Effective Way to Control the Performance of a Ceria-Based DeNOx Catalyst with Improved Alkali Resistance: Acid–Base Adjusting

Abstract

Compared with V2O5–WO3/TiO2, the ceria catalyst supported on sulfated zirconia (referred to as CeSZ) shows a superior alkali resistance for selective catalytic reduction of NO in flue gases. It reveals an unexpected result that a moderate amount of potassium (normally considered as SCR poisons) could even enhance the activity of CeSZ catalyst. To investigate this exceptional phenomenon, we studied the surface acid–base properties of CeSZ catalysts with different amounts of K and their influences on SCR performances. Although K resulted in a sharp decrease in Bronsted acid sites, the total acidity, especially strong acidity, barely changed when K/Ce was less than 0.4. It was proposed that a small amount of potassium could initially alter some Bronsted acid sites to Lewis ones, therefore retaining the majority of total acidity. Moreover, increased surface basicity due to K depositing led to an enhancement in NO chemisorption and oxidation, which is beneficial to the SCR process via the reaction of NO2 and N...