Promotional effect of Ce on Cu-SAPO-34 monolith catalyst for selective catalytic reduction of NOx with ammonia

Abstract The activity and hydrothermal stability of Cu-SAPO-34 and CuCe-SAPO-34 for selective catalytic reduction of NO x with ammonia (NH 3 -SCR) were investigated systematically. The catalysts were prepared by wet-impregnation method, and characterized by N 2 adsorption, X-ray diffraction (XRD), X-ray photoelectron spectrum (XPS), Ultraviolet-visible diffuse reflectance spectrum (UV–vis-DRS), H 2 -temperature programmed reduction (H 2 -TPR) and NH 3 -temperature programmed desorption (NH 3 -TPD). The experimental results of fresh catalysts suggested that Ce mainly existed on the surface of the catalyst and was well dispersed in the form of Ce 3+ , and its interaction with copper could improve the dispersion of copper species and increase the amount of isolated Cu 2+ ions, so that CuCe-SAPO-34 performed better NH 3 -SCR activity than Cu-SAPO-34. After hydrothermal aging at 800 °C for 12 h, the characterization results indicated that the introduction of cerium effectively improved the textural and structural stability of SAPO-34 since more cations at the exchange site of SAPO-34 could decrease the concentration of Si O(H) Al bond which was closely related to the damage of the SAPO-34 framework. Moreover, the addition of Ce could prevent the decrease of acid densities, promote the redistribution of CuO during hydrothermal aging and provide higher amount of isolated Cu 2+ ions, leading to superior hydrothermal stability of CuCe-SAPO-34 catalyst.