Effects of Si/Al Ratios and Alkali Cocations on Cu/SSZ-13 NH3-SCR Catalysts: Active Cu Species, Roles of Brĝnsted Acidity, and Hydrothermal Stabilities

Cu/chabazite NH₃-SCR catalysts have recently been commercialized as part of catalytic vehicle exhaust aftertreatment systems. In the present study, varying zeolite Si/Al and Cu/Al ratios provides important insights into the changing nature during reaction of the active Cu species in state-of-the-art Cu/SSZ-13 SCR catalysts, rationalizing quite variable reactivity behavior.