Effect of copper precursors on the catalytic performance of Cu-ZSM-5 catalysts in N2O decomposition

Five Cu-ZSM-5 catalysts were obtained by treating Na-ZSM-5(Si/Al ratio = 15) with aqueous solutions of different Cu precursors(CuCl2, Cu(NO3)2, CuSO4, Cu(CH3COO)2, and ammoniacal copper(II) complex ion). After being pretreated in flowing He at 500 ℃ to form active Cu+, these catalysts exhibited quite different activities in catalytic decomposition of N2O. CZM-AC(II)(prepared by ammoniacal copper(Ⅱ) complex ion) with 9.4 wt% Cu content was the most active among these Cu-ZSM-5 catalysts, achieving almost complete N2O conversion at 400 ℃.CZM-CA(prepared using Cu(CH3COO)2as the Cu precursor) with 2.8 wt% Cu content was the second most active catalyst among these Cu-ZSM-5 catalysts, achieving almost complete N2O conversion at 425 ℃. CZM-CC, CZMCN, and CZM-CS prepared by using Cu Cl2, Cu(NO3)2, or CuSO4as the Cu precursor with similar Cu contents(≈ 1.7 wt%) were the least active among these Cu-ZSM-5 catalysts, achieving ca. 90% N2O conversion at 500 ℃.XRD, ICP, SEM, TEM, EDX-mapping, and CO-IR experiments were conducted to characterize relevant samples.The superior activity of CZM-AC(Ⅱ) can be attributed to the high contents of total Cu+and dimeric Cu+among these samples. The influence of co-fed O2or H2O on the catalytic performance of typical samples was also studied.