Direct synthesis of submicron Cu-SAPO-34 as highly efficient and robust catalyst for selective catalytic reduction of NO by NH3
Abstract
High-performance and ultra-stable selective catalytic reduction (SCR) catalyst with low-cost is needed for controlling NOx emissions of the Euro 6 diesel vehicle. The combination of copper-tetraethylenepentamine (Cu-TEPA) and morpholine (MOR) as templates allowed the direct synthesis of highly active and hydrothermally stable submicron Cu-SAPO-34 catalyst for SCR of NOx with NH3 (NH3-SCR). It exhibited much better catalytic activity and hydrothermal stability than the reference catalyst synthesized with Cu-TEPA, diethylamine and tetraethylammonium bromide as templates. The origin of superior SCR performance of the submicron Cu-SAPO-34 catalyst was investigated by a series of characterization techniques including XRD, N2 sorption, NMR, NH3-TPD, H2-TPR, UV-vis-DRS and XPS. Consequently, the structure-performance relationship of the submicron Cu-SAPO-34 catalyst was well established. The isolated Cu2+ ions exist predominantly in submicron Cu-SAPO-34 with a plenty of Si (nOAl) (n = 1-4) structures. These Si coordination structures could generate a large number of Brønsted acid sites, which could be beneficial for NO reduction. The typical cubic crystal and isolated Cu2+ ions remain stable even after steaming at 800 °C for 12 h. Furthermore, the amount of isolated Cu2+ ions increase and copper oxides decrease and redistribute after steaming. The NH3-SCR kinetic test further proved the superior NH3-SCR performance of the submicron Cu-SAPO-34 catalyst.
- Publication:
-
Applied Surface Science
- Pub Date:
- August 2018
- DOI:
- 10.1016/j.apsusc.2018.04.076
- Bibcode:
- 2018ApSS..448..671C
- Keywords:
-
- NH<SUB>3</SUB>-SCR;
- Submicron Cu-SAPO-34;
- Direct synthesis;
- Hydrothermal stability