Highly Nitrogen-Rich Microporous Polyaminals Using N,N-Dimethylformamide and Formamide as the Starting Monomers for CO2 Adsorption and Separation

A series of highly nitrogen-rich microporous polymers are prepared from triazine-based tetraamines (p-BzDAT and m-BzDAT) and hexaamine (TMBDAT) with formamide (MF) and N,N-dimethylformamide (DMF). p-BzDAT and m-BzDAT are isomers with two triazinediamines para- and meta-substituted on a benzene ring, respectively, whereas TMBDAT has three triazinediamines 1,3,5-substituted on trimethylbenzene. The different geometry configurations and functionalities of the starting monomers result in tunable Brunauer–Emmett–Teller areas and pore sizes in the ranges of 842–1227 m2 g–1 and 0.53–3.82 nm, respectively. The synergistic effects of porosity parameters and CO2-philic groups including triazine rings and various amines in the porous polymer networks on CO2 adsorption and separations are systematically studied. Of interest is the observation that the sample derived from DMF and p-BzDAT displays simultaneously high CO2 uptake of 20.3 wt % and a dynamic CO2/N2 separation factor of 127.6 at 1 bar/273 K, which overcomes the adsorption selectivity trade-off dilemma often encountered in the previous studies, showing promising applications in the CO2 sequestration field.