Effect of V2O5/WO3-TiO2 catalyst preparation method on NOx removal from diesel exhaust

Abstract V 2 O 5 /WO 3 -TiO 2 catalysts were prepared by conventional impregnation (VWTi-con) and ultrasound-assisted impregnation methods (VWTi-HUST). Their catalytic performance was tested for the selective catalytic reduction (SCR) of NO with NH 3 . The effects of the preparation methods on the catalyst properties were studied. The catalysts were characterized by X-ray diffraction, scanning electron microscopy, Raman and X-ray photoelectron spectroscopy. Both structural investigation and NH 3 -SCR activity showed that the preparation method had a strong effect on the thermal behavior of the V 2 O 5 /WO 3 -TiO 2 catalysts. After a hydrothermal treatment, a significant loss of NO reduction activity was observed for the VWTi-con catalyst, which suffered severe sintering and even formed a rutile V x Ti 1- x O 2 solid solution, while the VWTi-HUST catalyst had the same good hydrothermal stability as a commercial catalyst, indicating that the VWTi-HUST catalyst can be used in a commercial diesel after-treatment system. The ultrasound-assisted impregnation method produced a stronger interaction between the vanadium species and WTi support, which stabilized the vanadium species in the reduced state.