Synergic Effect of Active Sites in Zinc-Modified ZSM-5 Zeolites as Revealed by High-Field Solid-State NMR Spectroscopy
Understanding the nature of active sites in metal-supported catalysts is of great importance towards establishing their structure–property relationships. The outstanding catalytic performance of metal-supported catalysts is frequently ascribed to the synergic effect of different active sites, which is however not well spectroscopically characterized. Herein, we report the direct detection of surface Zn species and 1H–67Zn internuclear interaction between Zn2+ ions and Brønsted acid sites on Zn-modified ZSM-5 zeolites by high-field solid-state NMR spectroscopy. The observed promotion of C-H bond activation of methane is rationalized by the enhanced Brønsted acidity generated by synergic effects arising from the spatial proximity/interaction between Zn2+ ions and Brønsted acidic protons. The concentration of synergic active sites is determined by 1H–67Zn double-resonance solid-state NMR spectroscopy.Together forever: High-field 67Zn solid-state NMR spectroscopy reveals the synergy between active sites in Zn-modified ZSM-5 zeolites. The internuclear spatial proximity/interaction between Zn2+ ions and Brønsted acid sites of the zeolites leads to a synergic effect in the C-H bond activation of methane.
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