Functionalized MOFs for Enhanced CO₂ Capture

Abstract

Based on computational studies, we propose new metal−organic framework materials, in which the bridging ligands have been functionalized by different substituents, with the aim of improving the CO₂ adsorption capacity of the material. The materials are based on the large-pore form of MIL-53(Al³⁺), with the following functional groups: OH-, COOH-, NH₂-, and CH₃-. For each form, adsorption heats and isotherms were simulated using the Grand Canonical Monte Carlo method which were found to be consistent with DFT calculations. The study illustrates the enormous impact of the functional groups in enhancing CO₂ capture in the pressure range 0.01−0.5 bar and at room temperature. It also provides important insights into the structural factors which play a key role in the CO₂ adsorption process in the functionalized MOFs. We propose the material (OH)₂-MIL-53(Al³⁺) as an optimal candidate for improved CO₂ capture at low pressures.