Abstract
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 12h, 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.
Published Version
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