Influence of CeO2 loading on structure and catalytic activity for NH3-SCR over TiO2-supported CeO2

Abstract

A series of supported CeO2/TiO2 catalysts were prepared to explore the influence of CeO2 loading on these catalysts for the selective catalytic reduction of NOx by NH3 (NH3-SCR). The catalysts were investigated in detail by means of XRD, Raman, H2-TPR, NH3-TPD, XPS, in situ DRIFTS, and NH3-SCR reaction. The activity of the catalyst is closely related to the content of CeO2. When the loading of CeO2 is near the dispersion capacity (1.16 mmol Ce4+/100 m2 TiO2), the catalytic activity is better. This may be because that the dispersed CeO2 is the active species and the catalyst has appropriate redox property, along with the larger amounts of surface Ce content and surface adsorbed oxygen species. Finally, a possible reaction mechanism via the Langmuir-Hinshelwood (L-H) mechanism is tentatively proposed to further understand the NH3-SCR reaction.