High Gas Uptake and Selectivity in Hyper-Crosslinked Porous Polymers Knitted by Various Nitrogen-Containing Linkers

By introducing various N-containing compounds as efficient linkers, a series of hyper-crosslinked porous polymers with high surface areas and gas-uptake values were synthesized by using the Friedel-Crafts alkylation reaction. Structural characterization indicated the presence of nitrogen atoms, and gas-sorption experiments revealed that the high gas uptake benefitted from the high surface areas and the incorporation of N-containing linkers as Lewis basic sites. Among these porous polymers, HCP-4 had the highest H₂ uptake of 9.29 mmol g^-1 at 77 K and 0.1 MPa and the highest C₂H₂ uptake of 6.69 mmol g^-1 at 273 K and 0.1 MPa, whereas HCP-3 showed the best CO₂ uptake of 4.42 mmol g^-1 at 273 K and 0.1 MPa. To understand better the important role played by nitrogen in these polymers, the isosteric heat of adsorption and adsorption selectivity of CO₂ over N₂ were calculated. The results showed that the triazine-based polymer HCP-1 had the highest CO₂ over N₂ selectivity of 75.4 at 295 K and 0.1 MPa, which makes it the most potential candidate for CO₂ capture.