Paving the Way for the Molecular-Level Design of Adsorbents for Carbon Capture: A Quantum-Chemical Investigation of the Adsorption of CO₂ and N₂ on Pure-Silica Chabazite

Pure-silica chabazite is a promising material for capturing CO2 from flue gases in adsorption-based carbon capture and storage. The adsorption of CO2 and N2 on pure-silica chabazite has been studied at the molecular level with Density Functional Theory in the finite cluster/supermolecule approach. Molar enthalpies of adsorption of CO2 and N2 have been calculated with excellent agreement (<1.0 kJ/mol) with the experimental values. Additionally, the experimental structural information available in the case of CO2 could be correctly reproduced and even better interpreted. Vibrational frequency shifts for both adsorbate molecules and site-specific information for the case of N2, which are not yet available from experiment, could be anticipated. The results of this work indicate that this type of analysis may pave the way for the development of a new generation of adsorbents, designed at the molecular level, for capturing CO2 from flue gases by adsorptive separation processes.