SO2 REMOVAL ACTIVITY AND ITS REGENERATION OF POLYACRILONITRILE BASED ACTIVE-CARBON FIBER (PAN-ACF)

SO2 removal activity of a commercially PAN-ACF, FE-300 was examined at 100-degrees-C in its repeated use by regenerating it at a temperature range of 400-1000-degrees-C, using model flue gas containing 1000 ppm SO2. The particular ACF showed an excellent removal activity after the heat treatment at 800-degrees-C (FE-300-800) providing a breakthrough time of 5.1 h. However its activity was so much reduced in the second successive runs to be 50% of the first run, when its ACF was regenerated before the successive are at 500-degrees-C, where adsorbed SO2 was completely recovered. High temperature of 800-degrees-C regenerated more the activity, although the breakthrough time was still 4.5 h in the second run, and decreased steadily in the successive runs. Such regeneration provoked a large carbon loss by evolving CO2 and CO after the recovery of SO2. The activity was almost completely regenerated when the ACF was treated with NH3 at 500-degrees-C after the complete recovery of SO2. NO was found reduced with NH3 at 500-degrees-C over the ACF after the recovery of SO2, exhibiting a conversion of 60% recovery of SO2 adsorption ability. Reduction with NH3 for the recovery of SO2 adsorption led to no carbon loss at the regeneration. The role of oxygen functional groups introduced by oxidative adsorption and desorption of SO2 are discussed for the oxidative adsorption of SO2 in the successive runs.