Plasma-enhanced low temperature NH3-SCR of NOx over a Cu-Mn/SAPO-34 catalyst under oxygen-rich conditions.

• Plasma-enhanced NH 3 -SCR of NO x over Cu-Mn/SAPO-34 is achieved at low temperatures. • There is no NH 3 slip and by-product formation in this process. • A maximum NO x removal of 80 % and 100 % N 2 selectivity are achieved. • Intermediates formed from the plasma NO oxidation promote the SCR of NO x. • Enhanced E–R reactions on the catalyst surface contribute to the enhanced NO x removal. In this work, a dielectric barrier discharge (DBD) plasma-enhanced NH 3 -selective catalytic reduction (NH 3 -SCR) of NO x over a Cu-Mn/SAPO-34 catalyst at low temperatures (<200 °C) and oxygen-rich conditions (14 vol.%) has been investigated using a two-stage post-plasma-catalytic (PPC) configuration. The results show a maximum NO x removal of 80 % and a 100 % N 2 selectivity without NH 3 slip or the formation of by-products at a low specific energy input (SEI) of 32 J/L. Adding water vapor (5.7 vol.%) into the plasma NH 3 -SCR process does not negatively affect the removal of NO x , while the presence of C 3 H 6 enhances the removal of NO x. In situ diffuse reflectance infrared spectroscopy (DRIFTS) combined with optical emission spectroscopic diagnostics has been employed to elucidate the reaction mechanism in the plasma-catalytic removal of NO x. We find that the formation of NO 2 via NO oxidation in the first stage plasma gas-phase reaction enhances the Eley-Rideal (E–R) reaction on the surface of the Cu-Mn/SAPO-34 catalyst in the second stage catalytic NH 3 -SCR of NO x. The Cu-Mn/SAPO-34 catalyst shows stable performance in the plasma-enhanced NH 3 -SCR of NO x after 5 cycles of catalyst regeneration. This work has successfully demonstrated a promising low-temperature plasma-catalytic solution for the effective NH 3 -SCR of NO x. [ABSTRACT FROM AUTHOR]