Effect of SO2 on SCR activity of MnOx/PG catalysts at low temperature

Palygorskite (PG)-supported manganese oxide catalysts (MnOx/PG) were prepared for the selective catalytic reduction (SCR) of NO with ammonia in the presence of SO 2 at low temperature. The influence of gaseous SO 2 on the performance of the catalyst was studied by means of specific surface area (Brunauer-Emmett-Teller, BET) analysis, scanning electron microscopy (SEM), thermogravimetric (TG) analysis, temperature-programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS). The results showed that the SCR activity of Mn10/PG was significantly inhibited by gaseous SO 2 at temperatures below 300°C. However, the SCR activity of Mn10/PG was markedly promoted by SO 2 in a higher temperature range of 300°C to 500°C. The sulphating of surface active species (MnOx) was suggested to inhibit the oxidation of NH 3 to NO leading to enhancement of the SCR activity at a higher temperature range of 300°C to 500°C and decrease in the SCR activity at temperatures below 300°C.