Improved NOx Reduction in the Presence of SO2 by Using Fe2O3-Promoted Halloysite-Supported CeO2–WO3 Catalysts

Currently, selective catalytic reduction (SCR) of NOx with NH3 in the presence of SO2 by using vanadium-free catalysts is still an important issue for the removal of NOx for stationary sources. Developing high-performance catalysts for NOx reduction in the presence of SO2 is a significant challenge. In this work, a series of Fe2O3-promoted halloysite-supported CeO2–WO3 catalysts were synthesized by a molten salt treatment followed by the impregnation method and demonstrated improved NOx reduction in the presence of SO2. The obtained catalyst exhibits superior catalytic activity, high N2 selectivity over a wide temperature range from 270 to 420 °C, and excellent sulfur-poisoning resistance. It has been demonstrated that the Fe2O3-promoted halloysite-supported CeO2–WO3 catalyst increased the ratio of Ce3+ and the amount of surface oxygen vacancies and enhanced the interaction between active components. Moreover, the SCR reaction mechanism of the obtained catalyst was studied using in situ diffuse reflectanc...