Controlled Synthesis of TiO2 Shape and Effect on the Catalytic Performance for Selective Catalytic Reduction of NOx with NH3

In this paper, the shapes of TiO2 were regulated by changing the solvent and hydrothermal temperature. CeO2-WO3/TiO2 catalysts were further synthesized by impregnation method and used for selective catalytic reduction (SCR) of NOx. By a series of regulations, the SCR performance was improved by the further modulation of TiO2 shape. The results showed that with the hydrothermal temperature increase from 80 to 200 A degrees C, and the shape of catalysts emerged particle state, rod-like structure, flower-like structure and large particle state, respectively. The formation process of flower-like TiO2 was proposed according to the shape change with the increase of hydrothermal temperature. Prominently, the shape of TiO2 precursor would change the crystallographic plane of CeO2-WO3/TiO2-A catalysts. When the hydrothermal temperature was 120 A degrees C, the catalysts showed the best SCR performance. This might be due to the high surface atomic ratio of O-alpha/(O-alpha + O-beta) and the high transformation of Ce3+ and Ce4+, which were beneficial for the SCR performance. CeO2-WO3/TiO2-A-120 also exhibited an excellent resistance of H2O. However, when enduring the SO2 or both enduring the SO2 and H2O, the activity of catalysts had an obvious decrease due to the production of Ce-2(SO4)(3).