Insights into Synergy of Copper and Acid Sites for Selective Catalytic Reduction of NO with Ammonia over Zeolite Catalysts
Wenyi Zhao, Menglin Shen, Yueran Zhu, Xudong Ren, Xingang Li
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.