One-step supramolecular fabrication of ionic liquid/ZIF-8 nanocomposites for low-energy CO2 capture from flue gas and conversion

Abstract

High-efficient capture of CO2 from flue gas at discharged temperatures (100–120 °C) and convert CO2 under mild condition is of vital importance for low energy consumption and emission reduction, which yet remains a great challenge. A one-step supramolecular strategy for incorporating amino-functionalized ionic liquids (AFILs) into ZIF-8 is proposed for capture and conversion of CO2 from flue gas at discharged temperatures. AFILs are attached through metal-coordination interaction between Zn (II) and the NH2 group on AFIL, by which the large BET surface area and high thermal stability inherited from ZIF-8 are maintained well. The nanocomposites with low IL consumptions can rapidly capture CO2 from the flue gas with a high capacity of 2.68 mmol·g−1 within 4 min and efficiently catalyze CO2 into cyclic carbonates with excellent yield (95.6%) and selectivity (97.0%) at 40 °C and 0.1 MPa. In-situ DRIFTS and DFT calculation elucidated the effective synergistic mechanism of multiple active sites (C2-proton on imidazolium ring, imidazolium cation, protons of methyl group, protons of methylene group, Cl anion and Zn (II)) for CO2 adsorption and conversion. The activities in both the CO2 capture and conversion can be easily recycled, endowing the nanocomposites with outstanding practical potentials.