Tetraphenyladamantane-Based Microporous Polybenzimidazoles for Adsorption of Carbon Dioxide, Hydrogen, and Organic Vapors

Tetraphenyladamantane-based microporous polybenzimidazoles were prepared through condensation polymerizations of 1,3,5,7-tetrakis(4-formyphenyl)adamantane with 3,3′-diaminobenzidine and 1,2,4,5-tetraaminobenzene tetrachloride, respectively, which exhibit large BET surface area up to 1023 m 2 g –1 and narrow pore size distribution with pore size locating at about 0.6 nm. The sorption measurements show that they can uptake 17.3 wt % CO 2 (273 K/1 bar), 1.6 wt % H 2 (77 K/1 bar), 98.0 wt % benzene, and 53.6 wt % cyclohexane (298 K, P / P 0 = 0.95). Moreover, according to the Henry’s law initial slope method and ideal adsorbed solution theory, the resultant polymers possess high CO 2 /N 2 selectivity (71) and CO 2 /CH 4 selectivity (12). The influences of porous structures, that is, porous size and distribution of the polymers, on the adsorption properties of gases and organic vapors are interpreted in terms of the pore-size-exclusive effect as well as variations of physicochemical parameters such as Henry’s constants, first virial coefficients, enthalpies of adsorption, and kinetic diameters, critical temperatures of adsorbates.