Developing hierarchical porous organic polymers with tunable nitrogen base sites via theoretical calculation-directed monomers selection for efficient capture and catalytic utilization of CO₂

We report herein a calculation-directed strategy to select nitrogen-containing monomers for the construction of nitrogen-doped hierarchical porous organic polymers (H-POPs) through alkylation-induced hypercross-linking of nitrogen-containing monomers. With the assistance of DFT calculations, four nitrogen-containing monomers with relatively strong interactions with CO₂ were identified. The as-designed H-POPs are large in BET surface areas (768 ~ 1177 m²/g) and have abundant hierarchical nanopores. The nature of nitrogen sites in H-POPs is precise and tunable, offering a great opportunity to investigate the criteria that are critical for the selective capture of CO₂. The synthesized H-POPs exhibit extraordinary CO₂ capacities (2.61 mmol/g at 0 °C and 0.15 bar), satisfactory IAST CO₂/N₂ selectivities (79.8 at 25 °C) and superb breakthrough performance for the separation of CO₂ from simulated flue gas. These characteristics are beneficial for the application of H-POPs in the catalytic cycloaddition of CO₂ to cyclic carbonate after metallization.