences of toluene removal efficiency on gas concentration ([O2]=15%, Q=500ml/min)

Figure 8. Dependences of ozone concentration on gas concentration ([O2]=5%, Q=500ml/min)

4. 4. The EffectThe Effect of Catalystof Catalyst

Figure 9. Removal efficiency of toluene by Figure 10. Ozone concentration with/without

the plasma process with/without the catalyst the catalyst

(Q=500ml/min, [O2]=5%, 200ppm toluene)

5. byproducts5. byproducts

CHCH44, C, C

77HH1616 and C and C77HH1212 (no oxygen) (no oxygen)

benzene ,Cbenzene ,C44HH44OO33 ([O ([O

22]=5%)]=5%)

DiscussionDiscussion Oxygen plays a very important role in the reaction.

e + O2 ＝ O + O(1D) (1)

O+ O2 = O3 (2) H·+ O = OH· (3) A higher O2 content leads to the generation of more highly reactive O ra

dicals , resulting in a higher removal efficiency. However, O2 has an adverse effect on toluene removal due to its electrone

gativity. So when the oxygen content is 10%, the removal efficiency is highest.

Ozone as the main long-living radical is transported to the catalyst and can take part in heterogeneous oxidation reactions on its surface.

This paper indicated a wire-plate dielectric barrier discharge reactor with catalyst in-situ. It confirmed that dielectric barrier discharge can promote the activation of the catalyst and restrain the formation of ozone to the utmost extent.

SummarySummary

An optimal toluene removal is achieved at around 10% of oxygen.

The wire-plate dielectric barrier discharge reactor with cobalt oxide catalyst in-situ is effective in destroying toluene and dissociate ozone.

THE END

thanks!thanks!