Promotion of Nonthermal Plasma on the SO2 and H2O Tolerance of Co–In/Zeolites for the Catalytic Reduction of NO x by C3H8 at Low Temperature

Abstract

Effects of nonthermal plasma (NTP) on the selective catalytic reduction of NO x by C3H8 (C3H8-SCR) over Co–In/zeolites were investigated in the presence of SO2 and H2O at low temperatures (<below 648 K). Co–In/H-(Beta/USY) displayed the highest low-temperature activity in the NTP-facilitated C3H8-SCR (PF-C3H8-SCR) hybrid system because of the enhancement of chemisorbed oxygen, acid sites, and weak adsorption species (NO2 − and NO x ) on Co–In/H-(Beta/USY). The assistance of NTP significantly promoted the tolerance of SO2 and H2O on both Co–In/H-Beta and Co–In/H-(Beta/USY) in C3H8-SCR reaction. Co–In/H-(Beta/USY) even exhibited excellent SO2 tolerance in the PF-C3H8-SCR hybrid system when a relatively high concentration of SO2 (1000–2000 ppm) and 7 % H2O were introduced into the feed gas. Sulfate species formed on the active sites of Co–In/H-(Beta/USY) were unstable because of the relatively low-temperature (below 600 K) desorption of sulfate species. The unstable sulfate species contributed slight inhibition to C3H8 activation and nitrogen-containing formation on the active sites of Co–In/H-(Beta/USY) in the PF-C3H8-SCR hybrid system. The PF-C3H8-SCR hybrid system with Co–In/H-(Beta/USY) may be a potential candidate for DeNO x industrial applications.