Preparation of CeWTiO_x catalysts via self-propagating high temperature synthesis and its NH₃-SCR performance

A series of CeWTiO_x catalysts were prepared by self-propagating high-temperature synthesis method, and their NH₃-SCR activities were evaluated. X-ray diffraction, N₂ adsorption-desorption, H₂-temperature-programmed reduction, X-ray photoelectron spectroscopy and NH₃-temperature-programmed desorption were performed to investigate the relationship between the catalyst activity and its physicochemical properties such as crystalline phase, specific surface area, redox ability and acidity. The results showed that 80% of NO conversion could be reached on the Ce₄₀W₁₀TiO_x catalyst sample in a range of 150-430 ℃. NO conversion of Ce₄₀W₁₀TiO_x could be kept above 97% in SO₂ atmosphere. The characterization indicated that the excellent low temperature activity and SO₂ resistance of Ce₄₀W₁₀TiO_x were mainly associated with the tungsten doping. The existence of tungsten weakened the strength of Ce-O bond, lowered the crystallinity and crystal size of CeO₂, increased the surface active oxygen content and the acid sites, thus improved the NH₃-SCR performance of the catalyst.