Comparative study on potassium poisoning of Cu-CHA catalysts for NH3-SCR: Stability and transformation of Cu2+ ions

Cu-chabazite based catalysts (Cu-SSZ-13 and Cu-SAPO-34) may suffer from chemical deactivation due to the deposition of alkali impurities on the surface of wall-flow particulate filters. In this work, the resistance of two Cu-CHA catalysts to potassium poisoning was compared, and the key factors affecting preservation and evolution of Cu 2+ ions were ascertained based on the experimental characterizations and DFT calculations. The feasibility of atom (Cu and H) at various sites (6MR and 8MR) in different types of zeolites (SSZ-13 and SAPO-34) upon K + attacking was compared. The stability of isolated Cu 2+ ions in the zeolite framework and the aggregates of detached copper species determined the catalytic performance of the poisoned catalysts. • Cu-SAPO-34 exhibits stronger potassium resistance than Cu-SSZ-13. • Majority of K + ions exchange the SSZ-13 framework bounded sites. • Potassium prefers to attacking Brønsted acid sites than Cu 2+ ions. • Loosely bounded Cu 2+ ions are more vulnerable to attack from potassium. • CuO x clusters instead of CuO crystallites form over the poisoned Cu-SAPO-34.