Abstract: NMR crystallography combines state-of-the-art highresolution solid-state NMR experiments with state-of-theart quantum chemistry calculations thus allowing determining structural and dynamic characteristics in a variety of systems. In this work, we are going to demonstrate different steps of NMR crystallography approaches with an example of supported oxide catalysts. The recent advances in NMR of oxide-based systems are primarily associated with the achievements in NMR spectroscopy of quadrupolar nuclei since the majority of NMR-observable isotopes of elements composing oxide systems possess quadrupole moments. Ultra-high magnetic fields (up to 23.5 T), ultra-high sample spinning (~ 100 kHz), as well as modern electronic components and devices together with a number of software programs allowing researchers to extract parameters of chemical shift and nuclear quadrupole interaction tensors, as well as their mutual orientation. The first step of the study was to test NMR crystallography approach on individual compounds. After, experimental NMR parameters of real catalysts were determined. Based on values obtained, several sets of models were proposed. For suggested models, NMR parameters were calculated by DFT. When a good matching between experimental and calculated NMR parameters was achieved, it was concluded that the 3D structure of surface sites is identified. It is very important that NMR crystallography in application to catalysts could serve not only for characterization of structure of surface sites, but also for characterization of their catalytic activity, for this we have to check catalytic activity of different sites by probe molecules (both experimentally and theoretically). The next step was connected with adsorption of test molecules (H2O, CO2, CH3OH, etc.) on real catalysts (experimental part) and on model surface sites (theoretical part). At this stage, it is reasonable to use additional experimental techniques (for instance, FTIR). In case of good agreement between experimantal and theoretical parameters, it is possible to determine 3D structures of active sites.

Cite: Lapina O.B. , Shubin A.A. , Papulovsky E.
NMR Crystallography as a Tool for Characterization of Active Sites of Solid Catalysts
In compilation 3rd Edition of International Conference on Advanced Spectroscopy, Crystallography and Applications in Modern Chemistry. 2018. – C.27-28. DOI: 10.21767/2470-9905-C1-005 РИНЦ OpenAlex

Identifiers:

Elibrary:	44633804
OpenAlex:	W2808249628

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