Cu‐SSZ‐13 Catalysts Designed Through Interzeolite Conversion Process From Different Structure Types of Zeolites for NH₃‐SCR‐DeNOx: Structure‐Property Activity Relationships and Intermediates Determination

The intermediates and their respective role in reduction and oxidation cycles in the selective catalytic reduction of NO xx with ammonia reaction mechanism (NH 3 ‐SCR‐DeNO x ) are widely and controversially discussed. To finally clear up the discussion, a variety of Cu‐containing CHA structure type zeolites (Cu‐SSZ‐13) were prepared using different zeolite sources, such as MFI, BEA and FAU structure type zeolites. Cu‐SSZ‐13 prepared samples were investigated as catalysts for NH 3 ‐SCR‐DeNO x . The structure‐property‐activity relationship of the Cu‐SSZ‐13 prepared samples varied depending on the applied initial zeolite. Cu‐SSZ‐13 catalysts prepared from MFI and BEA structure types of zeolites are more N 2 selective than Cu‐SSZ‐13 catalysts prepared from FAU structure type of zeolite. In situ spectroscopy, temperature‐programmed and transient techniques supported by density functional theory (DFT) were used to investigate the reaction mechanism and confirmed the intermediates of the reduction‐ and oxidation‐half cycles: NH 4 + , NH x − , [(NH 3 ) 4 Cu II 2 O 2 ] 2+ , NO 2 − /NO 3 − species. The SCR paths involved determine that the dominant reaction occurs between adsorbed NH 3 on the catalyst surface and NO from the gas phase, as well as the reaction between adsorbed NO x − (nitrites/nitrates) and NH 3 .