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 2 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 2 selectivity , SO 2 and H 2 O 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 x conversion (~100% at 100–250 °C) and N 2 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 3 , and reduced the effect of SO 2 on the active bidentate nitrate species, and thereby exhibiting good SO 2 resistance. X-ray photoelectron spectrometer (XPS) and NH 3 temperature-programmed desorption of (NH 3 -TPD) results show that HPW can inhibit the formation of metal sulfate , and SO 2 can be combined with Ce species more easily. The generated Ce 2 (SO 3 ) 3 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.