SO<sub>2</sub> Poisoning, Regeneration, and Impact on Dimer-Cu Intermediates in the NH<sub>3</sub>-SCR Reaction over Cu-Zeolites
Wenqing Ding, Yu Fu, Huibin Liu, Tongliang Zhang, Yu Sun, Zhongqi Liu, Sen Xue, Xuewang Han, Jinpeng Du, Peirong Chen, Yulong Shan, Yunbo Yu, Hong He
Abstract
This study demonstrates that Al-rich, high-Cu-loaded Cu-SSZ-13 exhibits superior resistance to SO 2 poisoning under actual SCR conditions. The high Cu content mitigates the risk of SO 2 -induced structural degradation. A key finding is that lower regeneration temperatures can lead to more severe secondary poisoning, while high temperatures induce hydrothermal aging. Thus, controlling the regeneration temperature is critical for maintaining long-term catalyst stability. Additionally, experimental results and DFT calculations show that SO 2 preferentially reacts with dimer-Cu species, especially hydrogenated dimer-Cu ([Cu II 2 (NH 3 ) 4 (OH)O] + ), resulting in significant sulfate accumulation. This interaction inhibits the redox cycle of Cu + /Cu 2+, thereby suppressing low-temperature activity. Overall, this work elucidates the mechanisms of SO 2 -induced deactivation in Cu-zeolite SCR catalysts and provides valuable insights into designing Cu-SSZ-13 catalysts with enhanced sulfur resistance through Cu-Al co-optimization.