Synthesis of nanosphere TiO2 with flower-like micro-composition and its application for the selective catalytic reduction of NO with NH3 at low temperature

TiO2 nanospheres consisting of flower-like nanopowders were synthesized by a solvothermal method, and Cu/TiO2(T) catalysts were prepared via an impregnation method. Their catalytic performances for the selective catalytic reduction of nitric oxide (NO) with ammonia (NH3-SCR) were investigated. Their structures, morphology and surface components were characterized via X-ray diffraction (XRD), Raman spectroscopy (Raman), scanning electron microscopy (SEM), N-2 adsorption-desorption isotherms, X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption of NO (NO-TPD) or O-2 (O-2-TPD) and temperature-programmed reduction of H-2 (H-2-TPR) or CO (CO-TPR). The largest specific surface area (236.78 m(2) g(-1)) is obtained for nanosphere TiO2 with flower-like morphology. XPS results show that there are CuO and Cu2O species in Cu(3)/TiO2(T) catalysts. The Cu(3)/TiO2(160) catalyst exhibits the best activity, and its T-95 temperature is 170 degrees C, and the temperature window of NO conversion over 95% is from 170 degrees C to 310 degrees C. This is due to the excellent redox properties and the adsorption properties of the catalyst. In situ DRIFTS results demonstrate that Lewis acid sites are involved in NH3-SCR reaction and the adsorption and activation of NH3 play a key role in the process of NH3-SCR over Cu/TiO2(T) catalysts.