A Microporous Organic Copolymer for Selective CO₂ Capture under Humid Conditions

Abstract

A cross-linked microporous organic copolymer, termed KFUPM-2, was synthesized through a Friedel–Crafts alkylation polymerization of phenothiazine, pyrrole, and p-formaldehyde in the presence of iron(III) chloride catalyst. KFUPM-2 was demonstrated to have intrinsic permanent microporosity with a Brunauer–Emmett–Teller surface area of 352 m2 g–1 and a high capacity (39.1 cm3 g–1 at 273 K and 760 Torr) and affinity (Qst = 34 kJ mol–1 and CO2/N2 selectivity of 51) toward CO2 as a result of its nitrogen-rich structure. To demonstrate its practical applicability, breakthrough measurements were performed using a gas mixture that mimicked the composition of an industrial flue gas stream (CO2/N2 = 20/80% v/v with 91% relative humidity). Accordingly, KFUPM-2 was shown to have an ultrahigh CO2 dynamic capacity (32 cm3 g–1 at 298 K) in the presence of water and was demonstrated recyclable over at least 10 cycles with mild regeneration conditions needed between each cycle.