Effect of Oxygen Content on
Toluene Decomposition in
Wire-Plate Dielectric Barrier
Discharge Reactor
Guo Yufang
Ph.D candidate
South China University of
Technology
Introduction
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:
applied voltage
gas flow rate
gas concentration
with/without catalyst
Experimental apparatus

A Dielectric barrier discharge（DBD)
reactor :wire-plate
Figure 1. Simplified structure of the wire-plate DBD reactor
Experimental setup
Figure 2.Schematics of the experimental setup
Results
1.The effect of oxygen concentration in the background
gas
50
Removal Efficiency(%)
40
35
5% O2
10% O2
15% O2
20% O2
10
0
5%
10%
15%
20%
45
8
Power (W)

30
25
20
15
6
4
2
10
5
0
0
0
2
4
6
8
10
12
0
2
4
6
8
10
Applied Voltage (kV)
Figure 3. Dependences of toluene removal
Figure 4. Dependences of input power
efficiency on oxygen content
on oxygen content
(Q=500ml/min, 200ppm toluene)
Applied Voltage(kV)
12

2. The Effect of Gas Flow Rates
300ml/min
500ml/min
700ml/min
20
300ml/min
500ml/min
700ml/min
5
Ozone Concentration(ppm)
Removal Efficiency(%)
25
15
10
5
4
3
2
1
0
0
2
4
6
8
Applied Voltage(kV)
10
12
0
0
2
4
6
8
Applied Voltage(kV)
10
12
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. The Effect of Initial Concentration of Toluene in
Background Gas
50
60
40
Removal Efficiency(%)
80
Removal Efficiency(%)
200ppm
600ppm
20ppm
100ppm
450ppm
600ppm
1300ppm
40
20
30
20
10
0
0
0
2
4
6
8
10
Applied Voltage(kV)
Figure 7a. Dependences of toluene
removal efficiency on gas concentration
([O2]=5%, Q=500ml/min)
12
0
2
4
6
8
10
Applied Voltage(kV)
Figure 7b. Dependences of toluene
removal efficiency on gas concentration
([O2]=10%, Q=500ml/min)
12
200ppm
600ppm
30
20
10
0
0
2
4
6
20ppm
450ppm
1300ppm
50
Ozone Concentration (ppm)
Removal Efficiency(%)
40
8
10
12
Applied Voltage(kV)
Figure 7c. Dependences of toluene
removal efficiency on gas concentration
([O2]=15%, Q=500ml/min)
40
30
20
10
0
0
2
4
6
8
Applied Voltage (kV)
10
12
Figure 8. Dependences of ozone concentration
on gas concentration ([O2]=5%, Q=500ml/min)
65
60
55
50
45
40
35
30
25
20
15
10
5
0
no catalyst
Co3O4-Al2O3/FN
no catalyst
Co3O4-Al2O3/FN
50
Ozone Concentration(ppm)
Removal Efficiency(%)
4. The Effect of Catalyst
40
30
20
10
0
0
2
4
6
8
Applied Voltage(kV)
10
12
0
2
4
6
8
10
12
Applied Voltage(kV)
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. byproducts
CH4, C7H16 and C7H12 (no oxygen)
benzene ,C4H4O3 ([O2]=5%)
Discussion



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 radicals , resulting in a higher removal efficiency.
However, O2 has an adverse effect on toluene removal due to
its electronegativity. 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.
Summary


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!