The X-ray absorption near edge structure (XANES) and X-ray emission spectroscopy (XES) features were modeled from first principles to aid in identification of reactants, intermediates and products at the active sites in zeolite based catalysts. The models show that the intensities of the XANES spectral features are sensitive to the Cu oxidation state, the number of solvating species (NH<sub>3</sub> or H<sub>2</sub>O), and the coordination environment around the Cu (see Figure 1). Additionally, we used XANES modeling studies of the Ga K-edge features in ZSM-5 to investigate possible configurations that could explain the Ga-Ga scattering signals that were observed experimentally. As for the modeling of the XES, the calculations confirmed, in agreement with the experimental results that are available in the literature, that this technique is a sensitive probe of the nature of the ligands. In particular, our modeling results show that it is possible to distinguish Cu-N and Cu-O bonds with this technique, as can be seen in Figure 2. Overall, our careful analysis of the XANES and the XES features of exchanged ions can help us gain further insights into the synchrotron-based experimental results, which could lead to a new understanding of the underlying reaction mechanisms.

Environmental sensitivity of spectroscopic properties for Cu ions in Cu-SSZ-13: XANES and XES studies from first principles

253rd National Meeting (2017)

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