Experimental investigation on the N2O formation during the selective catalytic reduction of NOx with NH3 over Cu-SSZ-13

N2O formation over Cu-SSZ-13 during selective catalytic reduction of NOx with NH3 under different conditions were experimentally investigated based on a flow reactor and in situ DRIFTS experiments. The results show that the nonselective catalytic reduction (NSCR) and the nonselective NH3 oxidation (NSNO) are the major pathways for N2O formation over Cu-SSZ-13. N2O formation at low and high temperatures usually occur via different mechanisms. The N2O formation at low temperatures is mainly ascribed to the decomposition of NH4NO3, which mainly form on Cu(OH)+, while at high temperatures, N2O is due to the NH3 oxidation by O2 and NOx. Besides, the effect of ANR, NO2/NOx ratio and O2 and H2O concentrations on the N2O formation were also studied. They all affect N2O formation, and the effects on the two mechanisms are totally different at low and high temperatures.