An efficient and sulfur resistant K-modified activated carbon for SCR denitrification compared with acid- and Cu-modified activated carbon

In this work and for the first time, an alkali metal potassium (K) as a promoter was loaded on an activated carbon (AC) to be used for selective catalytic reduction of NO from industrial flue gas. The denitrification activity of K-modified AC samples was investigated and compared with those of acid- and Cu-modified AC samples. The three modifications can enhance the denitrification activity of AC samples. To investigate the enhanced mechanisms of denitrification and SO 2 resistance, various AC samples were characterized by SEM, EDX, XRF, ICP, XRD, N 2 physisorption, H 2 -TPR, XPS, in situ DRIFTS and TPD. For the acid modification, the content of phenolic hydroxyl increases and then promotes the adsorption of NH 3 . For the loading of Cu, the appearance of Cu 2+ /Cu + sites with high catalytic activity promotes NH 3 and NO adsorption and changes the reaction pathway. For the loading of K, the adsorption capacity for NO increases nearly 12 times higher than that on Raw-AC, of which 85.0% is chemical adsorption. Moreover, three kinds of active nitrate species additionally forms, including nitro compounds, monodentate nitrate and nitrous oxide, which promote the denitrification reaction path. AC-Cu has poor sulfur resistance due to the sulfation of Cu, while AC-K show good sulfur resistance due to the enhanced adsorption of NO. The catalytic dissociation activity of N 2 O on AC-K makes the formation and decomposition of N 2 O into a dynamic equilibrium. As a result, AC-K has a high N 2 selectivity , while AC-Cu has poor N 2 selectivity.