REMARKABLE CATALYTIC ACTIVITY OF CALCINED PITCH-BASED ACTIVATED CARBON-FIBER FOR OXIDATIVE REMOVAL OF SO2 AS AQUEOUS H2SO4

Catalytic activity of a series of pitch-based activated carbon fibers (ACFs) was examined at room temperature for the oxidative removal of S O2 as aqueous H2SO4 which was continuously recovered at steady state. Calcination up to 900 degrees C in an inert atmosphere increased the a ctivity very markedly regardless of the ACF; however, higher temperatu res up to 1200 degrees C increased the activity of ACFs with larger su rface area (1000 m(2)/g) while the ACFs with smaller surface area lost activity very sharply. ACF with the largest surface area and calcined at 1100 degrees C resulted in the complete capture of 1000 ppm SO2 by ACF weigh/flow rate (W/F) 1 x 10(-3) g . min/mL under 10% H2O. Lower humidity reduced the activity, although larger W/F allowed complete re moval of SO2. TPDE measurements revealed CO evolution from the ACF in the range of 400-1100 degrees C, the amount and the range depending on the ACF. ACF with the highest activity appeared to be obtained when t he major CC-evolving groups were removed before marked reduction of th e surface area took place. ACF that evolved CO more exhibited higher a ctivity. The active site produced by CO evolution is discussed briefly .