BTC-based metal-organic frameworks: Correlation between relevant structural features and CO2 adsorption performances

The combined favorable properties of large surface area, permanent porosity and tunable pore size/functionality, have enabled metal-organic frameworks (MOFs) as ideal candidates for CO2 capture in post-combustion configuration. At the present, the volumetric capacity of MOFs toward CO2 is rarely studied and breakthrough experiments of simulated flue gas to evaluate the CO2 uptake capacity under dynamic conditions are not always performed. In this work three 1,3,5-benzenetricarboxylic acid (BTC) based MOFs differing in morphology and textural properties were produced and characterized by breakthrough experiments in order to assess the influence of MOFs structural/textural properties on CO2 sorption capacity. The selected BTC-base MOFs were: ZnHKUST-1 for its low surface area and for the presence of coordinatively unsaturated metal sites, Al-MIL-96 for the basic environment inside its pores and Fe-MIL-100 for its microporous character and high surface area. The experimental campaign evidenced that the CO2 uptake follows the Al-MIL-96 > Zn-HKUST-1 > Fe-MIL-100 order and that in all three BTC-MOFs the chemistry of the pores has a larger impact on CO2 sorption capacity than porosity under post-combustion conditions.