Imidazolium-based poly(ionic liquid)s@MIL-101 for CO2 adsorption and subsequent catalytic cycloaddition without additional cocatalyst and solvent

Imidazolium-based ionic liquid 1,n-dialkyl-3,3 '-bis-1-vinyl imidazolium dibromide (n = 2, 4 and 6) monomers were synthesized and further polymerized inside a MIL-101 framework to afford poly(ionic liquid)@MIL-101 composites (PIL-n@MIL-101, n = 2, 4 and 6). Furthermore, the ratio of poly(ionic liquid) to MIL-101 affected the structures of the composites. Different molar ratios of PIL-4/MIL-101 were prepared and characterized using elemental analysis, powder X-ray diffractometry, thermogravimetric measurements, N-2 adsorption/desorption and CO2 adsorption measurements. Thanks to the high Brunauer-Emmett-Teller surface area and porous structure of MIL-101 together with the incorporated poly(ionic liquid), PIL-4@MIL-101-0.5 exhibited good CO2 uptake capacity (42.7 cm(3) g(-1) at 100 kPa, 273 K). Additionally, due to the synergistic effects of the unsaturated coordinated Lewis acidic Cr sites and nucleophilic Br- in the PIL-4@MIL-101 composites, the developed composites exhibited efficient catalytic performance in the CO2 and epichlorohydrin cycloaddition reaction, with 99.6% conversion obtained at 90 degrees C and 1.0 MPa for 2.5 h without an additional cocatalyst or solvent. The composites also showed easy separation and better recycling stability. Combining the advantages of facile synthesis, excellent performance for CO2 adsorption and conversion, good thermal stability and recycling stabilities, the poly(ionic liquid)@MIL-101 composites are appealing candidates for application in CO2 capture and utilization.