Synergetic utilization of microwave - assisted fly ash and carbide slag for simultaneous desulfurization and denitrification: High efficiency, low cost and catalytic mechanism

A higher efficiency and lower cost catalytic absorption technology on synergetic utilization of microwave-assisted fly ash and carbide slag (FA-CS) with K2O/K2O2 as catalyst and absorbent was proposed systematically for desulfurization (De-SOx) and denitrification (De-NOx) in this paper. The optimal preparation conditions were a loading amount of 5% K2O as a catalyst and absorbent, a preparation of 5%K2O/FA-CS for 120 min at 900 degrees C and a reaction temperature of 150 degrees C. T-90% and T-80% for De-SO2 removal efficiency was 56 min and 41 min, and that for De-NOx removal efficiency was 13 min and 9 min. respectively. Based on the characterization and analytical results of the K2O/FA-CS, the synergetic utilization mechanism of microwave-assisted FA-CS was proposed for De-NOx and De-SO2 process. The coexisting K2+/K1+ in K2O/FA-CS and K2O2/FA-CS catalyst would also be reversibly oxidized and reduced, which were both helpful for the catalytic activation to promote the transformation from N2+ to N4+ and S4+ to S6+. In addition, The NO and SO2 was oxidized to NOx and SO(x )by the active oxygen (O*) that provided by the redox pair K2+/K1+ in K2O/FA-CS and K2O2/FA-CS catalyst, in which the newly formed NO x and 50 x was easily combined to form the unstable sulfur-nitrogen complexes in De-SO2 and De-NOx process. But the activation sites of CaO as adsorbent and co-existing K2+/K1+ ions on surface of K2O/FACS and K2O2/FA-CS catalyst could be poisoned by NOx(abs) and SOx(abs) to form the stable (Ca, K)SOx or (Ca, K) NOx, leading to a decline of adsorbent activity.