Boosting the catalytic performance of Cu-SAPO-34 in NOx removal via hydrothermal treatment.

• P modified Cu-SAPO-34 were prepared using bulk CuO particles as Cu2+ precursor. • The high-temperature hydrothermal aging significantly enhanced de-NO x performance. • The amount of active sites-isolated Cu2+ and Brønsted acid sites was greatly enhanced. • Phosphate ions also contributed to the catalysis performance of the aged samples. Phosphate ions promoted Cu-SAPO-34 (P-Cu-SAPO-34) were prepared using bulk CuO particles as Cu2+ precursor by a solid-state ion exchange technique for the selective catalytic reduction of NO x with NH 3 (NH 3 -SCR). The effects of high temperature (H-T) hydrothermal aging on the NO x removal (de-NO x) performance of Cu-SAPO-34 with and without phosphate ions were systematically investigated at atomic level. The results displayed that both Cu-SAPO-34 and P-Cu-SAPO-34 presented relatively poor NO x removal activity with a low conversion (< 30%) at 250-500°C. However, after H-T hydrothermal treatment (800°C for 10 hr at 10% H 2 O), these two samples showed significantly satisfied NO x elimination performance with a quite high conversion (70%-90%) at 250-500°C. Additionally, phosphate ions decoration can further enhance the catalytic performance of Cu-SAPO-34 after hydrothermal treatment (Cu-SAPO-34H). The textural properties, morphologies, structural feature, acidity, redox characteristic, and surface-active species of the fresh and hydrothermally aged samples were analyzed using various characterization methods. The systematical characterization results revealed that increases of 28% of the isolated Cu2+ active species (Cu2+-2Z, Cu (OH)+-Z) mainly from bulk CuO and 50% of the Brønsted acid sites, the high dispersion of isolated Cu2+ active component as well as the Brønsted acid sites were mainly responsible for the accepted catalytic activity of these two hydrothermally aged samples, especially for P-Cu-SAPO-34H. [Display omitted] [ABSTRACT FROM AUTHOR]