Decomposition of dichlorodifluoromethane (CCl2F2 or CFC-12) in a radio-frequency (RF) plasma system is demonstrated. The CCl2F2 decomposition fractions (ηCCl2F2) and mole fractions of detected products in the effluent gas stream of CCl2F/O2/Ar and CCl2F2/H2/Ar plasma, respectively, have been determined. The experimental parameters including input power wattage, O2/CCl2F2 or H2/ CCl2F2 ratio, operational pressure, and CCl2F2 feeding concentration were investigated. The main carbonaceous product in the CCl2F2//O2/Ar plasma system was CO2, while that in the CCl2F2/H2/Ar plasma system was CH4 and C2H2. Furthermore, the possible reaction pathways were built-up and elucidated in this study. The results of the experiments showed that the highly electronegative chlorine and fluorine would easily separate from the CCl2F2 molecule and combine with the added reaction gas. This led to the reactions terminated with the CO2, CH4, and C2H2 formation, because of their high bonding strength. The addition of hydrogen would form a preferential pathway for the HCl and HF formations, which were thermodynamically stable diatomic species that would limit the production of CCl3F, CClF3, CF4, and CCl4. In addition, the HCl and HF could be removed by neutral or scrubber method. Hence, a hydrogen-based RFplasma system provided a better alternative to decompose CCl2F2.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Condensed Matter Physics
- Surfaces, Coatings and Films