Rapid synthesis of hierarchical cerium-based metal organic frameworks for carbon dioxide adsorption and selectivity

The creation of innovative porous materials for CO2 capture and separation is proving extremely relevant for environmental sustainability and global warming mitigation. In this study, modified Ce-UiO-66 MOFs were synthesized in 10 min using simultaneous microwave and ultrasound irradiation method. The porosity of the MOF was altered using the soft-templating approach. This strategy resulted in the construction of a hierarchically micro-mesoporous structure with an average mesopore size of 11.10 nm. The as-obtained MOFs, abbreviated as CUT, were characterized with SEM, XRD, FTIR, TGA, BET, and evaluated as CO2 adsorbents. The results displayed preserved crystal structure, higher thermal stability up to 570 degrees C. The heightened diffusion of CO2 molecules to the micropores promoted by mesopore channels, endued CUT with an over-all CO2 adsorption uptake of 2.53 mmol/g at 273 K at 1 bar outperforming equivalent Ce-UiO-66 MOFs. Notably, the CUT adsorbent showed improved CO2/N2 IAST selectivity (34.2 vs 24.6) and CO2 isosteric heat of adsorption (Qst = 30.15 vs 25 kJ/mol) in contrast to pristine UiO-66 (Zr).