Fe2O3@SiTi core–shell catalyst for the selective catalytic reduction of NOx with NH3: activity improvement and HCl tolerance

Abstract

A core–shell structured Fe₂O₃@SiTi catalyst with a SiTi shell and Fe₂O₃ core was prepared and used for the selective catalytic reduction (SCR) of NO_x with NH₃. The thickness of the shell could be well controlled by the amount of TEOS added during the preparation procedure. The catalyst was characterized by techniques including STEM, XRD, BET, NH₃-TPD, XPS, and H₂-TPR. In comparison with Fe₂O₃, the Fe₂O₃@SiTi catalyst presented higher SCR activity, N₂ selectivity, better SO₂ resistance and HCl tolerance. The characterization results showed that the addition of the SiTi shell onto the Fe₂O₃ core enlarged the BET specific surface area, increased the number of surface acidic sites, led to the generation of more Fe²⁺ species and chemisorbed oxygen species, and influenced the reducibility of Fe₂O₃. The improvement of HCl tolerance of the Fe₂O₃@SiTi catalyst can be attributed to the fact that the SiTi shell prevents the Fe₂O₃ core from reacting with HCl to form FeCl₃.