Insight into the enhanced tolerance of Mo-doped CeO2-Nb2O5/TiO2 catalyst towards the combined effect of K2O, H2O and SO2 in NH3-SCR.

[Display omitted] • Sulfate increased the adsorption of NH 3 , but the increased NH 3 was not active. • Mo doping could inhibit the sulfation of the catalyst. • Mo doping could alleviate the competitive adsorption among NO x , H 2 O and SO 2. • Mo doping changed the reaction mechanism of CeO 2 -Nb 2 O 5 /TiO 2 catalyst. MoO 3 -doped CeO 2 -Nb 2 O 5 /TiO 2 catalyst was synthesized by a sol–gel method. It was found that Mo doping observably enhanced the tolerance of CeO 2 -Nb 2 O 5 /TiO 2 catalyst to the combined poisoning of H 2 O, SO 2 and K 2 O. Mo doping could restrain the generation of ammonium sulfate and metal sulfate on the surface of the catalyst. This came down to the large specific surface area, strong acidity and superior redox performance of CeO 2 -MoO 3 -Nb 2 O 5 /TiO 2 catalyst. In situ DRIFTS results indicated that K/S/H-CMNT catalyst still proceeded the SCR reaction according to the L-H and E-R mechanisms together, while K/S/H-CNT catalyst only followed the E-R mechanism. Mo doping could enhance the adsorption of NH 3 and NO x species in the presence of K 2 O, H 2 O, and SO 2. [ABSTRACT FROM AUTHOR]