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

•The bimetallic Cu-Ce-SAPO-34 monolith catalyst was firstly prepared.•The interaction between Ce and Cu could improve the dispersion of copper species and increase the amount of isolated Cu2+ ions.•The addition of Ce could promote the redistribution of CuO particles.•The addition of Ce could inhibit the degradation of acid density during hydrothermal treatment.•The introduction of Ce could obviously improve the hydrothermal stability of Cu-SAPO-34.

The activity and hydrothermal stability of Cu-SAPO-34 and CuCe-SAPO-34 for selective catalytic reduction of NOx with ammonia (NH3-SCR) were investigated systematically. The catalysts were prepared by wet-impregnation method, and characterized by N2 adsorption, X-ray diffraction (XRD), X-ray photoelectron spectrum (XPS), Ultraviolet-visible diffuse reflectance spectrum (UV–vis-DRS), H2-temperature programmed reduction (H2-TPR) and NH3-temperature programmed desorption (NH3-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 Ce3+, and its interaction with copper could improve the dispersion of copper species and increase the amount of isolated Cu2+ ions, so that CuCe-SAPO-34 performed better NH3-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 SiO(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 Cu2+ ions, leading to superior hydrothermal stability of CuCe-SAPO-34 catalyst.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (175 K)Download as PowerPoint slideThe CuCe-SAPO-34 performed superior NH3-SCR activity and hydrothermal stability than the Cu-SAPO-34 catalyst.