SO2- and H2O-Tolerant Catalytic Reduction of NOxat a LowTemperature via Engineering Polymeric VOxSpecies by CeO2

Selective catalytic reduction (SCR) of NOxoverV2O5-based oxide catalysts has been widely used, but it is still achallenge to efficiently reduce NOxat low temperatures under SO2and H2O co-existence. Herein, SO2- and H2O-tolerant catalyticreduction of NOxat a low temperature has been originallydemonstrated via engineering polymeric VOxspecies by CeO2. Thepolymeric VOxspecies were tactfully engineered on Ce-V2O5composite active sites via the surface occupation effect of Ce, andthe obtained catalysts exhibited remarkable low-temperatureactivity and strong SO2and H2O tolerance at 250 degrees C. The stronginteraction between Ce and V species induced the electron transferfrom V to Ce and tuned the SCR reaction via the E-R pathwaybetween the NH4+/NH3species and gaseous NO. In the presence of SO2and H2O, the polymeric VOxspecies had not been hardlyinfluenced, while the formation of sulfate species on Ce sites not only promoted the adsorption of NH4+species and the reactionbetween gaseous NO and NH4+but also facilitated the decomposition of ammonium bisulfate through weakening the strong bondbetween HSO4-and NH4+. This work provided a new strategy for SO2- and H2O-tolerant catalytic reduction of NOxat a lowtemperature.

Automated summary

Selective catalytic reduction (SCR) of NOx using V2O5-based oxide catalysts is a widely used technique, but reducing NOx efficiently at low temperatures in the presence of SO2 and H2O remains a challenge. In this study, engineering polymeric VOx species on CeO2 was found to enable SO2- and H2O-tolerant catalytic reduction of NOx at low temperatures. The polymeric VOx species were formed through the interaction between Ce and V species, and played a role in tuning the SCR reaction. In the presence of SO2 and H2O, the polymeric VOx species remained largely unaffected, while the formation of sulfate species on Ce sites promoted NH4+ adsorption, the reaction between gaseous NO and NH4+, and the decomposition of ammonium bisulfate.