Acid modification enhances selective catalytic reduction activity and sulfur dioxide resistance of manganese-cerium-cobalt catalysts: Insight into the role of phosphotungstic acid.

Improving the SO resistance of catalysts is crucial to driving commercial applications of Mn-based catalysts. In this work, the phosphotungstic acid (HPW) modification strategy was applied to improve the N selectivity, SO and HO resistance of the Mn-Ce-Co catalyst, and further, the mechanism of HWP modification on enhanced catalytic performance was explored. The results showed that HPW-Mn-Ce-Co catalyst exhibits higher NO conversion (~100% at 100-250 °C) and N selectivity (exceed 80% at 50-350 °C) due to more oxygen vacancies, greater surface acidity, and lower redox capacity. In situ diffused reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) reveal that HPW changed the reaction path of Mn-Ce-Co catalysts, promoted the adsorption and activation of NH, and reduced the effect of SO on the active bidentate nitrate species, and thereby exhibiting good SO resistance. X-ray photoelectron spectrometer (XPS) and NH temperature-programmed desorption of (NH-TPD) results show that HPW can inhibit the formation of metal sulfate, and SO can be combined with Ce species more easily. The generated Ce(SO) can not only protect Mn species but also increase the acid sites and weaken the poisoning effect of metal sulfate. This study provides a simple design strategy for the catalyst to improve the low-temperature catalytic performance and toxicity resistance.