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

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 NOx 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.