The effect of catalyst loading, composition, and calcination temperature on NH3 selective catalytic reduction (SCR) activity was investigated for metal vanadates of the type Fe x Al1–xVO4 (0 ≤ x ≤ 1, MeVO4) supported on TiO2–WO3–SiO2 (TWS). The optimized catalyst (4.5 wt % FeVO4/TWS calcined at 650 °C) showed an enhanced NO x reduction activity compared to the reference material 2.3 wt % V2O5/TWS. An activation effect was observed above a calcination at 600 °C and was investigated by means of X-ray diffraction, Brunauer–Emmett–Teller, diffuse reflectance infrared Fourier transform, and X-ray absorption near edge structure analyses. It was shown that the activation is due to the decomposition of FeVO4. VO x species disperse and migrate to the support material, while the iron species sinter to Fe2O3 particles. We provide strong evidence that the active species responsible for NH3–SCR in a FeVO4/TWS catalyst is not FeVO4 but VO x species that possess a similar coordination environment to the VO x species on conventional V-based catalysts. Due to the remarkable effect of the activation upon calcination, a very active and thermally stable SCR catalyst up to 700 °C was obtained.

No abstract

No abstract

No abstract

No abstract