Experimental Investigation on N₂O Formation during the Selective Catalytic Reduction of NOx with NH₃ over Cu-SSZ-13

N 2 O formation over Cu-SSZ-13 during selective catalytic reduction (SCR) of NOx with NH 3 under different conditions was experimentally investigated based on a flow reactor and in situ diffused reflectance infrared Fourier transform spectroscopy experiments. The results show that the NSCR and the nonselective NH 3 oxidation are the major pathways for N 2 O formation over Cu-SSZ-13. N 2 O formation at low and high temperatures usually occurs via different mechanisms. The N 2 O formation at low temperatures is mainly ascribed to the decomposition of NH 4 NO 3, which mainly forms on Cu(OH) +, while at high temperatures, N 2 O is formed because of the NH 3 oxidation by O 2 and NOx. Besides, the effect of ANR, NO 2 /NOx ratio, and O 2 and H 2 O concentrations on N 2 O formation were also studied. They all affect N 2 O formation, and the effects on the two mechanisms are totally different at low and high temperatures.