Versatile functionalization of de-fluorinated FMOF-1 towards enhanced carbon capture and separation: a predictive...

Area of Science:

• Materials Science
• Computational Chemistry
• Separation Science

Background:

• Fluorous metal-organic frameworks (FMOFs) are superhydrophobic materials with potential for gas adsorption.
• Existing FMOFs utilize -CF3 or -F groups, but their functionalization for enhanced CO2 capture is underexplored.

Purpose of the Study:

• To computationally design and analyze functionalized FMOF-1-X (X = -OCH3, -CN, -OH, -COOH, -NH2) for CO2 adsorption and separation.
• To evaluate the impact of functional groups on CO2, CH4, and N2 adsorption properties and selectivity.

Main Methods:

• Grand Canonical Monte Carlo (GCMC) simulations for adsorption isotherms of CO2, CH4, and N2.
• Molecular Monte Carlo simulations to determine Henry's constant (KH) and isosteric heat of adsorption (Qst0).
• MP2 quantum-mechanical simulations for binding energy (BE) calculations.
• Ideal Adsorbed Solution Theory (IAST) for predicting selectivity in binary gas mixtures.

Main Results:

• Functionalization systematically enhanced KH, Qst0, and BE compared to the parent FMOF-1.
• The -COOH functionalized FMOF-1 exhibited the highest CO2 uptake at low pressures and superior CO2/CH4 (59.6) and CO2/N2 (128.7) selectivity.
• The -OH functionalized FMOF-1 showed the highest CO2 uptake at high pressures (30 bar).
• All functionalized MOFs demonstrated higher CO2 uptake than the parent FMOF-1.

Conclusions:

• Replacing -CF3 groups with -OH, -COOH, or -NH2 significantly enhances CO2 adsorption capacity and selectivity in FMOF-1.
• The -COOH functionalized FMOF-1 is a promising candidate for efficient CO2 separation and capture.
• These findings support the application of functionalized MOFs in natural gas purification, landfill gas separation, and flue gas treatment.