In situ/operando spectroscopic studies on NH3-SCR reactions catalyzed by a phosphorus-modified Cu-CHA zeolite

The modification of Cu-exchanged zeolites with phosphorus represents a promising method to enhance their hydrothermal stability, which is of pivotal importance for catalysts that promote the selective catalytic reduction of NO with ammonia (NH3-SCR). In this study, we investigated the reaction mechanism of NH3-SCR catalyzed by a phosphorus-modified CHA zeolite that contains active Cu species (Cu-P-CHA), and assessed the effect of the phosphorus modification on the hydrothermal stability of the catalyst by employing in situ/operando spectroscopic methods. In their entirety, the combined results from in situ/operando IR, UV-vis, and XANES experiments revealed that the NH3-SCR process over Cu-P-CHA proceeds via the reduction of Cu(II) to Cu(I) followed by a reoxidation of Cu(I) to Cu(II). In addition, we found that the phosphorus modification improved the hydro thermal durability of the catalyst by retaining a higher amount of the redox-active Cu species and the zeolite framework.

Automated summary

The study investigates the reaction mechanism of NH3-SCR catalyzed by a phosphorus-modified CHA zeolite with active Cu species, revealing that the process involves reduction and reoxidation of Cu species. The phosphorus modification is found to enhance the hydrothermal durability of the catalyst, preserving more redox-active Cu species and the zeolite framework.