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

MoO3-doped CeO2-Nb2O5/TiO2 catalyst was synthesized by a sol-gel method. It was found that Mo doping observably enhanced the tolerance of CeO2-Nb2O5/TiO2 catalyst to the combined poisoning of H2O, SO2 and K2O. 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 CeO2-MoO3-Nb2O5/TiO2 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 NH3 and NOx species in the presence of K2O, H2O, and SO2.