Micro- and Mesoporous Carbons Derived from KOH Activations of Polycyanurates with High Adsorptions for CO2 and Iodine

The adsorption ability of porous carbons toward contaminants is closely related to the porous structures and the working functional groups. In this aspect, two porous carbons, with the potential use as adsorbents for CO2 and iodine, were prepared from polycyclotrimerizations (PCTs) of flexible bisphenyl A dicyanate (BPAC) and rigid binaphthalenyl dicyanate (BNC) cyanate ester monomers. Primarily, PCT reactions of BPAC and BNC generated the respective nonporous c-BPAC and c-BNC precursors, which contain high amounts of nitrogen and oxygen heteroatoms. Further KOH activations of c-BPAC and c-BNC produced the respective porous a-BPAC and a-BNC carbons, which mainly contain oxygen heteroatoms. The a-BNC derived from rigid BNC contains both micro- and mesopores and is high in adsorbing both CO2 (6.3 mmol/g) and iodine; in contrast, the microporous a-BPAC is lower in adsorbing CO2 (3.9 mmol/g) and iodine. The effects of molecular flexibility of the starting cyanate ester on the micro- and mesopore distribution as well as the CO2 and iodine adsorption behaviors of the porous carbons are therefore probed in this study.