Hydrothermal deactivation over CuFe/BEA for NH3-SCR

During the hydrothermal treatment process, the hydrothermal agglomeration could decrease Brønsted acid sites for NH3 adsorption and Cu/Fe ion sites for NO oxidation to NO2, which are the main factors for the lower deNOx activity of CuFe/BEA-A than CuFe/BEA. [Display omitted] •The decrease of Brønsted acid sites and redox sites is the major factor of hydrothermal deactivation over CuFe/BEA.•The collapse of BEA structure decreases the ability to absorb and active the reactant molecule NH3.•Aggregation of active species depresses oxygen vacancies and charge transfer between Cu/Fe.•Both CuFe/BEA and CuFe/BEA-HT follow E–R mechanism for NH3-SCR at 225°C. Hydrothermal deactivation over CuFe/BEA and CuFe/BEA-HT for the selective catalytic reduction of NO with NH3 (NH3-SCR) were investigated with different characterizations. The hydrothermal treatment destroys BEA skeleton, losing acid sites reacting with the aerial NOx. H2-TPR and XPS reveal that the hydrothermal treatment could weaken the interaction between Cu/Fe species and the surrounding other atoms, causing the aggregation of isolated and low nuclearity copper/iron species. Aggregated copper/iron oxides depress the redox property of CuFe/BEA-HT, producing the lower concentration of NO2. Besides, results of in situ DRIFTS also indicate that both CuFe/BEA and CuFe/BEA-HT follow Eley–Rideal (E–R) mechanism at 225°C.