Efficient Low-Pressure CO2 capture via ZIF-8 modified by deep eutectic solvents

To enhance CO 2 sorption efficiency under low-pressure conditions and effectively compete with N 2 sorption in flue gas, modifications are implemented aimed at improving the adsorption capacity and selectivity of ZIF-8, renowned for their robust stability. Deep eutectic solvent (DES) comprising tetraethylammonium chloride (TEAC), tetrapropylammonium chloride (TPAC), and tetrabutylammonium bromide (TBAB) as hydrogen-bond acceptors, along with ethanolamine (MEA) as the hydrogen-bond donor, were meticulously prepared for this purpose. ZIF-8 underwent modification through DES loading, resulting in the distinctive emergence of a “core-membrane” structure. Characterization revealed that the DES effectively adhered to the surface of ZIF-8 in a membrane-like structure, without altering the chemical structure or pore size of ZIF-8. The most significant enhancement in sorption capacity was observed with TPAC&MEA modification. Considering the presence of N 2 partial pressure in the flue gas, at 0.05 and 1 bar, the CO 2 adsorption capacities reached 1.92 and 3.03 mmol g −1 , respectively, increasing 71.11 and 4.00 times compared to pristine ZIF-8. The ZIF-8 exhibited a CO 2 /N 2 separation coefficient of 72.77, which increased to a maximum of 997.50 after DES modification. Additionally, the modified material demonstrated exceptional cyclic and thermal stability during testing. This study significantly elevates the CO 2 adsorption capacity and selectivity of solid materials within the low-pressure range, providing pivotal support for CO 2 capture and decarbonization efforts.