Functionalized Covalent Triazine Frameworks for Effective CO2 and SO2 Removal.

Building novel frameworks as sorbents remains a highly significant target for key environmental issues such as CO2 or SO2 emissions from coal-fired power plants. Here, we report the construction and tunable pore structure as well as gas adsorption properties of hierarchically porous covalent triazine-based frameworks (CTF-CSUs) functionalized by appended carboxylic acid/sodium carboxylate groups. The densely integrated functionalities on the pore walls bestow strong affinity to the as-made networks toward guest acid gases, in spite of their moderate Brunauer-Emmett-Teller surface areas. With abundant microporosity and integrated carboxylic acid groups, our frameworks deliver strong affinity toward CO2 with considerably high enthalpy (up to 44.6 kJ/mol) at low loadings. Moreover, the sodium carboxylate-anchored framework (termed as CTF-CSU41) shows an exceptionally high uptake of SO2 up to 6.7 mmol g-1 (42.9 wt %) even under a low SO2 partial pressure of 0.15 bar (298 K), representing the highest value for a scrubbing material reported to date. Significantly, such pore engineering could pave the way to broad applications of porous organic polymers.