In materials with higher Li + content, such as Li-4-SAPO-RHO and Li-5-SAPO-RHO, additional Li + ions occupy less stable positions within the 8MR. This significantly reduces C2H4 diffusion and completely blocks C2H6 adsorption, as confirmed experimentally. Overall, this analysis demonstrates the significant role of protons and Li + ions in modulating the diffusion barriers of C2H4 and C2H6, and shows that the synergy between protons (H + ) and Li + ions is crucial for the enhanced separation performance of C2H4 and C2H6 achieved with Li-2-SAPO-RHO.