A Mechanism for the Destruction of CFC-12 in a Nonthermal, Atmospheric Pressure Plasma

Abstract

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.

Catalytic nonthermal plasma reactor for the abatement of low concentrations of benzene

“…However, the product selectivity also depends on the water content in addition to VOC chemical structure. Some studies reported the optimal water vapor content for achieving the best VOC removal efficiency (Ricketts et al 2004;Sugasawa et al 2010: Karuppiah et al 2012). The effect of water vapor has been mostly studied with packed-bed DBD reactors for removal of benzene (Ogata et al 2000;Cal and Schluep 2001;Futamura et al 2002).…”

Plasma catalysis: A solution for environmental problems

“…Particularly high temperatures (~1250 °C) are needed to ensure that the halogenated components are safely destroyed without the formation of dioxins. We previously studied the destruction of dichlorodifluoromethane, CCl 2 F 2 , (CFC-12) in an air stream using only a plasma discharge [8]. By incorporating a range of catalysts into the plasma discharge in a one-stage configuration, we could significantly increase the destruction of the CFC-12 as is shown in Fig.…”

“…In these experiments, we again use a dielectric, barium titanate, packed-bed plasma reactor which can be heated up to 400 °C. The catalysts are combined with the plasma whose input power is 1 W, which is determined by integration of the current and voltage waveforms with a typical precision of ±10 % [8].…”

Destruction of Fluorinated Greenhouse Gases by Using Nonthermal Plasma Process

“…It should be noted that NO involved in reactions (19) and (20) is formed by the reaction between excited atomic nitrogen N( 2 D) and O 2 (Ricketts et al, 2004;Harling et al, 2005 …”