Fig. 5. Operando XAS and XES spectra of a Cu-CHA catalyst (Cu/Al = 0.48; Si/Al = 15) during NH3-SCR in the 150–400 °C range. (a) Cu K-edge XANES. (b) Magnitudes of FT-EXAFS spectra; (c) valence-to-core Cu Kβ XES; the inset reports a magnification of the Kβ′′ satellite peak, highly sensitive to the type of ligands. (d) Structural models of the main Cu-species identified by X-ray spectroscopy in the low- and high-temperature range under NH3-SCR conditions, including Cu+(NH3)2 and ZCu2+OH/ZCu2+NO3, respectively; colour code: green, Cu; grey, Si; yellow, Al; red, O; white, H. Unpublished figure reporting data from ref. 51.
