Benzimidazole-based hyper-cross-linked poly(ionic liquid)s for efficient CO2 capture and conversion

[Display omitted] •Benzimidazole-based hyper-cross-linked poly (ionic liquid)s (HPILs) were developed.•These HPILs had high BET surface area, abundant micro/mesoporosity with polyionic liquid networks.•These HPILs possess a high CO2 uptake with acceptable CO2/N2 selectivity and moderate isosteric heats (Qst).•These HPILs had a high CO2 conversion property under mild conditions (70 ℃, 0.1 MPa CO2 in 9 h). Porous materials with high Brunauer-Emmett-Teller (BET) surface area (SBET) and abundant ionic active sites facilitate efficient CO2 capture and conversion. Herein, a kind of novel benzimidazole-based hyper-cross-linked poly(ionic liquid)s (HPILs) were developed via the hyper-cross-linking strategy and the as-prepared HPILs possessed high SBET (485–780 m2/g), plentiful micro/mesoporosity, and abundant ionic active sites. The HPILs showed noteworthy CO2 uptake (79–143 mg/g at 273 K and 1.0 bar), moderate isosteric heats (32–45 kJ/mol), and acceptable CO2/N2 selectivity (IAST: 23–46). Intriguingly, HPILs-Cl-2 exhibited excellent catalytic activity for CO2 cycloaddition and 99% of propylene oxide was successfully converted to cyclic carbonates under mild conditions (70 °C, 0.1 MPa CO2, 9 h). This synthetic strategy is of great importance for the functionalized hyper-cross-linked polymers and the synthesized HPILs are promising for efficient CO2 capture and conversion under mild conditions.