Ultramicroporous Carbons Derived from Semi-Cycloaliphatic Polyimide with Outstanding Adsorption Properties for H2, CO2, and Organic Vapors

Ultramicroporous carbons (UMC-Ts) have been successfully prepared using nitrogen- and oxygen-rich porous semicycloaliphatic polyimide as a precursor in the presence of KOH at different carbonization temperatures of 600, 700, and 800 °C, respectively. The evolution of porous and chemical structures of the resultant carbons in the course of carbonization as well as their effects on adsorption of H2, CO2, benzene, and cyclohexane are studied in detail. Compared with the porous polyimide precursor, after carbonization treatment, the products exhibit the significantly increased BET specific surface areas from 900 to 2406 m2 g–1 and create large amounts of ultramicropores with the pore size smaller than 0.5 nm, leading to outstanding adsorption capacities for CO2 (34.0 wt %, 273 K/1 bar) and H2 (3.7 wt %, 77 K/1 bar). Moreover, it is interesting to observe that UMC-Ts possess extraordinarily large uptake for benzene (74.4 wt %, 298 K) and cyclohexane (64.8 wt %, 298 K) at the very low relative pressure (P/P0 = 0.1), showing promising applications in CO2 capture, H2 storage, and removal of toxic organic vapors.