Enhanced Durability of Monolithic V2O5–WO3/TiO2 Catalysts Prepared by a Novel One-Pot Method for the Selective Catalytic Reduction of NOx with NH3

摘要

In the present work, V2O5–WO3/TiO2 (VWT) catalysts were loaded onto a cordierite monolith through a novel one-pot method (OP) and a traditional incipient wetness impregnation method (IW). The catalysts were characterized and evaluated for NH3-SCR before and after hydrothermal aging at 600°C for 36 h. An analysis of catalyst activity showed that the hydrothermal stability of OP was much higher than that of IW. N2-sorption and X-ray diraction (XRD) results suggested that there were no signi cant di erences in the textural and structural properties of the two catalysts before and after aging, except for the formation of a small amount of WO3 crystallites on the surface of aged OP. Separate NH3-oxidation tests revealed that the NO selectivity of aged OP was signi cantly lower than that of aged IW, which resulted in a much higher NOx conversion at high temperatures during NH3-SCR. X-ray photoelectron spectroscopy (XPS), H2-temperature programmed reduction (H2-TPR), and Raman spectroscopy indicated that V and W species were more stable on the sur face of OP during aging rather than IW, thus inhibiting the aggregation of surface-active species and leading to a better hydrothermal stability. Furthermore, OP exhibited better adhesion of the washcoat when compared to IW and this VWT catalyst exhibited a good tolerance for SO2.