The synergy between H + and Li + ions within the flexible 8MR gate of the SAPO-RHO zeolite enables highly efficient separation of C2H4 and C2H6 with unprecedented selectivity. Due to the low cost and scalability of zeolites, this approach has the potential to replace traditional energyintensive cryogenic distillation for C2H4/C2H6 separation with cost-effective adsorptive separation technologies, offering a transformative solution for the industry . This study reveals a collective mechanism that enhances adsorptive selectivity through steric effects, equilibrium considerations, kinetic factors, and the 'trapdoor' effect. These findings provide a foundation for the rational design and synthesis of zeolitic adsorbents, paving the way for their application in other challenging separations. Examples include alkene/alkane mixtures, benzene derivatives, greenhouse gases from dilute emissions, and hydrogen isotopes (e.g., D2 and T2 from H2).