Electrostatically driven kinetic inverse CO2/C2H2 separation in LTA-type zeolites

The identical molecular size and similar physical properties of carbon dioxide (CO 2 ) and acetylene (C 2 H 2 ) make their adsorptive separation extremely challenging to achieve with most adsorbents. Reports on the separation of CO 2 and C 2 H 2 mixtures by zeolites are even rarer with the mechanism of adsorptive separation requiring further exploration. In this paper, we report that ion modulation of zeolite 5A promotes the difference in kinetic diffusion of CO 2 and C 2 H 2 , realizing the inverse separation of zeolite from selective adsorption of C 2 H 2 to selective adsorption of CO 2 . Creating a compact pore space restricting the orientation of gas molecules enables charge recognition. The positive electrostatic potential at the pore openings was utilized to hinder the diffusion of C 2 H 2 between the cages while ensuring the transfer of CO 2 , increasing their diffusion differences in pore channels and leading to the CO 2 /C 2 H 2 kinetic selectivity of 31.97. Grand canonical Monte Carlo (GCMC) simulation demonstrates that the CO 2 distribution in K-5A- β is significantly higher than that of C 2 H 2 . Dynamic breakthrough experiments verify the excellent performance of material in practical CO 2 /C 2 H 2 separation, for CO 2 /C 2 H 2 (50/50 and 1/99, V/V) mixtures can be separated in one step, thus directly generating high purity C 2 H 2 (> 99.95%), which provides a promising thought for the zeolite-based separation of CO 2 and C 2 H 2 .