Effects of WO3 doping on stability and N2O escape of MnOx–CeO2 mixed oxides as a low-temperature SCR catalyst

• MnOx–WOx–CeO2 catalyst presents above 80% NOx conversion at 140–300 °C.
• This catalyst shows high stability and low N2O escape during the 50 h activity test.
• Brønsted acid sites contribute to high N2 selectivity and higher CO2 tolerance.
• Inhibited formation of ammonium and metal sulfates results in high SO2 resistance.

MnOx–WOx–CeO2 catalysts synthesized using a sol–gel method were investigated for the low-temperature NH3-SCR reaction. Among them, W0.1Mn0.4Ce0.5 mixed oxides exhibited above 80% NOx conversion from 140 to 300 °C. In addition, this catalyst exhibited high stability and CO2 tolerance in a 50 h activity test at 150 °C. Substantially reduced N2O production and enhanced N2 selectivity were achieved by WO3 doping, which was due to the weakened reducibility and increased number of acid sites. The decreased SO2 oxidation activity as well as the reduced formation of ammonium and manganese sulfates resulted in a high SO2 resistance of this catalyst.

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