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)2 as 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,CZM-CN,and CZM-CS prepared by using CuCl2,Cu(NO3)2,or CuSO4 as 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 O2 or H2O on the catalytic performance of typical samples was also studied.