Insight into the SO2 poisoning mechanism for NOx removal by NH3-SCR over Cu/LTA and Cu/SSZ-13

Journal article, 2020

In this study, Cu/LTA and Cu/SSZ-13 catalysts are examined for sulfur poisoning and regeneration. The nature of the Cu species was probed with H2-TPR and in-situ DRIFTS. These characterizations collectively indicate that primarily Z2Cu is present in Cu/LTA, whereas Cu/SSZ-13 contains a higher concentration of ZCuOH. ZCuOH is proved to be more vulnerable to SO2 poisoning than Z2Cu sites in both Cu/zeolites. H2-TPR results suggest that the interaction of ZCuOH with the framework in Cu/LTA is much weaker than in Cu/SSZ-13, thereby leading to more susceptibility to SO2adsorption. Moreover, Cu/LTA can store more SO2 under NH3-SCR conditions in the presence of SO2, and it also has a slower deactivation rate due to the different location of generated (NH4)2SO4. Cu/LTA can be fully restored after regeneration at 750°C. However, Cu/SSZ-13 experiences a loss of activity at high temperature, which is attributed to newly formed CuOx clusters.