Mechanistic Investigation of the Promotion Effect of Bi Modification on the NH3-SCR Performance of Ce/TiO2 Catalyst

In this study, Bi was used as the modifier to elevate the performance of Ce/TiO2 catalyst for selective catalytic reduction (SCR) of NOx with NH3. Experimental results indicated that the CeBi/TiO2 catalyst with a Bi/Ce molar ratio of 0.15 exhibited excellent low-temperature SCR performance and SO2/H2O resistance compared with the Ce/TiO2 catalyst. Characterization results revealed that the introduction of a proper amount of Bi to Ce/TiO2 catalyst could generate more Ce3+ and chemisorbed oxygen species on its surface, along with the enhanced reducibility and surface acidity. From the results of an in situ DRIFT study, the formation of more adsorbed NH3 and NO2 species could be detected, as a result, greatly facilitating the low-temperature NH3-SCR reaction over CeBi/TiO2-0.15 catalyst through the Langmuir-Hinshelwood route.