Hydrocarbon and soot oxidation over cerium and iron doped vanadium SCR catalysts

Abstract

V$_{2}$O$_{5}$−WO$_{3}$/TiO$_{2}$ (VWTi) catalysts are widely employed for selective catalytic reduction (SCR) of NO$_{x}$. However, due to their poor thermal stability the application in diesel particulate filters (DPFs), i. e. 2‐way SCRonDPF is limited. In this study, the potential of Ce‐ and Fe‐doped VWTi systems for hydrocarbon and soot oxidation in addition to the SCR activity was systematically investigated for fresh and thermally aged samples. The formation of metal vanadates upon thermal aging, as identified by X‐ray diffraction, Raman and X‐ray adsorption spectroscopy, prevents drastic sintering of the support and maintains a high NO$_{x}$−SCR and hydrocarbon oxidation activity. Additionally, the doped VWTi catalysts show a slight increase of the CO$_{2}$ selectivity during hydrocarbon oxidation, which represents an important aspect for such multifunctional catalysts. Despite of the advantages, the formation of metal vanadates hinders the mobility of vanadium species and decreases the soot oxidation ability of the doped catalysts. Interestingly, a promising soot oxidation activity was identified for the VWTi−Fe sample after aging at 650 °C, which resulted in decomposition of the iron vanadate and generation of highly dispersed and mobile V$_{2}$O$_{5}$