Kinetic study of the continuous removal of SOx on polyacrylonitrile-based activated carbon fibres .1. Catalytic activity of PAN-ACF heat-treated at 800 degrees C

Continuous removal of SO2 as aqueous H2SO4 over polyacrylonitrile-based activated carbon fibres (PAN-ACF) was studied kinetically at room temperature to determine the effects of SO2 (20-1000 ppmv), O-2 (0-10 vol.%) and H2O (0-10 vol.%) concentrations and W/Q ratio (mass of ACF/volumetric flow rate of gas). An oxygen level > 3 vol.% was sufficient to provide steady-state removal of SO2. Higher inlet SO2 concentrations gave higher SO2 outlet concentrations, while more H2O and a higher W/Q ratio increased the SO2 removal. On the basis of this kinetic study, the rate-determining step is postulated to be aqueous H2SO4 desorption from the ACF bed, which makes sites available for further SO2 adsorption. Hence a lower SO2 concentration, more H2O, and a higher W/Q ratio are compensating factors in achieving the complete removal of SO2 by continuous recovery of aqueous H2SO4 at the outlet. (C) 1997 Elsevier Science Ltd.