Effects of Concentration and Adsorption Product on the Adsorption of SO2 and NO on Activated Carbon

The effects of various SO2 and NO concentrations on the adsorption capacity of activated carbon were measured experimentally for sequential and simultaneous adsorption of SO2 and NO in a fixed bed using an area integral calculation method. The results show that higher NO concentrations increase SO2 adsorption, especially for C-NO > 200 ppm; however, higher SO2 concentrations restrict NO adsorption with little NO adsorbed for CO2 > 700 ppm. The NO adsorption capacity decreases as the SO2/NO ratio increases, while the total adsorption capacity for SO2 and NO has a peak at SO2/NO = 1.7. The product analysis by XPS supports that NO promotes SO2 chemisorption, SO2 occupies both C-O and C=O groups, but NO occupies the C-O group. The TPD-MS measurement shows that most of the SO2 is chemisorbed, and the ion chromatography measurement indicates that 66.0% of the total adsorbed SO2 is oxidized to SO3. SO2 replaces the physisorbed NO, which is 94.3% of the total adsorbed NO, but cannot desorb the chemisorbed NO. TPD experiments show two NO desorption peaks at 200 and 280 degrees C, and almost all the NO desorbed as the temperature increases to 500 degrees C, with the chemisorbed NO being 5.6% of the total adsorbed NO.