One‐pot synthesis of Cu/SAPO‐34 with hierarchical pore using cupric citrate as a copper source for excellent NH₃‐SCR of NO performance

Abstract

Abstract It is still a serious challenge to develop a simple synthesized method of SAPO‐34 sieve modified by Cu with high NH 3 ‐SCR performance. The Cu/SAPO‐34 samples with hierarchical structure were synthesized for the first time using cupric citrate as copper source by one‐pot hydrothermal method which showed excellent NH 3 ‐SCR performance for NO removal. Among them, the 0.15Cu/SAPO‐34 catalyst with a Cu/Al ratio of 0.15 exhibited the widest temperature operating window (160–500 °C) and better hydrothermal stability. The physicochemical properties of 0.15Cu/SAPO‐34 was measured to understand the impacts of the Cu species on the NH 3 ‐SCR of NO activity by various characterization methods including XRD, NH 3 ‐TPD, N 2 adsorption‐desorption, XPS, EPR, UV‐vis, NH 3 ‐oxidation, NMR and in situ DRIFTS. The results reveal that the good activity is assigned to the isolated Cu species located at the site (I) in SAPO‐34, and the co‐existence of surface Cu 2+ and Cu + species with almost equal amounts. In addition, 0.15Cu/SAPO‐34 also possesses suitable acidic sites which are conducive to catalytic activity. The results of in situ DRIFTS suggest that the NH 3 ‐SCR reaction follows Eley‐Rideal mechanism over 0.15Cu/SAPO‐34.