Potassium poisoning impact on FeCu selective catalytic reduction catalyst: Structure and mechanism

Alkali metals bring great challenges to the elimination of NOx from stationary emissions in the selective catalytic reduction (SCR) reaction. The FeCu catalyst, as an eco-friendly and high-efficiency catalyst for NOx removal possesses wide application prospects. However, the poisoning effect of potassium is not clear. Therefore, the potassium poisoning catalyst was obtained by the wet impregnation means. The XRD, H2-TPR, NH3-TPD, XPS and DRIFT technologies were performed to study the influence of K poisoning. The results indicate that potassium causes damage to Cu-O-Fe construction. Then the Cu2+ in lattice of Fe2O3 separate out from Fe2O3 and form CuO which leads to the decline of acid sites and excessive NH3 oxidation. And it finally leads to the catalyst deactivation. After K poisoning, NO2, monodentate nitrates and nitrites cannot generate. Only bidentate nitrates can generate and then react with NH3 species on the Lewis acid sites to produce H2O and N2. Hence, the reaction rate has a slide.