Engineering Nanoporous Polyaminal Networks for Superior SO₂ Capture and Selectivity

Designing adsorbent materials with high SO 2 adsorption capacities and selectivity remains a significant challenge in flue gas desulfurization. This work focuses on developing two nitrogen-rich nanoporous polyaminal networks (NPANs), which demonstrate promising capabilities for SO 2 adsorption and separation. Two nitrogen-rich nanoporous polyaminal networks, NPAN-5 and NPAN-6, were synthesized via a one-pot method using thiophene-2,5-dicarbaldehyde and furan-2,5-dicarbaldehyde with 1,4-bis(2,4-diamino-1,3,5-triazine)-benzene, respectively. The Brunauer–Emmett–Teller (BET) specific surface areas of NPANs range from 838 to 956 m 2 ·g –1 . At 298 K and pressures of 0.1 and 1.0 bar, NPAN-5, featuring thiophene units, demonstrates a SO 2 adsorption uptake of 5.14 and 9.63 mmol·g –1, respectively, surpassing many previously reported materials. Furthermore, at room temperature, NPAN-6, containing furan moieties, exhibits unprecedented selectivity for SO 2 over CO 2 and N 2, with ratios reaching up to 78 and 9321, respectively. Dynamic breakthrough experiments reveal that NPANs effectively separate SO 2 from a ternary gas mixture comprising SO 2, CO 2, and N 2 at concentrations of 0.2, 10, and 89.8%, respectively. Notably, NPAN-6 achieves a prolonged SO 2 retention time of 218 min·g –1 and a saturation adsorption uptake of 0.42 mmol·g –1 . The remarkable SO 2 adsorption capacities and selectivities demonstrated by these nitrogen-rich nanoporous polyaminal networks underscore their potential to revolutionize industrial flue gas desulfurization.