estudio y caracterización de un plasma de microondas a presión ...

Concentration CO 2 (ppm)
10000
1000
100
10
Argon
Total flow rate: 1.0 L/min
MW Power: 600 W
CO 2
10 100 1000 10000
Concentration CCl 4 (ppm)
Capítulo 3
Figure 3.7: CO 2 concentration at the reactor outlet versus CCl 4 concentration introduced (the CO 2
concentration from the air has been substracted).
GC/MS analyses revealed the presence of byproducts including CO2 [22], NO
[23] and N2O [24]. In support of the carbon balance, shown in the lineal behaviour of the
figure 3.7, we do not detect any other carbon containing compounds, than CO2 and CCl4,
reason why the formation of CO2 should be the main pathway for the loss of atomic
carbon from fragmented CCl4, its concentration increasing with increase in that of CCl4
introduced into the plasma (figure 3.7). However, the variation of the CO2 concentration
at the reactor outlet as a function of the microwave power and of the gas flow is not
representative, due to the variation of the CCl4 destroyed with these parameters is in the
range of ppbv (virtually completely eliminated) versus the total concentration of CO2, in
the range of ppmv. The oxygen required for CO2 to form was obtained from atmospheric
air present as an impurity in the reactor, due to turbulences produced in the outlet hole.
The presence of air in the detector facilitated the formation of N2O and NO as a
result of the high temperature of the gas in the recombination chamber (around 400 ºC).
Unlike CO2, the concentrations of N2O and NO at the reactor outlet were not influenced
by that of CCl4 introduced into the plasma. On the other hand, an increase in flow-rate or
microwave power supplied to the torch increased the concentrations of these species
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