Effect of Zr Addition on the Low-Temperature SCR Activity and SO2 Tolerance of Fe-Mn/Ti Catalysts

Zr is added to the Fe-Mn/Ti catalyst to increase NO conversion and improve SO2 tolerance. It is found that 0.03 is the optimal ratio for Zr/(Ti + Zr). With this ratio, the NO conversion below 150 degrees C increases, and the SO2 poisoning is alleviated, while the further increase of Zr does not have a positive effect on NO conversion and SO2 tolerance. With Zr additive, more manganese oxides are reduced in the form of MnO2 and Mn2O3 at lower temperature in H-2-TPR, and the total amount of H-2 consumption rises, indicating better redox properties. It leads to the increase of NO complexes on the catalysts. Despite the small decrease of NH3 adsorption, the reaction via the L-H way is promoted and NO conversion increases. Furthermore, more nitrates and NO2 are formed in the reaction with SO2 on Fe-Mn/Ti Zr(0.03) compared to Fe-Mn/Ti, so the L-H reaction way is less inhibited by SO2 with Zr additive, and the SO2 tolerance of this catalyst is also improved.