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

Abstract

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.