Tailoring zeolite ERI aperture for efficient separation of CO₂ from gas mixtures

Constructing the metal cation-mediated low-cost inorganic sorbent with high separation efficiency in CO₂, N₂, and CH₄ remains a major challenge. Herein, we developed a series of alkali metal cations (Na⁺, K⁺, Rb⁺, Cs⁺)-exchanged ERI zeolites and adopted in the separation process of CO₂ among the gas mixture. Among the ion-exchanged zeolites, the zeolite K-ERI showed a high adsorption volume of 70.84 cm³g⁻¹ and an IAST selectivity of CO₂/CH₄: 6254, CO₂/N₂: 2872 at 298 K, respectively, far outweighed the reported metal cation exchanged zeolites. Combining powder X-ray diffraction crystallography and density functional theory calculations, we unequivocally unveiled that the metal cations located at s8r effectively tailored zeolite aperture, and metal cation-gas molecules interactions synergically restrained the pass-through capacity of CO₂ in ion-exchanged ERI framework. Such a unique host–guest interaction governed by metal cations in aluminosilicate zeolite ERI affords a general strategy for gas separation.