Direct evidence of the role of dispersed ceria on the activation of oxygen in NaX zeolite by coupling the 17O/16O isotopic exchange and 17O solid-state NMR

The possibility to understand the phenomena of oxygen diffusion in the solids may be decisive to explain the role of framework oxygen atoms in a catalytic mechanism or in catalyst regeneration steps. In this work, two highly efficient characterization techniques have been associated: the 17O/16O isotopic exchange and the 17O high field solid-state NMR spectroscopy. This combination leads to a powerful tool to investigate the interaction between gaseous dioxygen molecule and lattice oxygen atoms. Here, it permits to demonstrate the enhancement of the participation of zeolitic oxygen atoms in the exchange with the gas phase when ceria is simply mixed with NaX.

Graphical abstractAssociation of oxygen isotopic exchange and 17O solid-state NMR gives by a simple experimental approach the direct evidence that the presence of ceria over the external surface of the NaX is sufficient to enhance the capacity of the zeolite to exchange its oxygen atoms with the gas phase.Figure optionsDownload full-size imageDownload high-quality image (155 K)Download as PowerPoint slideHighlights► 17O/16O Isotopic exchange and 17O solid-state NMR have been originally combined. ► We report the capacity of the zeolite to exchange its oxygen atoms with the gas phase. ► The exchange is enhanced by the oxygen spillover from the ceria to the NaX surface.