Predicting flue gas component adsorption in CALF-20: A molecular dynamics study anchored by experimental CO2 capture
Year: 2025
Type: article
Abstract: This study investigates the efficacy of the zinc-triazole-oxalate-based metal-organic framework (MOF), CALF-20, for carbon dioxide (CO 2 ) capture, combining experimental analysis and molecular dynamics (MD) simulations. The CALF-20 adsorbent was successfully synthesized and characterized using XRD, FTIR, FESEM, and N 2 adsorption-desorption techniques, confirming its crystalline structure, chemical integrity, and mesoporous nature. Experimental adsorption studies at temperatures and pressures revealed a CO 2 uptake of approximately 4.72 mmol/g at 298 K and 1 bar. Isotherm and kinetic modeling indicated that adsorption is well described by the Freundlich and fractional-order kinetic models, suggesting a complex mechanism on a heterogeneous surface. Thermodynamic analysis confirmed the process is spontaneous and exothermic (ΔH° = −10.024 kJ/mol), characteristic of physisorption. MD simulations used the DREIDING force field in LAMMPS for the CALF-20 framework and single-component (CO 2 , N 2 ), binary (CO 2 N 2 ), and ternary (CO 2 N 2 H 2 O) simulations. Complementary ternary simulations in RASPA used DREIDING for CO2 and N2, but employed the TIP4P water model for H2O to improve the accuracy of water-adsorption predictions (hydrogen bonding and electrostatics). These simulations confirmed CALF-20′s higher affinity for CO 2 than for N 2 and provided mechanistic insight into moisture effects—competitive H 2 O uptake that modestly reduces CO 2 adsorption at higher pressures, while overall CO 2 selectivity is preserved. IAST-predicted selectivity for a CO 2 N 2 mixture (12.5:87.5 %) reached ∼140 at 298 K and 0.1 bar. CALF-20 also exhibited excellent cyclic stability, with negligible loss in capacity over 10 adsorption-desorption cycles. These integrated findings underscore the potential of CALF-20 as a robust, selective, and reusable adsorbent for post-combustion CO 2 capture applications.
Authors: Mohammad Sadegh Khodadadi, Ahad Ghaemi
Institution: Iran University of Science and Technology
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
SDG: Climate action
Open Access status: gold
Estimated APC paid: $2,050
OpenAlex ID: W4415536643