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 SO2 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, SO2 and H2O 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 NOx conversion (similar to 100% at 100-250 degrees C) and N-2 selectivity (exceed 80% at 50-350 degrees 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 NH3, and reduced the effect of SO2 on the active bidentate nitrate species, and thereby exhibiting good SO2 resistance. X-ray photoelectron spectrometer (XPS) and NH3 temperature-programmed desorption of (NH3-TPD) results show that HPW can inhibit the formation of metal sulfate, and SO2 can be combined with Ce species more easily. The generated Ce-2(SO3)(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. (C) 2021 Published by Elsevier Inc.

Automated summary

The HPW modification strategy improved the N-2 selectivity, SO2 and H2O resistance of the Mn-Ce-Co catalyst, and the mechanism of enhanced catalytic performance was explored. The results showed that HPW modification led to higher NOx conversion and N-2 selectivity, due to more oxygen vacancies, greater surface acidity, and lower redox capacity. The study provides a simple design strategy for catalysts to improve low-temperature catalytic performance and toxicity resistance.