Selective adsorption of CO2 in TAMOF-1 for the separation of CO2/CH4 gas mixtures
Santiago Capelo, Mabel de Fez-Febré, Salvador Rodríguez Gómez, Juanjo Cabezas‐Giménez, Raiana Tomazini de Oliveira, Irene I. Gallo Stampino, Anton Vidal‐Ferran, Jesús González‐Cobos, Vanesa Lillo, Óscar Fabelo, Eduardo C. Escudero‐Adán, Larry R. Falvello, J.B. Parra, Paolo Rumori, Gemma Turnes Palomino, Carlos Palomino Cabello, Stefano Giancola, Sofı́a Calero, José Ramón Galán‐Mascarós
Abstract
TAMOF-1 is a robust, highly porous metal–organic framework built from Cu2+ centers linked by a L-histidine derivative. Thanks to its high porosity and homochirality, TAMOF-1 has shown interesting molecular recognition properties, being able to resolve racemic mixtures of small organic molecules in gas and liquid phases. Now, we have discovered that TAMOF-1 also offers a competitive performance as solid adsorbent for CO2 physisorption, offering promising CO2 adsorption capacity ( > 3.8 mmol g–1) and CO2/CH4 Ideal Adsorbed Solution Theory (IAST) selectivity ( > 40) at ambient conditions. Moreover, the material exhibits favorable adsorption kinetics under dynamic conditions, demonstrating good stability in high-humidity environments and minimal degradation in strongly acidic media. We have identified the key interactions of CO2 within the TAMOF-1 framework by a combination of structural (neutron diffraction), spectroscopic and theoretical analyses which conclude a dual-site adsorption mechanism with the majority of adsorbed CO2 molecules occupying the empty voids in the TAMOF-1 channels without strong, directional supramolecular interactions. This very weak dominant binding opens the possibility of a low energy regeneration process for convenient CO2 purification. These features identify TAMOF-1 as a viable solid-state adsorbent for the realization of affordable biogas upgrading. The metal-organic framework TAMOF-1 offers high performance for CO2 capture and purification from model biogas streams, thanks to its high CO2 adsorption potential, good stability in humid conditions, and energy-efficient regeneration.