精细石油化工中间体国家工程研究中心（ERC）知识库

Morphology of 3D TiO₂ support was regulated by modulating the hydrothermal time. Notably, the increase of hydrothermal time could greatly promote the transformation of rod-like TiO2 to flower-like TiO₂, while the continuous increase of hydrothermal time damaged the integrity of flower-like TiO₂ and led to the appearance of large TiO₂ particles. After that, a series of CeO₂-WO₃/TiO₂ catalysts were prepared by a typical impregnation method. The catalytic performance of these CeO₂-WO₃/TiO₂ catalysts for the selective catalytic reduction of nitrogen oxides (NH₃-SCR) verified that NO_x conversion was greatly related to morphological integrity of flower-like TiO₂. Prominently, activity of CeO₂-WO₃/TiO_2-8 catalyst was still excellent after introducing H₂O and SO₂, and thus the combined CeO₂-WO₃/TiO_2-8 catalyst showed high catalytic activity and good resistance to H₂O and SO₂. Various characterizations indicated that the integrity of flower-like structure could evidently alter the surface atomic ratio of Ce³⁺/(Ce³⁺ + Ce⁴⁺) as well as acid sites. With the increase of surface atomic ratio of Ce³⁺/(Ce³⁺ + Ce⁴⁺), the SCR performance of the catalysts was obviously improved. In short, the superior catalytic performance of CeO₂-WO₃/TiO₂ for the SCR of NOx was related to the morphology of TiO₂ support, the highly dispersed active species, the valence of Ce, acid sites and lots of surface adsorbed oxygen.