Experimental and Computational Study of Functionality Impact on Sodalite–Zeolitic Imidazolate Frameworks for CO₂Separation

Abstract

This study deals with the enhancement of CO 2 uptake by ligand functionalization of zeolitic imidazolate framework (ZIF) materials. The ligand dipole moment could be considered as one of the main criteria for CO 2 adsorption enhancement. To verify this hypothesis, an experimental–computational study was performed on an isoreticular ZIF series with sodalite (SOD) topology using published structures (ZIF-8, ZIF-90, and ZIF-Cl) as well as hypothetical structures (ZIF-COOH and ZIF-NO 2 ) designated using DFT calculations. An analysis of structural and adsorptive properties was proposed for these materials used to separate CO 2 from CH 4, CO, or N 2 gas. The accuracy of the calculated results was validated by comparison with our own experimental results. An exponential relationship between the ligand dipole moments and the isosteric heat of adsorption of CO 2 was highlighted. Modifying the nature of the linker (dipole moment) allows a 5- to 7-fold improvement in CO 2 selectivity for CO 2 /CH 4, CO 2 /N 2, and CO 2 /CO mixtures.