Unveiling the Promoting Effects of Zr and the Hydrothermal Treatment on the NH<sub>3</sub>-SCR Activity of the Cu-SAPO-18 Catalyst
Yao Wang, Zhangpei Liu, Zhangpei Liu, Junhua Li, Pengfei An, Zhiming Liu, Zhiming Liu
Abstract
Selective catalytic reduction of NO x by NH 3 (NH 3 -SCR) remains challenging for diesel vehicles due to the complex exhaust condition. Cu-SAPO-18 zeolite has emerged as an efficient catalyst for the NH 3 -SCR process, attributed to its unique small pore configuration and high NH 3 -SCR activity. Herein, Zr-modified Cu-SAPO-18 has been fabricated and evaluated for the reduction of NO x . The addition of Zr to Cu-SAPO-18 led to enhanced activity, with the 0.05 wt % Zr-doped Cu-SAPO-18 catalyst achieving more than 90% NO x conversion across a temperature span of 230 to 470 °C. More importantly, hydrothermal aging at 750 °C further enhanced the activity significantly, achieving nearly 100% NO x conversion at 175 °C. The presence of Zr led to an increased amount of Cu 2+ species and acid sites, while the hydrothermal treatment promoted a significant increase in acidity and facilitated the conversion of some Cu 2+ to Cu x O y species, which is crucial for the enhanced activity. The present research provides insights into the development of high-efficiency small-pore zeolite-based NH 3 -SCR catalysts, offering valuable implications for both fundamental research and industrial catalysis.