Effects of WO3 and SiO2 doping on CeO2–TiO2 catalysts for selective catalytic reduction of NO with ammonia

Abstract

A series of CeO₂–WO₃/SiO₂–TiO₂ (CeW_xTiSi_y) catalysts with different loading amounts of WO₃ were synthesized by wet co-impregnation of ammonium metatungstate and cerium nitrate on a SiO₂–TiO₂ support, and were employed for the selective catalytic reduction (SCR) of NO by NH₃. The catalytic activity of the CeO₂/SiO₂–TiO₂ (CeSiTi) catalyst was enhanced by the addition of WO₃, and the W-containing catalysts showed higher hydrothermal stability especially between 550 and 600 °C. The introduction of WO₃ to the CeSiTi catalyst could produce more chemisorbed oxygen species, reducible subsurface oxygen species, acid sites and ad-NO_x species. Moreover, the modification of CeO₂–WO₃/TiO₂ (CeWTi) by SiO₂ could enhance the specific surface area, especially the aged specific surface area, thus improving the hydrothermal stability of the catalyst.