Optimized CO₂ Capture of the Zeolitic Imidazolate Framework ZIF-8 Modified by Solvent-Assisted Ligand Exchange

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Zeolitic imidazolate frameworks (ZIFs), particularly ZIF-8, are promising for CO2 capture.
• Structural modification via ligand exchange enhances CO2 absorption capacity.
• Solvent-assisted ligand exchange (SALE) is a key strategy for tuning ZIF properties.

Purpose of the Study:

• To investigate the effect of functionalized imidazole derivatives on CO2 adsorption in nanosized ZIF-8 (nZIF-8).
• To optimize CO2 capture capacity through SALE modifications and varying treatment times.
• To establish new benchmarks for CO2 adsorption in ZIF materials.

Main Methods:

• Solvent-assisted ligand exchange (SALE) was performed on nZIF-8 using various imidazole derivatives.
• Characterization of modified nZIF-8 structures to confirm topology and porosity maintenance.
• Low-pressure CO2 adsorption measurements were conducted at standard temperature and pressure (STP).

Main Results:

• SALE modifications maintained the sodalite topology and porosity of nZIF-8.
• Mixed-linker SALE products showed enhanced CO2 adsorption compared to pristine nZIF-8.
• Halogenated ligands increased CO2 uptake by 11-22%, while thiol and nitro groups yielded 32% and 100% increases, respectively.
• Optimized SALE treatment times led to record CO2 uptakes of 87 cm3 g-1 (SHbIm) and 98 cm3 g-1 (NO2Im).

Conclusions:

• Functionalized imidazole ligands significantly enhance CO2 adsorption in nZIF-8.
• Thiol- and nitro-functionalized ligands show exceptional performance for CO2 capture.
• The modified nZIF-8 materials demonstrate record-breaking CO2 adsorption capacities at low pressures, highlighting their potential for industrial applications.