Insights into Synergy of Copper and Acid Sites for Selective Catalytic Reduction of NO with Ammonia over Zeolite Catalysts

Abstract

Herein, we report the function of copper sites in Cu-SSZ-13, Cu-ZSM-5 and Cu-Beta catalysts with the same Si/Al ratio (14) and Cu/Al ratio (0.4) on selective catalytic reduction of NO with NH3 (NH3-SCR) and reveal the relationship between active sites (Cu sites, acid sites) and catalytic activity. The results show that the amount of isolated Cu2+ ions in the catalysts directly determines the formation of strong Lewis acid sites and reaction intermediate NO3− ions, thus affecting the low-temperature SCR performance, while the amount of highly stable Cu+ ions and Brønsted acid sites is related to the high-temperature SCR performance of the catalysts. Consequently, it contains enough isolated Cu2+ ions, highly stable Cu+ ions and Brønsted acid sites, which endows Cu-SSZ-13 with excellent NH3-SCR activity.