Investigation of Water and Sulfur Tolerance of Precipitable Silver Compound Ag/Al(2)O(3) Catalysts in H(2)-Assisted C(3)H(6)-SCR of NOx

[Image: see text] Ag/Al(2)O(3) catalysts containing different precipitable silver compounds (AgCl, Ag(2)SO(4), and Ag(3)PO(4)) were synthesized and investigated for NOx reduction in H(2)-assisted C(3)H(6)-selective catalytic reduction (SCR). The samples were systematically characterized by N(2) adsorption, X-ray diffraction (XRD), UV–Vis, X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HR-TEM). N(2) adsorption revealed that the introduction of anions (Cl(–), SO(4)(2–), and PO(4)(3–)) did not significantly affect the surface and structural properties of the Al(2)O(3) support. However, XRD patterns and HR-TEM images indicated that the addition of Cl(–) anions caused the agglomeration of silver species to form large AgCl particles on the AgCl/Al(2)O(3) catalysts. In contrast, the silver species dispersed well on Ag(2)SO(4)/Al(2)O(3) and Ag(3)PO(4)/Al(2)O(3) catalysts. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) revealed that partial oxidation of C(3)H(6) on Ag(2)SO(4)/Al(2)O(3) produced large amounts of reactive enolic species, while it tended to yield inert formate on AgCl/Al(2)O(3). As a result, Ag(2)SO(4)/Al(2)O(3) catalysts, especially 3% Ag(2)SO(4)/Al(2)O(3), exhibited superior water and sulfur tolerance in H(2)-assisted C(3)H(6)-SCR.