Characterization of WMnCeTiOx catalysts prepared by different methods for the selective reduction of NO with NH3

In this work, WMnCeTiOx catalysts were prepared by three methods: coprecipitation (CP), deposition precipitation (DP), and sol–gel (SG). The effects of the preparation methods on the performance of the selective catalytic reduction of NOx with NH3 at 160–360 °C have been investigated systematically. XRD, BET, XPS, H2-TPR, NH3-TPD and in situ DRIFTS were used to characterize the physicochemical properties of the prepared WMnCeTiOx catalysts. The results showed that WMnCeTiOx catalysts prepared by CP and DP methods exhibited much better NH3-SCR performance in a temperature range of 160–300 °C than that prepared by the SG method. Moreover, the WMnCeTiOx catalyst prepared by the CP method exhibited a superior SO2 and H2O tolerance compared with those prepared by the DP and SG methods. According to characterization results, the excellent performance of the WMnCeTiOx(CP) catalyst could be ascribed to its highly dispersed active components, larger surface area, higher concentrations of Mn4+ and surface chemisorbed oxygen, more surface acid sites, stronger reduction capacity and better adsorption capacity for NH3 and NO. The in situ DRIFTS results indicated that the NH3-SCR reaction on all the prepared WMnCeTiOx catalysts obeyed both Langmuir–Hinshelwood and Eley–Rideal mechanisms.