Effect of CO2 on the DeNO(x) Activity of a Small Pore Zeolite Copper Catalyst for NH3/SCR

Abstract

Exposure of CuSSZ13 to CO2 at temperatures below 300 degrees C can deactivate its low-temperature deNOx activity during NH3/SCR, with the severity of deactivation being dependent on reaction temperature. The adsorption of NO on Cu2+ ion is inhibited by CO2 due to its competitive adsorption, while NH3 adsorption on acidic sites of CuSSZ13 is largely unaffected by CO2, as evidenced by NO- and NH3-TPD in the presence of CO2. Under O-2-rich conditions, CO2 forms unidentate carbonates on Cu2+ sites suppressing the formation of nitrates, a key reaction intermediate essential for NOx reduction during the NH3/SCR reaction, as revealed in an in situ FTIR study.