A non-thermal, atmospheric pressure plasma with a titanium dioxide catalyst were combined to destroy difluorochloromethane, CCl 2 F 2 , (CFC-12) in gas streams of nitrogen and air using two configurations; one where the catalyst was incorporated directly into the plasma and the other where the catalyst was downstream of the plasma. The single stage reactor, in both gas streams, gave significant enhancement of the CFC-12 destruction with high energy efficiency. Both configurations decreased NOx production when processing in air. No loss in catalyst surface area or activity was observed.
The destruction of CFC-12 (CF2Cl2) has been studied in an AC, nonthermal, atmospheric pressure plasma
reactor packed with barium titanate beads. The extent of the destruction in air ranges between 8% and 40%
depending on the conditions. The decomposition products in air as determined by infrared spectroscopy are
CO, CO2, and COF2. It is deduced that the undetected chlorine and fluorine is present as F2 and Cl2. A
chemical mechanism for the decomposition is proposed. Large concentrations of NO, NO2, and N2O are also
formed. Destruction in a stream of pure N2 is about twice as effective as in air under corresponding conditions.
The addition of a small amount of water (∼0.03%) or oxygen (∼0.02%) to the nitrogen carrier gas increases
the destruction efficiency but the presence of molecular hydrogen (≤2%) brings about no enhancement. It is
suggested that in all cases, the primary decomposition step involves dissociative electron attachment to the
CF2Cl2. This is confirmed by the observed differences in the destruction in pure nitrogen and in air.
A non‐thermal, atmospheric‐pressure plasma has been used to study the effect of temperature on the plasma destruction of DCM in an air stream using a BaTiO3 packed‐bed reactor, co‐filled with TiO2 and γ‐Al2O3 catalysts. Comparisons have been made with plasma alone, catalysis alone and combined plasma/catalysis to determine any synergistic effects of combining plasma and catalysis. Plasma/catalysis is the most successful method for destroying DCM over 125–400 °C. TiO2 was more effective than γ‐Al2O3 for plasma/catalysis. The energy efficiency of plasma/catalysis processing compared to catalysis alone is considered by examining the input power required to achieve equivalent destructions, finding that an energy reduction of ≈30% can be achieved by plasma activation of the catalyst.magnified image
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