To validate these findings, solid-state 7 Li MAS NMR experiments and theoretical calculations of the chemical shifts were performed for 7 Li-2-SAPO-RHO (figs. and). The NMR results showed that the chemical shift at -0.6 ppm corresponds to the Li1 positions, while shifts at -1.0 and -1.9 ppm are associated with the Li2 sites. These combined analyses provide a detailed understanding of the structural features responsible for the high C₂H₄/C₂H₆ selectivity of Li-2-SAPO-RHO. Specifically, the strategic placement of Li⁺ ions within the framework plays a critical role in its exceptional separation performance.