Improving the low-temperature SO2 and H2O resistance and N2 selectivity of manganese oxide(MnOx) catalysts is a major challenge in achieving industrial applications. This issue can be effectively addressed by using phosphotungstic acid (HPW) modified MnCeOx-N aerogel catalysts. The HPW-MnCeOx-N catalysts demonstrated excellent NOx conversion (∼100 % at 150–400 °C) and N2 selectivity (>90 % at 50–400 °C). Notably, even under challenging conditions such as 250 ppm SO2 at 250 °C, the catalytic activity of HPW-MnCeOx-N remained largely intact. The NOx conversion was still able to be maintained at 95 % even under the influence of 10 vol% H2O. This represents a significant improvement of 14 % and 5 % compared to the unmodified MnOx-N and MnCeOx-N catalysts, respectively. The integration of HPW within the lattice structure of the HPW-MnCeOx-N catalyst results in an increased number of oxygen vacancies and stronger surface acidity. The interaction between HPW and CeO2 promotes the formation of Ce4+-O-W species, which in turn modifies the redox properties of the MnCeOx-N catalyst. This modification leads to a suppression of NH species formation, thereby improving the selectivity towards N2 production. Physicochemical analyses have shown that the presence of HPW alters the reaction pathway of the MnCeOx-N catalyst, increasing the adsorption of NH3 species and significantly enhancing the generation of bidentate nitrate species, thereby facilitating the reaction through the L-H mechanism. On the HPW-MnCeOx-N catalyst, SO2 mainly inhibits the generation of monodentate nitrate and bridged nitrate species, while having little effect on the major active bidentate nitrates.
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