17O-EPR determination of the structure and dynamics of copper single-metal sites in zeolites

• Published in: Nature communications Vol. 12; no. 1; p. 4638
• Main Authors: Bruzzese, Paolo Cleto, Salvadori, Enrico, Jäger, Stefan, Hartmann, Martin, Civalleri, Bartolomeo, Pöppl, Andreas, Chiesa, Mario
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 30.07.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 119/118; 639/301/299/1013; 639/638/77/885; 639/638/77/887; Catalysis; Copper; Humanities and Social Sciences; Labeling; Metal oxides; Metals; Migratory species; multidisciplinary; Science; Science (multidisciplinary); Selectivity; Water pressure; Zeolites
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-021-24935-7

The bonding of copper ions to lattice oxygens dictates the activity and selectivity of copper exchanged zeolites. By 17 O isotopic labelling of the zeolite framework, in conjunction with advanced EPR methodologies and DFT modelling, we determine the local structure of single site Cu II species, we quantify the covalency of the metal-framework bond and we assess how this scenario is modified by the presence of solvating H 2 16 O or H 2 17 O molecules. This enables to follow the migration of Cu II species as a function of hydration conditions, providing evidence for a reversible transfer pathway within the zeolite cage as a function of the water pressure. The results presented in this paper establish 17 O EPR as a versatile tool for characterizing metal-oxide interactions in open-shell systems. The identification of catalytically active sites with atomic-scale precision occupies a central place in the theory and practice of heterogeneous catalysis. Here the authors assess the nature of the copper-oxygen bond in a Cu-CHA zeolite and recover the microscopic structure of single-metal sites.