Comparison of support synthesis methods for TiO2 and the effects of surface sulfates on its activity toward NH3-SCR

Abstract

CeO₂–H₂SO₄/TiO₂ catalysts with different TiO₂ supports (those obtained from sol–gel method and the one-pot method and industrial TiO₂ support) were prepared by an impregnation method and used for the selective catalytic reduction of NO_x with NH₃. The effects of different TiO₂ supports on molecular structure, surface acidity, and catalytic activity of the CeO₂–H₂SO₄/TiO₂ catalyst were investigated. The addition of SO₄²⁻ inhibited the transformation of TiO₂ from anatase phase to rutile phase. Furthermore, the excellent dispersion of CeO₂ promoted the catalyst performance, which is mainly related to different TiO₂ supports. In addition, the formation of sulfate salts increased the surface acid sites of the catalysts. However, excess Ce₂(SO₄)₃ covered the surface active sites, which in turn decreased the SCR activity. In addition, the CeO₂–H₂SO₄/TiO₂ catalyst support prepared by sol–gel method possessed the best catalytic performance; the working temperature window was 275–450 °C.