Destruction of Tetrafluoroethane with Atmospheric Nonthermal Plasma Created in Dielectric-Packed Bed Reactors

This study investigated the nonthermal plasma destruction of 1,1,1,2-tetrafluoroethane (HFC-134a) over a temperature range up to 400 degrees C with three different packing materials and a simulated exhaust gas consisting of HFC-134a, oxygen and nitrogen. The characteristics of the packing materials, including alumina, zirconia and glass beads, were comparatively examined with respect to the efficiency of HFC-134a destruction and the formation of byproducts. When alumina was used, the plasma reactor showed different behaviors according to the reactor temperatures. Below 150 degrees C, the destruction efficiency slowly increased with increasing the temperature, whereas there was a steep increase in the destruction efficiency with increasing the temperature over 150 degrees C, reaching 100% destruction efficiency at about 400 degrees C. The temperature of 150 degrees C was found to correspond to the threshold temperature for catalytic HFC-134a destruction over alumina. On the contrary, with zirconia and glass beads as the packing material, the temperature dependence of the destruction efficiency was not as significant as with alumina beads, indicating that zirconia and glass beads have no or negligible catalytic activity and the HFC-134a destruction resulted mainly from gas-phase reactions. With zirconia and glass beads; carbonyl fluoride (COF2) was detected as a byproduct from the processed gas, but with alumina it disappeared, moving the process towards the total oxidation.