Selective catalytic reduction of NO_x by NH₃ over V₂O₅-WO₃ supported by titanium isopropoxide (TTIP)-treated TiO₂

Although the selective catalytic reduction (SCR) of NO_x is the most effective way to reduce related emissions, the V₂O₅-WO₃/TiO₂ catalyst which is most used for this purpose has a narrow operation temperature range of 300–400 °C and, therefore, has limited applicability. Hence, better catalysts with more abundant active sites and a wider range of acceptable temperatures (240–450 °C) are required, especially because heating at ≥350 °C allows for removal of ammonium sulfate, a catalyst poison that is formed during SCR. Herein, we aim to produce such catalysts by treating the TiO₂ support with titanium isopropoxide (TTIP) at several TTIP/TiO₂ mass ratios, as this treatment is expected to increase the number of catalytically active sites and facilitate the dispersal of active materials. The optimal performance, which was observed for the catalyst prepared at a TTIP loading of 5 wt%, was ascribed to the increased thermal stability caused by the high extent of W dispersion and the formation of V⁴⁺ by the reaction of V⁵⁺ with surface Ti³⁺. Therefore, these results pave the way for the fabrication of more efficient NO_x removal catalysts.